Avirulent rotavirus infections protect calves from disease with and without inducing high levels of neutralizing antibody.
Two bovine rotaviruses, C3-160 and 17/4, which multiplied in calves without inducing disease, were studied for their ability to protect against disease caused by a virulent rotavirus, CP-1. Rotavirus 17/4 and the virulent virus CP-1 cross-neutralized poorly and, on the basis of 20-fold differences in neutralization titres, belonged to different serotypes. Rotaviruses C3-160 and CP-1 were more closely related: neutralization of the CP-1 virus by C3-160 antisera was within 20-fold of the homologous titre although neutralization of the C3-160 virus by CP-1 antisera was not. Nine gnotobiotic calves infected with either C3-160 or 17/4, had rotavirus antibody in their faeces and/or serum 21 days after oral inoculation as detected by indirect immunofluorescence and IgG, IgM and/or IgA antibodies by ELISA. As expected from the antigenic relationships between the viruses, the sera and faeces from the four calves infected with C3-160 contained moderate levels of neutralizing antibody to the virulent virus CP-1 and the sera and most of the faeces from the five calves infected with 17/4 contained undetectable or low levels. When challenged with CP-1 on day 21, four age-matched controls developed disease whereas all of four calves previously infected with C3-160 and four of five calves previously infected with 17/4 were protected from disease. It was concluded that avirulent rotavirus infection provided protection against disease caused by a virulent rotavirus even when one of the avirulent viruses was poorly related to the virulent virus by neutralization. Mechanisms other than neutralizing antibody appeared to be important in protection.
Bridger
J C
JC
Agricultural and Food Research Council Institute for Animal Disease Research Compton Laboratory, Berkshire, U.K.
Oldham
G
G
D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis*; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology / Q000382:microbiology* / Q000517:prevention & control; D005243:Feces / Q000382:microbiology; D009500:Neutralization Tests; D012401:Rotavirus / Q000276:immunology* / Q000302:isolation & purification / Q000472:pathogenicity; D012400:Rotavirus Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D014774:Virulence
D000914:Antibodies, Viral