Aquaculture & Fisheries

Biography

Biography: Deepika Anand

Abstract

Shrimp aquaculture industry has faced severe economic losses due to devastating diseases affecting shrimp especially white spot syndrome (WSSV) and vibriosis which caused massive mortality in many species of penaeid shrimp. In order to generate protection strategies against diseases, it is essential to gain better understanding of the defense system of shrimp. Innate immunity is the first-line of defense in shrimps. Previously, we characterised MyD88 and TRAF6, two innate immune genes in the Toll pathway of Penaeus monodon and studied the response of these genes against WSSV challenge both in vivo and in vitro which revealed that Toll-pathway in P. monodon responds to WSSV infection. Dorsal (NF-kappa B homolog) and Cactus (IkB homolog), two downstream signalling molecules in the Toll-pathway have been characterised from Litopenaeus vannamei and Fenneropenaeus chinensis showing varied antibacterial/antiviral response. In the present study, the temporal expression profiles of Dorsal and Cactus from tiger shrimp, P. monodon in response to white spot syndrome virus (WSSV) and Vibrio harveyi was studied in post-larvae and selected tissues of juvenile of P.monodon after immersion challenge as well as upon injection in adult shrimp. Moreover, the response of these genes was also studied upon WSSV challenge in vitro in primary haemocyte cultures of P. monodon. PmCactus and PmDorsal displayed varying expression pattern in response to immersion challenge with WSSV in PL-18 and most of the tested tissues of juveniles. However, complete down-regulation of PmDorsal could be noticed in hepatopancreas at all time points. Upon injection, PmCactus expression was up-regulated in haemocytes and lymphoid organ at most of the time-points tested. Peak up-regulation was observed at 24 hours post-infection for both gill and midgut. PmDorsal expression was up-regulated in haemocytes and gill at all time-points. However, up-regulation was noticed only at few time-points for both lymphoid organ and midgut. PmCactus and PmDorsal showed up-regulated expression in response to WSSV at early time-points tested, 6 hours and 2 hours respectively in vitro in primary haemocyte cultures. Similarly, varied temporal expression pattern of these immune-relevant genes could be noticed upon challenge with Vibrio harveyi. The modulation of expression of these genes in response to WSSV in vivo as well as in vitro and V. harveyi in vivo suggests their possible role in immune responses in shrimp against viruses as well as bacteria.