Preparation of a new monoclonal antibody against subgroup A of avian leukosis virus and identifying its antigenic epitope

Abstract This study focuses on preparing the monoclonal antibody (MAb) against subgroup A of avian leukosis virus (ALV-A) and identifying its antigenic epitope. The ALV-A gp85 gene with a size of 1005bp was amplified and expressed into a recombinant protein with a size of 46KD in E. coli. The products expressed after purification were inoculated into BALB/c mice for preparing antibody-secreting splenic lymphocytes and further obtaining hybridoma cells. Finally, one new hybridoma cell (A18GH) secreting MAb against ALV-A was screened, and the MAb was able to detect ALV-A/K strains in an indirect immunofluorescence assay (IFA), but not ALV-B/J strains. A total of 14 overlapping truncated ALV-A gp85 protein segments were expressed and eight peptides containing different antigenic amino acids were artificially synthesized for analyzing the antigenic epitope of the MAb using a western blot or an ELISA, and the results indicate that the antigenic epitope consists of seven amino acids within the 146-ATRFLLR -152 region of the ALV-A gp85 protein. A biological information analysis shows that the antigenic epitope has a high antigenic index and develops a curved linear spatial structure. Further, its 7 amino acids are completely within the 17 representative ALV-A strains, 4 are within the 11 ALV-K strains, and fewer are within the ALV-B/J/E strains. This study will significantly assist in a further understanding of the protein structure and function of ALV-A, and in the establishment of specific ALV-A detection methods.