Reoviridae, Togaviridae (Final) Flashcards
General properties of Reoviridae
- structure
- genome
- replication location
- nonenveloped, spherical
- 3 concentric layers: outer, intermediate, inner
- genome: segmented dsRNA
- viral replication in cytoplasm
Blue Tongue virus
- family, genus
- type of disease
- hosts, reservoir
- danger (OIE)
- Reoviridae, Orbivirus
- an infectious, non-contagious, insect-borne disease
- sheep most susceptible
- cattle are primary reservoir
- List A disease of OIE
Transmission of Blue Tongue virus
- arthropod-borne
- Cullicoides species
- transplacental transmissin
- venereal transmission
Clinical signs of Blue Tongue in sheep
- salivation, edema of muzzle, reddening of nasal mucosa
- mucopurulent nasal discharge
- crust on nostrils and lips
- erosion and reddening of buccal mucosa
- cyanosis and necrotic ulceration of tongue
- abortion
Diagnosis of Blue Tongue
- clinical signs
- virus isolation
- immunofluorescence
- PCR
- agar gel diffusion, ELISA
- necropsy, histology
African Horse Sickness
- family, genus
- type of disease
- hosts
- danger (OIE)
- Reoviridae, Orbivirus
- infectious, non-contagious, arthropod-borne disease
- hosts are horses, donkeys and mules
- List A OIE
African Horse Sickness transmission
- transmitted by Cullicoides speces
- dogs can contract fatal form by ingesting infected carcass material
Clinical Signs of African Horse Sickness
Acute (pulmonary) - Dunkop - nasal discharge, blood stained - pulmonary edema with hemorrhage Subacute (cardiac) - Dikkop - edema of supraorbital fossa, neck, and eyelids - hydropericardium - edema of muscles and colon mucosa
Diagnosis of African Horse sickness
- clinical signs
- necropsy and histopathology
- virus isolation
- ELISA, virus neutralization test
- PCR
What is the major cause of severe viral diarrhea in young mammals and birds?
Rotaviruses
Transmission of Rotaviruses
- fecal-oral transmission
- fomites
Pathogenesis of Rotaviruses
- ingestion of viral particles
- infection of mature enterocytes in intestinal villi (damages cells)
- non-structural protein 4 (NSP4) acts as enterotoxin
- malabsorption
- diarrhea
Rotavirus symptoms
- severe diarrhea in young animals
- anorexia, dehydration, mild fever
- feces watery to pasty, pale yellow
Diagnosis of Rotavirus
- polyacrylamide gel electrophoresis
- ELISA
- electron microscopy
- hybridization assays
- PCR
- FAT
- rapid immune chromatographic test
What vaccines are available for Rotaviruses?
Equine RV vaccines - inactivated adjunvanted liquid vaccine in single dose Bovine RV vaccines - Scourguard: inactivated - Guardian: killed
Avian Reovirus
- genus
- main disease caused
- hosts
- Orthoreovirus
- Viral arthritis/tenosynovitis
- chickens, turkeys, ducks
Avian Reovirus
- transmission
- pathogenesis
- fecal-oral route, transovarial, inhalation
- after intestinal replication, virus spreads via bloodstream to all parts of the body
- pathogenic viruses locate in hock joint
Avian Reovirus
- clinical signs
- lameness
- viral arthritis/tensosynovitis
- swollen and inflamed hock joints
- ruptured gastronemius tendons
- stunting syndrome, malabsorption, pale bird syndrome
- atrophy of pancreas
Avian Reovirus
- diagnosis
- prevention
- clinical signs, necropsy, virus isolation, ELISA, PCR
- live and killed vaccines
- aim for passive immunity to chicks from maternal antibodies following vaccination of breeder hen
General Features of Togaviridae
- structure
- genome
- replication location
- spherical, enveloped, icosahedral
- envelope has 80 spikes with E1/E2 proteins
- linear, single stranded pos sense RNA
- replication in cytoplasm
Eastern Equine Encephalitis
- family, genus
- hosts
- transmission
- Togaviridae, Alphavirus
- horses and humans
- reservoirs: passerine birds, reptiles and rodents
- humans and equines are dead-end hosts
- spread via mosquitoes
- enzootic transmission cycle
Eastern Equine Encepalitis
- pathogenesis
- inoculation via mosquito bite
- virus replicates in different cells and organs
- viremia
- enters CNS via blood
- replication in neurons, vascular endothelial cells, and glial cells
- apoptosis of neuronal and glial cells
- encephalitis
Eastern Equine Encephalitis
- clinical signs in horses
- fever, anorexia, depression
- hypersensitive to sound
- periods of colic before neuronal disease
- walk into objects or in circles
- involuntary muscle movements
- inability to hold up head > head pressing or leaning back > incoordination > complete paralysis
Western Equine Encephalitis
- compared to EEEV
- hosts/reservoirs
- transmission
- lower fatality in humans, less virulent in horses
- reservoirs: passerine birds, lagamorphs, rodents, domestic and wild birds
- transmitted via mosquito
- enzootic and epizootic transmission cycles
Western Equine Encephalitis
- clinical signs in horses
- most are mild or asymptomatic
- depression, fever, blindness, inability to swallow, paralysis, convulsions, death
Venezuelan Equine Encephalitis Virus
- subtypes, cycle, virulence
- A, B, C: epizootic/epidemic cycle, virulent for equines
- D, E, F: enzootic/endemic cycle, not virulent for equines
Venezuelan Equine Encephalitis Virus
- transmission (cycles)
Enzootic: - primary vector: Culex spp. mosquito - host: rodents - accidental hosts: human and equines Epizootic: - primary vector: mosquitoes - equine is amplifying host - human is dead-end host
Venezuelan Equine Encephalitis
- clinical signs in horses
- anorexia, fever, depression, encephalomyelitis, head hung low, involuntary muscle movements, flaccid lips, dropped ears, incoordination, blindness, paralysis, death
Diagnosis of Equine Encephalitis virus
- clinical signs
- necropsy and histology
- virus isolation
- immunohistochemistry
- ELISA
- RT-PCR
- hemagglutination inhibition
- complement fixation
Prevention of Equine Encephalitis virus
- formalin inactivated EEEV and WEEV vaccines
- horses should receive one dose followed by booster in three weeks
- tissue cultured attenuated vaccine for VEEV
