Glycosylation as a host defense strategy for multiple alphaviruses

Project Summary To gain access to cells, most viruses attach to receptor molecules. While many virus receptors have been identified, the impact of post-translational modifications on receptor function remains understudied. Glycosylation is a major type of post-translational modification of cell surface proteins, and viruses often exploit cell surface glycans for entry. However, given the extreme heterogeneity of glycosylation, it is unlikely that all glycans play equivalent roles in host-virus interactions. This proposal posits that specific glycosylation patterns can disrupt virus-receptor interactions, serving as a host defense mechanism against viral entry. My preliminary studies identify β1,3-N-acetylglucosaminyltransferase 2 (B3GNT2) as an interferon-stimulated gene that strongly inhibits multiple alphaviruses, including Venezuelan equine encephalitis virus (VEEV). B3GNT2 catalyzes the biosynthesis of poly-N-acetyllactosamine (polyLacNAc) chains leading to heavy and bulky glycosylation of LDLRAD3, a host receptor for VEEV. Consistent with its role in receptor glycosylation, B3GNT2 reduces VEEV attachment to the cell surface. Based on these findings, I hypothesize that B3GNT2 inhibits VEEV entry by glycosylating the viral receptor and may protect against VEEV-induced pathogenesis in vivo. Given its broad antiviral effects against multiple alphaviruses, I further hypothesize that B3GNT2 inhibits other alphaviruses including Chikungunya virus (CHIKV), through a similar mechanism. In the K99 mentored phase, I will integrate biochemical, cell biological, and glycan-based approaches to define the antiviral mechanism of B3GNT2 against VEEV (Aim 1) and investigate its antiviral role in VEEV pathogenesis using mouse models (Aim 2). In the R00 phase, I will extend these studies to CHIKV infection in B3gnt2 knockout mice and define the role of polyLacNAc glycosylation in blocking receptor-mediated entry of multiple alphaviruses (Aim 3). These studies will provide key insight into how host cells prevent viral entry through glycosylation and establish experimental tools to explore the broader role of glycosylation in host-pathogen interactions.