Human immunodeficiency virus (HIV) has no more than nine genes expressing approximately twenty
proteins. When T lymphocytes and macrophages in a body are infected with HIV, these
proteins work in turn at specific time and location, causing
acquired immunodeficiency syndrome (
AIDS), a disease yet to be overcome. Since the elucidation of molecular mechanism of
HIV proteins should lead to remedy of
AIDS, the author has been engaged in the study of HIV
protein in the past decade. Described herein are
viral protein X (Vpx), uniquely found in HIV-2, and its homologous
protein Vpr found both in HIV-1 and -2. We found that Vpx enhances genome nuclear import in T lymphocytes, and is critical for reverse transcription of
viral RNA in macrophages. This finding on the function in macrophages corrected long-term misleading belief. Furthermore, functional region mapping of Vpx was performed. In 2011, the
protein SAMHD1 was identified as the host restriction factor counteracted by Vpx, by foreign researchers. After that, our independent study demonstrated the presence of SAMHD1-independent functions of Vpx in T cells, in addition to its SAMHD1-dependent functions in macrophages. Another topic of this review is
Gag protein. Recently, it has reported by overseas researchers that PI(4,5)P2 (one of
phosphoinositide) regulates Pr55(Gag) localization and assembly. In this study, we determined the binding affinity between N-terminal MA domain of Pr55(Gag) and various
phosphoinositide derivatives using surface plasmon resonance. The results suggested that both negatively charged
inositol phosphates and hydrophobic acyl chain are required for the MA binding.