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IP6 Virology Exam 3
BVDV,BD,EHD,BTV
| Question | Answer |
|---|---|
| What is the genus of BVDV? | Pestivirus (enveloped RNA virus) |
| What are the 2 distinct biotypes of BVDV? whic one is the MC? | Cytopathic (CP) and Non-cytopathic (NCP): NCP is the most common |
| Which biotype of BVDV is able to cross the placenta and establish permanent persistent infection? | NCP strain of BVDV |
| What are the primary hosts of BVDV? what other spp can get it? | Cattle are primary; sheep,goats,llamas, alpacas, camel, deer can also get BVDV |
| Can cattle infected with the NCP biotype of BVDV ever conver tot the CP biotype? | Yes! they commonly develpe acute, fatal mucosal dz when this mutation occurs |
| What are the 2 cell types BVDV likes to replicate in? | epithelial (skin, GI, respiratory) and Immune cells (macrophages/lymphocytes) |
| If a non-immune, pregnant cow is infected with BVDV before 75 days of gestation what is the most likely outcome? | Virus will kill embryo or fetus |
| T/F an aborted fetus can be an important source of virus exposrue for the herd? | true |
| If infection with BVDV occurs around 75-125 days of gestation witha NCP strain what is the MC outcome? | Persistently infected calf (PI). b/c the fetal immune system doesn't recognize the BVDV as foreign. |
| T/F PI claves do not mount an antibody repsonse to the virus? | True-b/c don't recognize as foreign |
| Excessive virus BVDV replication occurs in the ____ ______, and it is the basis for the ante-mortem IHC skin test | hair follicles |
| What is the MC source of infection with BVDV in a herd? | a PI calf |
| If a calf is infected around 125-180 days of gestation what is the MC outcome? | teratogenic lesions are seen (hydrocephalus, cerebellar hypoplasia, hydranencephaly, defective myelination, cataracts, micropthalmia) |
| MC outcome is a calf infected after 180 days gestation? | A calft is immunocompentant at 180 days and in most cases will survive and clear the virus but will seroconvert. The calf will be healthy and immune to that strain of BVDV |
| T/F a calf infected after 180 days will have anti-BVDV antibodies at birth? | True |
| What are the 3 Major routes of transmimssion for BVDV? | 1. transplacental 2. direct respiratory or oral contact 3. Less common=indirect contact (blood feeding flies/fomites) 4. Less common=breeding-BVDV can be transmitted in semen and spread thru AI |
| What is the MC outcome for an immunocompetent, seronegative non-pregnat cow infected with BVDV? | 70-90% will develop subclinical infection or mild enteric/respiratory dz. They will seroconvert and clear vius and devleop long-lasting immunity to that particular isolate. |
| What are the signs of sever, acute BVDV (4) | bloody diarrhea, sudden death and evidence of widespread hemorrhages (epistaxis, mucosal hemorrhages). Thrombocytopenia. |
| PI calves are unthrify and usually develop fatal mucosal dz by what age? | 6-24month |
| What are the clinical signs of BVDV mucosal dz? | profuse watery diarrhea (possibly bloody), oral ulcerations, mucopurlunt nasal discharge, lameness and erosions in the interdigital cleft. Death within 5-7days |
| when mucosal dz occurs in PI calves, herd morbidity is ____, but mortality is _____ | morbidity low, mortality is very high (>90%) |
| what are the 3 ways mucosal dz occurs in a PI calf? | 1.NCP->CP biotype 2. PI calf gets super-infected with new CP biotype from others in the herd 3. calf is vaccinated with Modified Live Vaccine strain and it mutates to induce mucsal dz |
| T/F cattle infected with BVDV are more likely to succumb to secondary infections from other pathogens | True! BVDV is immunosuppressive |
| What is the most characteritic lesion of BVDV and the way it can be distinguished from Rinderpest? | Fibrinonecrotic inflmaation and erosion of Peyer's patches |
| Where would you expect to see ulcerations/eronsion in an animal that suffered from mucosal dz (BVDV)? | ulcerations will be along the entire GIT from mouth to colon. |
| T/F laboratory diagnosis is necessary to differntiate b/t BVDV from rinderpest and malignant catarrhal fever? | true |
| T/F serological tests are the best test to Dx BVDV? | False, serologic tests are not helpful in diagnosis |
| What are 3 tests that would be most useful for dx of BVDV? | 1. Ag-capture ELISA (used to screen herds) 2. IHC on ear punch skin biopsy (used to ID PI calfs) 3. RT-PCR detects viral ag from tissue samples (submit lu, sp, ln) |
