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181 Cards in this Set
- Front
- Back
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circoviruses (key features)
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-icosohedral (no envelope)
-small circular ssDNA -dividing cells only -resistant -host specific |
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circoviruses (examples)
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-porcine circovirus (PCV-2): postweaning multisystemic wasting syndrome (PMWS)
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circoviruses (summary)
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-small and simple ssDNA genome
-complex diseases: infects proliferating cells of lymphoid tissue (immunosuppression allows secondary infection) -species specific -emerging disease: porcine circovirus (PCV-2) |
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parvoviruses (key features)
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-icosohedral capsid (no envelope)
-small, linear ssDNA genome -dividing cells only -persists in environment -crosses placenta -diseases of young animals -generally species specific |
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parvoviruses (examples)
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1. feline panleukopaenia virus (FPV)
2. canine parvovirus (CPV) 3. porcine parvovirus (PPV) |
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feline parvovirus (FPV)
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1. panleukopaenia: decreased WBC cound, killing of lymphoid and myeloid cells
2. enteritis: killing of stem cells in crypts 3. cerebellar hypoplasia: infection of germinal epithelum of neonatal kittens (+/- 2 wks) -cause of fading kittens |
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canine parvovirus (CPV-2)
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infection of rapidly dividing cells:
1. enteritis (blunted villi) 2. leukopaenia 3. myocarditis in neonates -maternally derived antibodies can interfere with vaccine |
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porcine parvovirus (PPV)
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-associated with repro problems: manifests as SMEDI (Stillbirth, Mummification, Embryonic Death & Infertility)
-effect depends on stage of gestation: early = resorptions, late = stillbirth -infection by oronasal or venereal route -subclinical in sows -controlled by vaccination |
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parvoviruses (summary)
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1. small linear ssDNA genome
2. requires actively dividing cells + can cross placenta 3. young animals 4. stable in environment: rigorous cleaning after outbreak 5. emerging virus: CPV-2 (-2a,2b,2c - cross species transmission) |
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DNA viruses
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-circoviruses
-parvoviruses -adenoviruses -papillomaviruses -asfarviruses -herpesviruses -poxviruses |
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adenoviruses (key features)
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-icosohedral capsid
-larger dsDNA genome -enocodes own DNA polymerase -multiple antigenic serotypes (many animals) -mostly mild respiratory disease -highly immunogenic |
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adenovirus (importance of capsid)
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-fibre & penton bind to proteins on cell surface: determines tissue infectivity
-can cause haemagglutination: haemagglutination inhibation test (HAI) for diagnosis -hexon is most abundant capsid protein: major target for host immune system |
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adenoviruses (genome)
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-larger
-can inect quiescent cells & "push" them into division -express protein that favors virus replication, transcription, translation over those of host cell -express proteins which impede hosts immune system: allows more time for virus to grow |
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adenoviruses (examples)
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-canine adenoviruses 1 and 2
-equine, ovine, porcine, bovine adenoviruses: respiratory and/or entereic infections -avian adenoviruses |
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canine adenoviruses (CAV 1 and 2)
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-CAV-1: infectious hepatitis; respiratory, renal, and occular disease; systemic disease (puppies)
-CAV-2: respiratory disease -vaccines based in CAV-2 cross protective for CAV-1 + less side effect than CAV-1 based vaccine |
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adenoviruses (summary)
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-larger, more complex genome
-encode factors which allow manipulation of host: stimulating cell division, controlling cell processes, avoiding immune response -fibre binds cell receptors, can cause haemagglutination, and antibodies to it used to discriminate between serotypes -hexon is major target of immune system: immunity is robust and long lasting |
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DNA viruses (replication)
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all replicate in nucleus, except:
1. African swine fever virus 2. poxviruses |
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African swine fever virus
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-large, linear dsDNA: icosohedral capsid & enveloped
-virus particles contain RNA polymerase: transcription begins upon entry -warthogs & bushpigs are natural host (subclinical) -transmitted by soft tick -clinically similar to classical swine fever (pestivirus): grossly enlarged spleen, haemorrhagic skin lesions, rapidly fatal |
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arthropod borne viruses (arboviruses)
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1. biological vectors: replicates within arthropod which acts as resevoir and host
-African swine fever virus -louping ill virus (flavivirus) -equine encephalitis virus 2. mechanical vectors: does not replicate within arthropod (direct transmission) -myxoma virus (myxomatosis) -equine infectious anaemia virus |
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African swine fever virus (summary)
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-spreads to domestic pigs by Ornithodorus spp. ticks, by recycling of pig meat products, or by direct contact through respiratory tract
-inapparent infectoin of wild pigs in Africa but causes a fatal disease in domestic pigs -notifiable in EU -present in Sardinia |
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poxviruses (key features)
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-very large DNA virus (in cytoplasm)
-lesions of skin -produce homologues of host cell products that sabbotage immune system -some zoonotic and can be fatal -used as vectors for deliver of new medicines |
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poxviruses (diseases)
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-orthopoxviruses: cowpox (cats), ectromelia (mice), camel pox, (variola, vaccinia)
-parapoxviruses: orf (sheep), bovine papular stomatitis, paravaccinia (cattle) -capripoxviruses: sheep pox, goat pox, lumpyskin disease (cattle) -suipoxviruses: swine pox -leporipoxviruses: myxomatosis, shope fibroma -avipoxviruses: fowl pox, pigeon pox, canary pox, wild birds |
