Protein analysis of geographic isolates of shrimp white spot syndrome virus

Six geographic isolates of the white spot syndrome virus (WSSV) of penaeid shrimp, from China, India, Thailand, South Carolina, Texas, as well as from crayfish kept at the US National Zoo in Washington D. C, were compared by electron microscopy and sodium sulfate polyacrylamine gel electrophoresis ( SDS-PAGE). Amino acid compositions of four of the major structural polypept ides of the South Carolina WSSV were analyzed, and three of the four polype ptides were partially sequenced from their NH2 termini. The morphologies of purified virions of the six geographic isolates of WSSV were indistinguish able by transmission electron microscopy. By SDS-PAGE, the protein profiles of the six isolates were very similar, but not identical. They all contain ed three major polypeptides with sizes of approximately 25, 23 and 19 kDa. A fourth major polypeptide at the 14.5 kDa position was observed in four of the geographic isolates. The WSSV isolated from crayfish presented a sligh tly different structural protein profile, particularly with regard to the p rotein in the 19 kDa range that appeared larger in size than those of the o ther isolates. The NH2 terminal amino acids of the 25, 23 and 14.5 kDa poly peptides of the South Carolina WSSV were sequenced as MDLSFTLSVVTA, MEFGNLT NLDVA, and VARGGKTKGRRG, respectively. No significant homologous sequence w as found in the GenBank. These protein sequences have been submitted to the SWISS-PROT Protein Data Bank and assigned the accession numbers P82004, P8 2005 and P82006.