ROLE OF CIRCULATING MATERNAL ANTIROTAVIRUS IGG IN PROTECTION OF INTESTINAL MUCOSAL SURFACE IN TURKEY POULTS

The effect of circulating maternally transferred IgG on immunity of tu rkey poults to rotavirus infections was investigated. Specific-pathoge n-free (SPF) turkey hens were hyperimmunized with avian group A rotavi rus 2 weeks before the laying cycle. SPF poults designated positive fo r group A rotavirus (Rab+) and negative for such maternal antibody (Ra b-) were challenged orally with the homologous virus at 2, 5, or 12 da ys of age (challenge Groups 1, 2, and 3, respectively). Poults were ex amined at 3 and 6 days postinfection (PI) for clinical signs, gross le sions, histopathological changes in the small intestine, rotavirus in intestinal contents, and D-xylose absorption as an indicator of the in testinal absorptive function. In challenge Groups 1 and 2, rotavirus t iters in the intestinal contents were significantly lower in Rab+ poul ts than in Rab- poults at 3 days P1. Gross lesions and D-xylose absorp tion results were consistent with the virus-shedding data. Histopathol ogical changes were moderate and comparable in Rab- and Rab+ poults. I n challenge Group 3, however, no significant differences were observed between Rab- and Rab+ poults in any of the examined parameters. Resul ts provided evidence that circulating maternally derived IgG has an im portant role in protection of the intestinal mucosa against rotavirus infection during the first week of life. It is suggested that protecti ve immunity afforded by maternal IgG is titer-dependent.