In vivo immunological changes occurring at different time intervals in white spot syndrome virus infected shrimp, treated with anti-WSSV drug derived from terrestrial plants

White spot syndrome virus (WSSV), is the most contagious pathogen of cultured shrimp that causes mass mortality, leading to huge economic loss to the shrimp industry. The lack of effective therapeutic or prophylactic measures has aggravated the situation, necessitating the development of antiviral drugs. With this objective, the antiviral activity of the drug, (TP22C derived from the terrestrial plant) in the host, Litopenaeus vannamei was evaluated. The immunological and physiological changes aggravated by WSSV in the host, and the in vivo efficacy of the drug in the host – pathogen interaction were analyzed. The survival percentage of the treated (with TP22C) WSSV infected host was 86%. Significant results were obtained from the cytotoxicity assays of the drug in the host. A total of 10 parameters such as, total hemocyte count, clotting time, oxyhemocyanin, hemolymph pH, hemolymph ammonia, phenoloxidase activity, respiratory burst activity, superoxide dismutase, oxygen consumption and ammonia excretion were examined for healthy (NEG), WSSV infected (POS) and test sample (TS) shrimps. Significant differences (p < 0.01) were observed between the POS, NEG and TS in the variables at different time intervals post infection with WSSV. In the case of POS, significantly (p < 0.01) reduced variables were observed when compared to the NEG. In contrast, significant (p < 0.01) elevations were observed in the TS after a certain time interval due to the anti-WSSV activity of TP22C. Neither the VP 28 gene nor the immediate early genes (ie) were expressed in the host at the 42 nd and 84 th hrs. Thus, in accordance with the above results it can be concluded that acute WSSV infection triggers alterations in immunological and physiological parameters in L. vannamei and at the same time the drug is efficient enough to combat the deadly virus and can increase the survivability of the host.