RESUMO
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.
