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53 Cards in this Set
- Front
- Back
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Herpesviridae means what in Greek
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to creep or crawl
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what is herpes distribution and who does it infect
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WW w >100viruses known
infects vertebrates, mammals and birds |
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what are two types of herpes infections
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lytic - acute
latent with potential for reactivation (time for reactivation varies with virus) |
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Are herpes viruses high or low mortality
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low xcept immunocompromised and cancer inducing
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Describe Herpes Viruses
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ds DNA, linear but circularizes on infection.
large icosahedral nucleocapsid enveloped nucleocapsid surrounded by tegument(can vary within single virion) encodes large number of proteins (>70) mRNA transcribed by host RNA polymerase |
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What are herpes subfamilies
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alphaherpes - simplex 1 and 2
varicella HHV 3 - zoster(hzv) Betaherpes - cytomegalo HH5 Roseolovirus HHV6 & HHV7 Gammaherpes - Lymphocrypto-HHV4 - EBV Rhabino - HHV-8 |
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Which HHV transmit via contact
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HHV-1 cold sores
HHV-2 genital ulcers HHV-4 EBV -mono, burkett's lymphoma, hodgkins HHV-6 Exanthum subitum(6th dz) |
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Which HHV transmit via saliva
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HHV-4 EBV - mono, hodgkins and burkett's lymphoma
HHV-5 CMV -organ infections and neonate & immunocompromised HHV-6 Exanthum subitum (6th ds) HHV-7 UNKNOWN DZ |
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Which HHV transmits via urogenital secretions
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HHV-5 CMV
HHV-7 UNKNOWN DZ |
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What does HHV-8 cause
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KAPOSI'S SARCOMA
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Describe alphaherpes characteristics
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often broad host range
short reproductive cycle rapid spread, many cell types, destructive latency in sensory ganglia HSV 1 AND 2, HZV |
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Describe betaherpes characteristic
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restricted host range
long reproductive cycle slow spread, enlarge cells form latency in secretory, RES, kidneys,etc. CMV, HHV6, HHV7 |
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Describe gammaherpes characteristics
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narrow host range
relatively long repro cycle primarily lymphoblastoid, lysis of epithelial and fibroblastic cells Latency in b or t cells HHV 8, EBV |
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primary HSV infection
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direct contact-active lesion or asymptomatic shedding
LYTIC infection of mucosal and epithelial cells(inhibit host macromolecular synthesis) VESICLES - HSV1: kissing or saliva, facial/oral mucosa, 50-90% world population + HSV-2: sex, genitalia, 10% world pop infected HSV to children often asymptomatic |
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ARE HERPES PAINFUL
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YES
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HSV LATENCY
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HSV1 - TRIGEMINAL GANGLIA
HSV2-Sciatic ganglia Residence as CIRCULAR EPISOMES(neurons are probably non-permissive for lytic replication) LAG - latency assoc transcript(only 1 viral transcript in latency infected neurons) |
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Do Herpes virus produce proteins and if so, what is purpose
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yes, they interfere with host defenses
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What does 'neurons immunologically privileged'mean?
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'blood brain barrier' for example. viruses can cross (unlike most bacteria) but immune system can't clean them up there. Neurons are also protected.
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What causes reactivation of HSV
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Stressful stimuli(fever, sunlight, menses, emotional stress)
varies from month to yearly travel down neuron to infect epithelial cells come back to tissue originally infected heals in 2 weeks |
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what are severe forms of HSV
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immunocompromised
neonates (often with encephalitis) in utero or peri-natal almost always symptomatic post-neonatal period encephalitis(usually fatal if untxed) keratoconjunctivitis herpes whitlow - DDS |
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Antiviral tx for HSV
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Acyclovir/Valacyclovir/famvir
guanine analogues inc into replicating DNA and terminate chain. Effective HSV1, 2, 3 (VZV) NON-TOXIC |
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HH3 Varicella zoster virus
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closely related to HSV
Lytic inf of epidermal cells(skin layer) Latent inf of ganglia highly contagious CHICKEN POX/SHINGLES |
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EPIDEMIOLOGY OF VZV
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WW
Universal infection in temperate peaks in winter/spring pre-95 4 million cases 100 deaths ~50% tropical population |
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Describe incubation
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10-21 days
upper respiratory respiratory route spread disseminate thru blood |
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describe symptoms
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itchy vesicular rash, self limited in <1 week, low mortality(1%)
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what do chicken pox classically look like
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'dew drop on rose petal' initially
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COMPLICATIONS OF CHX POX
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more often seen in adults
Common - bacterial superinfection of skin Rare - viral pneumonia, CNS involvement(enceph, ataxia), hepatitis or other organ involvement |
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VZV VACCINE - VARIVAX
