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Genus Rotavirus
Reoviridae
| Question | Answer |
|---|---|
| Major cause of: | enteritis involving the small intestine in neonates of all domestic animals |
| THEY ARE HOST SPECIFIC | |
| Serogroups (Which one affects domestic animals): | 7 different variations (A-G) based on differences in VP6. MOST ROTAVIRUSES AFFECTING DOMESTIC ANIMALS BELONG TO SEROGROUP A. |
| Serotypes are recognized based on: | antigenicity of the outer capsid, GLYCOPROTEIN VP7 (G serotypes) and SPIKE PROTEIN VP4 (P serotypes). Therefore, serotype-specific neutralizing antibodies are produced to VP7 and VP4 antigens |
| Prupose of VP4 and VP7: | VP4: attachment and penetration of the virus. VP7: uncoating |
| Affects what age of animal: | Neontes, 1-8 weeks of age. Severe disease in neonates less than 3 weeks of life but is rarely seen here |
| Transmission? Fecal excretion? Max shedding? Survival rate? Carrier State? | Ingestion of contaminated food, water, or fomites. HIGH, 1x10^11 viral particles/gram of feces. Occurs on the 3rd and 4th days following infection. Survive for SEVERAL MONTHS in feces. YES, in some survivors |
| Importance of VP4 and pathogenesis: | Cell attachment and entry and it's cleavage products (VP5 and VP8).CLEAVAGE IS NECESSARY FOR INFECTIVITY and is carried out by pancreatic enzymes TRYPSIN and CHYMOTRYPSIN. VP4 neutralizing antibodies can bind to and neutralize VP5 and VP8 proteins |
| Relationship with rotaviruses and mature enterocytes: | Enterocytes are immature when first made in the crypts and then mature to cuboidal cells on the tips of the villi. They absorb. ROTAVIRUSES doesn't allow the cuboidal enterocytes to mature. |
| Immature cuboidal enterocytes: | Cannot absorb as well and they have a reduced enzymatic activity (DISACCHARIDASE)-> diarrhea and acidosis. More resistant to viral infection, resulting in a self-lmiting infection |
| Importance of disease in suckling animals: | undigested lactose in milk causes bacterial growth and fermentation and this contributes to acidosis |
| Characteristic clinical feature: | White Scours or Milk Scours |
| Morbidity vs. Mortality: | 100% vs. 0-50% |
| Causes a more severe form of the disease: | reduced colostrum intake, E.coli, Dehydration, secondary bacT infection....MOST RECOVER IN 3-4 days! |
| Different from other diseases like this how: | NO BLOOD...ONLY WATER LOSS! |
| Prevention and control: | Antibody must be present continuously in the lumen of the gut to prevent infection in newborns. Dams are vaccinated with inactivated vaccine to promote higher levels of antibody in the colostrum and milk (vaccinate 4-6 weeks prior to birth) |
| Can modified-live vaccine be given too? | YES, no viremia |