Enhanced infection of an X4 strain of HIV-1 due to capping and colocalization of CD4 and CXCR4 induced by capsianoside G, a diterpene glycoside

We investigated whether capsianosides, diterpene glycosides, extracted from Capsicum plants could affect human immunodeficiency virus type 1 (HIV-1) infection. Significant effect on virus infection in MAGI/CCR5 cells was neither observed for the X4 virus by capsianosides II, XI, and A, nor for an R5 virus by capsianoside G. Apparent enhancement of X4 HIV-1 infection by capsianoside G was observed and exclusively related to the usage of the CXCR4 coreceptor. The capsianoside G-treated cells had no change in the expression level of CD4, CXCR4, and CCR5, however, colocalization and capping of CD4 and CXCR4, but not of CD4 and CCR5 was observed. Our results suggested that capsianoside G enhanced X4 virus infection at the level of viral penetration through the capping and colocalization of receptors needed for infection.