bovine viral diseases 2 - Nicole Flashcards
what does BRDC stand for
Bovine respiratory disease complex
is BRDC a single factorial or multifactorial disease
multi factorial
how does BRDC lead to antimicrobial resistance
metaphylactic administration of antimicrobials in response to BRDC
what actually leads to the severe outcomes of BRDC
involvement of many bacteria
clinical signs of BRDC
excreting of saliva, mucous, purulent discharge
which season is BRDC associated with
winter (first 40 days on feed in a feedlot)
what disease is usually associated with summer
pneumonia (pasture based pneumonia)
what are 4 important viruses associated with bovine respiratory disease complex
- boine herpesvirus 1 (BHV1/IBR)
- bovine parainfluenza 3 virus (PI3)
- bovine respiratory syncytial virus (BRSV)
- bovine viral diarrhea virus (BVDV) –> lots of respiratory effects and immune suppression
what family and genus is BRSV classified under
Family: Paramyxoviridae
Genus: Pneumovirus
what is BRSV closely related with
HRSV (human respiratory syncytial virus)
what is the important thing to remember about the genome of all viruses within paramyxovirinae
all have the same build and act in the same way (very little different structural change between viruses within this group)
BRSV clinical signs
weight loss due to lots of breathing efort
describe the seasonality of BRSV
peak infection in fall and winter (possibly into early spring)
- summer: ~60% negative
- winter - ~0% negative
draw the similarities between BRSV and HRSV
both have similar pathology, clinical signs, prevalence, duration of shedding, peak season of incidence
what is a syncytium
a polynucleated cell. cells merging together. numerous in individuals infected with BRSV or HRSV
what percentage does BRSV account for in epizootic respiratory diseases in dairy
60%
what percentage does BRSV account for in epizootic respiratory diseases in beef
70%
mortality of BRSV
2-3 –> 20%
what is the pathogenesis of BRSV closely related to? why?
closely related to host response: hsot system goes into overdirve –> protein excretion in lungs and trachea –> whipped cream –> hard to breath through
des vaccination induce disease or decrease disese for BRSV
vaccine induces immune responce which could induce disease
is there cytopathology evident in individuals infectd with BRSV
no, lungs will still be intact, just lots of host response
what are the natural hosts of BRSV
cattle
what does BPIV3 stand for
bovine parainfluenza virus type 3
how is BRSV and BPIV3 transmitted
direct contact between animals, aerosols, humans as a passive vector
what percentage of calves are infected with BRSv and BPIV3 in the first 24 months
70%
is BRSV and BPIV3 persistent, why?
we dont think its persistent. very difficult to show re-excretion of virus. Most likely gets re-introduced
describe the pathogenesis of BRSV BPIV3
pathogen enters the body via respiratory tract –> penetrates/degrades the mucous –> invades EPITHELIAL CELLS of upper resp tract via binding to sialic acid on cell membranes –> replicate in respiratory tract –> virus excreted with nasal discharge
where does PI3 replicate well in? is this the same for BRSV
PI3 replicates well in pulmonary alveolar macrophages. this induces immune supression: phagocytosis and prostaglandin production is suppressed. this is NOT the case for BRSV
does BRSV induce immune supression or heightened immune response
in BRSV infections, the host immune system causes damage due to pro-inflammatory genes being upregulated and extensive mast-cell degeneration in peracute cases
which is BRSV more pathogenic in: young calves or neonates? why?
young calves (6 weeks of age). maternal antibodies and way animal is mounting immune response accounts for BRSV being more pathogenic in young calves vs. neonates
what do BRSSV clinical outcomes depend on
age, immunological status, presence of specific antibodies, immunosupression, route and dose o infection, virulence of particular strain
how many days post infection is the peak of clinical signs in animals infected with BRSV BPIV3
4-6 days afetr infection
major clinical signs of BRSV BPIV3
- fever (up to 40*C)
- depression, lack of appetite or anorexia
- increased respiratory rate: grunting, open mouth breathing, stretched neck, saliva pouring, tongue out
- airways obstructed through overproduction of mucous: coughing, nasal discharge, pulmonary emphysema and edema, crackles and wheezes
which has generally more severe clinical signs. BRSV or BPIV3?
