Analysis Of Expression Profile Of Equine Host Restriction Factors Induced By EIAV Different Virulent Strains And Correlation With Immune Protection

Equine Infectious Anemia Virus(EIAV)belongs to the Retroviridae family and shares a similar genomic structural,functional features and life cycle with other lentiviruses,such as HIV-1.Most of the infected horses with EIAV could progress into a inapparent carrier stage.Importantly,an attenuated EIAV vaccine was developed by Dr.Rongxian Shen through serially passing,which could provide the effective immune protection against the virulent EIA strain and control an EIA pandemic in China.Until now,Chinese attenuated EIAV vaccine is the unique lentivirus that demonstrated effectively protection.Therefore,EIAV system is a unique and useful model for studying the lentivirus pathogenesis and immune protection mechanisms.Host restriction factors could interfere with the steps of the virus life cycle and then display antivirus function through different mechanisms.As for EIAV,many equine host restriction factors,including the equine A3Z3,IFITM3,SAMHD1,SLFN11,TRIM5α,Tetherin and Viperin,had been reported can restrict EIAV replication in vitro,but little is known about the expression of host restriction factors during EIAV infection and whether these can be modulated to the advantage of the host.In this study,we firstly used the unique EIAV strains system to explore the characteristics of the expression profiles of multiple restriction factors induced by different virulent EIAV strains and further to investigate whether the clinical protection of the EIAV-infected horses is related to the expression of host restriction factors.In order to investigate these issues,the mRNA levels of several equine restriction factors from the horses and target cells infected by different virulent EIAV strains respectively were analysed by quantitative real-time PCR.In addition,EIAV vaccinated horses were applied as model animals against virulent strains,and experimental horses were divided into immune protected hourses and unprotected hourses based on the incidence of EIA,then the correlation between the expression of restriction factors and immunoprotection was analyzed.Our data showed that the expression of the seven equine restriction factors were all upregulated by EIAV vaccine strain and the virulent strain.Although infection with the EIAV high virulent strain also up-regulated these immune restriction factors,the degree of Tetherin,A3Z3,SAMHD1,SLFN11 and TRIM5α were lower than that of EIAV vaccine strain.According to the vivo data,we also observed that the expression of all the restriction factors increased up on EIAV vaccine infection.While for EIAV virulent strain infection,only A3Z3,IFITM3 and Tetherin were increased.Importantly,in the early stage of infection(1-5d),the expression of SLFN11 and Viperin from the protected horses were significant higher than those of unprotected group(p<0.05).And in the late stage of infection(15-60d),the A3Z3,SAMHD1,SLFN11,TRIM5α and Viperin from the protected group were significant higher than those of unprotected group(p<0.05).In the late stage,the expression of SLFN11 and Viperin were negatively correlated with viral load(p<0.001;p<0.05).Our results indicate that the expression of host restriction factors induce by the two EIAV strains infection are different,and the persistent high level of host restriction factors may affect the establishment of protective immunity.In conclusion,our findings contribute to the cognitionof EIAV infection and innate immunity,and then establish the foundation for the further study of pathogenesis and immune protection mechanisms.