Reoviridae Flashcards
How many capsid layers do reoviruses technically have?
Three:
Outer layer: T=13
Inner layer: T=2
Middle layer between the two
Describe the genome of reoviruses?
dsRNA ranging from 10-12 segments
Where does reovirus replication occur?
The cytoplasm
T or F: Reoviruses are vulnerable to general reassortment?
TRUE. Because segmented genome! Progeny viruses have gene segments of both virus ‘A’ and virus ‘B’
Under which genus and subfamily is African horse sickness and Bluetongue virus classified?
Subfamily: sedoreovirinae
Genus: Orbivirus
Under which subfamily and genus is the avian reovirus classified?
Subfamily: spinareovirinae
Genus: orthoreovirus
Who are the most susceptible hosts to BTV?
Sheep, particularly fine wool and mutton breeds in Europe and SOME deer (white-tailed)
What hosts are known to have an inapparent BTV infection?
Cattle, goats, and some wild ruminants
Cattle are the primary reservoir!
T or F: BTV is infectious AND contagious
F. It is infectious and non-contagious
What ‘list’ under the OIE does Bluetongue fall under?
List A! Aka you need to report that ish
How many segments of dsRNA is contained in the BTV genome?
10
How are different BTV strains classified?
Antigenic differences of outer shell proteins
What arthropod transmits BTV?
Culicoides variipenis var sonorensis all over
Culicoides insignis in the Southeast
What are the different ways BTV can be transmitted?
Arthropod-borne, trans-placental, and venereal
Which serotypes are most likely found in the U.S?
10, 11, 13, 17 and then serotype 2 is mainly in the Southeast
Pathological signs of BTV?
Vascular endothelium damage, IV coagulation, tissue necrosis, edema, hemorrhage, congestion, abortion, CNS malformations
Symptoms of a severe febrile reaction?
Profuse salivation, muzzle edema, reddening of nasal mucosae, mucopurulent nasal discharge often blood stained, and crust formation on nostrils and lips
Clinical findings of BTV in sheep?
Cyanosis, necrotic ulceration of tongue, erosion of dental pad, necrosis, hyperemia, ulceration in oral cavity, coronitis, laminitis, facial swelling, aborted fetuses
How do you diagnose BTV?
Tissue culture or in embryos
Detection of antigen via mmunohistochemical tests i.e. immunofluorescence, immunoperoxidase tests
Detection of nucleic acids via PCR
Detection of antibody using ELISA or AGID
Necropsy, histology
Prevention of BTV?
VECTOR CONTROL and attenuated vaccines (however, are serotype specific)
T or F: African Horse Sickness (AHS) can sometimes infect dogs via ingestion of infected carcass material of horses
True!
T or F: AHS has a fairly low mortality rate
FALSE. Mortality rate is 75-90% in horses
Which ‘list’ is AHS on according to the OIE?
List A! Enzootic in sub-Saharan Africa but you need to report that shiz
Which outer capsid protein dictates serotyping?
VP2, but VP5 protein variation also contributes
*There are at least 9 serotypes identified thus far
Describe the genome of the AHS virus
10 segments of dsRNA
How is AHS transmitted
Blood from infected horses OR ZEBRAS (reservoir) is ingested by Culicoides and then the midge bites/infects horses
Clinical findings in horses with Dunkop (acute pulmonary) sickness?
Profuse nasal discharge, may become blood stained, interlobular edema, petechiae, pulmonary edema, fluid accumulation in trachea, frothy lung fluid
Clinical findings in horses with Dikkop (subacute cardiac) sickness?
Edema of supraorbital fossa and neck and eyelids, conjunctiva congestion, hydropericardium, muscle edema, cecal petechiae , hydroperitoneium, colon edema
Prevention and control of AHS?
Vaccination in enzootic areas, vector control, reduced vector exposure, slaughter of sick animals
Describe the rotavirus genome
11 segments of ds RNA, classified based on the VP6 protein (at least 8 groups)
Which group of rotavirus is the most common?
Group A Rotaviruses because of viral diarrhea in young animals
Which 2 outer capsid proteins elicit protective antibodies and have formed the basis of current rotavirus vaccines?
VP7 and VP4
RVA Strain Wa: G1P1A[8]
G1: G genotype/serotype (G genotypes and serotypes are the same)
1A: P serotype (at least 14 P serotypes)
[8]: P genotype (at least 37 P genotypes)
Remember this for some reason?
Transmission routes of rotaviruses?
Fecal oral most likely because of large number of viruses, can survive in environment so can be transmitted through contaminated objects, water, food
Where does the rotavirus replicate
Mature enterocytes on the villi of upper small intestine
Other ‘directions’ rotavirus particles can take other than to the mature enterocytes?
NSP4 acts as enterotoxin, activates phospholipase C pathway, calcium efflux from ER, activation of calcium-chloride channels, stimulation of free nerve endings, malabsorption and fluid secretion leading to diarrhea
Symptoms of rotavirus?
Severe diarrhea in young animals, anorexia, dehydration, sometimes fever
Watery feces pale yellow in color
Diagnosis of rotavirus?
Polyacrylamide Gel Electrophoresis (PAGE)*
ELISA, EM, PCR, FAT
Describe the genome of Orthoreovirus and what condition does it cause?
10 segments of dsRNA
Viral arthritis, tenosynovitis in chickens!
What are the hosts and transmission routes of orthoreovirus?
Meat-type chickens, turkeys with necrotic foci in liver, spleen, kidneys
Transmission: fecal oral, transovarial, inhalation
Where do orthoreoviruses localize?
Hock joint–cause arthritis
After traveling through the blood throughout the body
Clinical findings in animals with orthoreoviruses?
Lameness, swollen and inflamed hock joints, inflammation of synovial membranes, ruptured gastrocnemius tendons, stunting syndrome, atrophy of pancreas
Diagnosis of avian reovirus?
Necropsy, virus isolation from affected joints in embryo kidney, liver, or lung cell cultures, serological testing, PCR
How do you prevent avian reoviruses?
Live/killed vaccines available, vaccines aim at offering passive immunity to chicks from their maternal antibodies OR active immunity after early vaccination with a live vaccine
