Molecular Epidemiological Investigation On Abalone Shriveling Syndrome-associated Virus And Herpes-like Virus And Its Related Research

Abalone shriveling syndrome-associated virus(AbSV) was first discovered inDongshan Fujiang province, and then the yields of cultured abalone in southern coastof China have been severely affected by an epidemic of continuous outbreaks of afatal disease for many years. Quantitative PCR technology was applied to study thecontent of virus in each tissue of Haliotis diversicolor Reeve after being injected withAbSV. The results show that virus in liver was much more than other tissue includingmuscle, mantle and gill. And the juvenile hybridized abalone were infected throughcollecting them into the same tank with Haliotis diversicolor Reeve who carringAbSV, and the result showed that the mortality rates as high as100%after infectedfor5days.AbSV as a confirmed virus of Abalone, it often reported after the first outbreak,and the loss is very serious, but there are not reports about epidemiologicalinvestigation about AbSV. In this research the abalone samples were collected alongthe southern coast of China including Dongshan Fujian，Shantou, Shanwei、Huidongin Guangdong from2012April to2013January，and the DNA was extracted to bedetected for AbSV by quantitative PCR. The results showed that all the5farmsexisted AbSV; and the positive rate of AbSV in Huidong(Haliotis diversicolor Reeve)were highest of these five places, and the second place was Shanwei(Haliotisdiversicolor Reeve and hybridized abalone), the third one is Dongshan sea area(Haliotis diversicolor Reeve), there are a lowest virus content and the positive rate atShantou and Dongshan(Haliotis diversicolor Reeve). It is different from AbSVcontent and the positive rate of each sampling points in the monitoring time, but thepeak period is8-10month. The diseases caused by the Abalone herpes-like virus(AbHV) is one of theserious abalone diseases, once infected with the virus, the fatality rates will exceed90%. The virus disease broke out in America, Australia, Europe and Taiwan, it alsoreported suspected cases in Fujian, China, but the popular feature of the virus isunclear. So the study detected the AbHV contents of abalone in Guangdong andFujian by QPCR, The results show that the five farmed point have a certain degreeinfection by AbHV, there are a low levels of infection on the whole. The highest pointof the positive rate is Huidong(27%), followed by Shanwei(24%), while the positiverate of the other three points are less than20%. And the time point of view, the peakperiod of the virus-positive rate for November and December, it is up to60%.AbSV caused the large-scale disease of Haliotis diversicolor Reeve for the firsttime since the spring of1999, and it repeated outbreaks from2000to2005, but therewere a little reported since2006. But through a large number of molecularepidemiology survey data, we found that AbSV still exists in the part of the farmingabalone. Why AbSV exists but does not cause large-scale abalone disease, whether itis the genome mutations lead to toxicity reduction. So this study detected genemutations of the AbSV genome, First of all, designed synthesis of specific primersaccording to the reported AbSV whole genome sequence, and amplified genome byPCR, Sequencing stitching results were blasted with the original AbSV genome. Theresults show that, there are multiple base mutation in AbSV genome, the most seriousmutations at18965-22273bp, the similarity is only78%at18965-19655bp, only83%similarity at20998-22273bp, the similarity is even lower at19656-20997bp,perhaps no homology; it predicted protein before and after AbSV mutation through avariety of online tools, it showed changed obviously that the structure and function ofthe translated protein before and after AbSV mutation, this may be related to thedecreasing pathogenicity, but the results need further experimental to verificate.