Submitted to: Hybridoma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 2001
Publication Date: N/A
Interpretive Summary: Avian coccidiosis is an economically important disease for the poultry industry caused by several species of protozoa belonging to the genus Eimeria. Coccidia parasites replicate in the intestinal tract through an intricate life cycle and cause severe damage to the gut. Host protective immune responses following infection are complex complicating efforts to develop effective vaccination strategies to control this disease. In this study, ARS scientists, in collaboration with scientists at the Changwon and Seoul National Universities, cloned chicken recombinant scFv genes from chicken hybridoma cell lines by PCR and expressed them in E. coli for testing of their biological function against coccidia parasites. The results presented here represent the first instance of scFv antibodies against a pathologically important organism inflicting severe negative economic impact on the poultry industry. Availability of these antibodies will lead to better identification of potential vaccine antigens of coccidia and novel strategy for coccidiosis.
In our previous attempt to generate monoclonal antibodies (mAbs) against coccidia parasites that more accurately reflect the natural avian humoral immune response, we produced two chicken B cell hybridomas, 5D11 and 2-1. While both cell lines secreted antibodies reactive with sporozoites of Eimeria acervulina, they were produced in yields too low to conduct meaningful in vivo studies. To circumvent this problem, we produced four single chain variable fragment (scFv) antibodies from the VH and VL genes of hybridomas 5D11 and 2-1. The concentration of these recombinant antibodies expressed in E. coli and purified to homogeneity was 5 - 10 mg per liter. Three of the antibodies exhibited antigen binding specificity to Eimeria surface antigens equivalent to that of the native mAbs. Nucleotide sequence analysis of the VL genes from hybridomas 5D11 and 2-1 and genomic DNA revealed vestiges of gene conversion with Vl pseudogenes. These recombinant scFv antibodies will prove useful for further characterization of natural Eimeria surface antigens as potential vaccine candidates.