Question

Identify the six classifications of antiretroviral drugs and discuss how and why each is used for the treatment or prevention of HIV. The following video may be helpful:

Answer 1

HIV or Human Immunodeficiency virus is the causative arganism of AIDS( Acquired immunodeficiency syndrome) which is one of the most common sexually transmitted infection affects the immune system of the body.

The Food and Drug Administration (FDA)-approved antiretroviral drugs used for treatment of HIV-1 infections are classified under six classes based on their molecular mechanism and resistance profiles.They are nucleoside-analog reverse transcriptase inhibitors (NNRTIs), non–nucleoside reverse transcriptase inhibitors (NNRTIs), integrase inhibitors, protease inhibitors (PIs), entry inhibitors, and coreceptor or Chemokine receptor antagonists (CCR5 antagonists). Usually HIV is treated with combination of two or three classes of these drugs.

Use in the treatment or prevention of HIV

(1) Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) ; These classification of drug is consisered as the first-line HIV treatment combination. They inhibit the reverse transcription process in the production of proviral DNA in the host cells and by acting on the reverse transcriptase protein. Thus stop the replication of virus in the host.

(2) Non-nucleoside reverse transcriptase inhibitors (NNRTIs) ; These drug bnind with the reverse transcriptors enzyme and stop the reverse transcription process.

(3) Integrase inhibitors ; Integrase inhibitors stop the integration of viral DNA to the host cell by targeting a protein in HIV called integrase which binds to host cell DNA and prepares an area on the viral DNA for integration.

(4) Protease inhibitors (PIs) ; These drugs inhibit the protease enzyme which is required for assembly of new viral particles and there by make the new virions immature which can not infect other new cells.

(5) Entry inhibitors ; These are two types, CCR5 inhibitors and fusion inhibitors. The  CD4 receptor and a co-receptor (CCR5 or CXCR4) are two receptors found on the human cells where the HIV virus can bind and form envelop to enter into the cells. CCR5 inhibitors binds to the corresponding receptors and thereby stop the HIV to enter into cells.

(6) coreceptor or Chemokine receptor antagonists (CCR5 antagonists) ; These drugs bind to hydrophobic pockets of the CCR5 receptors Thus HIV virus fails to recognize them and stop the virus to enter into host cells.