Preparation and epitope analysis of monoclonal antibodies against soft shelled turtle iridovirus (STIV)

Eight stable monoclonal hybridomas were successfully produced by immunization of Balb/C mice with purified soft-shelled turtle iridovirus (STIV) antigen. The Mabs obtained were three kinds of isotype. Mab 2A4 was subclass IgA, Mab8E1 was subclass IgG2a, and the other Mabs 1D3, Mab2H1, Mab3A1, Mab4B5, Mab5E1 and Mab6F2 were subclass IgG1. ELISA(enzyme linked immunosorbent assay) assays showed that eight Mabs could specifically recognize the antigen of STIV, and had no cross reaction with the cell lines EPC, Co, FHM. The ELISA titers of ascites were between 10⁵ and 10⁶. Immunofluorescent studies showed that all Mabs (except for Mab5E1) had fluorescence characteristics, and the specific fluorescence signals appeared in the cytoplasm of STIV-infected (EPC) cells. None of the Mabs possessed the ability to neutralize STIV in vitro cell cultures. In this experiment, Western-blot was used to analyze the epitope of monoclonal antibodies against STIV. It demonstrated that Mab1D3 and Mab2A4 reacted specifically to a single linear protein with an approximately molecular weight of 84 ku and 35 ku respectively, Mab3A1 reacted with two STIV proteins at molecular weight of about 14 ku, 16 ku. The results suggested that these three Mabs target conformation-independent determinants within STIV protein. The identity of the target antigen of the other five Mabs could not be determined by Western-blot. These Mabs against STIV might be specific and sensitive, and they might also be used to detect STIV and analyze its structure proteins.