| This study mainly aimed at establishment of a bio-assay detection of white spot syndrome virus(WSSV)of Procambarus clarkii,and then investigated on the possible infections of white spot syndrome virus in several P.clarkii populations,in Hubei province.Finally,the activity difference of the enzymes relating to immune between the crayfish infected with white spot syndrome virus and the normal individuals has been compared.The results are as follows: 1.The establishment of the bio-assay detection method of white spot syndrome virusIn the experiment,the primers of PCR for the detection has been designed and optimized.Then different sampling tissues of crayfish,such as tentacle,chelicera,pleopod,artus and caudal fan,have been compared based on the detection effect and the survival rate.A method for bio-assay detection of white spot syndrome virus was developed for genetic breeding of crayfish,crayfish.The test result shows that the detection method can detect white spot syndrome virus more accurately and the artus is the best of all the sampling tissues for the detection,which can insurance the less harm to the crayfish and the better detection effect.2.Investigation on the possible infections of white spot syndrome virus in several P.clarkii populations,in Hubei provinceIn this experiment,the epidemic status of white spot syndrome virus of crayfish in seven areas of Hubei province was investigated in the form of clinical investigation and collection of crayfish samples from October 2015 to August 2017.The result reveals that more than 65% of the crayfish were detected as WSSV positive from regions of Qianjiang,Jianli,and Xindi in Honghu,and approximately 40% of the samples from the regions of Ezhou,suizhou,and Luoshan town in Honghu were detected as WSSV positive.In 2015,2016 and 2017,the positive rates of white spot syndrome virus were 49.6%,61.5%,40.2% respectively.The sequencing results of the WSSV positive samples show that in the feature sequence region of some samples,A/T base mutation was found.The phylogenetic tree ananlysis indicated that a farther genetic relationship is between the WSSV samples with A/T base mutation and 17 subspecies of WSSV in GenBank.But there is a closer genentic relationship between the samples without A/T base mutation and the subspecies from Bangladesh(KJ719075)and Australia(MF161441).3.Comparison of activities of immune related enzymes between crayfish individuals infected with WSSV and normal individualsIn this experiment,activities of catalase,superoxide dismutase,acid phosphatase,and alkaline phosphatase were used as indicators to compare the activity difference in the serum between crayfish individuals infected with WSSV and normal individuals and the number of survival between crayfish individuals infected with WSSV and normal individuals during culturing has also been compared.The results reveal that the mean activity of catalase in the serum of crayfish individuals with WSSV was higher than that of the normal ones and there was a significant difference between the two groups(P<0.05);the mean activity of superoxide dismutase in the serum of crayfish individuals with WSSV was lower than that of the normal ones and there was a significant difference between the two groups(P<0.05);the mean activities of acid phosphatase and alkaline phosphatase in the serum of individuals with WSSV were both lower than those of the normal ones.There was no significant difference in the activities of two enzymes between the two groups(P> 0.05).The survival rate of crayfish group with WSSV is less than that of the normal group.It is presumed that the oxidative stress reactions may occur to the crayfish with WSSV,leading to a significant change in the activity of catalase and superoxide dismutase in the serum.However,the activities of acid phosphatase and alkaline phosphatase have no significant change in the early infection of WSSV. |
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