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poxviruses (mechanisms of immune evasion)
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-many gene products that are homologues of host genes (sabotage immune response)
-target many primary host immune mediators: complement, chemokines, interleukins -enhance viral environement: epidermal growth factor homologe (more cells to infect), vascular endothelial growth factor homologue |
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ectromelia
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-orthopoxvirus
-disease of lab mice -rapidle spreading, acute, fatal |
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orthopoxviruses
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-cowpox (cats)
-ectromelia (mice) -camel pox -(variola, vaccinia) |
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parapoxviruses
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-orf
-bovine papular stomatitis -pseudocowpox *all closely related & potentially zoonotic |
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orf
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-parapoxvirus
-contagious pustular dermatitis -typically affects mouth and nasal planum (also eyelids, feet, teats) -crusty lesions which can bleed -may prevent lambs from suckling -live vaccine (only for affected flock) |
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bovine papular stomatitis
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-parapoxvirus
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pseudocowpox
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-parapoxvirus
-cattle -"horseshoe" scabs -milker's nodules in humans |
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capripoxviruses
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-sheep pox
-goat pox -lumpskin disease (cattle) |
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sheep pox
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-capripoxviruses
-economically most important pox disease -endemic in Africa, Mid East, India -skin lesions -extensive lung lesions -notifiable -genetically similar to goat pox |
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lumpy skin disease
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-capripoxviruses
-high morbidity, low mortality -prolonged recovery affects productivity -insect vector |
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leporipoxviruses
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-myxomatosis
-shope fibroma |
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myxomatosis
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-leporipoxvirus
-flea/mosquito vector -disease of rabbits -skin tumors: proliferation of undifferentiated mesenchymal cells in dermis (become 'myxoma' cells) -swollen head, eyelids, genitalia, purulent cunjunctivitis -cottontail rabbit: only mild disease |
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shope fibroma
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-leporipoxvirus
-North American rabbit disease -benighn, self-limiting 'tumors' -antigenically related to myxoma virus: can be used as vaccine against myxomatosis -used in Australia as biological control of rabbit problem |
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fowlpox
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-lesions on non-feathered areas of ski
-arthropod vector (arbovirus) -proliferation & necrosis of epithelial cells -vaccine widely used |
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poxviruses (key points)
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-very large DNA viruses in cytoplasm
-all produce skin lesions -many important diseases -some zoonotic & can be fatal -homologues of host cell genes as virulence factors -used as vectors for delivery of new vaccines |
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virus detection (methods)
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-electron microscopy
-virus isolation -haemagglutination -detection of viral antigen -detection of viral nucleic acid |
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electron microscopy (advantages & disadvantages)
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advantages:
-usefule when you don't know what you're looking for -useful for confirming ID disadvantages: -specialist equipment and techniques -need alot of virus -virus must be present at time of clinical signs -expensive -time consuming |
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virus isolation (advantages & disadvantages)
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advantages:
-specific diagnosis (gold standard) -more specific typing -allows titration disadvantages: -slow (days to weeks) -requires specialized lab -requires virus to infect cell culture -secondary confirmation often required |
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haemagglutination (viruses)
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-parvoviruses
-adenoviruses -orthomycoviruses (influenza) -paramyxoviruses *non-specific but specificity can be achieved by blocking agglutination with specific anti-viral antibody: haemagglutination inhibition (HAI) |
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bovine papillomavirus (BPV types)
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-fibropapillomas: BPV-1 & 2 (face teats, penis, back
-mixed): teats, udders, skin -papillomas: back, upper GIT, teats, udders |
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papillomavirus proteins
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-E5 (most impt): induction of cell proliferation, evasion of immune system
-E1-E3: replication, transcription |
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bovine papillomavirus (BPV cancers)
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-BPV-2: bovine urinary bladder cancer
-BPV-4: bovine upper GIT cancer -BPV-1: bovine penile cancer and equine sarcoid -HPV-16 (and others): ano-genital cancer -bracken ferm poses risk to GIT (BPV-4) & bladder cancers (BPV-2) |
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pappilomavirus (life cycle)
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-takes place above basal membrane
-linked to cell differentiation -from basal layer outwards |
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bovine papillomavirus (BPV and sarcoids in horses)
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-fibroblastic tumor (BPV-1) on head/ears, limbs, abdomen, sites of trauma/healed wounds
-type: occult (flat), nodular, verrucous (warty), fibroblastic, mixed, malignant -outcome of infection differs btwn horse & cattle: 1. cattle: productive for infectious virus; papillomas eventually regress due to CMI 2. equine: sarcoid non productive for virus; rarely regess |
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papilloma virus (requirements for oncogenesis)
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-persistent infection
-latency -co-factors (extrinsic & intrinsic): bracken fern in cattle, eg. -constitutive expression of early genes: E5 -poor immune response -immune evasion by viral proteins -accumulated genetic changes |
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bovine papilloma virus (E5 role in cancer & immune evasion)
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-in sarcoids & bladder cancers
