Prevalence of antibodies to four bovine rotavirus strains in different age groups of cattle

Prevalence of neutralizing antibodies to 9 rotavirus strains representing 7 G-serotypes in sheep sera

Neutralizing antibodies to 9 rotavirus strains representing serotypes G1, G3, G5, G6, G8, G9, and G10 were investigated in 212 ovine serum samples from 3 age groups, 1-week-old lambs, 2- to 3-months-old lambs and adult sheep. All sera from 1-week-old lambs had neutralizing antibodies to all 9 rotavirus strains. Both neutralizing antibody titers and prevalences to all 9 strains markedly decreased in the 2- to 3-months-old lamb group and increased again in the adult sheep group. Also, adult sheep sera neutralized a larger number of rotavirus strains than 2- to 3-months-old lamb sera. The highest neutralizing antibody titers and prevalences were found to strains B223 and K923, representing serotype G10, to strain RRV, representing serotype G3, and to strain NCDV, representing serotype G6, indicating that these could be the predominant 3 rotavirus serotypes in Spanish sheep. The rotavirus serotypes infecting sheep observed by us differ from those described for cattle, where G6 is the most prevalent serotype followed by G10, and G3 has been seldom found. Very low prevalences were observed for strains WA and OSU representing serotypes G1 and G5 respectively, suggesting that they probably do not infect sheep and neutralizing antibodies found are derived from heterotypic responses to other serotypes. Intermediate prevalences and titers were found to strains UK (serotype G6), 69M (serotype G8) and WI61 (serotype G9). Neutralizing antibodies distinguished between different strains sharing their VP7 specificity: B223 and K923, a bovine and an ovine serotype G10 strains, and NCDV and UK, two serotype G6 bovine rotavirus strains with different VP4 antigen.

In situ inactivation of animal viruses and a coliphage in nonaerated liquid and semiliquid animal wastes

The persistence of five animal viruses, representing picorna-, rota-, parvo-, adeno-, and herpesviruses, and the coliphage f2 was determined in the field by exposing the viruses to different animal wastes and by adopting an established filter sandwich technique. This technique allows us to copy the natural state of viruses in the environment, where adsorption onto or incorporation into suspended solids may prolong virus survival. Using filter sandwiches either equipped with porous (15 nm in diameter) or poreless polycarbonate (PC) membranes, it was possible to differentiate between overall virus inactivation and the effect of virucidal agents that act through poreless PC membranes. Depending on ambient temperature, pH, and type of animal waste, values for time, in days, required for a 90% reduction of virus titer varied widely, ranging from less than 1 week for herpesvirus to more than 6 months for rotavirus. Virus inactivation progressed substantially faster in liquid cattle manure, a mixture of urine and water (pH > 8.0), than in semiliquid wastes that consisted of mixtures of feces, urine, water, and bedding materials (pH < 8.0). Hitherto unidentified virucidal agents that permeate poreless PC membranes contributed substantially to the overall inactivation. On the other hand, substances that protect rotavirus and possibly other viruses from inactivation may be present in animal wastes. Together, the study showed that viruses contained in manure may persist for prolonged periods of time if stored under nonaerated conditions. At times of land application, this may lead to environmental contamination with pathogens.

Rotavirus infection in calves, piglets, lambs and goat kids in Trinidad

Faecal samples from diarrhoeic and non-diarrhoeic calves, piglets, lambs and goat kids were collected and screened by a latex agglutination test to detect the presence of group A rotavirus antigen. Of a total of 470 animals screened, 138 (29.4%) had faecal samples positive for rotavirus antigen. The prevalences of infection were 27.7% (73/264) in calves, 27.8% (45/162) in piglets, 48.6% (18/37) in lambs and 28.6% (2/7) in goat kids. Rotavirus antigen was not detected in calves and lambs < 1 week old and in piglets < 2 weeks old. The highest prevalence was found in calves between the ages 1-6 weeks (72.6%); piglets, 2-8 weeks (91.1%) and in lambs 1-8 weeks (88.9%). The overall prevalence of infection was 39.9% for diarrhoeic and 13.4% for non-diarrhoeic animals and the difference was statistically significant (P < or = 0.001; X2). Differences among husbandry systems in relation to the prevalence of rotavirus infection were not statistically significant (P > or = 0.05; X2). The relatively high prevalence of rotavirus infection in the young animals tested, coupled with the detected significantly higher infection rates in diarrhoeic animals, indicate that rotavirus may be important in livestock diarrhoea in Trinidad.

Bovine rotavirus type detection by neutralizing monoclonal antibodies

A series of monoclonal antibodies were developed against bovine rotavirus Q17. Among the five high affinity antibodies characterized, two (RQ 31 and RQ 4) were able to neutralize type G 6 viruses and may be specific for PB 1 type virus. Seventy seven feces from diarrheic calves were tested by "double sandwich" ELISA using four monoclonal and one polyclonal anti-rotavirus antibodies. The combination of mono- and polyclonal antibodies thus appears to be a more efficient strategy for detection and typing of bovine rotaviruses.