lecture 5- bovine virology Flashcards
what is BRDC
bovine respiratory disease complex
when does BRDC typically occur
first 40 days in a feedlot
what is one bacteria associated with BRDC that may lead to severe outcomes?
Mannheimia haemolytica (others too)
what season is BRDC most common
winter
what are the 4 viruses associated with BRDC?
BHV1/IBR (Bovine Herpesvirus 1 –> infectious bovine rhinotracheitis)
BPIV3 (bovine parainfluenza virus 3)
BRSV (bovine respiratory syncytial virus)
BVDV (bovine viral diarrhea virus –> mucosal disease)
what is BHV1
bovine herpesvirus 1
what is BPIV3
Bovine parainfluenza type 3
what is BRSV
bovine respiratory syncytial virus
which family is BRSV and PI3 a part of?
family: paramyxoviridae
what is significant about the genomes of viruses within paramyxovirinae?
they have the same genetic building blocks
what subfamily is BRSV a part of?
pneumovirinae
when does BRSV flare up?
winter, when cold
at what age does BRSV usually infect cattle?
<6 months
how is BRSV transmitted?
contact or aerosol
what is the prevalence of BRSV in individuals who are older than 3 years old
> 95%
what is the duration of shedding of BRSV?
1-12 days
what is characteristic of BRSV microscopically?
the presence of syncytium (giant, multi-nucleated cells)
what is the % mortality of BRSV?
2-3%, but up to 20%
is BRSV more common in dairy or beef cattle?
beef
does BRSV impact all hosts similarly?
no- pathogenesis is related to host response
can vaccination induce disease of BRSV?
yes… be aware of vaccine timing
is it likely that cattle infected with BRSV and BPIV3 can be persistently infected?
no- more likely re-introduction if they become infected again
how is BPIV3 transmitted?
contact or aerosol
what % of calves are infected with BRSV and BPIV3 within their first 2 years?
70%
what is the pathogenesis of BRSV and BPIV3?
enter body via respiratory tract
penetrate/degrade mucous
invade epithelial cells of upper resp tract by binding to sialic acid residues on cell membrane
replication occurs predominantly in resp tract
virus excreted in nasal discharge
BRSV and BPIV3 bind to _____ residues on cell membranes to invade
sialic acid
where does BRSV and BPIV3 predominantly replicate?
respiratory tract
through what do infected animals excrete BRSV and BPIV3?
nasal discharge
what can BPIV3 do during replication that BRSV cannot?
BPIV3 replicates well in pulmonary alveolar macrophages, which induces immune suppression because phagocytosis and prostaglandin production is suppressed.
how does BRSV infection cause damage through the hosts immune system?
proinflammatory genes are upregulated and extensive mast-cell degranulation (creates cytokine storm)
is BRSV more pathogenic in neonates or young calves? why?
more pathogenic in young calves because they have developed an immune system, which then goes into overdrive upon BRSV infection (creates cytokine storm)
what are clinical signs of BRSV and BPIV3
fever, depression, lack of appetite, anorexia, increased resp rate/effort, coughing, nasal discharge, pulmonary emphysema dn edema
what is more severe, BPIV3 or BRSV?
BRSV is more severe, typically
what is one way to diagnose Malignant Catarrhal fever versus mucosal disease, if the sick cow has a history of being involved with 4H?
it is more likely MCF if the cow has been around sheep
what is MCF
malignant catarrhal fever
what is the etiology of MCF?
ovine herpesvirus 2 infection in bovines
what are clinical signs of MCF/herpes virus 2
fever
depression
cattharal inflammmation
severe eye lesions
swollen lymph nodes
lameness
CNS signs
what is a distinctive lesion of MCF?
severe eye lesions
what kind of virus is herpesvirus
large double stranded enveloped DNA virus
what species are infected by bovine herpes virus 1?
cattle and buffalo
what can BHV-1 lead to?
upper resp disorders, conjunctivitis, genital disorders, immune suppression
what does BHV-1.1 impact?
respiratory tract, aborted fetuses*
what does BHV-1.2a impact?
respiratory tract, genital tract (IBR), infectious pustular vulvovaginitis (IPV), balanopostitis (IPB), abortions
what does BHV-1.2b impact?
