reoviridae

Question 1

what is the structure of a reovirus?

Answer 1

non-enveloped, nearly spherical in outline.3 concentric layers - outer, middle and inner capsule

Question 2

what is the genome of a reovirus like?

Answer 2

segmented dsRNA, ranging from 10-12 segments, depending on genus

Question 3

where does reovirus replication occur?

Answer 3

in the cytoplasm

Question 4

t/f reovirus genetic reassortment occurs b/w viruses w/in a genus or a serogroup

Answer 4

true - can even have RNA segments mixed from human and animal viruses

Question 5

what are two major diseases from the genus orbivirus?

Answer 5

african horse sickness virusbluetongue virus

Question 6

what is a reovirus that is important to humans?

Answer 6

colorado tick fever virus, genus coltivirusalso small mammals, zoonotic

Question 7

what does genus orthoreovirus cause in birds?

Answer 7

Avian reovirus - multiple serotypeschickens, turkey, geese, ducksarthritis, enteritis, respiratory dz, myocarditis, nephrosis, etc

Question 8

what is bluetongue?

Answer 8

an infectious, non-contagious, insect-borne dz of domestic and wild ruminants caused by the bluetongue virus (BTV), a member of the genus orbivirus

Question 9

what are the most susceptible hosts to BTV?

Answer 9

sheep (especially fine wool and mutton breeds that are common in europe) and white-tailed deer

Question 10

what host has inapparent infection with BTV?

Answer 10

cattle, goats, and some wild ruminantsCattle are the primary reservoir and amplifying host

Question 11

t/f - bluetongue is a “List A” dz of the Office of International Epizootics

Answer 11

true; big deal

Question 12

describe bluetongue’s etiology, and the genome of the virus

Answer 12

BTV (ovine orbivirus) belongs to genus Orbivirus, in the family Reoviridaethe BTV genome consists of ten segments of dsRNA

Question 13

how is BTV transmitted?

Answer 13

-biologically by Culicoides spp (biting midge)-USA, mostly Culicoides variipennis var sonorensis*except southeast US, where it is C. insignisless significant: also occasional transplacental and venereal

Question 14

which BTV serotypes are found in the USA?

Answer 14

10, 11, 13, and 172 as well, mainly in the southeast US

Question 15

What is the pathology of BTV in sheep?

Answer 15

-damage to vascular endothelium-intravascular coagulation-necrosis of tissues and organs supplied by damaged capillaries-edema-hemorrhage-congestion-abortion(abortive form of BTV in enzootic areas)-CNS malformations

Question 16

What are some clinical findings of BTV in sheep?

Answer 16

-profuse salivation, edema of muzzle, reddening of the nasal mucosae-mucopurulent nasal discharge, often blood-stained. crust formation on nostrils and lips-cyanosis, necrotic ulceration of tongue-erosion of dental pad, necrosis, hyperemia and ulceration in oral cavity-coronitis, laminitis –> lameness-facial swelling-aborted, macerated fetuses

Question 17

what are the major tools for diagnosing BTV?

Answer 17

-detection of antigen: immunohistochemical tests, such as immunofluorescence, immunoperoxidase tests-detection of nucleic acid: PCR-detection of antibody: agar gel immunodiffusion test (AGID), competitive ELISA

Question 18

what is key to preventing BTV?

Answer 18

vector control

Question 19

what is african horse sickness?

Answer 19

AHS is an infectious, non-contagious, arthropod borne dz of horses, donkeys, and mules

Question 20

t/f- Dogs can contract AHS

Answer 20

true; sometimes they contract a highly fatal form of AHS, resulting from the ingestion of infected carcass material from horses that have died from AHS

Question 21

how does the OIE classify african horse sickness?

Answer 21

List A infectious dzenzootic in sub-saharan africa, although occasional outbreaks reported in northern africa, middle east, and europe.

Question 22

what is the etiology of african horse sickness?

