Tolerance of Macrobrachium rosenbergii to white spot syndrome virus

The susceptibility of Macrobrachium idella, M. lamerrae and M. rosenbergii to white spot Ž . syndrome virus WSSV was tested by immersion challenge, oral route and intramuscular injection. Their susceptibility to WSSV was compared with that of Penaeus indicus and P. monodon. The WSSV caused 43.3% and 53.3% mortality in M. lamerrae and M. idella, respectively, by immersion method and 53.3% and 66.7% mortality in M. lamerrae and M. idella, respectively, by oral route. This virus caused 100% mortality in M. idella, M. lamerrae, P. indicus and P. monodon when the animals were injected WSSV intramuscularly. Moribund animals were screened for the presence of WSSV by western blot or histopathology. The results indicated the susceptibility of marine shrimp and freshwater prawn to this virus except M. rosenbergii. This virus failed to produce mortality with any of the methods of infection applied in M. rosenbergii. The exact mechanism of tolerance of M. rosenbergii to WSSV is not known at present and the possibilities for this tolerance are discussed. q 2000 Elsevier Science B.V. All rights reserved.