Reoviridae Flashcards
What are the 3 genera of veterinary importance in reoviridae?
- orthoreovirus: arthritis and tenosynovitis in poultry
- orbivirus: arthropod borne, infect horse (African horse sickness), ruminants (bluetongue)
- rotavirus: enteritis in neonatal farm animals
Mammalian reovirus 1-3
Orthoreovirus
- isolated from many species of mammals
- hepaloencephalomyelitis in mice
Avian reovirus 1-11
Orthoreovirus
- chickens, turkeys, geese
- arthritis, nephrosis, enteritis, chronic respiratory disease, myocarditis
Bluetongue virus 1-25
Orbivirus
- sheep, cattle, deer
- bluetongue
African horse sickness 1-9
Orbivirus
- horse, donkey, mule, zebras
- african horse sickness
Equine encephalosis virus 1-5
Orbivirus
- horse
- abortion and encephalitis
Epizootic hemorrhagic disease of deer virus 1-2
Orbivirus
- deer
- epizootic hemorrhagic disease
Ibaraki virus
Orbivirus
- cattle (not in US)
- acute febrile disease similar to bluetongue
Palyam virus 1-6
Orbivirus
- cattle (not in US)
- abortion, congenital abnormalities
Rotaviruses
Host specific, infect virtually all animals
- enteritis
Colorado tick fever virus, Eyach virus
Coltivirus
- zoonotic, small animals and humans
- colorado tick fever
Aquareovirus
Viruses of fish and shellfish
Reoviridae genome
Segmented (10-12), double stranded RNA genomes
- 10 for othoreovirus and orbivirus
- 11 for rotavirus
- 12 for coltivirus
Disease of orthoreoviruses are usually insignificant, except in ______
Rodents, chickens, and turkeys
Which genera of reoviruses is vector-borne?
Orbivirus
- have a resulting seasonal effect
Orbiviruses have 3 layers: ______, ______, and _____
- inner core layer: VP1, VP4, VP6
- Core layer: VP3 and VP7 (group specific antigen)
- outer layer: VP2 and VP5 that are responsible for induction of immune response
Rotaviruses often cause disease in ______
New-borne animals after maternal antibody has waned
- diarrhea is more severe than with other viruses
What are the 7 major subgroups of rotavirus?
A-G based on VP6
- A: pathogens from humans, cattle, etc
- B: human pathogens only
- C and E: swine only pathogens!!!
- D and F: pathogens from fowl
What is the most abundant viral protein, that is the major determinant of group reactivity?
VP6
- is the target of common diagnostic assays
Reoviral replication
Involves synthesis of viral mRNA and genomic RNA by RNA dependent RNA polymerase
- is packed within virion particles
- reason why reoviral genomic RNA is NOT infectious!!
T/F: Genetic reassortment occurs between viruses within each genus or subgroup
True
Bluetongue infects both _____ and _____
Domestic and wild ruminants
Bluetongue shares a common antigen with _______ and _______
Epizootic hemorrhagic disease of deer virus and African horse sickness virus
Virulence of bluetongue virus
Varies due to 25 serotypes
- only 5 serotypes recognized in US
- seroprevalence of cattle in US is >18%
Does bluetongue virus survive outside the host?
No
- transmission due to animal carcasses or meat products is not possible
Is the cattle or sheep industry more heavily affected by bluetongue in the US?
Cattle industry
- cattle are often not noticeably ill, but they carry the disease for months after initial infection
Bluetongue virus is transmitted by _______
Culicoides midges
- disease is prevalent in mid-summer to early fall
- female midges take up bluetongue viruses as they feed on blood of infected animals
What midges make up the complex that is most involved in the spread of bluetongue virus?
- C variipennis variipennis
- C variipennis sonorensis
- C variipennis occidentalis
Sheep affected with bluetongue
Swollen lips and tongue
Cattle and goats affected with bluetongue
Usually subclinical, only 5% develop disease
General symptoms of bluetongue
Fever, listlessness, lack of appetite, rapid breathing
- mucous membranes of eyes, nose and mouth turn red and lips become swollen
- 7-12 days in the disease you get lameness with petechical hemorrhage at coronary band and hooves may slough
Bluetongue infection of pregnant animals
May result in abortion, stillbirth, or weak live birth
- early embryonic loss and decreased reproductive efficiency
What is the most definitive means of BTV diagnosis?
Virus isolation from blood of viremic animals
Bluetongue is a ______ disease
List A
- internationally regulated!!!
Control of BTV
Based on vaccination of animals in endemic areas and decreasing number of insect vectors by bringing animals inside around dusk
Is there a universal vaccine for bluetongue?
No, all vaccines are serotype dependent
What is the number one viral agent to cause diarrhea in new borne calves?
Bovine rotavirus
Transmission of BTV can also occur _______
Transplacentally
- cannot be transmitted between mammals
Unlike rotavirus, BTV is susceptible to _______
Common disinfectants and low pH
- rotavirus are stable in wide range of environments
_____ and _____ are neutralizing antigens and must be considered when vaccinating
VP4 and VP7
