Molecular cloning, sequence analysis and tissue expression of penaeidin from white spot syndrome virus infected Penaeus monodon shrimps of Indian coastal region

Immune related genes like penaeidins have been characterized and the sequence diversity among penaeidins from various shrimp isolates are well documented. However, no attempt has been made to study the differential expression and sequence variations of these genes in Indian context. Genes coding for penaeidin was PCR amplified and sequenced from hemocyte cDNA of wild caught Penaeus monodon shrimps from India infected with white spot syndrome virus (WSSV). An elevated expression of penaeidin was observed in the hemocytes of infected shrimps compared to uninfected ones and tissue expression was confined only to the gills of infected shrimps. The N-terminal signal peptide, which is a conserved feature among all the penaeidins, was shown to have one substitution in the Indian isolate. Besides this, there were ten substitutions following the signal peptide region exclusive to the Indian isolate. Phylogenetic analysis suggested a close relatedness of penaeidin from the Indian isolate with the homologs from other P. monodon and P. chinenis and a distant origin with the other isolates. An elevated level of penaeidin during WSSV infection suggests that penaeidin might have a function in defending shrimps against viral infections.