Unraveling alphavirus neuroinvasion: Molecular insights from a stem cell based blood-brain barrier model

PROJECT SUMMARY Alphaviruses are mosquito-borne viruses that can cause arthritis and fatal encephalitis in humans with no approved therapeutics. Encephalitic alphaviruses, like Sindbis (SINV) and chikungunya (CHIKV) viruses, must cross the barriers protecting the central nervous system and therefore are neuroinvasive. The central nervous system is primarily protected by tightly connected brain microvascular endothelial cells (BMECs), pericytes, and astrocytes, which together constitute the blood-brain barrier (BBB). Genetic determinants of neuroinvasion reside in the alphavirus E2 glycoprotein and host factors that interact with the E2 glycoprotein have been identified. However, the relationship between neuroinvasive residues on E2 and the cell-specific expression of host interactors are not well characterized in the context of neuroinvasion. Our lab models the BBB by using pluripotent stem cell derived BMECs (iBMECs) that recapitulate the in vivo neuroinvasive phenotypes of alphaviruses and flaviviruses. Using this model, we have demonstrated that alphavirus neuroinvasion correlates with the ability to efficiently infect BMECs. Therefore, we hypothesize that the alphavirus E2 glycoprotein must interact with a BMEC-specific host factor to efficiently infect BMECs and cross the BBB. We will first determine how previously identified neuroinvasive E2 residues on SINV and CHIKV confer the ability to efficiently infect BMECs. Furthermore, we will identify the host factor that neuroinvasive alphaviruses hijack for efficient BMEC infection and characterize its interactions with E2. This work will elucidate virus-BBB interactions that facilitate neuropathogenesis, providing a foundation for therapeutic research. Under the fellowship training plan, I will advance my abilities in experimental design and science communication by executing, presenting, and publishing the results of this project, as well as through coursework and teaching as required by my doctoral program. My research training will take place in a rigorous and multidisciplinary scientific environment at the University of California, Los Angeles, where I have access to all the materials and expertise necessary for the completion of this project.