-inhibits acidification of lysozomes -activates platelet derived growth factor (PDGF) -replicates in epithelium away from immune cells -down regulates MHC-I (retains in cells) |
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bovine papilloma virus (genes involved in GI & urinary bladder cancer in cattle)
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1.Ha-Ras:
-rearranged & overexpressed -mutated 2. telomerase: activated 3. FHIT: down regulated |
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herpesvirus (summary)
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-large, complex (structurally & genetically)
-ubiquitous & highly host adapted -clinical disease mainly in young -disease of respiratory, reproductive, & nervous system (some assoc. with cancer) -latency -unstable in environment (has envelope) -icosahedral, dsDNA |
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herpesvirus (envelope glycoproteins)
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-adsorption & penetration
-cell to cell spread -targets for immune response (virion & infected cell) -interaction w/ immune response (complement & Fc binding) |
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herpesvirus (replication)
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-in nucleus: encodes enzymes for nucleotide metab & genome replication (including DNA polymerase so can replicate in quiescent cells)
-expression is coordinately regulated: immediate early, early & late mRNAs -envelope initially acquired from nuclear membrane -virions released through ER or on cell death |
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herpesvirus (cell-free vs. cell-associated infectivity)
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1. cell-free infectivity: virion enters cell, replicates, releases infectious virus which infects next cell
2. cell-associated infectivity: virion enters cell, infects next cell by direct cell-cell transfer (facilitated by envelope glycoproteins) |
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herpesvirus (latency)
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-persistence of viral genomes (usually extrachromasomal) in slected cells
-no replication but physio changes can reactivate (immune suppression, UV light, stress, etc) -life long infection -can reactivate w/o clinical signs (silent shedders) & transfer to tothers |
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herpesvirus (immune evasion)
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-hides in cells in latent form (unseen by immune sys)
-can spread cell to cell (avoiding humoral immune response) -avoid humoral response (change immunodominant epitopes) -interfere with celllular response (disable peptide presentatino by MHC) -interfere with immune effector function (block apoptosis, mimic cytokines, chemokine & receptors) |
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herpesvirus (classification)
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-alpha: variable host range, short replication cycle, rapid spread, lytic, latent in sensory neurones (eg. feline herpesvirus)
-beta: restricted host range, long replication cycle, slow growth, cytomegalia (giant cells), latent in variety of tissues -gamma: narrow host range, lymphotropic (T or B), non-productive (no particles), transformation of lymphocytes (tumors), latent in lymphoid tissue |
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herpesvirus of vertibrates
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-all domestic spp. (except sheep)
-commonly transmitted by close contact (mucosal tissue) or by aerosol (fomites, aborted foetal tissue) -persistent infection: periodic (reactivation) or continuous virus production -cause immunosuppression (secondary bacterial infection) |
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herpesvirus (feline & canine)
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-FHV: cat 'flu' (respiratory disease with long term damage possible), latent in trigeminal ganglion, kittens esp. susceptible
-CHV: still births, fading puppies (hypothermia favors replication), kennel cough |
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herpesvirus (equine)
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-9 equine herpesviruses
-EHV-1 (alpha): respiratory disease* (most impt), abortion, paralysis, ocular lesions, peracute vasculitis -EHV-4 (alpha): respiratory disease*, (abortion) *equine rhinopneumonitis (notifiable OIE) |
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herpesvirus (bovine)
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-BHV-1 (alpha): infectious bovine rhinotracheitis & bovine pustular vulvovaginitis (notifiable OIE)
-respiratory diesease, genital lesions, abortion, enteritis, ocular lesions, generalized disease in calves -BHV-2 (alpha): bovine mammillitis, pseudo-lumpyskin disease -BHV-5 (alpha): encephalitis |
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herpesvirus (pig)
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-pseudorabies virus (alpha) [Aujeszkys disease): no longer in UK or US (notifiable)
-reproductive failure* (resorptions, abortions, stillbirths,...), neurological disease in piglets -cats, dogs, cattle: dead end hosts (fatal neurological disease) |
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herpesvirus (carp)
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-emerging virus
-notifiable |
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malignant catarrhal fever
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-herpesvirus (gamma)
-wildebeest associated (AHV-1) -sheep associated (OHV-2) -both can be transferred to cattle & pigs |
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herpesvirus (dead end hosts)
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-not natural host
-virus does NOT spread -may be fatal -examples: PRV (swine) infection of dogs & cats, malignant catarrhal fever (wildebeest/sheep) in cattle |
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herpesvirus (cancer)
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-gamma associated
-T or B lymphotropic -non productive infection resulting in cell proliferation -Epstein-Barr virus: transformation of B lymphocytes -Marek's disease: transfers T lymphocytes, cell associated from feather follicles |
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herpesvirus (key points)
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-large dsDNA, enveloped virions
-grouped base on biological properties + sequence relatedness: alpha, beta, gamma -infect all animals (multiple HV per species) -some assoc. with oncogenesis -persists in host by latent infection of particular cell types -infection of dead end host can result in death (PRV, MCF, eg.) |
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herpesvirus (gene therapy vector)
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-neural tropism: delivery of therapeutic agents to CNS
-infect non-dividing cells -large genomes: space for large/multiple therapeutic genes |
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RNA viruses (ssRNA + sense)
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-picorna
-calici -flavi -toga -arteri -corona |
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RNA viruses (ssRNA - sense)
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-orthomyxo
-paramyxo -borna -rhabdo |
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RNA viruses (dsRNA)
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-reo
-birna |
