Molecular cloning, expression analysis and characterization of peroxiredoxin during WSSV infection in shrimp Fenneropenaeus indicus.

Innate immunity is the first line of defense in shrimps against invading pathogenic microorganisms. Peroxiredoxins (PRX) are the family of antioxidant proteins that play a crucial role in reduction of oxidative stress in host during viral infection. Peroxiredoxin from Fenneropenaeus indicus was identified, cloned and expressed in prokaryotic expression system. The Fi-PRX protein consists of two conserved Cys residues and belongs to typical 2-cys PRX family. The phylogenetic analysis revealed a close evolutionary relatedness of Fi-PRX with the PRX from Drosophila melanogaster PRX1 and distant origin with PRX sequences from other shrimp isolates Fenneropenaeus chinensis, Litopenaeus vannamei and Penaeus japonicus. Fi-PRX transcripts are constitutively expressed in hemocytes and tissues (gills, heart and muscle) and down regulated during 12 h, 24 h and 48 h of WSSV challenged shrimps. Fi-PRX protein levels correlated well with the corresponding levels of Fi-PRX transcripts in hemocytes and tissues of WSSV challenged shrimps. Recombinant Fi-PRX reduces insulin only in the presence of DTT suggesting that the antioxidant function of the protein is thiol dependent. These findings suggest that antioxidant activity of Fi-PRX play a significant role in neutralization of excessive free radicals and ROS generated during viral invasion.