BPIV3 generally less severe, although similar clinical signs (cough seromucoid nasal and occular discharge
if you have a respiratory tract issue in a calf that is just born, is it likely BRSV
NO! animals infected with BRSV are 6wks old or older
where do animals show clinical signs first when infected with BRSV. what follows?
animals first show upper respiratory tract disease followed by lower respiratory tract disease
what is one explaination for the difference in severity of clinical signs of BRSV in calves 6 weeks of age versus neonates
proinflammatory cytokines (ex. TNF-alpha) have stronger responses in older animals –> stronger immune response –> more severe clinical signs in response to BRSV
pathological findings for BRSV
Interstitial pneumonia. BRSV scattered and consolidated in pieces of lung
what is a lot of the damage of BRSV due to
the immune response enhanced by BRSV and PI3 –> leads to further tissue damage
what is the important species that Ovine herpes virus 2 is able to infect
bovines
what is the major clinical sign of ovine herpesvirus 2 in bovine
Malignant catarrhal fever
what are the clinical signs of ovine herpesvirus 2 in bovines
- high fever
- depression
- catarrhal inflammation; erosions and mucopurulent exudation affecting the upper respiratory, ocular and oral mucosa
- severe eye lesions!!!!! (panophthalmitis, hypopyon, corneal opacity)
- swollen lymph nodes
- lameness
- CNS signs: depression, trembling, hyporesponsiveness, stupor, agressieness, convulsions)
… all die 2 weeks later
describe the morbidity and mortality of ovine herpesvirus 2 in bovine ***
morbidity: low, individuals in herd
mortality: 100%!!! THEY ALL DIE IF INFECTED
can ovine herpesvirus be transmitted cow to cow?
no. can only be transmitted sheep –> cow
what clinical signs are included for MCF (malignant catarhal fever)
keratitis on eye, lesions, exudate and blisters on upper respiratory (nose and mouth)
what kind of virus is bovine herpesvirus type 1
large DNA enveloped virus
what animals is BHV-1 restricted to?
cattle and buffalo. does not stably cross species barriers
what clinical disorders can bovine herpes virus lead to?
upper respiratory, conjuntivitis, genital disorders and immune suppression
which of the three BHV-1 subtypes are most prevalent in north america?
type 1 (BHV-1.1)
describe the clinical signs of BHV-1.1
respiratory tract and aborted fetuses (abortion storms)
describe the clinical signs of BHV-1.2a
respiratory and genital tracts such as IBR, infectious pustular vulvovaginitis (IPV) balanopostitis (IPB0 and abortions
descrie the clinical signs of HBV-1.2b
respiratory disease (no lungs only respiratory tract, IPV/IPB but no abortion
what makes BHV-1 more pathogenic
bacterial infection following BHV-1 viral infection –> all dead
BHV-1 pathogenesis
direct nose-noe contact (or aerosols in short distance) –> enters epithelial cells in upper airways and nerves –> lysis of infected cells (necrosis and apoptosis) –> lysis of ciliate epithelium in trachea –> no mucocilliary clearance –> bacteria deposition in alveoli –> immunosuppression** (apoptosis of CH4+ cells, reduced expression of MHC 1 and MHC II, downreg of type 1 interferon)
what part of the pathogenesis of BHV-1 is really significant for bacteria to take advantage of
immunosupression: apoptosis of CD4+ cells, reduced expression of MHC I and II and downregulation of type I interferon
ways in which BHV-1 can be transmitted
- BHV-1 excreted in nasal fluids at a high concentration
- virus can be transmitted by semen
how long can BHV-1 be excreted in nasal fluids
10-17 days with a peak at 4-6 days post infetion
clinical outcomes of BHV-1
respiratory disease
nasal lesions (clusters of grayish, necrotic foci)
reovery in 4-5 days in absence of bacterial pneumonia
abortions at the same time of respiratory disease
BHv-2 related diseases
- conjuctivitis