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picornaviruses & caliciviruses
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-small ssRNA (+ve sense)
-icosahedral, NOT enveloped -persistent infections -antigenic variation -immune evasion -in cytoplasm |
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picornaviruses & caliciviruses (replication)
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-in cytoplasm
-pos. sense genome can act as mRNA (genome RNA is infectious) -encode viral polymerase -genome acts as mRNA so viral polymerase transcribed early |
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picornaviruses (viruses)
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CHEAT (mnemonic):
1. Cardiovirus (encephalomyocarditis) 2. Hepatovirus (avian encephalomyelitis) 3*. Enterovirus (swine vesicular disease, porcine enterovirus) 4*. Apthovirus (foot and mouth disease) 5*. Teschovirus (porcine teschovirus) -unclassified: turkey, duck hepatitus viruses |
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picornaviruses (key facts)
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-PicoRNA: small +ve sense RNA
-restricted host ranges -resistant (no envelope) -transmission faecal-oral (fomites, aerosol) -antigenic variation -differentially sensitive to pH (FMD sesitive to low pH) -persistent infection (FMD, SVD): carrier animals -diagnosis by ELISA (Ag detection) or virus isolation |
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picornaviruses (porcine)
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1. swine vesicular disease (human enterovirus subgroup): FMD like lesions (notifiable); transmit via abrasions on feet, sometimes oral lesions, faeces, fomites, ingestion
2. SMEDI (Stillbirths, Mummification, Embryonic Death, Infertility): oral-faecal transmission + transplacental 3. teschovirus: porcine viral encephalomyelitis (Talfan/Teschen disease), infection of motor nerves, fever, tremors, paralysis, death (up to 90% mortality), notifiable |
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foot and mouth disease
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-apthovirus (picornavirus)
-cloven hoofed animals (cattle, pigs, sheep) -fever, aoral/feet/teat lesions -low mortality but high morbidity (high economic impact) -dairy: reduced milk yield -beef: reduced growth -pigs shed most virus -clinical picture: cattle & pigs worst -cattle most sensitive to infection -carriers (persist in pharynx): cattle & sheep -virus shed before clinical signs (short incubation): control difficult |
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picornaviruses (key points)
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-small, simple RNA viruses
-associated with vesicular disease & encephalomyelitis -rapid replication & high virus output -FMD one of most contagious viruses known -notifiable: SVD, FMD, Teschen |
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caliciviruses
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-star of david appearance
-single capsid protein -vesivirus: feline* and canine calicivirus, vesicular exanthema of swine (extinct) -lagovirus: rabbit haemorrhagic disease virus -porcine & bovine caliciviruses -exist in marine species (ocean resevoir) |
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calicivirus (feline)
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-respiratory virus (cat 'flu')
-chronic stomatitis -nasal/ocular discharge (rhinitis/conjunctivitis, oral lesions, fever, lameness) -major feline pathogen: can be fatal in kittens -recovery assoc. with carrier state (clinically healthy cats shed from tonsils & proximal mucosa) |
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feline calicivirus (FCV) vs. feline herpesvirus (FHV)
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-both assoc. with persistence
-both major viral causes of upper resp. cat 'flu' (note: NOT orthomyxovirus influenza virus) -both URT & mouth ulcers -FCV: chronic, productive infection -FHV: periodic virus shedding (due to reactivation of latent virus) |
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feline calacivirus (persistence)
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-persists through antigenic variation in response to immune selection
-over time virus becomes more homogenous & more vulnerable to attack by immune sys -favors production of mutants |
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rabbit haemorrhagic disease virus
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-calicivirus
-necrotic hepatitis: death in 2 days (95% mortality) -faecal-oral transmission (inhalation, insects) -used for rabbit control in Australia |
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caliciviruses (key points)
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-typically associated with respiratory, vesicular, haemirrhagic disease, gastroenteritis
-typically do not grow in culture (FCV is exception) -FCV persists as quasispecies (mutants) -emerging diseases: RHDV, potential transmission from resevoir species in ocean -RHDV as biocontrol agent in Australia |
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birna- and reoviruses
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-dsRNA linear segmented
-ea. segment encodes for 1 or more proteins that can mutate through reassortment -NOT enveloped (stable) -replicate in cytoplasm -virion size: birna = 60, reo = 80 |
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birnaviridae
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-Bi RNA = 2 segment RNA genome
-aquabirnavirus: infection pancreatic necrosis (PIN) in fish -avibirnavirus: infectious bursal disease in chickens |
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infectious pancreatic necrosis (PIN)
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-aquabirnavirus
-young salmon & trout -high mortality: gut haemorrhage, pancreatic necrosis -major threat to salmon farming industry |
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infectious bursal disease of chicks (Gumboro disease)
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-avibirnavirus
-3 to 6 week old chicks -kills immature B lymphocytes in bursa of fabricus -kills T lymphocytes in thymus -causes Severe Combined ImmunoDeficiency (SCID) -recovered chicks immunosuppressed -vaccination of breeders, chicks |
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reoviridae
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-Respiratory Enteric Orphan (REO) virus
-rotavirus -orbivirus -capsid layered: inner & outer |
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rotavirus
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-reovirus (latin: wheel)
-major cause of diahrrhea (scours) in very young calves & pigs -infection of enterocytes at TIPS of villi in SI (c.f. parvo in crypts & corona on sides of villi) -faecal-oral transmission (waterborne) -vaccines available for dam (boost colostral Ab) |
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rota- vs. corona- vs. parvovirus(infection of enterocytes)
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-rotavirus: tips of the villi
-coronavirus: side of the villi -parvovirus: crypts of villi |
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orbivirus
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-reovirus (latin: ring)
-bluetongue -African horse sickness -arthropod transmitted: replicate in vector |
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bluetongue
