Multiple drug resistance gene product

Plasmid-mediated resistance to tetracyclines is widespread. Tetracycline-resistant organisms show decreased intracellular accumulation of the drugs. Resistance mechanisms include decreased activity of the uptake systems and the development of mechanisms (efflux pumps) for active extrusion of tetracyclines. Plasmids that include genes involved in the production of efflux pumps for tetracyclines commonly include resistance genes for multiple antibiotics. 

Saquinavir is a peptide-like substrate analog that inhibits HIV protease after binding to its active site and is active against both HIV-1 and HIV-2 maturation. It blocks splicing of the viral polyproteins, which results in the production of immature viral particles that lack the ability to infect other cells. The resistance to saquinavir is associated with mutations in protease genes G48 V and L90 M, whereas secondary mutations are associated with codons 36, 46, 82, 84, 101, 154 and 184 multiple mutations are necessary to render strong resistance to the drug. 

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