Investigation and study on carrying stat us of White Spot Syndrome Virus(WSSV) i n shrimps and other aquatic animals by dot-blot hybridization

About 836 samples of Penaeus chinensis(625 inds), P .Japonicus(211 inds) and 213 other aquatic animal samples were collected from the cultural farms in Liaoning，Hebei, Tianjin，Shandong，Jiangsu and Zhejiang Provinces during 1996-1998 .The method of dot-blot hybridization was employed and a digoxigenixrlabelled probe was used to detect the White Spot Syndrome Virus(WSSV) in the samples .The results show that the WSSV can be detected in the shrimp samples collected from April to Nove mber each year and the detectable peak appears in June that the positive rate gets to 42 .6%and the secondary peak is in July and May when the positive rates get to 31 .6%and 24 .5%, respectively .Otherwise, WSSV can be detected at different stages of the shrimps，including the parents，ovum, larvae, post1arvae，mysis，juveniles and adults，among which the positive rate is the highest in the postlarvae (36 .4%) and the second highest in the mysis(34 .6%).On the Sasis of body length of shrimp，the positive rate is the highest in the group of body length 1 .1-2 .0 c m and the second highest in the group of 5 .1-6.0 cm .The positive rate is 16 .8% for P.Chinensis and 45 .0%for P. japonicus .Among the other animal samples, WSSV can be detected in arte mia, nereidae, copepoda, amphipoda, noxrpenaeid shrimp, crabs and fishes and the positive rate of WSSV is more than 20% in copepoda, a mphipoioda, amphipoda, non- penaeid shrimp and crabs.