Flaviviruses, pestiviruses, alphaviurses Flashcards
genus in flaviriridae family
- flaviviruses
- pestiviruses
flaviviruses
- west nile virus
- St. Louis encephalitis virus
- wesselbron dx
- yellow fever dx
- tick borne encephalitis
- looping III
pestiviruses
- bovine viral diarrhea
- border dx
- hog cholera (classical swine fever)
togaviruses
- eastern, wester, venezulenan encephalitis viruses
flaviviridae features
- enveloped virus
- e protein
- ssrna
- positive sense
- 1 long open reading frame
flaviviridae genome features
- 5’ end of genome capped, 3’ end no poly a (5’ like mammalian genome, 3’ diff than mammalian protein)
flavivirdae host
broad host insect and vertebrate
st louis encephalitis virus type
flavivirus
st loud encephalitis
- mosquito-bird-mosquioto cycle
- causes signficant human dx
wesselsbron virus type
flavivirus
wesselsbron virus affects who
- sheep mainly
- cattle, horses, swim sub clinically
wesselbron virus sheep where and signs
- in subsaharan africa
- fever, jaundice, sq edema
- abortion
zoonotic flaviviruses
- St. Louis encephalitis
- wesselbron dx
- louping III
west nile virus transmission
- mosquito transmitted virus ‘
- maintained in birds
- transmitted to horses and humans
west nile virus in us
endemic
horses and humans and west nile relatinoship
- these are dead end hosts for virus virus does not aim to get into human or horse goes from insect to mammal
- don’t really see horse to horse or human to human transmission
west nile virus horses presentation
- most susceptible to infection and dx
- most = subclinical infections
- clinical- see cns signs
- 1/3 clinical horses die
diagnosis of westnile in horses and contaminant level
- fa of infected tissues or csf
- bl3 contaminant
why use igm vs igg for serology
- advantage to igm is that you detect it sooner
westnile virus vac available
- inactivate vac in horses = good efficacy (canarypox virus vectored subunit vac)
flavivirus transmitted by tick
- powassan virus in North America
- louping III
flavivirus transmitted by tick infection and replication
- infect small mammals
- replicate in ticks
- bld meal at every stage so every meal = chance to transmit
flavivirus transmitted by tick transmission
- transtadially(through insect stages)
- transovarially (through eggs)
louping III virus type
flavivirus
louping III causes what
infectious encephalomyelitis of sheep
louping III affects who
- sheep primarily
- horse, cattle, deer
louping III in sheep
- infectious encephalomyelitis of sheep
- sheep = viremia, biphasic febrile response
- 2nd stage = enter cns -> neuro
louping III vac?
yes, inactivated
flaviviruses general patterns
- broad hosts and cell tropism including insect and ertebrate
- many are zoonotic and affect cns
- many have vaccines that work against them
westnile mortiality
- 5% humans
33% horses
bovine viral diarrhea virus type
- pestivirus genus within flaviviridae family
bvd starins
- 2 strains
- type 1
- type 2
- antigenic cross protection btwn two virus types
type 1 bvd
mild dx
type 2 bvd
more seere dx
bovine viral diarrhea affects who
- post natal infection in non-preg cattle
- pregnant cattle
- sheep, deer, bison, wild ruiinnts
bovine viral diarrhea post natal infection in non-pregnant cattle -> ?
- GI tract dx
- mucosal dx
- fever
- leukopenia
- occular/ nasal discharge
- erosive stomatitis
- lwr milk production
- immunosuppression -> secondary infections
bovine viral diarrhea pregnant cattle -> ?
if transplacental transmission - fetal death - low birth weight - retinal dysplasia - cerebellar dx if persistently infected for life - immune tolerant, shed virus - +/- mucosal dx later in life
if bovine viral diarrhea infects calves > 125 days of gestation
clear the virus
cytopathic biotype bovine viral diarrhea
- SEVERE
- anorexia
- profuse watery d+
- nasal discharge
- erosive/ ulcerative sotmatitis
- death
bovine viral diarrhea pathogenesis in normal cattle
mild wide growing virus can -> GI ulcers
histology bovine viral diarrhea
- destruction of gi tract at various levels
- mucosal dx in persistently infected animals
- cerebellar lesions!