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live attenuated
1995 developed for kids chemotherapy variable use significant protection 70-90% may increase zoster incidence????? |
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Describe Zoster - shingles
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v painful on trunk to midline (does not cross)
upper back self-limiting 1-3 weeks post - herpetic neuralgia (pain in the rash) month-years recurrect zoster is rare |
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Can u get zoster on the face
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yes, if in trigeminal nerve
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ZOSTER PATHOGENESIS
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infectinon in childhood (chxpox)
then LATENT VZV in dorsal root ganglia of spinal cord then REACTIVATION in elderly or immunocomp then PAINFUL ERUPTION OF VESICULAR LESION |
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Who's at risk for Zoster
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elderly
AIDS leukemia chemo Increased risk for mom and baby if primary during pregnancy |
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ZOSTAVAX - zoster vax
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2006
large dose of VARIVAX single, safe dose >60 years reduces shingle 51% and post-herpetic neuralgia 67% Effective even if prior episode contraindicate in immunosup and pregnant |
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HHV4 EBV
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named after epstein barr
oral secretions transmission latent in B lymphocytes(episome) most infected by 3 years ! inf - infant, asymptomatic young adult - mono LONG TERM CARCINOGENIC POTENTIAL Not a sole cause of chronic fatigue |
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EPV PATHOGENESIS
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oral mucosa infection and replica
B lympho infected and stimulated to proliferate (life long latent inf) T cells stimulated to control B cells - Infectious Mono Continuous intermittent seeding or orpharyngeal epi by B cells. low grade lytic infection shedding in saliva, may decline in time |
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infectious mononucleosis
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KISSING DISEASE
fatigue fever rash swelling of lymph nodes/spleen/liver PROLONGED CONVALESCENCE - low mortality |
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Model for Latent EBV
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see notes
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Herpes Virus cell transformation
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viral replication is incomplete but genes stimulate DNA = proliferation and transformation
host defense interference |
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What are Cancers associated with EB virus
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Burkitt's lymphoma(5-8 age)AFR
Nasopharyngeal (age 30+) SEA Hodgkins(10-30 years)WW T cell lymphoma(<6 mos/>30 yrs) WW Imunoblastic Lymphoma (<6mos to 10 years) WW |
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What is Burkitt's lympoma
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Big JAw - childhood malignancy in subSaharan Africa
Cancerous B cells in lymph nodes Chemo cures/fatal if not txed. Associated w/Malaria suppression of CTL's |
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Nasopharyngeal Carcinoma
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WW, SE Asia, Eskimos and n and E Africa
genetic and environmental factors epithelial cells of nasopharynx |
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Hodgkins Lymphoma
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young adults with 2nd peak ~ 45
WW, more common in industrialied countries responds to chemo |
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EBV and Immunocompromised systems
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increased risk
shortened latency btw acute and development of cancer (<6 mos) two forms of lymphoma in AIDS= Burkitt's - early Late -failure of CTL's to control B cell population |
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CMV HHV
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epithelial cells infected in vivo(restricted host range in culture)
cell enlargement & intranuclear inclusions Contrast to HSV - stimulates host-cell DNA, RNA and protein synthesis(rather than shut down) |
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Epi of CMV
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WW
Close contact (saliva/breast milk/urogenital secretions) and blood transfusions Infected as infants most dz in immunocomp |
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CMV PATHOGENESIS
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initial lytic infection of epi cells
gene expression impair host immune response virus shedding to perist for years(latency) esp if infected early. Infection kept in check by CTL's in immunocompetent hosts |
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What is severe form of CMV
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newborns depending on timing of mother infection
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CMV in newborns
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if mother reactivation:congenital - <2%and newborn asymptomatic
if new mother infection: congenital 50% 10% newborns symptomatic - CNS dz in short and or long term deafness, blindness, seizures, microcephaly MOST COMMON INFECTIOUS CAUSE OF DEAFNESS IN US |
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CMV IN immunocompromised adults
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organ transplant and AIDS
Symptoms when CD4 count low Any organ lungs, cns, g-i most common/severe CMV retinitis in 20% AIDS PTS. |
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HHV 6 AND 7
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recent discovery
Tropism for lymphocytes(CD4 T) asymptomatic infection often HHV6 - mild febrile/rash in kids(6th disease - roseola infantum or exanthem subitum) severe in immunocomp no dz with HHV7, so far |
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HHV 8
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Latent inf in B cells
Sexual transmission Ass w Kaposi's SArcoma - seen as most common tumor inHIV |
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DX of Kaposi Sarcoma
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Asthenia and feverish for months
Weight loss lesion and edema for weeks HIV + often dark colored skin areas(change in toes/not painful) |
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What is only nonhuman herpesviruzs known that is highly pathogenic for humans
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Cercopithecine Herpesvirus - 1(Monkey Virus B)
causes HSV-1 type dz/latent Transmission to human via bite or secretions. Human get severe CNS/hi mortality Acyclovir may be beneficial |