| What 4 things should you do to prevent/control BVDV? | 1.Quarantine and test cattle before mixing with your herds 2. Identify an eliminate all PI cattle 3. Routine herd immunization/annual revacc 4. If there is an outbreak in naive herd, vaccinate cattle with inactivated vacines. |
| T/F BVDV is zoonotic? | False! |
| What is the Genus of Bluetongue virus? What type of genome does it have? | Orbivirus; ds-RNA |
| How many serotypes of bluetongue virus are there? how many in the US? | 25 total types, 5 in SW USA |
| What type of animals does Bluetongue virus infect? | ruminants |
| BTV causes severe dz in what spp? | sheep and wild ruminants like deer |
| T/F BTV causes mild clinical signs in cattle and goats? | True-they can be infected but mild or subclinical signs (cattle considered a resivoir) |
| What is the major mode of transmission for BTV? | The Culicoides biting midge |
| What time of the year is BTV most likely to occur? | late summer or autumn, declines when frost kills off midges |
| T/f iatrogenic transmission occurs by resuing needles? | true |
| BTV is stable in the environment and resistent to several disinfectants. You should use disinfectants with ________ and acid because they are most effective | iodophores |
| Pathogenesis of BTV: it is transmitted to the ruminant by the bit of the _________. It replicates in the ______. | Culicoides biting midge; replicates in the local lN |
| BTV replicates in the local LN then disseminates to the ______ & _______ | macrophages and endothelial cells |
| The pathological result of BTV are what 3 major things? | 1. vascular necorsis 2. hemorrhage (leading to DIC) 3. thrombosis |
| After an incubation period of 1 week, sheep infected with blue tongue get what clinical signs? | fever, nasal discharge, edema of the face, gums, lips and dental pad; swelling and cyanosis of the tongue (blue tongue) and red-brown vertical line on coronary band |
| How do you test for blue tongue virus? | PCR, Virus Isolation from salivary glands/blood |
| Name 2 control measures used for BTV? | 1. repellents for cullicoides 2. polyvallent, non-replicating vaccines used in endemic areas |
| T/F Modified Live vaccines are acceptable to use in sheep to treat for BTV? | False! they cause abortion and severe congenital defects like arthrogyprosis |
| T/F Bluetongue virus is zoonotic? | False |
| Besides Bluetongue virus, what other viral disease is transmitted by Culicoides midges? | Epizootic hemorrhagic disease (EHD) |
| What is the primary host of Epizootic hemorrhagic disease (EHD)? | white-tailed and mule deer |
| In deer with EHD what are the clinical signs and lesions that occur? | similar to sheep with bluetonge, they get generalized hemorrhagic dz and DIC; acute form is characterized by severe edema of the head and necks and pulmonary edema |
| In peracute lesions (of deer) with EHD what lesions are normally found? | found dead with no apparent lesions |
| How is EHD MC diagnosed? | PCR on tissues &virus isolation can be done or IFA |
| T/F EHD is zoonotic? | false |
| What type of vaccine could you use if you were a deer farmer? | Killed vaccine available |
| What genus is Border disease virus in? | pestivirus |
| What is the common name for border dz virus? | hairy shaker dz |
| host spp for border dz? Clinical signs? | sheep and goats but MC in sheep; unthriftiness, tremors, delayed myelination in the CNS, long hair coat |
| How is border dz transmitted? | direct contact b/t sheep,PI carrier lambs are MC cause of virus infection |
| If a lamb is infected with BD prior to 45d gestation what occurs? | Abortion, the virus causes necrosis of placenta and fetal death/abortion |
| If lamb infected day 40-70 what happens? | persistent infection; low birthweight, poor conformation, tremors, excessively hair birth coat |
| In adult and adolescent non-pregnant immunocompentant sheep infection often shows what signs? | subclinical |
| Lambs with persistent BD infection are similar to PI cows with BVDV. what congenial lesions do they have in common? | arthrogryposis, hydrancephaly, cerebellar dysplasia |
| What are 3 ways to diagnose? | PCR, IHC, IFA |
| Prevention/Control of border dz (2) | 1.cull all lambs with tremors soon after birth (PI) 2. serologic testing of replacemtn ewes at 6mo |
| T/F Border disease is zoonotic? | false |
| T/F there is a vaccine avialble for BD? | False |
Created by:
rccola19
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