Targeting cellular cofactors in HIV therapy

Abstract

Besides viral proteins cellular factors play a key role in the replication of the human immunodeficiency virus HIV-1. The outcome of virus replication is determined by the balance between the activity of a number of cellular dependency factors and restriction factors. Whereas the first are essential cofactors for diverse steps in the viral replication cycle, the latter counteract virus replication by sensing particular viral components as non-self, often as mediators of the innate immune system. Cellular cofactors include receptors for HIV-1 entry, LEDGF as cofactor for the viral integrase, the RNA helicase DDX3 involved in the nuclear export of unspliced viral RNAs, and diverse cellular kinases that promote viral replication. Cellular restriction factors are often antagonized by HIV-1 accessory proteins in order to counteract their restrictive function on viral replication. Although cellular cofactors in the HIV field are understood as factors promoting viral replication, we add a subchapter on the most important restriction factors (Trim5α, APOBEC3G, SAMHD1, and tetherin/BST-2). Today highly active antiretroviral therapy (HAART) mostly targets HIV proteins like reverse transcriptase, protease, or integrase to specifically interfere with virus replication. However, the identification of cellular cofactors and the increasing knowledge on their mode of action at defined steps in the HIV-1 replication cycle have opened new avenues towards the development of HIV-1 inhibitors. Here we summarize the most important cellular factors involved in HIV-1 replication along with therapeutic approaches developed to target them, preferentially without harming their normal cellular function.