Final Exam - Reoviridae Flashcards
Genus Orbivirus
African horse sickness virus, Bluetongue virus
Genus Orthoreovirus
Avian reovirus multiple serotypes
Genus: Rotavirus
RVA (Group A Rotavirus)
Blue Tongue Virus
An infectious non-contagious, insect-borne disease of domestic and wild ruminants
Blue Tongue Virus Hosts
Most susceptible and common - Sheep and white tailed deer
Inapparent Infection - Cattle, goats and some wild ruminants.
List A Disease
Blue tongue virus is a list A disease in the OIE. They are transmissible diseases that have the potential for very serious and rapid spread, irrespective of national borders, that are serious socio-economic or public health consequence and that are of major importance in the international trade of animals and animal products.
Blue Tongue Virus Genome
Consists of ten segments of double stranded RNA (dsRNA)
Transmission - BTV
Arthropod (Insect)-borne transmission. Transmitted by certain species of Culicoides, a biting midge.
Can also be transmitted trans-placentally and venereal transmission.
Pathology of BTV
- Damage to vascular endothelium
- Intravascular coagulation
- Necrosis of tissues and organs supplies by damaged capillaries
- Edema
- Hemorrhage
- Congestion
- Abortion (abortive form of BTV disease in enzootic areas)
- CNS malformations
Clinical Findings of BTV in Sheep
Severe febrile reaction. Profuse salivation, edema of muzzle, reddening of nasal mucosae. Mucopurulent nasal discharge, often blood stained. Crust formation on nostrils and lips. Linear erosion and reddening of the buccal mucosa. Cyanosis, necrotic ulceration of ht etongue. Erosion of dental pad, necrosis, hyperemia, ulceration in oral cavity. Coronitis and laminitis causing lameness. Extensive facial swelling and aborted, macerated fetuses.
Clinical Findings of BTV in Cattle
Erosions in the buccal cavity, drooling of saliva. Hemorrhage and congestion of muzzle. Ulcerative glossitis and stomatisis. Serous to mucopurulent nasal discharges, erosions on the muzzle with sloughing of the mucosa. Ulceration of teats, coronitis and lamness, lachrymation, hyperemia and edema of conjunctiva, edema of face, abortion and congenital deformities.
Diagnosis of BTV
Clinical signs, virus isolation: by tissue culture of in developing chick embryos. Detection of Antigen (immunohistochemical tests, such as immunofluorescence, immunoperoxidase test). Detection of nucelic acid (polymerase chain reaction (PCR)). Detection of antibody (agar gel immunodiffusion test (AGID), competitive ELISA). Necropsy findings, histology.
Prevention of BTV
Attenuated vaccines which are serotype specific. Vector control.
African Horse Sickness (AHS)
List A infectious disease of the OIE. Infectious, non-contagious, arthropod borne disease of horses, donkey, and mules.
Transmission of AHS
Transmitted by Culicoides species that occurs regularly in most countries of sub-saharan Africa. At least two field vectors involved: C. imicola and C. bolitinos
Pathogenesis of AHS
Infected horse or a zebra inapparently infected (reservoir) are bitten by Culicoides. Healthy horse bitten by Culicoides and become infected. Pathogenesis is the same as bluetongue in sheep.
Clinical Findings of AHS - Acute (Pulmonary) Horse Sickness (Dunkop).
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. Frothy fluid in lungs. Fluid accumulation in trachea. Pulmondary edema with hemorrhage.
Clinical Findings of AHS - Subacute (Cardiac) Horse Sickness (Dikkop)
Edema of supra-orbital fossae and neck. Edema of eyelids. Congestion in conjunctiva. Hydropericardium. Edema of muscles, Serosal petechiae on the apex of the cecum. Hydroperitoneum, severe edema of the mucosa of the colon. Numerous petechiae in the serosa of the large intestine.
Diagnosis of AHS
Clinical signs, necropsy and histopatholgy, virus isolate, serology (ELISA, virus neutralization test), detection of viral nucleic acid (PCR and RT-PCR).
Prevention and Control of AHS
Vaccination in enzootic areas. Control of vector population. Reduced exposure to biting insects. Slaughter of sick or viremic animals.
