Transplacental transfer of schistosomal circulating anodic antigens in cows.

The present work investigated the transplacental passage of circulating anodic schistosome antigens (CAA) and the production of foetal antibodies in response to antigenic stimulation in Schistosoma mattheei infected cows. Three groups were available: six calves born to non-infected cows received colostrum from a pool from non-infected cows (group 1), six calves born to non-infected cows (group 2) and six calves born to infected cows (group 3) received colostrum from a pool from infected cows. Schistosoma-specific IgG (1) antibody and CAA levels were measured in the colostrum pools, the sera collected from the cows, and the sera collected from the calves at birth, after intake of colostrum and at day 30. The specific IgG (1) antibody levels were significantly higher in the sera from cows of group 3. In four cows of group 3 high CAA levels were detected. The specific IgG (1) antibody levels were 0.646 and 0.176 OD for the infected and non-infected colostrum pool, respectively, and the CAA levels were 5667 and 2557 pg CAA/mL, respectively. At birth high levels of specific IgG (1) antibody and CAA were detected in 4 calves of group 3; levels in the other two calves were negligible. After intake of colostrum, specific IgG (1) antibody levels of group 1 increased slightly at day 1 to become again insignificant at day 30. In group 2 specific IgG (1) antibody levels increased significantly between days 0 and 1, to decrease, although not significantly, at day 30. Finally, in group 3 the delta OD values increased at day 1 and remained high until day 30. After intake of colostrum the CAA level increased very slightly for groups 1 and 2 to become again undetectable at day 30. In group 3 a nonsignificant decrease in CAA levels was observed at day 1 followed by a further significant decrease to reach low levels at day 30. The suggested intrauterine antigenic stimulation may be important not only for generating immune responses to natural early infections, but also for enhancing the immunogenicity and efficacy of vaccines administered to newborns.