Answer 22

-virus belonging to genus orbivirus-at least 9 antigenic serotypes of AHS virus, based on variations in outer capsid protein VP2 and to a lesser extent VP5 proteins

Question 23

describe transmission and pathogenesis of AHS

Answer 23

-transmitted by culicoides; at least the following two species - imicola and bolitinos-zebras, inapparently infected reservoirs. culicoides bites, then passes to horse. pathogenesis identical to bluetongue in sheep

Question 24

clinical findings in acute(pulmonary) horse sickness (Dunkopf)

Answer 24

-profuse nasal discharge of serous fluid and froth-frothy discharge becomes blood stained-lung exhibits severe interlobular edema, petechiae on the pulmonary pleura-pulmonary edema w hemorrhage-frothy fluid in lungs

Question 25

clinical findings in subacute (cardiac) horse sickness (Dikkop)?

Answer 25

-edema of supraorbital fossae and neck-edema of eyelids-hydropericardium-edema of muscles-serosal petechiae on the apex of the cecum-hydroperitoneum-numerous petechiae in the serosa of the large intestine

Question 26

how do you prevent/control african horse sickness?

Answer 26

-vaccination in enzootic areas-control of vector-reduce exposure to biting insects-slaughter sick or viremic animals

Question 27

Rotaviruses are one of the major causes of severe viral ______ in the young of mammals and birds

Answer 27

diarrhea

Question 28

This virus had a characteristic wheel like appearance, and eventually came to be known as _______

Answer 28

rotavirusrota means wheel

Question 29

describe the structure and classification of rotaviruses

Answer 29

-11 segments of dsRNA-VP6 protein middle layer-based on differences in VP6 protein and gene, rotaviruses are classified into at least 8 groups/species, designated as RVA-RVH-RVAs (group A rotaviruses) are the most common cause of viral diarrhea in the young of humans and wide variety of animal species and birds

Question 30

describe the classification of RVA strains

Answer 30

rotavirus group A:-G-genotypes are based on variations in VP7 (glycoprotein)-P-genotypes and P-serotypes are based on VP4 (protease-sensitive protein)example RVA strain Wa: G1P1A[8]-G1 = G1 is G geno/serotype-P1A = 1A is P serotype-[8] = 8 is P genotype

Question 31

rotavirus: Infected stool contains _______ number of viruses

Answer 31

large

Question 32

rotavirus: _________ transmission is the most likely route of rotavirus spread

Answer 32

fecal-oral

Question 33

rotavirus: The main site of viral multiplication is the mature __________ on the villi of __________

Answer 33

enterocytes; upper small intestine

Question 34

describe rotavirus pathogenesis

Answer 34

-infection of mature enterocytes in intestinal villi-intestinal villus cells damaged during virus replication and release (stunted villi)-diarrhea*remember NSP4 - nonstructural protein 4 - acts as enterotoxin

Question 35

signs of rotavirus?

Answer 35

-severe diarrhea in young animals-profuse diarrhea, anorexia, dehydration, occasionally mild fever-feces are watery to pasty in consistency, often pale yellow, sometimes with mucous and blood flecks

Question 36

best tool to diagnose rotavirus?

Answer 36

polyacrylamide gel electrophoresis (PAGE)

Question 37

etiology of avian reovirus? describe the genome.

Answer 37

genus orthoreovirus10 segments of dsRNA

Question 38

what is avian reovirus?

Answer 38

involved in a variety of dz conditions in domestic poultry, of which the most important is viral arthritis/tenosynovitis in chickens

Question 39

what are the hosts of avian reovirus?

Answer 39

-viral arthritis/tenosynovitis predominantly dz of meat-type chickens (broilers) and is an important cause of leg weakness.-reoviruses have also been isolated from turkeys with tenosynovitis. In muscovy ducks, reoviruses cause high moribidity and mortality, with necrotic foci in the liver, spleen and kidneys.

Question 40

major routes of avian reovirus transmission?

Answer 40

Fecal-oral!!!transovarialinhalation

Question 41

pathogenesis of avian reovirus?

Answer 41

pathogenic viruses localize in the hock joint, where the cause arthritis

Question 42

clinical findings of avian reovirus?

Answer 42

-lameness, viral arthritis/tenosynovitis-swollen, inflamed hock joints, with clear synovial fluid and inflamed synovial membranes-ruptured gastrocnemius tendons

Question 43

prevention of avian reovirus?

Answer 43

-live and killed vaccines available-since chicks are most susceptible to avian reovirus infection immediately after hatching, protocols aim at offering passive immunity to chicks from maternal antibody following vaccination of the breeder hens, or by active immunity after early vaccination with a live vaccine.