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-orbivirus (reovirus)
-antigenically diverse (vaccination implications) -disease of sheep (+deer) -cattle important resevoir (subclinical) -midge vector (culicoides spp.) fever, changes to mucus linings of mouth, nose (cyanosis of tongue), coronary band: reproductive disorder, vascular disease -notifiable |
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African horse sickness
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-orbivirus (reovirus)
->75% mortality -cardiac/respiratory disease: death in 1 wk -midge vector -notifiable |
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birna- & reo- viruses (key points)
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-segmented dsRNA viruses (can mutate by reassortment)
-reoviruses: multiple capsids -birnaviruses: IPN, IBD -rotaviruses (reo-): important cause of diahrrea -orbivirus (reo-): arthropod borne (midge) |
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themes (picorna-, calici-, reo- viruses)
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-persistent infections: picorna, calici
-antigenic variation: picorna, calici -immune evasion: calici -athropod transmitted: reo |
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flavi- & togaviruses
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-pos. sense linear RNA: genome acts as mRNA
-replicates in cytoplasm -icosahedral, enveloped (sensitive) -envelope acquired from cytoplasmic membranes -virions size: flavi = 40, toga = 60 |
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flaviviridae
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-flaviviruses
-pestiviruses |
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flaviviruses
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-transmitted by mosquitos or ticks (virus grows in vector)
-louping ill (hard ticks) -west nile virus (mosquitos) -potential zoonosis through vector -assoc. with encephalitis |
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louping will virus
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-flavivirus
-transmitted by sheep tick (ixodes ricinus: hard tick) -neurological disease in sheep, red grouse, cattle, horses, man (dead end hosts) -grows in tick gut & salivary glands, feeds 2x/yr (spring/autumn) |
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pestiviruses
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-flaviviridae (but not flavivirus)
-bovine: BVD/mucosal disease (BVDV) -ovine: border disease (BDV) -swine: hog cholera (aka classical swine fever: CSFV) -antigenically releated & infective across species -transplacental transmission -peristent infections -generally noncytopathic in vitro -potential vaccine contaminants |
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border disease virus
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-pestivirus
-disease of lambs but also pigs (not cattle) -transplacental transmission: foetal neurological damage -'hairy shakers' (also caused by BVDV in 15% of cases in UK) |
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classical swine fever (hog cholera)
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-pestivirus
-natural host: wild boar -oronasal transmission (ingestion) -high morbidity & mortality -infects cattle, sheep subclinically -discoloration of skin |
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bovine viral diarrhea virus (BVDV)
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-pestivirus
-diahrrea -repro effects: decreased fertility, abortion, congenital defects, stunted calves -immunosuppression -sheep & pigs also -transplacental transmission -2 biotypes: 1. noncytopathic (NCP): major cause of BVD 2. noncytopathic & cytopathic involved in mucosal disease (MD) |
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bovine viral diahrrhea virus (BVDV biotypes)
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1. noncytopathic (NCP): major cause of BVD
2. cytopathic (CP) -NCP & CP involved in mucosal disease (MD) |
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bovine viral diahrrhea virus (BVDV & persistent infections)
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-cow infected with noncytopathic (NCP) BVD in 1st - 4th month of gestation
-calf immunotolerant: virus circulating at high levels but BVDV recognized as self -calf is resevoir in herd -only NCP biotype involved in persistent infections |
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bovine viral diarrhea virus (outcome of BVDV infection early in gestation)
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-abortions, stillbirths
-stunted -normal (resevoir of virus) |
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bovine viral diarrhea virus (mucosal disease: MD)
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-only in persistently infected animals (sporadic)
-affected animals have both noncytopathic (NCP: acquired from inection in utero) AND cytopathic (CP) BVDV -acute and chronic forms |
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bovine viral diarrhea virus (mechanism for induction of mucosal disease)
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1. persistently infected animal (NCP in utero)
2. mutation of NCP to CP variant 3. antigenicity of NCP = CP: so animal is immunotolerant to CP (immune sys can't taget so acute?) 4. can get recombination of NCP with antigenically related CP: new cytopathic variant (delayed onset of acute mucosal disease) if antigenically distinct CP: immune sys can target so outcome variable |
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pesitivirus (vaccine contamination)
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-most pestiviruses are noncytopathic: contamination may not be apparent
-live vaccines are not inactivated and may harbour pestivirus contaminants which will replicate in vaccinated animals -now screened using RT-PCR |
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flaviviruses (key points)
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-neurological disease in natural and accidental hosts
-transmitted by tick/mosquito vectors -louping ill (sheep), west nile virus (birds) |
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pestiviruses (key points)
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-infect cross species
-tranaplacental transmission -abortion/foetal defects -noncytopathic (NCP) pestiviruses persist in foetuses infected prior to development of immune system (resevoir) -exosure of persistently infected animals to cytopathic (CP) antigenically related to persistent NCP strain: mucosal disease (MD) -NCP viruses are potential vaccine contaminants |
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togaviridae
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-alphaviruses
1. eastern equine encephalitis (avian resevoir) 2. western equine encephalitis (avian resevoir) 3. venezuelan equine encephalitis (small mammal resevoir) -transmitted by mosquito -domestics & man are incidental (dead end) hosts: zoonotic |
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equine encephalitis viruses
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-togaviruses
-mosquito vector: incidence correlates to mosquito #s (peak in late summer) -fever, encephalomyelitis -eastern equine encephalitis (EEE) has highest mortality (90%) compared with Venezuelan (50%) and western (20%) -North/South America (notifiable in UK) |
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flavi-, toga- viruses (themes)
