Effect Of Resveratrol On Infection Of PPV In Vitro And Its Mechanism

Porcine parvovirus(PPV)is one of the main pathogens causing reproductive disorder in pregnant sows,and the clinical symptoms includ abortion,stillbirth,mummified fetus,litter size et al.The virus can also infect the boar and is difficult to be eradicated.Virus exists in infected boars,sperm cell,spermatic cord,epididymis and accessory gland,which can easily infect susceptible sows during artificial insemination or mating,causing huge economic losses to the pig industry.For the prevention and treatment of PPV infection,vaccination or drug treatment is generally used,which can bring risks to animal safety and also accompany by stress or drug resistance.Resveratrol is a natural plant extract,has antioxidant,anti-inflammatory,antiviral and other biological effects.In this study,we investigated the effect of resveratrol against porcine parvovirus infection in vitro in PPV porcine testis and Leydig cells.The results are as following:1.Firstly,a real-time quantitative PCR assay was established through using construction of a plasmid containing PPV NS1 gene fragment,which was used as the template for detection of PPV.Porcine Leydig cells were isolated and cultured.Content of PPV viral nucleic acid was detected in Leydig cells after infection with PPV using the establied qPCR.The results showed that tiny amount of PPV viral nucleic acid could be detected in cells after 3 h and 6 h infection,then increased rapidly and reached a higher level at 48 h,but decreased at 72 h.2.To study the effects of resveratrol on PPV infection cells in vitro,two different treatment means were used.When porcine Leydig cells were incubated with PPV followed by treatment with resveratrol,level of the viral nucleic acid was significantly decreased though detection by established quantitative PCR assay,results from further study showed that the inhibitory effect of resveratrol on PPV virus may be related to the increase of IFN-beta and IFN-gamma in cells.However,when pre-treated cells with resveratrol followed by PPV infection,virus nucleic acid content in cell and cell culture medium was increased.3.In this study,the effect of resveratrol on the local tissue infection of PPV was further studied through establishing 3D tissue culture model.When the Matrigel was diluted with medium(1:1,v/v),the tissue culture model was failed.When using primary Matrigel,morphology of the cultured testis tissues showed no obvious difference compared to normal testis tissue on day 3;structure of the seminiferous tubule was uncompact in cultured tissue on day 7;the cultured testis collapsed and no obvious boundaries between seminiferous tubule and severe necrosis were observed in testis on day 14.PPV could infect the 3D cultured testis when incubated the tissues with PPV followed by seeding the explant in Matrigel.Number of copies of the PPV viral nucleic acid was not significantly changed after the intervention of resveratrol in the PPV-infected tissue model by using real-time fluorescent quantitative PCR.These results indicated that resveratrol could inhibit the infection of PPV in Leydig cells of piglets,but the effect on testis tissue was not obvious,it need further research.Methods established in the present study can provide a new idea for the study of virus infection and control,and provide a theoretical basis for the development of resveratrol as a functional feed additive.