Hantavirus Infection Induces Heat-Shock Protein Expression That Leads To The Association Of HSP70 With Viral Proteins

The expression of heat-shock proteins(HSPs) is characteristic of all organisms hi response to a variety of stresses, the response was called heat shock response(HSR).HSPs play important physiological functions in protein folding, transport and assembly in normal condition, and protect the cell from the deleterious effects of stresses. In our research, New-born mice less than 72hr of age were inoculated intrabrainly with the 100 LD50 of Hantavirus (76-118). At the 8 th day ,mice died from the deadly brain diseases. Brains were removed to prepare tissue sections and tissue extracts for the experiments. The hantavirus infection, hsp70> GRP94 induction and then- colocalization hi brain of infected suckling mice were demonstrated by double immunohistochemical staining and laser scan cofocal microscopy. The possible interaction between HTV nucleocapsid protein(HTV-NP) and HSP70 was further analyzed by immunoprecipitation of infected tissue extracts with antibodies to either HSP70 or to viral nucleocapsid protein and demonstrated by SDS-PAGE and Western blotting. The results showed that HTV infection caused increased levels of HSP70 and GRP94 expression at the cytoplasmas of neurons in the brains of suckling mice, the HTV-NP protein colocalized with HSP70 and GRP94. Monoclonal antibody ( McAb ) against HSP70 could coimmuno-precipitate the HTV-NP, and similarly McAb against HTV-NP could coimmunoprecipitate HSP70 from virus-infected tissues extracts, but not from mock-infected tissue extracts. Antibody, which recognizes one of these two proteins, does not cross-react with the other. Thus, the association between HSP70 and HTV-NP was specific. Our results indicated that Hantavirus infection can directly induces HSP70 and GRP94 expression. The finding that HSP70 was associated with the nucleocapsid protein of HTV may suggest a functional role of these complexes in the viral life cycles. The potential value of HSP70-HTV-NP complex is to be used as vaccine to prevent and treat hemorrhagic fever with renal syndrome by elicitation the specific cytotoxic T lymphocyte immune response against HTV.