Safe and effective HIV vaccines offer the most hope of stopping the spread of HIV disease worldwide. Although HIV transmission is in theory largely preventable, in practice, without the development of an effective vaccine, HIV will continue to infect millions throughout the world. The ideal vaccine for worldwide use will be inexpensive to manufacture, provide protection against all subtypes of HIV, require minimal if any boost, protect against all methods of spread of HIV for years, and be easily administered, stable to heat, and widely accessible (Merigan et al., 1999). An understanding of the molecular and immunological mechanisms of HIV pathogenesis is necessary in the development of a successful HIV vaccine. Both humoral and cell-mediated immune responses specific for HIV gene products have been identified. This essay describes immune responses to HIV and recent advances towards the development of a safe protective vaccine against HIV.
HIV is a member of the lentivirus family of animal retroviruses which are capable of long term latent infection of cells and short term cytopathic effects (Abbas et al.,
2003). A HIV virion contains two identical strands of ribonucleic acid (RNA) and associated enzymes, including reverse transcriptase, integrase, and protease, packaged within a core composed of p24 capsid protein with a surrounding p17 protein matrix, all surrounded by a phospholipid bilayer envelope derived from the host cell (Abbas et al., 2003). Virally encoded membrane proteins (gp41 and gp120) are bound to the envelope. Interaction of an HIV surface glycoprotein (gp 120) with CD4 is necessary but not sufficient for entry (Letvin, 2002). Two major types of HIV have been identified as HIV-1 and HIV-2.
HIV Infection begins when the envelope glycoprotein (Env) of a viral particle binds to both CD4 and a coreceptor that is a member of the chemokine receptor family (Abbas et...