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-arthropod vectors: flavi, toga
-emerging disease: west nile in horse, man -pathogenic variants generated in situ: BVDV -zoonotic: west nile, encephalitis viruses -persistent infection: BVDV |
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coronaviruses (common features)
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-respiratory, enteric, & neurologic pathogens
-highly contagious -mutate frequently -helical w/ pos. sense ssRNA (genome can act as mRNA) |
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nidovirales
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-coronaviruses
-arteriviruses -nido = 'nest': nested sets of mRNAs encode viral protein complement |
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coronaviruses
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-coRoNA
-linear +sense ssRNA, enveloped (not resistant) |
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coronaviruses (common)
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-PIG: TGEV (intestine), PRCV (respiratory), HEV (respiratory/CNS), EDV (intestine)
-CHICK: IBV (respiratory/urogenital) -DOG: CCoV (intestine), CRCoV (respiratory) -CAT: FCoV (intestine/?macrophages) -MAN (all respiratory): HCV 229E, HCV 0C43, SARS |
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coronaviruses (canine)
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-canine enteric CoV (CCoV): types I & II [group 1]
-canine respiratory CoV (CRoV) [group 2] - |
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coronaviruses (porcine)
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-TGEV: transmissable gastroenteric virus
-PRCV: porcine respiratory coronavirus (evolved from TGEV - less pathogenic) -HEV: haemagglutinating encephalomyelitis (respiratory/CNS) -EDV: porcine epidemic diarrhea virus |
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coronavirus (feline)
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-biotypes:
1. FECV (FCoV): feline enteric coronavirus 2. FIPV: feline infectious peritonitis virus (acute = effusive, wet form; chronic = non-effusive, dry form) -spread by contact w/ faeces or litter -15% become lifelong carriers (shed), 70% get transient infections |
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feline infectious peritonitis (FIP): pathogenesis
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1. FCoV changes to FIPV (reason not understood)
2. replication in macrophages 3. immune complex formation in blood vessels 4. immune mediated vasculitis 5. wet (leakage of fluid from BVs) or dry form |
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feline infectious peritonitis (FIP): types
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-Type I FCoV: purely feline, most prevalent, possible cell-associated
-Type II FCoV: arise from recombination of type I & CCV, less common in field |
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coronaviruses (mutation)
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-mutate/recombine easily giving rise to different biotypes
-TGEV --> PRCV -FCoV/FECV --> FIPV ??? |
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aminopeptidase-N
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enzyme highly expressed at brush borders of:
-respiratory epithelium -gut epithelium -nerve cells |
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coronaviruses (control)
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-vaccination: IBV, CCoV (but RNA viruses mutate)
-quarantine: SARS, TGEV, FCoV (antibody testing and isolate) -hygiene: SARS/FCoV |
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SARS
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-coronavirus
-severe acute respiratory syndrome -possibly from palm civet (from bat?) |
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arteriviridae
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1. arterivirus
2. equine arteritus virus 3. porcine reproductive respiratory syndrom (PRRS) -host specific -grow in macrophages & endothelial cells (tissue specific tropism) -transmitted respiratory, venereal route, placental (abortion) |
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equine arteritis virus
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-arteriviridae
-transmitted: respiratory, venereal route (including AI) -infected stallions asymptomatic carriers -mares infected at mating (80%) do not become carriers -replicates in endothelial cells -fever, conjunctivitis, respiratory disease -clinical disease in adult mares is rare -infection uterine tissues/transplacental: abortion -control: vaccine -diagnosed: detect by virus neutralizing antibodies/isolation |
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coronaviruses (summary)
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-large ssRNA enveloped virus
-in cats, dogs, pigs, poultry (man) -respiratory, enteric, neurologic -recombine to form new variants -emerging viruses: SARS, CCoV, PRCV |
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porcine reproductive & respiratory syndrome (PRRS)
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-transmitted by close contact (respiratory), transplacental, airborne
-abortion in naive sows -mainly respiratory disease in piglets -infects macrophages: immunosuppression (secondary infections) -can persist months in carrier -emergine disease |
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arteriviruses (summary)
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-equine (equine arteritis virus)& porcine (PRRS)
-notifiable diseases -carrier animals shed virus |
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paramyxoviridae (structure)
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-non segmented, -ve sense ssRNA (100-600nm)
-helical, enveloped (all helical are enveloped -haemagglutinin (H) -nuraminidase (N) |
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paramyxovirises (ID)
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1. virus isolation:
-cytopathic effect -formation of syncitia (multi-nucleate cells) 2. electron microscopy: -cytoplasmic & intranuclear inclusion bodies (herpes & endenovirus only intranuclear, rabies cyto only) |
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paramyxoviruses (viruses)
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-morbillivirus: canine distemper, rinderpest, peste des petits, measles (man)
-respirovirus: parainfluenza virus type 3 -rubulavirus: parainfluenza type 2, mumps (man) -avulavirus: New Castle disease -henipavirus: nipah, hendra virus -pneumovirus: respiratory syncytial viruses -metapneumovirus: turkey rhinotracheitis virus |
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paramyxoviruses (pathogenesis)
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-epitheliotropic & neurotropic (wide range of infected tissues)
-replicate in cytoplasm (inclusion bodies in nu & cyto) -respiratory disease -neurological disease -alimentary tract disease -lymphoid tissue in the case of canine distemper |
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paramyxoviruses (immunity)
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-effective immune response in most animals: antibodies are neutralizing, vaccination is protective
-some establish persistent infections (evade immune system) |
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morbilliviruses
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-family: paramyxovirinae
