Chikungunya virus infection impairs osteogenic differentiation of bone marrow-derived mesenchymal stem cells

Chikungunya virus (CHIKV) is a positive-sense, single-stranded RNA virus, belonging to the genus alphavirus in the family Togaviridae. The virus is spread by the Aedes species (sp.) mosquitoes in tropical and subtropical regions of the world. CHIKV causes Chikungunya fever (CHIKF), where the acute stage of infection is characterized by high fever, headache, rash, and polyarthralgia. In 30-40% of cases, patients develop a chronic stage with debilitating joint pain persisting for months to years imposing a burden on the population in terms of disability adjusted life years (DALY). Presently, no vaccines or treatment options are available for this infection. Prior investigations reveal that CHIKV infection is associated with bone pathology; however, the molecular mechanism underlying CHIKV-induced bone pathology remains poorly defined. Studies show that disruption of osteogenic differentiation and function of bone marrow-derived mesenchymal stem cells (BMMSCs) can lead to bone pathologies. However, to date pathogenesis of CHIKV infection in this context has not been studied. In the current study, we investigated the susceptibility of BMMSCs to CHIKV and studied the effect of infection on BMMSCs-derived osteogenic cells. To our knowledge, for the first time we report that CHIKV can productively infect BMMSCs. We observed a decrease in the intracellular and extracellular alkaline phosphatase (ALP) activity and reduction in calcium phosphate deposition in infected cells compared to mock-infected control. Thus, we conclude that CHIKV infects BMMSCs and disrupts function of osteogenic cells.\n\nImportanceAlthough studies have shown association of bone pathology and CHIKV infection, the pathogenesis of infection causing altered bone homeostasis is not fully understood. Here, we demonstrate for the first time that BMMSCs are susceptible to CHIKV infection. Furthermore, we observe that infection causes disruption in the function of BMMSC- derived osteogenic cells. Impaired function of these osteogenic cells will likely lead to a disruption in bone homeostasis and in part, provides a mechanism for the observed bone pathology associated with CHIKV pathogenesis.