PASSIVE-IMMUNITY TO BOVINE ROTAVIRUS IN NEWBORN CALVES FED COLOSTRUM SUPPLEMENTS FROM COWS IMMUNIZED WITH RECOMBINANT SA11 ROTAVIRUS CORE-LIKE PARTICLE (CLP) OR VIRUS-LIKE PARTICLE (VLP) VACCINES

Heterotypic passive immunity to IND (P[5]G6) bovine rotavirus (BRV) wa s evaluated. Three groups of calves (n = 5 per group) were fed 1% pool ed colostrum supplements (birth to 7 days of age) from BRV seropositiv e cows vaccinated with recombinant SA11(P[2]G3) rotavirus-like particl es (VLPs), recombinant SA11 rotavirus core-like particles (CLPs), or i nactivated SA11 rotavirus (SA11). Control calves (n = 5 per group) rec eived either pooled colostrum from unvaccinated (BRV field exposure se ropositive) control cows, or no colostrum. IgG1 antibody titers to IND BRV for the pooled colostrum were: 1048576 (VLP); 1048576 (CLP); 2621 44 (SA11); and 16384 (control colostrum). Elevated titers of BRV neutr alizing (VN) antibodies were present in VLP colostrum (98000), and SA1 1 colostrum (25000), but not in CLP colostrum (1400), compared to colo strum from nonvaccinates (2081). Calves were orally inoculated with vi rulent IND BRV at 2 days of age and challenged at post-inoculation day (PID) 21. Calves were monitored daily for diarrhea and faecal BRV she dding through PID 10 and post-challenge day (PCD) 10. After colostrum feeding, the IgG1 antibody titers were highest in serum and faeces of calves fed VLP and CLP colostrum, but VN and IgA antibodies were highe st in calves fed VLP colostrum. After BRV inoculation, calves fed colo strum from vaccinated cows had significantly fewer days of BRV-associa ted diarrhea and BRV shedding than control calves. All calves fed VLP colostrum were protected from diarrhea after BRV inoculation; two calv es shed BRV. In the CLP colostrum group, one calf developed BRV-associ ated diarrhea and all calves shed virus. In the SA11 colostrum group, three calves developed BRV-associated diarrhea and four calves shed vi rus. BRV-associated diarrhea and shedding occurred in 9 of 10 control calves. Active IgM antibody responses occurred in faeces and/or serum of most calves after BRV inoculation. However, the highest active anti body responses (IgM and IgG1 in serum, and IgM, IgG1 or IgA in faeces) after BRV inoculation were in calves fed control or no colostrum, in association with clinical diarrhea in most of these calves. After chal lenge at PID 21, BRV-associated diarrhea and shedding were of short du ration or absent, in all groups These results demonstrate the efficacy of colostrum from VLP vaccinated cows to provide heterologous, passiv e protection against BRV diarrhea and shedding in calves. In compariso n, calves fed CLP or SA11 colostrum were only partially protected agai n-st BRV diarrhea or shedding. (C) 1998 Elsevier Science Ltd. All righ ts reserved.