The Mechanism Of The Virus Protein Of HIV And HBV Interact With Host Cell

ADIS?acquired immunodeficiency syndrome?is one of the most serious infections wich is caused by HIV?human immunodeficiency virus?.The disease can break down human immune system and lead to serious complications,with no specially valid medicine.So,HIV pathogenesis researches and potential drug targets are important for human health and social stability.Nef protein is a negative regulator of HIV,and mainly expressed in CD4+T cells.Nef induces the AIDS-like symptoms that the amout of apoptotic cells increase.Nef gene mutation or deletion is significantly associated with the occurrence of Long-term Nonprogressors/Slowprogressors AIDS?LTNP/LTSP?.Nef down-regulates the expression of some cell surface receptors,such as CD4,CD28,CD86,MHC-I and MHC-II,interfering the clearance and surveillance of immune cells,wich can allow the immune evasion of HIV-1.It also can suppress apoptosis by directly binding to some pro-apoptotic repressors and kinases,prolonging the survival of infected cells,wich benefits for viral replication and infectivity.We found that Nef can interact with the C-terminus?169-380 aa?of cytochrome b?Cyto b?by yeast two-hybrid experiment,then we make sure that they can form a complex in vivo by co-immunoprecipitation experiments,and their binding associate with Fas-mediated apoptosis pathway.Currently the study about mitochondrial apoptosis pathway,the researchers foucs on cytochrome C?Cyto c?.Cyto c plays critical role in mitochondrial apoptosis pathway.Cyto c combines with Apaf-1and other auxiliary proteins forming a complex named apoptosome.The apoptosome then actives caspases and results apoptosis ultimately.Our results demonstrated that Cyto b is part of Fas-mediated apoptosis,furthermore this pathway is caspase-independent and different to the classical apoptotic pathway mediated by Cyto c,with absent of apoptosome.Our study also found Nef can inhibit apoptosis induced by Apaf-1,which illustrated that Nef is a negative regulator of Cyto c-mediated apoptotic pathways.In addition,we used anti-fas monoclonal antibody C11 to active the fas apoptotic pathway,and find the evidence that the direct binding of Nef and Cyto b inhibits the Fas apoptotic pathway.HIV-1_BA-L is the pseudovirus of HIV-1 type B,we made it and infected Jurkat T cells with HIV-1_BA-L,finding that HIV-1 inhibits Fas apoptosis pathway by interacting with Cyto b.However,we know little about Cyto b-related apoptosis pathway so far,but the in-depth knowledge of the the passway is helpful for the study of deeper mechanisms of immune escape mediated by Nef.Our research explored possible mechanisms that HIV-1 interacts with host cell,and it requires further in-depth discovery.Hepatitis B virus?HBV?infection not only can cause acute or chronic hepatitis,but also closely related with liver failure,cirrhosis and liver cancer.Hepatitis B is an important infectious disease worldwide,with high infectivity and mortality.At present,we still lack of effective treatments for hepatitis B.The aim of Hepatitis B treatment is sustained suppression of HBV replication,reducing damages to hepatocytes,delaying the development of liver cirrhosis?LC?and hepatocellular carcinoma?HCC?.HBV is difficult to completely removed from the body,which owns complex immune escape mechanisms.Interferon?IFN?is a widely expressed cytokine,with many biological activitives such as anti-virus,anti-tumor and immunomodulatory.The physiological role of IFN is to regulate the transcription of genes induced by IFN signaling pathways.Once viruses infect human,they primarily activate innate immunity,the effect of IFN-induced factor is body's first line to defense against infection.Thus,the mechanisms HBV escaping from congenital immunity related to IFN are of practical significance.Interferon induced transmembrane protein family?IFITM?is an important effector induced by IFN,with anti-viral and anti-tumor functions.They mainly induced by IFN?through Jak-stat1 signaling pathway,and with broad-spectrum anti-viral effects,such as the HIV,SARS coronavirus?SARS-CoV?,Influenza A virus?IAV?,Dengue virus?DFV?and Vesicular stomatitis virus?VSV?and so on.However,the anti-HBV mechanisms of IFITM were rarely reported.HBV e protein has a strong immunomodulatory effects,and quite important to the pathogenesis of hepatitis B.We studied the possible mechanisms of HBV immune evasion.By yeast two-hybrid experiments,we find that BAF200 interacts with HBe.BAF200 is encoded by ARID2.However,HBe is a secreted protein,so it is difficult to actually interact with BAF200 sited within the nucleus.Unlike HBe,most HBV core protein?HBc?exist in cytoplasm,above all they have similar sequence with HBe,so we speculated that HBc can interac with BAF200 in vivo as well.To prove this inference,we performed co-immunoprecipitation experiments,and the results made sure that the interaction between HBc and BAF200 does exist.SWI/SNF is kind of chromatin remodeling complex and owns two forms-BAF and PBAF,their subunits mostly the same,but BAF250 only exists in BAF,BAF200 and BAF180 are unique for PBAF.According to researches,compared to BAF,only PBAF complex has the function regulating the transcription which dependented on hormone receptor-ligand activity in nucleus.Our experiments confirmed that the expression of IFITM1 depends on BAF200 instead of BAF180.Moreover,we found that phosphorylation of STAT1 has no affect on the regulation of BAF200 by IFN?,suggesting the IFN?-induced signaling pathways is independent of JAK-STAT1.By transfecting HepG2 cells with pHBV1.31 plasmid,we analyzed by ELISA and Real-Time PCR and proved that the stimulation of IFN?can significantly reduce the amout of HBeAg,HBsAg and the copies of HBV DNA.The results hinted that that IFN?has antiviral activity against HBV.In addition,we interfered the gene transcription of IFITM1 in HepG2 and HepG2.2.15,and confirmed that IFITM1mediated cell proliferaton induced by IFN?.In conclusion,this part of study proved that,HBc inhibits the expression of IFITM1 induced by IFN?through binging to BAF200.It is probably one of the mechanisms of HBV immune evasion,and provides a potential drug target for HBV treatment.In summary,we discussed the interactions between HIV Nef protein and HBV HBc protein with host cells,enriched the understanding of relevant infection and immune escape mechanisms.