Poxviruses and Rabies Flashcards
describe poxvirus characteristics
DNA, double stranded, asymmetric capsid, both enveloped and uneveloped
what characteristics of poxvirus distinguish it from other viruses?
it has an asymmetrical capsid and can be infectious enveloped or unenveloped
does the virion require host RNA polymerases?
no, it carries its own.
poxviruses are the only viruses that carry a DNA dependent RNA polymerase with them
where do poxviruses form their inclusion bodies?
cytoplasm
what do inclusion bodies indicate
they indicate sites of virion or nucleocapsid assembly.
can be used to help distinguish viruses
molluscum contagiosum
poxvirus transmitted by intimate cutaneous contact
causes white skin papules- bumps on the skin
much worse in immunosuppressed
resolves on its own w/ t-cell immunity
harmless
how is molluscum contagiosum transmitted?
intimate cutaneous contact
how long is the incubation period for molluscum contagiosum?
2-8 weeks
why can it be difficult to diagnose molluscum contagiosum
grows poorly in culture
smallpox characteristics
DNA, double stranded, asymmetric, both enveloped and nonenveloped
smallpox transmission
respiratory
describe smallpox infection
infects respiratory mucosa and lymph,
establishes viremia that attacks lungs, liver, spleen
second viremia infects skin
what is the clinical presentation of smallpox
papules, vesicles, pustules.
lesions in oral mucosa are the main source of new infection
smallpox virus vaccine
live- vaccinia virus
how many serotypes of smallpox are there?
1
how many other animals act as resevoirs for smallpox?
0- just humans
complications of smallpox vaccinations
encephalitis
vaccinia necrosum- spreading necrosis at site of infection d/t t-cell immunity
eczema vaccinatum- pread of lesion in pre-exisitng eczema
generalized vaccinia- spread of lesions in the absence of eczema
heart infection
when is the smallpox vaccination useful?
prior to infection or w/in 4 days of infection
what other treatments work for small pox
passive immunization w/ IgG
rhabdovirus characteristics
RNA, single stranded, minus strand, enveloped, helical
rabies
rabies transmission
bite from infected animal
rabies infection
no viremia- tropism for nervous system
replicates into salivary glands
incubation period of rabies
week to months
rabies prognosis untreated?
human and canines- fatal
rabies symptoms
fever, anorexia
Later: hydrophobia (d/t swallowing pain), paralysis, coma, death
rabies diagnosis
negri bodies- cytoplasmic inclusions in nerve cells
uses fluorescent Abs to confirm
where are herpes inclusion bodies?
nucleus
rabies vaccine
killed vaccine
can be given any time during the incubation period, but once CNS symptoms begin, will not stop death
rabies treatment
combination of passive and active
IgG given to delay symptoms and then killed vaccine used to activate active immunity
used in all cases of unknown bites or prophylactically w/ vets
how does transmission usually occur in the US?
bites from wild animals’ (bats, foxes, racoons, etc.)
dogs are not a big source (except near mexican border) b/c of vaccination requirements