Rotavirus
One of the major causes of severe viral diarrhea in the young of mammals and birds. Has a characteristic wheel like appearance.
RVAs (Group A rotaviruses)
Are the most common cause of viral diarrhea in the young of humans and a wide variety of animals species and birds.
VP6 Protein Middle Layer
Rota virus structure - base don differences in VP6 protein and VP6 gene, rota viruses are classified into at least 8 groups/species, designated as RVA-RVH.
VP7 and VP4
Outer capsid VP7 and VP4 proteins elicit protective antibodies, forming the basis of current rota virus vaccines.
RVA Strain Wa: G1P1A[8]
G1 is a G genotype/serotype.
P1A[8]: 1A is P serotype and [8] is P genotype.
Rotavirus Transmission in Animals and Humans
Infected stool contains large number of viruses. Fecal oral transmission is the most likely route of rotavirus spread. Virus can survive in environment, is resistant to common disinfectants and can be transmitted through contaminated objects, water, or food. The main site of viral multiplication is the mature enterocytes on the villi of upper small intestine.
Rotavirus Pathogenesis
Ingestion of rotavirus particles. NSP4 (nonstructural protein 4) acts as an enterotoxin. Activation of phospholipase C pathway, release of IP3. Calcium efflux from ER to cytoplasm. Activation calcium chloride channel. Release of peptide from endocrine cells of gut which stimulate free nerve endings. This leads to infection of mature enterocytes in intestinal villi. Intestinal villus cells damaged during virus replication and release. Malabsorption and fluid secretion. Diarrhea.
Rotavirus Symptoms
Severe diarrhea in young of different animals, such as calves (1-3 weeks), lambs (
Rotavirus Diagnosis
- Polyacrylamide Gel Electrophoresis (PAGE)
- ELISA. Commercial kits are available, such as Dako kit
- Electron Microscopy
- Hybridization assays
- PCR
- FAT
- Rapid immuno-chromatographic test, such as “the QuickTest Rotavirus Strip test”
Equine Rotavirus Vaccine
Equip Rotavirus, Pfizer. Inactivated adjuvanted liquid vaccine in single dose syringes for administration to pregnant mares. Each single vaccine dose contains 1 mL of an inactivated oil adjuvanted vaccine of Equine Rotavirus H2 strain.
Bovine Rotavirus Vaccine - SCOURGUARD 4K, Zoetis
Aduvated. Bovine rota-coronavirus inactivated virus, Cl. perfringens type C toxoid, E. coli Bacterin. For vaccination of healthy, pregnant cows.
Bovine Rotavirus Vaccine - Guardian, Merck
Bovine rotavirus-coronavirus vaccine, killed virus, Cl. perfringes types C and D, E. coli bacterin-toxoid. For vaccination of healthy, pregnant cows.
Avian Reovirus
Avian reoviruses are involved in a variety of disease conditions in domestic poultry of which the most important is viral arthritis/tenosynovitis in chickens.
Avian Reovirus Hosts
Meat-type chickens (broilers). Sometimes turkeys, Muscovy ducks.
Avian Reovirus - Transmission
Fecal oral route, transovarial and inhalation
Avian Reovirus - Pathogenesis
After intestinal replication , the virus spreads via the bloodstream to all parts of the body. Pathogenic viruses localize in the hock joint, where they cause arthritis.
Avian Reovirus - Clinical Findings
Lamness, viral arthritis/tenosynovitis. Swollen and inflamed hock joints. Clear synovial fluid and inflammation of synovial membranes. Ruptured gastronemius tendons. Stunting syndrome/ malabsorption/pale bird syndrome. Atrophy of pancreas.
Avian Reovirus - Diagnosis
Clinical signs, necropsy, virus isolation (reovirus can be isolated from affected joints in primary chick embryo kidney, liver, or lung cell cultures, or via the yolk sac or chorioallantoic membrane of embryonated chicken eggs. Serological tests (ELISA, virus neutralization test). Detection of nucleic acids (PCR).
Avian Reovirus Arthritis Prevention
Live and killed vaccines are available. Since chicks are most susceptible to avian reovirus infection immediately after hatching, vaccine protocols aim at offering passive immunity to chick from maternal antibody following vaccination of the breeder hens, or by active immunity after early vaccination with a live vaccine.
