S-25. Passive transfer of rotavirus antibodies to neonatal foals confers protection against rotaviral diarrhoea

Group A rotavirus (RV) is the major cause of diarrhoea in young ones of all livestock animals below two months of age. The transfer of maternally derived antibodies through colostrum and milk confers protection to neonates against several infectious diseases. We evaluated lactogenic RV-antibody transfer between mares and their new borne foals (n=41) and protection afforded by it to foals in an organized equine farm. For this, mare serum (7-days before foaling & on the day of foaling), colostrum on day of foaling and foal sera (on day of foaling before suckling, day 2, 7 and 14 after foaling) were collected and tested for RV antibody by a blocking ELISA. RV-antibodies were detected in the serum of only 13 out of 41 (31.7%) pregnant mares. RV antibody titre in colostrums correlated with serum level and was 10–100 times higher than in serum on the day of foaling. None of the foals before suckling had RV antibodies in their sera. Foals after suckling RV negative mares (n=28) remained sero-negative for RV antibodies till 14 days of age, whereas, 11 out of 13 foals after suckling RV antibody-positive mares seroconverted within 2 days. All the foals were monitored daily for clinical signs of diarrhoea for 2 weeks and stool samples collected from foals developing diarrhoea. None of the foals (n=11) with lactogenic RV antibodies in their sera develop diarrhoea during the period of study. However, 11 out of 28 (39.3%) sero-negative foals borne from sero-negative mares developed diarrhoea due to rotavirus as detected by sandwich ELISA and RT-PCR. The study confirms that lactogenic RV antibody transfer confers significant protection in neonatal foals against RV diarrhoea. Rotavirus vaccination in mares during pregnancy may significantly increase lactogenic RV immunity and reduce the incidence of diarrhoea in foals.