|Budget Amount *help
¥1,900,000 (Direct Cost : ¥1,900,000)
Fiscal Year 1996 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1995 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Enveloped viruses assemble at host cell membrane. It is believed that the viral proteins are selectively incorporated into the virus envelope and cellular membrane proteins are largely excluded. However, there are several reports describing that some cellular proteins are into the virus envelope, but the mechanisms for selective incorporation of cellular proteins have not been fully understood.
Rabies virus, a member of rhabdovirus family, contains a negative-strand RNA genome encoding five structural proteins : glycoprotein, matrix protein, and three genome-associating proteins. In addition to these five viral proteins, rabies virus incorporates cellular proteins in the virions. We found that a constitutive type of heat shock protein 70, but not an inductive type of heat shock protein 70, was incorporated into the rabies virions grown on BHK-21 cells. Moreover, we found that ERM family proteins, which were linkers between cell membrane and microfilament, were associated with the viral glycoprotein in the infected cells and thus incorporated in the virions. the rabies virions grown on BHK-21 cells efficiently incorporate a transmembrane protein (vap21) homologous to human MIC2 gene product (CD99). Among them, two monoclonal antibodies recognized a 21-kDa protein (vap21) that was efficiently assembled in the rabies virus envelope. Immunofluorescence microscopy revealed that the distribution of vap21 at cell surface was altered by rabies virus infection and the distribution of vap21 in the infected cells was nearly coincident with that of matrix protein of rabies virus. These results suggest that some cellular proteins are incorporated into the rabies virion by selective mechanisms rather than random ones. Accordingly, identification of cellular proteins incorporated into enveloped virus particles will provides insights into the pathogenicity of the viruses.