bovine diarrheal virus diagnosis
- hx
- path lesions
- non-cytopathic so use antibody staining
bovine viral diarrhea epidemiology (spread, level of consistent infection)
- direct and indirect contact
- persistently infected have high levels of virus
bovine diarrheal virus vac
- yes
- modified live can -> inected cattle getting mucosal dx
border dx of sheep what kind of virus
- pestivirus genus within flaviviridae family
border dx of sheep affects who
adult sheep - subclinical infectin fetal infection - dead -deformed -mummified lambs **congenital dx in lambs** -low birthweight -poor viability -hairy shakers
pathogenesis border dx of sheep
- defective myelination of nerve fibers in cns
- tolerant persistent infection = possible
control border dx of sheep
- be careful of what introduce where and when and what you test and if you have immune prepared popuation you are introducing new animals to
diagnosis border dx of sheep
- hx
- path lesions
- non-cytopathic so use antibody staining
classic swine fever/ hog cholera virus type
- pestivirus genus within flaviviridae family
classic swine fever/ hog cholera virus type
- gi
- cns
- fever
- conjunctivitis
- pneumonia
classi swine fever/ hog cholera virus type signs
- diffuse hyperemia
- purport abdomen and ears
- gi
- cns
classic swine fever/ hog cholera w/ in a herd
- many pigs in herd ill
- young may die or become lifelong shedders
- older pigs secondary bacterial infections -> 100% mortality
hog cholera pathogenesis
- oronasal infection infect lymphoid organs and endothelial cells
- can severely affect most major organs
- V BAD DX
hog cholera lesions
- hemorrhages
- leukopenia
- thrombocytopenia
- infarctions
- DIC
- encephalitis w/ perivascular cuffing
hog cholera chronic cases
- necrotic lesions large intestinal mucosa
- bacterial infection of lungs
- atophy of lymphoid tissues
hog cholera persistently infected piglets
- can be immune tolerant and lifelong shedders
diagnosis of hog cholera
- hx
- path lesions
- non-cytopathic so use antibody staining
hog cholera transmission
- contact btwn swine
- indirect transport of virus
- can survive in frozen pork
control hog cholera
- test and slaughter policy
- vac effective (attenuated)
pestiviruses general
- genus of flaviviridae fam
- positive sense ssRNA
- one open reading frame
togaviradae family members and surface contains what
- alpha viruses (30 members)
- spikes 2 glycoprotein (E1 and E2)
togavirade family general features
- envelope
- ssRNA
- positive polarity
- 5’ methylated cap and poly-a
togaviridae rna genome
- subgeneric rna encoding structural proteins
togaviridae affects who and affect on their cells
- insect, avian, and mammalian cells
- kills mammalina cells
- less effect on insect cells
alphavirus what kind of virus
-togaviridae
alphavirus types of viruses
- eastern equine encephalitis
- western equine encephalitis
- venezuelan equine encephalitis
eastern and western equine encephalitis presntiaton
- subclinical or
- fever, anorexia, depression, neuro signs
venezuelan equine encephalitis presentaiton
- systemic dx
- fewer neuro signs that EEE, WEE
wee, eee, vee fatality level
HIGH fatality levels
pathogenesis alphavirus
- mosquito bite -> virus to local lymphoid tissue -> systemic spread -> replicate -> CNS -> neuronal necrosis
immunity if survive alphavirus
long lived IF survive
alphavirus vac
- yes
- inactivated and attenuated
eastern equine encephalitis seasonality / maintained how
- seasonal w/ vectors
- maintained in birds
venezuelan equine encephalitis cycle
- mosquitos and small mammals
eee found where
endemic north America, central and norther south america
wee found whree
widely distributed in plains and west in birds and mosquitos
vet found where
endemic in venezuela Colombia and peru
alphavirus spread
epidemics can spread rapidly
