Lecture 16: Bunyaviruses and Picornaviruses Flashcards
What is structure of bunyaviruses
Segmented, enveloped, - sense ssRNA
do bunyaviruses L-segment use DNA-dependent DNA polymerases or RNA dependent RNA polymerases
RNA dependent RNA Polymerases
how do bunyaviruses attach to host cells
via envelope glycoproteins
what viruses are included in genus orthobunyaviruses
- Akabane virus
- Schmallenberg virus
- Cache valley virus
orthobuynaviruses infect who
ruminants
how are orthobunyaviruses transmitted
biting arthropods- vector borne
what is pathogenesis of orthobunyaviruses In pregnant vs non-pregnant animals
Pregnant: virus has predilection for infecting fetal cells of CNS and skeletal muscle—> virus mediated destruction of tissue—> abortion and/or congenital abnormalities
Non-pregnant: asymptomatic or mild infections with subsequent immunity
t or f: akabane virus is FAD
true
who does akabane virus affect
cattle sheep, goats
what is vector for akabane virus
culicoides midges
what are some signs of akabane virus
porencephaly, hydrancephaly, arthrogryposis, mummified fetuses, aborted or premature fetuses, encephalitis
Sheep outside U.S. with the following signs- what likely cause
Akabane virus
t or f: schmallenberg virus is FAD
true
who does schmallenberg virus affect
cattle, sheep, goats
what are vectors for schmallenberg virus
culicoides midges and mosquitoes
what are some signs of schmallenberg in adult cattle
mild to moderate disease- reduced milk production, fever, anorexia, malaise, diarrhea
what are some signs of schmallenberg disease in adult sheep and goats
little to no signs, likely missed
what are some signs of schmallenberg in pregnant animals
stillbirths, abortions, congenital defects, in newborns- flaccid paralysis, ataxia, blindness
newborn lamb died shortly after birth- presented with flaccid paralysis, ataxia and blindness. What wrong and likely cause
porencephaly
Cause: schmallenberg virus
t or f: cache valley virus is FAD
false
what is mode of transmission for cache valley virus
mosquitoes
where is cache valley virus found
North America
What is one of the leading causes of reproductive loss and arthrogryposis in ruminants, primarily sheep
cache valley virus
t or f: cache valley virus is zoonotic
true
How is rift valley fever transmitted
mosquitoes
who does rift valley disease affect
sheep, cattle, gaots
t or f: rift valley fever is not zoonotic
false
Where is rift valley fever endemic
eastern and Southern Africa (FAD)
what is mode of transmission for rift valley fever
aedes and culex
What is enzootic cycle for rift valley fever
wildlife are potential maintenance hosts
what is epizootic epidemic cycle for rift valley fever
livestock amplification hosts and secondary bridge vectors involved
outbreaks of rift valley fever are correlated with __
heavy rainfall and localized flooding
what is pathogenesis of rift valley fever
- Localized replication at site of entry
- Viremia spreads virus to liver and other organs leading to widespread cellular necrosis
- In pregnant animals the virus crosses the placenta and leads to extensive cytolysis and fetal death
Liver of aborted lamb, what is likely cause
right valley fever
what are signs of rift valley fever in mature animals
Splenomegaly, enlarged LN’s, liver necrosis
non-specific signs: fever, lethargy, jaundice, diarrhea, blood-tinged mucopurulent nasal d/c
What are some signs of rift valley fever in pregnant animals
abortion and high mortality rate in newborns
where is Nairobi sheep disease found
central and Eastern Africa (FAD)
how is Nairobi sheep disease spread
tick borne- brown ear tick
who does Nairobi sheep disease affect
sheep and goats
t or f: nairobi sheep disease is zoonotic
true
what is a potential reservoir host for Nairobi sheep disease
African field rat
what is pathogenesis of Nairobi sheep disease
- Virus spread through bloodstream infecting and replicating in vascular endothelial cells in several organs
- Acute hemorrhagic gastroenteritis
- Pregnant animals abort
what is clinical signs of Nairobi sheep disease
hemorrhagic gastroenteritis, fetid dysentery, fever, abortion in pregnant animals, dehydration
how do you dx bunyaviruses
- RT-PCR to detect viral RNA
- ELISA, IFA, or VN to detect anti-viral antibodies
vaccines are available for what bunyaviruses
akabane virus, schmallenberg virus, rift valley fever virus
what is structure of picornaviruses
small naked, + sense ssRNA
t or f: picornaviruses are very stable due to naked structure
true
FMD is a __disease primarily of __animals
vesicular disease of cloven-hoofed animals
FMD is FAD endemic where
africa and Asia
how is FMD spread
shed in secretions and excretions of infected animals
FMD is one of the most __animal diseases with important economic losses
contagious
What is mortality rate of FMD in adult vs young animals
adults: low mortality
Young: high due to myocarditis
what is pathogenesis of FMD
- Primary replication site in oropharynx
- Spreads via lymph
- Replicates in various epithelial tissues
who serves as carriers for FMD
infected ruminants that carry virus in pharynx for months to years
what are some clinical signs of FMD in cattle
vesicular lesions: mouth, feet, tongue, teats, udders
Fever
Hypersalivation
Decreased milk production
Lameness
Abortion
how does FMD cause abortion
pyrexial response, does not cross placenta
what are some signs of FMD in pigs
foot lesions severe, snout and tongue lesions, lameness
what are some signs of FMD in sheep, goats, and wild ruminants
oral and foot lesions
t or f: FMD is zoonotic
true
T or f: swine vesicular disease is FAD
true
how is swine vesicular disease transmitted
direct or indirect transmission
t or f: swine vesicular disease is not zoonotic
false
what is pathogenesis of swine vesicular disease
- Entry through damaged skin or ingestion
- Replicates locally and spreads via lymphatics to blood
- Infection of multiple tissues
t or f: virus shedding occurs before onset of clinical disease in swine vesicular disease
true
what are some signs of swine vesicular disease
fever, vesicular lesions that heal quickly, lameness
Senecavirus A is a vesicular disease of __
pigs
what are some signs of Senecavirus A in pigs
vesicular lesions on snout, oral mucosa, coronary bands, fever, lameness, diarrhea in piglets
what are two stereotypes of porcine teschoviruses
- Teschovirus encephalomyelitis
- SMEDI syndrome
Porcine teschovirus is ubiquitous in swine population through world. Transmission through __
fecal-oral
Porcine teschoviruses: teschoviruses encephalomyelitis stereotype is associated with virulent stains of __
PTV-1
how is PTV: teschovirus encephalomyelitis transmitted
direct or indirect contact with infected pigs, primary mode is feco-oral
what is pathogenesis of PTV: teschovirus encephalomyelitis
- Ingested virus replicates in intestinal tract and associated lymph tissue
- Virus sheds into feces
- Viremia occurs and results in spread to CNS
what are some signs of severe cases of teschovirus encephalomyelitis
ataxia (first sign), fever, anorexia, seizures, nystagmus, ascending paralysis
what are some signs of mild disease of teschovirus encephalomyelitis
ataxia, paresis
what does Teschovirus SMEDI syndrome cause
stillbirth, mummification, embryonic death, infertility
Teschovirus SMEDI syndrome is pathogenic only to __and __
embryos ante fetuses
how is teschoviruses SMEDI syndrome transmitted
fecal-oral route followed by infection of intestinal tract then transplacental spread
how do you dx picornaviruses
ELISAs or VN assays, RT-PCR
how do you control picornaviruses
disinfecting, movement restrictions, slaughter affected with FMD, vaccinate for FMD, exposure gilts to older sows or mummified fetuses before breeding to prevent SMEDI
