Differential expression of akirin gene in black tiger shrimp Penaeus monodon in response to immunostimulant administration and infections with Vibrio harveyi and white spot syndrome virus

The akirin gene, which is strictly localized in the nucleus, plays a critical role in regulating antimicrobial peptide transcription, and has parallel functions to NF-kappa B signaling pathway in both vertebrates and invertebrates. In shrimp, the akirin gene is expressed as innate immunity in response to microbial infection. In the present study, expression of akirin gene in Penaeus monodon with respect to Vibrio harveyi and white spot syndrome virus (WSSV) infections and immunostimulant (beta-glucan) administration were investigated by quantitative polymerase chain reaction. The gene was expressed in various tissue samples of healthy shrimp. Maximum level of expression was immediately after V. harveyi infection, suggesting that it may be an early response gene. Gene expression was remarkably upregulated in the lymphoid organ, gill, and hepatopancreas, whereas downregulation was observed in hemocytes compared with the control. In the case of WSSV-infected samples, the akirin gene was significantly downregulated in the lymphoid organ but there was no significant difference in expression pattern in hemocytes compared to the control. In gill tissue, maximum expression was observed after 2 hr of infection, the same in hepatopancreas. Experimental challenge of beta-glucan fed shrimp infected with V. harveyi and WSSV resulted in significant upregulation of akirin gene expression in lymphoid and gill tissue

Protection of Litopenaeus vannamei against White Spot Syndrome Virus using bacterially expressed recombinant envelope proteins VP39 and VP28

White spot syndrome virus (WSSV) is a highly virulent shrimp pathogen, causing huge economic loss to the aquaculture industry. We investigated the efficacy of recombinant VP39 protein against WSSV infection in Litopenaeus vannamei by intramuscular and oral administration, and also compared the efficacy with recombinant VP28 (rVP28). The VP39 is a 283 amino acid protein encoded by the structural gene vp39 which acts as an important mediator for virus entry to the host. Shrimp orally vaccinated with rVP39 and rVP28 showed a cumulative mortality of 50% and 60% respectively following challenge, and this indicates that rVP39 had a better protective effect against WSSV infection compared with rVP28. Vaccination by intramuscular injection with rVP39 and rVP28 resulted in survival rate of 60% and 50%, respectively. The transcriptional profiling of viral genes of vaccinated shrimp with recombinant viral proteins of VP28 showed higher transcriptional levels than VP39. The transcriptional level of rVP39 vaccinated animals was delayed by 6 days after WSSV infection, while the delay was only 4 days in the case of rVP28. These results indicate that vaccination delays the transcription of envelope genes of WSSV in shrimp. The present study could demonstrate the importance of VP39 as a prominent candidate for vaccination against WSSV

Differential expression of akirin

The akirin gene, which is strictly localized in the nucleus, plays a critical role in regulating antimicrobial peptide transcription, and has parallel functions to NF-kappa B signaling pathway in both vertebrates and invertebrates. In shrimp, the akirin gene is expressed as innate immunity in response to microbial infection. In the present study, expression of akirin gene in Penaeus monodon with respect to Vibrio harveyi and white spot syndrome virus (WSSV) infections and immunostimulant (beta-glucan) administration were investigated by quantitative polymerase chain reaction. The gene was expressed in various tissue samples of healthy shrimp. Maximum level of expression was immediately after V. harveyi infection, suggesting that it may be an early response gene. Gene expression was remarkably upregulated in the lymphoid organ, gill, and hepatopancreas, whereas downregulation was observed in hemocytes compared with the control. In the case of WSSV-infected samples, the akirin gene was significantly downregulated in the lymphoid organ but there was no significant difference in expression pattern in hemocytes compared to the control. In gill tissue, maximum expression was observed after 2 hr of infection, the same in hepatopancreas. Experimental challenge of beta-glucan fed shrimp infected with V. harveyi and WSSV resulted in significant upregulation of akirin gene expression in lymphoid and gill tissue