- infectious balanopostitis IPV
- infectious vulvovaginitis
- infectious bovine rhinotracheitis (IBR)
- encephalitis
- mastitis
- abortion
clinical signs of respiratory disease due to BHV-1
high fever, conjunctivitis with lacrimal discharge, anorexia, coughing, excessive salivation, nasal discharge, inflamed nares, dypsnea
how long is the incubation period for respiratory and genital forms of BHV-1 infection
2-6 days
how long post infection of BHV-1 can abortions be seen
100 days
describe the morbitity and mortality of BHV-1 infection
mortality: up to 10%
morbidity: up to 100%
clinical signs of infectious bovine rhinotracheitis
- serous rhinitis with hyperemia and edema of mucosa
- lesions that extend to trachea and sinus if complicated with secondary bacterial infections
- copious nasal excretion
- mucosa in sinuses develop catarrhal purulent exudate
- purulent inflammation of larynx and trachea (associated with edema and hemorrhage of trachea)
is pneumonia part of the primary disease of infectious bovine rhinotracheitis
pneumonia is a complication and not part of the primary disease
is bovine infectious rhinotracheitis an upper or lower respiratory airway disease
upper rep. disease only
describe the stability of BHV-1 in the environment
- resistant to environemtnal influences (at 4*c stable for one month)
- can survive 1 year in frozen semen in liquid nitrogen
- enveloped virus: sensitive to organic solvents (etc. chloroform, ether, acetone)
are there vaccines available for bovine herpes virus
lots of vaccines available (killed, modified live, intranasal) –> indication of problem
why can you not vaccinate cattle younger than 6 months old
because there is interference with maternal antibodies. can infect younger than this but you cannot vaccinate
what is the purpose of a marker vaccine. which virus are marker vaccines available for?
marker vaccines allow you to distinguish between wild type infected versus vaccinated individuals. if you have all proteins, you know that the individual is wild-type infected, versus the vaccine is missing some proteins from the virus which makes it incompetent
what is important to remember about herpes virus vaccines
all herpes virus vaccines dont work well:
- dont block infection 100%, can still have some viral transmission and replication but is slower and has a smaller outbreak
- can compartmentalize based on vaccine status and stop transmission between herds
what 2 viruses and 2 bacteria and 1 parasite make up to complex for scours
- bovine corona virus
- bovine rotavirus
-e.coli - salmonella
- coccidiosis (cryptosporidium)
genus and family of rotavirus
genus: rotavirus
family: reoviridae
what kind of genome and virus is rotavirus
segmented genome, no envelop, multilayered capsid
out of the 7 serogroups for rotavirus, whicsh is the major cause of infection in domestic animals
a - G: A is the major cause of rotaviral infection
how does rotavirus undergo genetic reassortment
co-infection of cells with different rotavirus strains belonging to the same serogroup (A,B,C) undergo mixing of genome segments
clinical signs of BRV
- diarrhea in calves 1-2 weeks of age
- peracute diarrhea cu
incubation period for BRV
1-2 days (very short)
when is BRV shed
5-7 days
how is BRV shed
feces, contaminate environement (no envelope, resistant)
where does BRV replicate
replicates in the cytoplasm of epithelial cells of small intestinal villi
how does BRV cause Maldigestive/malabsorbtive diarrhea
- destruction of mature enterocytes in villi –> altered metabolism, malabsorptive or osmotic diarrhea)
- activation of enteric nervous system by vasoactive components from damaged cells (increases intestinal motility + secretory diarrhea)
- secretion of viral enterotoxin
- increases concentration of intracellular calcium –> raises paracellular permeability
- kills host cells: malabsorbtive or osmotic diarrhoea
