Current evidence and future directions for targeting HIV entry - Therapeutic and prophylactic strategies

Great strides have been made in developing potent antiretroviral regimens that block human immunodeficiency virus (HIV) transcription and assembly. Despite these therapeutic advances, problems of drug resistance, latent viral reservoirs, and drug-induced toxic effects that compromise effective viral central point to the need for new classes of anti-HIV drugs with different modes of action. One promising approach involves blocking HIV entry into human cells, a complex process that involves multiple protein interactions. The process of HIV entry begins with binding of the viral envelope glycoprotein to both the CD4 receptor and one of several chemokine receptors and ends with fusion of viral and cell membranes. Conceptually, there are 3 steps in the HIV entry process that could serve as therapeutic targets: binding of the viral envelope glycoprotein with the CD4 receptor, binding of the envelope-CD4 complex to chemokine receptors, and fusion of the viral and cell membranes. Preclinical and clinical assessment of these entry inhibitors is ongoing and will determine if they possess properties required for drug licensure. Moreover, the worldwide epidemic is largely occurring in developing countries that cannot afford these drugs: a prophylactic vaccine is necessary and urgent. New knowledge of the HIV-envelope glycoprotein has also provided insight into possibilities for the design of novel HIV vaccines.