Fig. 2.

The functions of CypA in the lifecycle of HIV. ①CypA binds directly to the HIV-1 capsid, positively modulates viral infectivity by stabilizing the capsid, changing uncoating, improving the efficiency of reverse transcription and nuclear import, and negatively regulates viral infectivity by delaying capsid core uncoating and inhibiting the nuclear entry of HIV-1 in a cell type-dependent manner. ②CypA can help block the nuclear shape and early events of HIV infection in SUN2-overexpressed cells by interacting with SUN2. And SUN2 is an essential host protein for the positive effects of CypA on HIV-1 reverse transcription and infection. ③MxB protein can inhibit HIV replication and infection by hindering the nuclear import and integration of HIV-1 DNA in a CypA-dependent manner. ④ The successful establishment of capsid-CypA interaction could disrupt the restricting effect of TRIM5α on HIV-1 before the completion of reverse transcription. ⑤SUN1 regulates HIV infection by participating in the HIV-1 nuclear entry process through the mechanism dependent on the interaction between capsid and CypA in an unclear mechanism