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• Anti HIV drugs – HIV patients are treated with a combination of reverse transcriptase, integrase and protease inhibitors. As well as a CCR5 receptor antagonist.
• Entry – The HIV attaches to the T cell surface and needs to bind to 2 receptors – CD4 (found on T cells) and CCR5 receptors (transmembrane proteins that spans the T cell)

  HIV can infect only when it binds to both the receptors.
• The 2 membranes fuse upon HIV attachment to the receptors. Viral RNA emptied into cell through endocytosis and HIV takes over synthesizing many copies.
• Reverse transcriptase is an enzyme that converts RNA to DNA which is used as a template strand. Not all virsues are alike as reverse trancriptase makes mistakes whilst reading the RNA sequence. Viruses from the same host cell may have small shape or enzyme difference.
• Intergration – DNA made from reverse transcriptase is then integrated using the integrase enzyme into the hosts chromosomal DNA. After incorporation of the DNA it is now a provirus.
• Translation – HIV RNA has 9 genes which code to make all structural proteins and enzymes.
• Protease – translated viral RNA has a chain of many individual proteins. Proteins need to be cut to make it functional. Protease acts as a chemical scissors to cut chain into small components.
• Assembly – RNA packaged and leaves the host cell through budding (exocytosis) and takes a lot of the T cell membrane containing viral surface proteins to bind to other immune cells.
• Nucleoside RT inhibitor mechanism of action – 3’OH is lacking of the cyclic sugar, termination of the DNA chain elongation occurs. Known as a suicide substrate.
• Non nucleoside RT inhibitor mechanism of action – (nevirapine) – directly binds to RT and blocks RNA and DNA dependent activties thus disrupting enzyme active site.
• HIV protease inhibitors – group of drugs that were used in combination with RT inhibitors for HIV treatment.

  HIV protease responsible for post modification of proteins. It also assmebles and releases the viral particles.

  The inhibitors are competitive antagonist for the natural substrate peptide.

  SAQUINAVIR, RITONAVIR and INDINAVIR
• Protease inhibitors – they mimick the protein chain structure that the enzyme would usually cut. This chain then binds to the protease active site, preventing further protein chain cleavage. This leads to the protease not being functional at all.