bunyaviridae Flashcards
bunyaviridae general
virions spherical, enveloped, glycoprotein spikes, no matrix protein, three nucelocapsid segments with helical symmetry, segmented negate sense, ssRNA
three segments large L medium M and S small, cytoplasmic replication, cytocidal for vertebrate cells, genetic reassortment can occur between the segments, budding into golgi
bunyavidirdae genera
arthropod borne-orthobunyavirus-akbane virus
phlebovirus-rift valley fever
non arthropod-borne-hantavirus-hantaan virus
phlebovirus->rift valley fever
sheep cattle goats, percutaneous or aerosol exposure to humans or bites may infect humans, humans prob dead end hosts, located in rift valley
rift valley fever biological transmission
primary vector= Aedes
Secondary vector: Culex and Anopheles, culicoides (mechanical)
rift valley fever transmission
enzootic cycle -mosquitoes
epizootic-heavy rainfall, massive mosquito out break all lead to human epidemic, very high newborn death rate
rift valley fever transmission 2
the virus is transmitted transovarially among floodwater, virus can survive in mosquito eggs Aedes increase with heavy rains, infected could become viremic, high proportion of animals and humans at risk because of amplification with biting midges
Rift valley virus path
rapid replication and reaches high titer, virus replicates in liver and other major organs cause widespread necrosis, encephalitis, hepatic necrosis, renal failure, and shock, 90-100% of pregnant animals abort
Rift valley sheep clinical signs
mortality in young lambs, young animals surviving the hepatic infection may show encephalomyelitis,90-100 percent ewes abort; less sever in cattle but same signs
rift valley fever Dx
should be expected after heavy rains
rift valley control
attenuated vaccines, inactivated vaccine in vitro both produced from mouse brain, vector control also important
Akabane-orthobunyavirus
congenital disease of cattle, sheep, goats
transmission-biting midges and mosquitos
aka bane path
bite and pregnant ruminant infected, virus reaches fetus from maternal circulation, most severe fetal lesions in cattle occur during infection within 3-4 months of gestation, encephalomyelitis, hydraencephaly, arthrogryposis
akabane clinical signs
not usually seen in young animals, can cause seat or abotion of baby or premature birth and hydraencephaly, arthrogryposis
akabane Dx
look for neutralizing antibody in serum collected from aborted fetuses or from newborn calves, kids, or lambs before ingestion of colostrum, must be isolated from placenta
akabane control
reportable disease, inactivated vaccine available in japan and australia
