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42 Cards in this Set
- Front
- Back
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Recombination
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Exchange of genes between 2 chromosomes by crossing over within regions of significant base sequence homology
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Reassortment
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When viruses with SEGMENTED genomes (i.e. influenza) exchange segments
-high frequency recombination -cause of worldwide flu pandemics |
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Complementation
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when 1 of 2 viruses that infect the cell has a mutation that results in a nonfunctional protein
-the nonmutated virus "complements" the mutated one by making a functional protein that serves BOTH |
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Phenotypic mixing
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occurs with simultaneous infxn of a cell with 2 viruses
-genome of virus A can be partially or completely coated (forming pseudovirion) with the surface proteins of virus B -Type B protein coat determines infectivity; progeny from infxn have a type A coat encoded by its type A genetic material |
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Viral Vaccines: live
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live attenuated: humoral and CMI
MMRV Polio (sabin's oral) Small pox Yellow fever Influenza (nasal) MMR: the only live vaccine that can be given to HIV+ (not in AIDS) |
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Viral Vaccines: killed
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RIP Always
Rabies Influenza Polio (Salk) hepatitis A |
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Recombinant vaccines
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HBV: antigen is recombinant HBsAg
HPV: 6,11, 16,18 |
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ADenovirus
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naked dsDNA virus
febrile pharyngitis: sore throat, acute hemorrhagic cystitis pna conjunctivitis: watery "pink eye" diarrhea |
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Parvo
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5th disease
naked ssDNA B19 virus: aplatic crises in SCA slapped cheeks in children: erythema infectiosum Hydrops fetalis and death (RBC destruction in fetus) PUrse RBC aplasion and rheumatoid arthritis-like sxs in adults -reticular lacy rash on trunk and extremities |
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Polyomavirus
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JC: progressive multifocal leukoencephalopathy in HIV
-see cytoplasmic inclusions in oligodendrocytes |
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Latent herpes viruses
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HSV-1: trigeminal ganglia
HSV-2: sacral ganglia VZV: trigeminal and DRG EBV: B cells CMV: mononuclear cells |
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CMV
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congenital, transfusion, sex, saliva, urine, TRANSPLANT
mono (neg Monospot), pna, esophagitis owl's eye inclusions in infected cells |
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HHV-6
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6th disease: exanthem subitum
Roseola: high fevers for several days that can cause seizures; then diffuse macular rash when fever gone |
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VZV
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chicken pox: resp transmission; will have IgG a.b. 10 yrs later
shingles: can transmit through contact with vesicle |
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HSV
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Tzanck test: smear of opened vesicle to detect multinucleated giant cells
*for HSV-1, 2, VZV infected cells have intranuclear Cowdry A inclusions |
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EBV
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HHV-4
reactive circulating cytotoxic T cells (atypical lymphocytes = Downy cells) assoc with HOdgkin's, Burkitt's, nasopharyngeal carcinoma, thymic carcinoma, oral hairy leukoplakia Monospot: heterophile antibodies detected by agglutination of sheep RBCs can look like strep throat: but if you give amox, will get a rash with EBV |
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Reoviruses
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dsRNA
segmented Coltivirus: Colorado tick fever; flu-like Rotavirus: #1 cause fatal diarrhea in chidlren; winter; day-care *villous destruction with atrophy --> decreased absorption of Na and H2O |
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Picornavirus
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+ssRNA
PERCH: Polio Echo Rhino Coxsacie HAV RNA translated into 1 large PolyPeptide that is cleaved by proteases into functional viral proteins *causes aseptic meningitis (except rhino and HAV) *myocarditis *all are enteroviruses (fecal oral) except rhino Echo: aseptic meningitis, myocarditis Coxsackie: herpangina (febrile pharyngitis), hand, foot, mouth disease, myocarditis Polio: motor neurons of anterior horn |
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Rhinovirus
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nonenveloped RNA virus
common cold **acid labile (destroyed in stomach acid; unlike other picornaviruses) |
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Calicivirus
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NOR-CAL
+ssRNA Norwalk virus: viral gastroenteritis -not just in winter (like rota) |
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Flaviviruses
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+ssRNA
HCV Yellow fever Dengue St Louis encephalitis West nile |
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Yellow fever
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flavivirus