respiratory disease, IPV/IPB, NOT abortion
which subtype of BHV-1 is most prevalent in north america
BHV-1.1
how is BHV-1 transmitted?
direct nose-to-nose contact or aerosol over short distances
also through semen
which cells does BHV-1 infect?
enters epithelial cells, but resides in ganglion cells when in latent period
how does BHV-1 cause pathology?
lysis of infected cells- necrosis and apoptosis
why is lysis of ciliated epithelium important in regards to BHV-1?
without functional ciliated epithelia, bacteria is deposited in alveoli (unable to push pathogens out of trachea)
how does BHV-1 cause immunosuppression (3 ways)
- apoptosis of CD4+ cells
- reduced expression of MHC I and MHC II molecules
- down regulation of type 1 interferon
what diseases/pathologies are related to BHV-1?
-c onjunctivitis
- IPV
- IBR
- infectious vulvovaginitis
-encephalitis
- mastitis
- abortion
what is IBR
infectious bovine rhinotracheitis
IBR is caused by
BHV-1
what are distinctive lesions of IBR?
nasal lesions of numerous clusters of grayish necrotic foci on the mucous membrane of septal mucosa
eye lesions, keratitis
when can abortions occur with IBR?
can occur at the same time as respiratory disease, but also up to 100 days after incubation
in regards to IBR, _____ is a complication and not a part of the primary disease
pneumonia
what are clinical signs of IBR?
-serous rhinitis with hyperemia and edema of mucosa
- lots of nasal discharge
true or false: herpes viruses are resistant to environmental influences
true !!
how to avoid herpes viruses?
soap! (its an enveloped virus)
vaccinations
what is something to consider when giving live vaccines?
can cause abortion
can cause sickness
(if given at an inappropriate time)
what is a marker vaccine
A marker vaccine is a vaccine which allows for immunological differentiation of infected from vaccinated animals
how do you diagnose BRD/scours?
multi-lab panel
what can cause scours?
bovine coronavirus or bovine rotavirus
(also E. coli, Salmonella, Coccidiosis)
Nidoviruses are ____ (DNA or RNA)?
RNA viruses
how are nidoviruses released from an infected cell
lysis of host cell
what is the family of rotaviruses?
Reoviridae
what is the classification of rotaviruses?
naked double stranded RNA viruses with segmented genomes
how many serogroups of rotaviruses are there? which are we concerned with as vets?
7 groups (A-G)
A causes infection in domestic animals, while B and C are found in clinical cases
how many capsid layers do rotaviruses have
3- outer, intermediate, and inner
how many segments do rotaviruses have? which antigens do we care about?
11 segments code for 12 proteins. We care about the P and G antigens because they create pathologies
why is the segmentation of rotaviruses important?
allows for genetic reassortment
what are the clinical signs of BRV?
diarrhea, malabsorption
what cells does BRV target? what is the significance?
replicates in cytoplasm of epithelial cells of call intestinal villi
significant because this causes maldigestion and malabsorption.
true or false: BRV causes crypt necrosis
FALSE- BRV targets the villi of the small intestine
what is the structure of BRSV and PI3? (paramyxo)
enveloped, negative sense
what is the replication strategy of BRSV and PI3? (recall they are a part of the family Paramyxoviridae)
ssRNA- (virion RdRp –> mRNA)
What family is BHV-1 a part of
Herpesviridae
what is the structure and replication strat of BHV-1
enveloped, dsDNA (cellular RNA pol2 –> mRNA)
What is the family of bovine rotavirus (BRV) ?
Reoviridae
what is the structure of BRV?
naked, segmented genome (multi-layered capsid)
what is the replication strat of BRV? (family Reoviridae)
dsRNA (virion RdRP –> mRNA)
common bovine viruses with GI disease
BVDV (Flavi)
BRV (Reo)
BCV (Corona)
common bovine viruses with repro disease?
BVDV (Flavi)
common bovine viruses with resp disease
BRDC:
BHV1 (Herpes)
BPI3 (Paramyxo)
BRSV (Paramyxo)
BVDV (Flavi)
what bovine disease is commonly associated with lymphosarcoma
BLV
what is the order of Arterivitidae, Coronaviridae, and Roniviridae? are these all RNA or DNA ?
Nidovirales - all RNA