Characterization of a late gene encoding for MCP in soft-shelled turtle iridovirus (STIV).

Major caspid protein (MCP) is the major structural component of virus particles and revealed to be very responsible for classification of new tentative iridovirus isolates. In this paper, the complete sequences of MCP gene was firstly identified and characterized from soft-shelled turtle iridovirus (STIV). The MCP, classified as a late transcript by drug inhibition, encodes a protein of 463 aa with a predicted molecular weight of 50kDa. Indirect immunofluorescence (IIF) and virus neutralization assay were developed to determine the sensitivity and virus neutralizing activity of MCP-specific antiserum. Furthermore, the MCP temporal expression pattern during STIV infection in vitro was characterized by Western blot and RT-PCR assays. The results suggest that STIV could be classified as a member of genus Ranavirus in family Iridoviridae and has cell-type-specific programs of viral gene expression.