author(s)
Vijay S Atnur, Vijayakumar S, Muttappa Khavi and Indrani Karunasagar

abstract
White spot syndrome Virus (WSSV) is a major threat to commercial shrimp farming. The prevalence of this virus infection has been studied in Bhimavarm and Nellore district of Andhra pradesh. In Bhimavaram coast, Out of 148 samples, 42 (28.37%) showed more than 80% infection rates. The sample from Bhimavaram area positive for WSSV only in nested PCR. None of the samples showed reaction in non nested PCR suggesting that the intensity of infection in the individual animal was low. In Nellore coast, a total 87 samples were analyzed out of which 44 (50.51%) samples had higher rate of infection of more than 80%. The infection rate and WSSV prevalence was higher in Nellore compared to Bhimavaram. It is possible that these are derived from brood stock with high degree of infection. The prevalence of WSSV in P. Monodon brood stock varies widely depending on the region and this may account for the difference in the infection rate observed in larvae in different regions.