Proteomic profiling of chikungunya virus-infected human muscle cells: reveal the role of cytoskeleton network in CHIKV replication.

Unlabelled: Chikungunya virus (CHIKV) is an arthropod-borne, positive-sense, single-stranded RNA virus belonging to genus Alphavirus and family Togaviridae. The clinical manifestations developed upon CHIKV-infection include fever, myositis, arthralgia and maculopapular rash. Thus, the re-emergence of CHIKV has posed serious health threats worldwide. Due to the fact that myositis is induced upon CHIKV-infection, we sought to understand the dynamic proteomic regulation in SJCRH30, a human rhabdomyosarcoma cell line, to gain insights on CHIKV pathogenesis. Two-dimensional gel electrophoresis (2DE) in combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to profile differential cellular proteins expression in CHIKV-infected SJCRH30 cells. 2DE analysis on CHIKV-infected cells has revealed 44 protein spots. These spots are found to be involved in various biological pathways such as biomolecules synthesis and metabolism, cell signaling and cellular reorganization. siRNA-mediated gene silencing on selected genes has elucidated the biological significance of these gene-translated host proteins involved in CHIKV-infection. More importantly, the interaction of vimentin with non-structural protein (nsP3) of CHIKV was shown, suggesting the role played by vimentin during CHIKV replication by forming an anchorage network with the CHIKV replication complexes (RCs).

Biological Significance: Chikungunya virus (CHIKV) is a re-emerging virus that has caused various disease outbreaks in Africa and Asia. The clinical symptoms of CHIKV-infection include fever, skin rash, recurrent joint paint, and myositis. Neuronal implications and death may be resulted from the severe viral infection. Up to date, there are no effective treatments and vaccines against CHIKV-infection. More importantly, little is known about the differential regulation of host proteins upon CHIKV infection, hence deciphering the viral-host cell interactions during viral infection provide critical information on our understanding on the mechanisms of virus infection and its dependency of host proteins for replication. In light of the muscle-related clinical manifestations of myositis resulting from CHIKV-infection, human rhabdomyosarcoma cells, SJCRH30 were utilized in this protein profiling study, in order to decipher the pathogenesis of CHIKV. This study has identified an arrays of host proteins that are differentially regulated upon CHIKV infection including that of the cytoskeletal protein, vimentin that plays significant role in aiding the replication of CHIKV within the host cells through 2DE assay. Immunofluorescence assay further shows that the novel interaction between cytoskeleton structure and CHIKV replication complex by forming an intercalating network around the replication complexes and facilitating various stages of the virus life cycle. This novel finding has inevitably led to a deeper understanding of CHIKV pathogenesis in revealing the importance of host proteins during CHIKV replication, as well as contributing to the development of specific antiviral strategies against this medically important viral pathogen.