-measles virus (man) -canine distemper virus -peste des petits ruminants |
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canine distemper virus
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-morbillivirus (paramyxovirinae)
-acute: encephalitis, pneumonia, rhinotracheitis, conjunctivitis, gastroenteritis -chronic: "old dog" encephalitis, "hardpad" (in epidermis) -canidae (dog, fox, wolf, etc) & mustelidae (mink, ferret, otter, badger, etc), procyonidae (racoon, panda), felidae (lion, leopard, possibly cat & tiger) |
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canine distemper (histopathology)
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-inclusion bodies (eosinophilic): intranuclear & cytoplasmic
-formation of syncytia (multinucleate cells): macrophages, epithelial cells (lungs, lymph nodes) |
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canine distemper (pathogenesis)
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-morbillivirus (paramyxovirinae)
-replication in lymph nodes (7-10d) -to tonsils, lymph nodes, spleen, bone marrow -to lungs: replication in alveolar macrophages -immune suppression: seconary bacterial infection of URT |
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canine distemper (epithelial tissue)
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-morbillivirus (paramyxovirinae)
-respiratory tract: rhinotracheitis; pneumonia -alimentary tract: gastroenteritis -conjunctivitis -gall bladder, liver, pancreas -urinary bladder, kidney |
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canine distemper (nervous tissue)
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-morbillivirus (paramyxovirinae)
-brain: neuro degeneration, demyelination, nonsuppurative encephalomyelitis, lymphocytic cuffs around BVs (& plasma cells) -persistence in CNS: reactivation (cell to cell spread) & immune response ("old dog encephalitis") |
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canine distemper (skin)
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-morbillivirus (paramyxovirinae)
-footpads: hyperkaratosis ("hardpad") |
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canine distemper (diagnosis)
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-morbillivirus (paramyxovirinae)
-virus isolation -serology: virus neutrilization test -histopath (post-mortem) -PCR |
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rinderpest virus
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-morbillivirus (paramyxovirinae)
-cattle plague -respiratory & alimentary tract disease (not neurones) -high fever, nasal & ocular discharge, xs frothy salivation, oral & nasal erosions/ulcerations, constipation followed by diarrhea, death -necrosis & haemorrhage of ruminal mucos, haemorrgic enteritis w/ erosion of peyer's patches (taken up by M cells) -direct contact: faecal contamination of water, respiratory aerosis, movement -also wild ungulates & pigs |
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peste des petits ruminants (PPR)
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-morbillivirus (paramyxovirinae)
-acute to subacute contagious viral diseas of goats & sheep-stomatitis-pneumoenteritis (pseudo-rinderpest) -related to rinderpest: similar pathology & epidemiology -erosive stomatitis, conjuctivitis, diarrhea, pneumonia -ocular, nasal & oral mucopurulent discharge, ulcers & necrotic plaques on oral mucosa (no vesicles) |
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measles
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-morbillivirus (paramyxovirinae)
-humans -fever, rash -conjunctivitis -pneumonia -encephalitis -otitis media |
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rubulaviruses
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-family: paramyxovirinae
-mumps virus (man) -parainfluenza viruse type 2 -la piedad michoacan virus -menangle virus -tioman virus |
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parainfluenza virus type 2 (CPiV)
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-rubulavirus (paramyxovirinae)
-a cause of kennel cough (infectious tracheobronchitis) -other causes of kennel cough: bordatella bronchiseptica, canine adenovirus type 2 |
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henipaviruses
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-family: paramyxoviridae
-nipah virus*: pigs & humans (outbreaks in Malaysia & Singapore) -tioman virus -hendra virus |
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avulavirus
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-family: parmyxoviridae
-formerly part of rubulaviruses -Newcastle disease virus: domestic fowl, turkeys, pheasant, ducks, geese |
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Newcastle disease virus
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-avulavirus (paramoxyviridae)
-tissue tropism: 1. neurotropic form: encephalitis (faecal-oral) 2. respiratory form: pneumonia (inhalation) 3. viscerotropic form: systemic disease |
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respiroviruses
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-family: paramyxovirinae
-parainfluenza virus type 3: respiratory disease in humans, calves & lambs |
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pneumoviruses
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-family: paramyxovirinae
-respiratory syncytial viruses: acute viral respiratory disease in young childern & housed claves |
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metapneumoviruses
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-family: parmamyxoviridae
-turkey rhinotracheitis virus: acute respiratory disease & orbital sinusitis ("swollen head syndrome") in turkey poults & now spread to chickens -emerging disease -also: human metapneumovirus |
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rhabdoviridae
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1. lyssavirus: rabies & rabies-related viruses (mammals)
2. vesiculovirus: -vesicular stomatitis virus (ruminants, pigs, horses) -spring viraemia of carp (fish) -pike fry rhabdovirus (fish) 3. ephemerovirus: ephemeral fever virus (cattle - midge vector) 4. novirhabdovirus: -infectious haematopoeietic necrosis virus (fish) -viral haemorrhagic septicaemia virus (fish) -snakehead rhabdovirus (fish) |
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rabies virus
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-lyssavirus (family: rhabdoviridae)
-bullet shaped, enveloped, 380nm x 95nm -helical, -ve sense RNA -no haemagglutinin or neuraminidase |
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rabies virus (biotypes of genotype 1: classical rabies)
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-lyssavirus (rhabdoviridae)
-fox: main resevoir in western europe -dog: mid east, africa, e. europe (urban or street rabies) -bat: N. & S. America (transmitted to cattle & humans) -raccoon: N. America -skunk: N. America |
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rabies virus (pathogenesis)
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-lyssavirus (rhabdoviridae)
1. bite wound (infected saliva) 2. entry to sensory nerve (ACh receptor) 3. entry to spinal cord (retrograde axonal transport) 4. replication in brain 5. passage in cranial nerve to salivary gland 6. behavioral changes: makes more likely to bite another animal (more aggression or less fear) 7. death from damage to respiratory center: fatal if reaches CNS (vaccination blocks transmission) |
