Screening Of Anti-Spring Viremia Of Carp Virus And Micropterus Salmoides Rhabdovirus Fermented Chinese Herbs And Evaluation Of Their Effects

Spring viremia of carp virus(SVCV)is a single-stranded negative-stranded RNA virus belonging to the genus SVCV,family Elasmoviridae,that causes Spring viremia of carp(SVC)in a variety of carp species,including Cyprinus carpio,and causes high mortality and economic losses.Micropterus salmoides rhabdovirus(MSRV)is a linear singlestranded negative-stranded RNA virus belonging to the genus Micropteridae.This virus seriously affects largemouth bass,causing high mortality and severe economic losses to the largemouth bass farming industry.So far,there are no drugs that can effectively control SVCV and MSRV.herbs have the advantages of low toxicity,versatility and low drug resistance,and their antiviral effects have received wide attention.The fermentation of herbs can increase the content of some of the active ingredients of herbs,improve the efficacy of herbs,reduce the toxicity of herbs as well as toxic side effects,and also enable the generation of new active ingredients and other advantages,which have a broader application prospect in the control of aquatic diseases in China.In this study,we screened herbs with good inhibitory effect on SVCV and MSRV from a variety of fermented herbs,and determined their antiviral effects at the cellular level and fish body level,and the main findings were as follows:1.The toxicity of eight fermented herbs(L1,L2,L3,L4,L5,X1,X2,ZHS)on EPC cells was detected by MTT method,and the results showed that there was no significant change in cell survival rate after treatment with fermented herbs L1,L2,L3,X1,X2 and ZHS,which did not cause significant damage and toxicity to EPC cells.The herbs L4 and L5 caused damage to the cells at 4 mg/m L treatment,and the cell survival rate decreased by about 50% after L4 treatment and by about 80% after L5 treatment.In addition,the herbs X1 and X2 exhibited a growth-promoting effect on EPC cells;2.Screening the antiviral effects of eight herbal drugs(L1,L2,L3,L4,L5,X1,X2,ZHS)against SVCV and MSRV by relative fluorescence quantification,and successfully screening X1 drug,which had good antiviral effects against both SVCV and MSRV and could significantly inhibit the proliferation of virus in cells;3.X1 drug has good antiviral effect on SVCV and MSRV at the cellular levelThe antiviral effect of fermented herb X1 was verified at the cellular level by cytopathic effect(CPE)observation,cellular viral load determination,and virus titer detection by empty spot assay.The results showed that X1 fermented herbal drug could significantly inhibit CPE caused by SVCV and MSRV;could significantly inhibit the proliferation of SVCV and MSRV at the cellular level,and could reduce the SVCV and MSRV titers by about 10-fold;4.X1 drug has good antiviral effect against SVCV and MSRV at the fish levelAt the fish level,through survival rate assay,tissue viral load assay and histopathological observation,it was found that X1 fermented herbal drug increased the survival rate of zebrafish by 16.7% at the fish level;in zebrafish intestinal and brain tissues,X1 could significantly inhibit virus proliferation in the tissues;through histopathological observation,it was found that X1 fermented herbal drug could inhibit SVCV-induced intestinal and brain tissue lesions caused by SVCV,as observed by histopathology;X1fermented herbal medicine increased the survival rate of largemouth bass by 20% at the fish level;in the liver and spleen tissues of largemouth bass,X1 was able to significantly inhibit virus proliferation in liver and spleen tissues;through histopathological observation,it was found that X1 fermented herbal medicine was able to inhibit The histopathological observation revealed that X1 fermented herbs could inhibit the lesions of liver and spleen tissues caused by MSRV.In conclusion,this study successfully screened fermented herbs with significant antiviral effects on SVCV and MSRV,which showed good effects at the cellular level and fish level.It provides new ideas for the application of herbal medicines in aquaculture and provides a reference for the development of anti-SVCV and MSRV drugs.