Effect of different pH and salinity levels on the viability of Penaeus monodon baculovirus (MBV) in Penaeus semisulcatus

The virucidal effect of pH and salinity on Penaeus monodon baculovirus (MBV) was investigated by water borne inoculated methods exposing PL12 Penaeus semisulcatus for 10 hours and observing for 10 days at temperature 28- 30°C. For this purpose, one thousand virus free PL12 of P. semisulcatus were divided into five groups and each group placed in a 10 L plastic basin containing chlorine-treated sea water at 35ppt. The salinity of basins water after 12 hours changed to 5, 10, 20, 30 and 40ppt using synthetic sea salt. To study the effect of pH, solution with various pH of 3, 5, 7, 8, 9 and 12 were prepared using IN NaOH and IN HCL to Na2HPO4 solution. For transmission of MBV, an aliquot of approximately 10 frozen infected larvae were used for each experiment by water born inoculated method. Ten hours after inoculation, the shrimp were removed from jar and introduced into another jar with the same salinity or pH. During 10 days experiment, the rate of infection (ROI), severity of infection (SOI) and accumulative mortality were varied among the MBV-infected. Penaeus mondon baculovirus was able to infect Penaeus semisulcatus at salinity ranging from 5-40ppt whereas at pH 3 and 12, MBV was completely inactivated MBV was not able to infect larvae at pH 5, 7, 8 and 9.