Effects Of IFITM On Proliferation Of Classical Swine Fever Virus

Classical swine fever(CSF)is a highly contagious disease caused by Classical swine fever virus(CSFV).At present,CSF is prevented by stamping-out(non-vaccination)and systemic prophylactic(vaccination)policies in worldwide.However,in the current pig industry,a large number of recessive and atypical infections have brought great chal enges to the prevention and control of CSF.In this case,he study of the antiviral genes of swine itself indicates another direction for the prevention an t d control of CSF.Interferon?induced transmembrane proteins(IFITM)family,especially IFITM1,2,3 can inhibit a growing number of enveloped-viruses.However the specific antiviral mechanisms of IFITMs are still unclear,and the impact of IFITMs on CSFV has not been reported.This study mainly focused on the effects of IFITM1,2 and 3 on the proliferation of CSFV,in order to explore whether IFITMs can inhibit the proliferation of CSFV.The following results are obtained by experiments:1.Three fusion expression vectors of IFITM1,2,3 with tag-EGFP were built.Using the fluorescence microscope,we observed that IFITM1 was mainly located on the cell membrane,while IFITM2 and IFITM3 were positioned in the cytoplasm.And after the inoculation of CSFV,these proteins changed their location.Results also showed that IFITM1,2,and 3 were partly co-localize with LAMP1.However,following the inoculation of CSFV,those three proteins had more co-localize with the LAMP1 through the confocal microscope.2.The resluts proved that IFITM1,2,and 3 could inhibit the viral entry of CSFV but not the attachment on PAMs.3.Porcine alveolar macrophages(PAM)cell lines that stably overexpress or knockdown mediated by shRNA the expression of IFITM1,IFITM2 and IFITM3 were established.The proliferation of CSFV was significantly inhibited in cell lines overexpressing three proteins.In contrast,when CSFV was inoculated in the shRNA cell lines,the proliferation of CSFV was significantly higher compared to control.It was also found that CSFV inhibited the expressions of IFITM1,2 and 3 in PAMs.As for the interactions between IFN and IFITMs,the resluts showed that IFN-? stimulated the expressions of IFITM1,2 and 3,and IFITM1,2 and 3 negatively regulated on the mRNA levels of IFN-? and IFN-?.In conclusion,this study confirmed that IFITM1,2,and 3 could inhibit the proliferation of CSFV,and preliminarily determined the subcellular localization of IFITM1,2 and 3 in PAMs.