Mis-localized nucleoporin POM121C potently inhibits nuclear entry of HIV-1 but leads to the outgrowth of viral escape mutants.

Nuclear entry of HIV-1 involves specific interactions between the viral capsid and components of the nuclear pore complex. FG-repeat sequences present in many nucleoporins play important roles in HIV-1 nuclear entry. We previously reported that overexpression of the FG repeat-containing C-terminal fragment of the nucleoporin POM121C (residues 614-987), termed POM987, inhibits HIV-1 infection. However, the mechanism underlying this inhibition remained unclear. Here, we identified HIV-1 escape mutants that are resistant to POM987-mediated restriction and mapped the responsible mutations to two amino acid positions in the capsid protein. POM987 bound the incoming HIV-1 capsid core and inhibited viral nuclear entry. In contrast, the escape mutant showed reduced interaction with POM987 and restored nuclear entry and integration in POM987-expressing cells. These findings indicate that the antiviral activity of POM987 is mediated by capsid-dependent inhibition of HIV-1 nuclear entry and suggest that capsid-nucleoporin interactions could provide a potential target for developing novel antiviral therapies. IMPORTANCE: HIV-1 can infect non-dividing cells. This requires interaction with nuclear pore proteins, including POM121C. A mis-localized fragment of POM121C potently inhibits nuclear entry through direct interaction with the incoming capsid core. Escape variants acquire mutations at specific capsid residues, enabling them to evade this interaction and thereby restore nuclear import.