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rabies virus (clinical signs)
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-lyssavirus (rhabdoviridae)
1. furious form (dogs, occasionally cats): -restlessness, anxiety -loss of fear of humans -aggression, biting -hyperaesthesia -"hydrophobia" 2. dumb form (cattle, sheep, horses, dogs, cats): -depression -paralysis -may progress from dumb furious form or develop dumb from start |
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rabies virus (diagnosis)
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-lyssavirus (rhabdoviridae)
1. saliva: -PCR -virus isolation 2. serology -fluorescent antibody virus neutralization (FAVN) -ELISA |
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rabies virus (control)
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-lyssavirus (rhabdoviridae)
-quarantine -control of strays -vaccination of dogs & cats -PETS -control in wildlife (eg. vaccine baits) |
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orthomyxovirus (structure)
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-segmented, enveloped, helical
-replicates in nucleus -2 envelope glycoproteins: haemagglutinin & neuraminidase (key targes of humoral immune response) -antigenic drift/shift: interspecies transmission with pandemic potential -antiviruals used against human influenza: block budding (eg. Tamiflu) -myxo = mucus |
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orthomyxoviruses of vet significance
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1. influenza A (equine i., swine i., human i., fowl plague)
2. isavirus (fish): infectious salmon anaemia (emerging disease) |
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influenza A viruses (resevoir)
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-orthomyxovirus
-wild aquatic birds (alimentary tract) -infection largely asymptomatic -transmitted by faecal-oral route (waterborne) -all H (16 H types) & N (9 N types) |
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influenza A (key points)
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-infection usually restricted to respiratory tract
-transmitted by aerosol -16 H (haemagglutinin) & 9 N (nueraminidase) types: few types infect species other than birds |
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influenza A (antigentic shift/drift)
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-drift: spontaneous mutations in surface antigents --> selection of variants in a partially immune population
-shift: major change in surface antigenicity assoc. with reassortment or recombination (swapping H's or N's between human & bird strains of influenza) |
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influenza A (transmission)
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-pig can be infected by human & non-human strains: 'mixing vessel'
-can get direct transmission from birds to man or horse |
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influenza A (canine)
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-emerging disease
-new strain from genetic shift in equine flu (H3N8): dog new host |
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orthomyxoviruses (key points)
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-influenza A viruses
-proteolytic cleave of HA critical for pathogenicity -cross species transfer -antigenic shift & drift (pandemic/panzootics) -control: vaccination, surveillance, eradication of infected birds |
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highly pathogenica avian influenza (HPAI or fowl plague)
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-pathogenic H5 & H7 strains of avian influenza virus
-turkey & chickens: mortality up to 100% -pathogenicity assoc. with cleave of HA -economic impact on poultry business & potential for zoonosis |
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influenza A virus (emergence of zoonotic virus from wildlife resevoir)
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1. interspecies contact
2. cross-species virus transmission 3. sustained transmission 4. virus adaptation to new species |
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influenza A virus (human pandemics)
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1. virus of different antigenic type circulating in another species: able to replicate & cause disease
-from pigs infected w/ human/animal/avian reassortments -adaptation of avian virus in pigs (or in man) -direct (eg. birds to man) 2. adaptation, drift, shift in new host Pandemic: must transmit efficiently in new host -currently little circulating H5: little immunity |
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influenza A virus (steps in pandemic)
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1. emergence of new strain
2. infection of, and disease in, humans 3. efficient transmission human to human |
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bornavirus
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-bornaviridae (from order mononegavirales: also paramxyoviridae & rhabdoviridae)
-enveloped, -ve sense ssRNA -neurological disease (potentially fatal) in horses (sheep, cattle, cats): infects neurones -behavioral changes, paralysis, blindness -noncytolytic: (T cell) immune mediate damage (doesn't kill neurone but affect immune sys response) -replicates in nucleus (paramyxo, rhabodo replicate in cytoplasm) -zoonosis?: human psychiatric disorders |
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transmissible spongiform encephalopathis (classification)
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-sheep/goat: scrapie
-mink: trasmissible mink encephalopathy (TME) -mule deer/elk: chronic wasting disease (CWD) -cattle: bovine spongiform encephalopathy (BSE) -mna: kuru, Creutzfield-Jakob disease (CJDO, Gerstmann-Straussler-Sheinker disease (GSS), fatal familial insomnia (FFI) |
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transmissible spongiform encephalopathis (clinical signs)
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-pruritis: "nibble relex" (scrapie)
-behavioral changes: nervousness/excitability, aggression -ataxia/changes in gait -weight loss (normal appetite) -disturbances in body homeostasis -excessive salivation (CWD) -other (less comon): defective vision, fits, etc. |
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transmissible spongiform encephalopathis (prion hypothesis)
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-PRION = PRoteinaceous Infectious particle
-protease resistant protein (PrP = prion protein) co-purifies infectivity -gene encoding PrP part of host chromosome |
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transmissible spongiform encephalopathis (neuropathology)
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-neuronal vacuolation - usually confined to grey matter: spinal cord, brainstem, midbrain, cerebellum (scrapie & BSE)
-neuronal degeneration & loss by apoptosis -astrocytic hypertrophy/hyperplasia & microglial activiation -amyloid plaques -no overt inflammatory response |
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transmissible spongiform encephalopathis (mode of infection)
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-predominantly oral route of transmission
-scrapie (& other TSEs) replicate in lymphoid tissue: 1st signs detected in GALT -minimal pathology assoc. with lymphoid infection -no immune response (tolerance) -immunodeficient animals relatively resistant |
