AGPAT1 is a novel Chikungunya virus receptor on human cells

Chikungunya virus (CHIKV) is a medically important alphavirus whose host receptor is not fully understood. We identified AGPAT1 from the human Huh7 cell plasma membrane binding with CHIKV particles <i>in vitro</i>. The CHIKV binding with AGPAT1 was demonstrated on Huh7 cell plasma membrane by confocal microscopy. The AGPAT1 antibody inhibited CHIKV binding to cells, reducing the virus uptake in Huh7, ERMS, HAP1, and the primary mouse fibroblast cells. CHIKV binding, uptake, and replication were significantly reduced in the AGPAT1 knockout HAP1 cells, and the ectopic expression of AGPAT1 rescued the reduced virus binding, uptake, and replication. AGPAT1, together with CHIKV E2, was found to localize in the early endosomes, early during the virus infection. AGPAT1 interacted with the E1 surface on the E1-E2 dimer of CHIKV envelope proteins <i>in silico</i>. The E1-AGPAT1 interacting amino acid residues identified in the computational studies were experimentally verified. AGPAT1 was also shown to have a role in the binding and uptake of another alphavirus, Ross River virus. These data demonstrate an important role for AGPAT1 as a novel host receptor involved in CHIKV binding and uptake in human cells.IMPORTANCEChikungunya virus (CHIKV) is a medically important alphavirus. Identifying its receptor on human cells will aid in the development of novel antivirals. We have identified AGPAT1 as a novel CHIKV receptor on several human cells. We provide data showing the interaction of AGPAT1 with the E1 protein of CHIKV E1-E2 dimer present on the virion surface and identify the amino acid residues involved in the interaction. AGPAT1 was also shown to have a role in the binding and uptake of Ross River virus, another alphavirus. AGPAT1 is a protein involved in lipid metabolism and has not been reported to have a direct role in any virus infection or as a virus receptor. Thus, this work identifies AGPAT1 as a novel receptor for CHIKV on human cells and demonstrates that AGPAT1 has implications for understanding the virus pathogenesis and designing the receptor-blocking CHIKV antivirals.