Study On The Effect Of Recombinant CVN Protein On Porcine Reproductive And Respiratory Syndrome Virus In Vitro

Porcine Reproductive and Respiratory Syndrome?PRRS?was a worldwide viral infectious disease caused by porcine reproductive and respiratory syndrome virus?PRRSV?infection in the world.The disease was characterized by typical symptoms such as abortion of pregnant sows and respiratory diseases of piglets,which brought huge economic losses to the pig industry and seriously restricted the healthy development of animal husbandry.At present,the prevention and control of PRRS was mainly based on vaccine immunity,and there was no specific medicine for it yet.The vaccine used in the pig farm were commercial PRRS attenuated vaccine and inactivated vaccine,but it could not provide protection for the pig safely and efficiently.There were some potential safety hazards in the attenuated vaccine,and the inactivated vaccine was easy to fail,and the genomic variation of the virus could cause great hindrance to the prevention and control of the disease.Effective antiviral drugs were considered as one of the main means to prevent and control the disease.It was the goal of the pig industry to develop economic and efficient targeted drugs.Cyanovirin-N?CVN?is an antiviral protein extracted from cyanobacteria and has a broad spectrum of antiviral properties.CVN had a stable physical and chemical properties,and had a good antiviral effect on type A and B influenza viruses and HIV,which was a new potential antiviral drug.In this study,the CVN gene was artificially synthesized by biology company based on the CVN gene sequence of Genebank?DQ668406.1?and vector pMAL-c5x-CVN was constructed.The soluble recombinant CVN protein was expressed by optimizing the IPTG induction condition.The cytotoxicity of recombinant CVN to Marc-145 cell was tested using the cck8 kit and anti-PRRSV assay was performed within safe concentrations.Then the Experiments were carried out on about three stages of PRRSV infection,which were adsorption,penetration and replication,to investigate the anti-PRRSV effect of CVN on Marc-145 cells in vitro.The results of TCID₅₀ test and indirect immunofluorescence assay and QPCR viral load assay showed that CVN could against PRRSV in the stage of penetration,and there were no obvious effect in the stage of adsorption and replication.This study provided a theoretical basis for the research and development of new anti-porcine reproductive virus and respiratory syndrome virus drug.