Preliminary Study on Intracellular Synthesis and Translocation of Rabies Virus M Protein

Objective Rabies virus (RABV) is a highly neurotropic virus, which composes of five structural proteins, such as nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G) and RNA-dependent RNA polymerase (L). The RABV genomic RNA, combining with N, P and L proteins, constitute the ribonucleoprotein complex (RNP).M proteins plays a particular role in regulating the synthesis and assembly of the structural proteins of RABV.However, it is not clear where the intracellular synthesis and translocation sites of M proteins are and whether there are differences in M proteins in different cell lines among RABV strains.The co-localizations of M protein with ER and Golgi, M protein with G protein and M protein with RNP in N₂A and BHK cells were studied to determine the intracellular synthesis pathway and translocation of RABV M proteins.

Method TCID₅₀ of different RABV strains (CVS-11, SRV-9 and PB4) in N₂A or BHK cells were determined.Co-localization of M protein with ER and Golgi as well as with G protein and RNP (represented by N protein) in ER and Golgi apparatuses were performed by Immunofluorescent.

Result The titers in the different RABV strains had certain differences.All the M proteins in different RABV strains were co-localized with ER and Golgi.M protein also co-localized with G protein as well as with N protein; however, the co-localization of M protein and G protein was mainly in ER and Golgi, while that of M protein and N protein in cytoplasm.

Conclusion The synthesis and processing of the RABV M proteins were carried out through ER-Golgi pathways.The study results confirmed the synthesis and translocation cellular sites of RABV M proteins, and enriched the data for assembly and budding process of RABV virions.