Applying Avnv Molecular Biological Diagnostic Techniques To Detecting And Analyzing The Main Hosts Of Avnv

The scallop Chlamys farreri is one of the major species cultured in North China. Acute Viral Necrosis Virus(AVNV) was proved to be a spherical virus which caused massive mortality in Chlamys farrei. AVNV molecular biological diagnostic techniques were used to detect Chlamys farreri, plankton, fouling organisms and the shellfish from 9 provinces in China,to study the host range and transmission route of AVNV.Loop-mediated isothermal amplification(LAMP) was used to detect the Chlamys farreri from two different sea areas for culturing scallops in 2008 and 2009,to research the pattern of AVNV infection and proliferation in vivo and investigate the disease control effect of shellfish and seaweed maricuhur.High positive ratio of scallops was detected in Liuqinghe sea area during 08 and 09.The highest positive ratio detected is the wild seedlings in Augest 08,the number is 75%. The positive ratios of three different seedlings in July are higher than these from other months. The positive ratios of Penglaihong,the artificial breeding and the wild seedlings are 20%,70% and 80%.The time that highest positive ratio detected was in agreement with large-scale death happened.High water temperature was an important environmental stress factor of Chlamys farreri infected AVNV.The Sangou Bay is the shellfish and seaweed maricuhur sea area,the scallops cultured in this area carried less AVNV than that in Liuqinghe.The ratios of the Penglaihong,the artificial breeding and the wild seedlings are 50%,60% and 0,while the positive ratios were lower during the massive mortality.After the time of massive mortality,we made statistics of the mortality of the three seedlings in two sea areas.The mortalities of Penglaihong,the artificial breeding and the wild seedlings are 39.1%,40.7% and 45.3% in Liuqinghe, while the mortalities of Penglaihong,the artificial breeding and the wild seedlings in Sangou Bay are 96.8%,89.2% and 90%.In conclutian,the pattern of shellfish and seaweed maricuhur may reduce the ratio of scallops carry AVNV,most important is that it can also decrease mortality.The plankton from Liuqinghe Qingdao and Sanggou Bay Rongcheng in 2009 were catched by plankton net.The AVNV copy numbers carried by plankton were identified by FQ-PCR. The results showed that plankton in August from both two sea areas could carry the virus, and the virus number carried by plankton was different with different particle size, time and sea area.The plankton with same particle size of Liuqinghe sea area carried more AVNV copy numbers than that of Sanggou Bay sea area at the same time.The plankton particle size less than 200 mesh which carried the largest amount virus, viral DNA numbe reached 9.45×106 copy/mg total DNA, followed by plankton particle size between 60 mesh—200 mesh, the plankton particle size larger than 60 mesh carried the least amount virus.In Conclusion, the plankton can carry AVNV,is the important host of AVNV.The fouling organisms which attached scallop farming cages in 09 were detected to reseach whether they can carry AVNV or not.The result shows that Mytilus edulis, Crassostrea gigas, Styela clava and Skeleton shrimp can carry AVNV,they are the hosts of AVNV.AVNV was not detected in Hiatella orientalis,so Hiatella orientalis may not the host of AVNV. The AVNV carried by fouling organisms can infect Chlamys farreri or not,we need study in the future.From November 06 to November 09,586 shellfishes were collected from 21 sea areas 9 provinces in china, consist of 16 bivalvia and 4 gastropoda.All of the shell,9 kinds were detected that can carry AVNV, consist of Chlamys farreri,Patinopecten yessoensis, Chlamys nobilis, Ruditapes philippinarum, Mytilus edulis, Perna viridis, Crassostrea gigas, Crassostrea rivularis, Babylona areolata; 11 kinds were not detected that can carry AVNV, consist of Paphia undulata, Argopecten irradians, Pinctada margaritifera, Vasticardium flavum, Pinctada martensii, Tegillarca granosa, Bullacta exarata, Pteria penguin, Meretrix meretrix, Haliotis discus hannai.But owing to the restriction of regions,time,and numbers of samples,further studies is needed to decide whether these species can carry ANNV.