Proviral DNA Synthesis in HIV: Background

Abstract

Human immunodeficiency virus (HIV) stores its genetic information in the form of RNA. This RNA genome is introduced into the target cell during infection. The virus belongs to the family of retroviruses, as it is able to reverse the normal flow of genetic information from DNA to RNA by copying its RNA genome into DNA using the viral enzyme reverse transcriptase (RT). Each viral particle contains two copies of positive-strand RNA genome enclosed by a core composed of 2,000 copies of the capsid (CA) protein. The RNA genome is tightly bound to nucleocapsid proteins (NC) and other enzymes needed for the early steps of viral infection and is protected by a capsid surrounded by a shell composed of matrix (MA) proteins. The shell is located underneath the virion envelope, a plasma membrane of host-cell origin. During infection, the viral envelope fuses with the cell membrane, releasing the capsid into the cytoplasm. Thereafter, the RNA genome undergoes a multistep process of conversion into DNA within the reverse transcription complex (RTC) (Fig. 2.1). After reverse transcription, the newly synthesized DNA is integrated into the host nuclear genome and permanently linked with their target cells.