Studies on the age resistance of swine to group A rotavirus infection.
To determine whether swine become naturally age resistant to group A rotavirus infection, colostrum-deprived, rotavirus-naive newborn pigs that were raised in isolation (n = 34) were studied. Neonatal pigs and pigs 1, 2, 4, 6, 8, 10, and 12 weeks of age were inoculated orally with group A porcine rotavirus or mock inoculum and euthanatized at 24, 31, or 48 hours post-infection. Nine sections of small intestine, cecum, and colon were harvested and immunohistochemically examined for evidence of rotavirus replication within enterocytes. Infectivity was semiquantified by intestinal segment, and a composite score was obtained for each animal. In pigs inoculated at 1 week of age, enterocyte infection was mild and scattered; all other pigs became infected regardless of age or region of intestine, and older animals that became infected had infectivity scores similar to those of younger animals. In a second more limited study, pigs raised in the same isolation environment (n = 11) but previously exposed to virus and demonstrating rotavirus serum antibody had a much lower degree of enterocyte infection at 8, 10, and 12 weeks of age (2, 4, and 6 weeks, respectively, after initial exposure to virus). Age resistance to clinical rotavirus disease in swine is due to factors other than an age-dependent development of resistance of enterocytes to infection, at least through 12 weeks of age.
Gelberg
H B
HB
Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana.
D000375:Aging / Q000276:immunology*; D000818:Animals; D000831:Animals, Newborn; D007422:Intestines / Q000276:immunology / Q000382:microbiology*; D012401:Rotavirus / Q000276:immunology* / Q000502:physiology; D012400:Rotavirus Infections / Q000276:immunology / Q000662:veterinary*; D013552:Swine; D013553:Swine Diseases / Q000276:immunology*; D014779:Virus Replication