Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 1997
Publication Date: N/A
Interpretive Summary: Avian coccidiosis is a major parasitic disease of poultry which cost the poultry industry >$600 million annual loss. No vaccine is currently available. To develop a recombinant vaccine strategy, understanding of host immunity to coccidian parasites is crucial. In this study, an ARS scientist collaborates with NIH scientists to investigate the immunological basis for the genetic control of coccidiosis. The results show that one of the genetic factors controlling disease resistance to coccidia infection is associated with transforming growth factor-B production. This knowledge will assist poultry scientists and industry to develop better control strategies against coccidiosis.
Expression of transforming growth factor-betas 2, 3 and 4 (TGF-B) in the chicken intestine and spleen was investigated following infection with coccidia parasite. Coordinate expression of the mRNAs for TGF-Bs 2, 3 and 4 was detected in the embryonic intestine by 8 days, with maximal expression of the mRNAs for TGF-Bs 2 and 4 occurring at 12 and 19 days, respectively, while expression of TGF-B3 mRNA remained constant during this time. While specific antibodies for TGF-B2, 3 and 4 could only detect weak immunohistochemical staining of the intestinal epithelium in 4-, 12-, and 16-day-old embryos, intense staining for TGF-Bs 2, 3 and 4 was detected in the tips of the intestinal villi of 19-day-old embryos. Expression of TGF-B4 mRNA increased progressively with developmental age, with expression in the adult spleen being significantly higher than in the embryonic and hatchling spleen. Immunohistochemical staining of spleens showed a selective increase in the level of reactive TGF-B4 with increasing developmental age, while staining for TGF-Bs 2 and 3 was constant during development. After infection of 2-month-old chickens with a coccidia parasite, expression of TGF-B4 mRNAs increased 5-8-fold in intestinal intra- epithelial lymphocytes and 2.5-fold in spleen cells, while expression of the mRNAs for TGF-Bs 2 and 3 remained constant in these cells. The results of this study suggest that TGF-B, and in particular, TGF-B4, may play a role in infection of coccidia in the chicken.