Aedes mosquitos monkey or human reservoir *liver, kidney, tongue (white in center, red on outside) sxs: high fever, black vomitus, jaundice; councilman bodies (acidophilic inclusions) in liver |
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Influenza
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Orthomyxo
enveloped ssRNA with segmented genome Hemagglutinin: promotes viral entry Neuraminidase: promotes progeny virion release **can get fatal bacterial superinfxn bc damages mucociliary clearance (s. pneumo, s. aureus, h flu) Genetic shift: pandemic; reassortment of viral genome Genetic drift: epidemic; minor antigenic change based on random mutation |
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Togavirus
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+ssRNA
Rubella EEE, WEE Rubella causes German 3-day measles fever, postauricular tenderness, LAD, arthralgias, fine truncal rash (head, then down) TORCH infxn: PDA, PS |
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Paramyxoviruses
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PaRaMyxovirus
-ssRNA Parainfluenza: croup RSV: bronchiolitis Measles (Rubeola) Mumps **all contain surface F protein (fusion) which causes resp epith cells to fuse and form multinucleated cells RSV: give ribavirin to tx; Palivizumab px to neutralize F protein |
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Rubeola
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Measles
3C's: cough coryza conjunctivitis Koplik spots (CMI response in endothelial cells of dermal capillaries) SSPE: subacute sclerosing panencephalitis years later, giant cell pneumonia *paint can rash that includes hands and feet (unlike rubella) |
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Mumps
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paramyxovirus
Parotitis Orchitis Meningitis *can cause sterility (esp after puberty) |
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Rabies
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Negri bodies: cytoplasmic inclusions in neurons; often in purkinje cells of cerebellum
BULLET-shaped capsid -weeks-months incubation if exposed: get px vaccination immediately fever, malaise --> agitation photophobia, hydrophobia --> flaccid paralysis, coma death *bats, raccoons, skunks, coyotes **migrates RETROGRADE up nerve axons (to DRG then brain) |
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HBV
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Blood borne
Both acute (adult) and chronic (child) sexual contact, parenteral, preg mom ***cellular RNA polymerase transcribes RNA from DNA template ***Reverse transcriptase transcribes DNA from RNA intermediate ***but the virion enzyme is a DNA-dependent DNA polymerase give newborns with active hepB mom HBIG + active immunity |
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HCV
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+ssRNA flavivirus
Chronic, CIrrhosis, carcinoma, carriers IVDU hypervariable region prone to mutation RNA-dependent-RNA polymerase lacks 3'-5' exonuclease activity production of host a.b. lags behind production of new mutant HCV strains --> no immunity! |
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HDV
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delta agent
requires HbsAg as its envelope can coninfect or superinfect (worse!) |
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HEV
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high mortality in preggers
enteric, epidemics |
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HIV
gp120 |
envelope protein
attachment to host T cell |
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HIV
gp41 |
envelope protein
fusion and entry protein |
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CXCR4 and CCR5
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HIV binds CXCR4 and CD4 on T cells
Binds CCR5 and CD4 on macrophages **homozygous CCR5 mutation = immunity heterozygous: slower course |
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HIV genes
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env: gp120 and gp41
gag: p24 (capsid protein) pol (reverse transcriptase) Reverse transcriptase synthesizes dsDNA from RNA dsDNA integrates into host genome (integrase helps do this) Diploid genome: 2 molecules of RNA |
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AIDS dx
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CD4 <200
or HIV+ with AIDS indicator condition or CD4:CD8 < 1.5 ELISA/Western blot: look for a.b. to viral proteins -often false neg in first 1-2months -often false pos in babies born to infected moms (bc anti-gp120 crosses placenta) |
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Time course
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1. flulike
2. feeling fine (latent) 3. falling count 4. final crisis **during latent phase, virus replicates in lymph nodes |
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Opportunistic Infxns
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<400: thrush, tinea pedis, shingles, reactivation TB, bacterial infxns
<200: PCP, HSV, cryptosporidiosis, isospora, cocci <100: toxo, candida esophagitis, histo <50: MAC, crypto meningitis, CMV retinitis/esophagitis |
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HIV neoplasms
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Kaposi's (HHV8)
Invasive cervical ca (HPV) primary CNS lymphoma NHL (EBV) |
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HIV encephalitis
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late in course, virus gains CNS access via macrophages
*see microglial nodules with multinucleated giant cells |
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Prions
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conversion of normal cellular protein: prion protein (PrPc) from alpha helix to beta-pleated PrPsc, which resists degradation from proteases and facilitates further conversion
***spongiform encephalopathy in gray matter; vacuoles in cytoplasm of neurons and pmns *no inflammation leads to dementia, ataxia, death sporadic: Creutzfeldt-Jakob disease: rapidly progressive inherited: Gerstmann-Straussler-Scheinker syndrome acquired: Kuru |
