Drug-resistant strains of HIV continue to be transmitted in the United Kingdom, but this does not appear likely to have a major effect on the response to antiretroviral (ARV) treatment, aidsmap reports. Publishing their findings in Clinical Infectious Diseases, researchers examined 1,140 samples of drug-resistant HIV taken from treatment-naive individuals between 1997 and 2011 and kept in the UK Drug Resistance Database.
The researchers looked for three common resistance mutations: the T215Y and related mutations, which confer resistance against Zerit (stavudine, d4T) and Retrovir (zidovudine, AZT) (rarely used in the UK today); K103N, which leads to failure with Sustiva (efavirenz) and Viramune (nevirapine); and L90M, which leads to resistance against Invirase (saquinavir) and Viracept (nelfinavir) (also rarely used).
These mutations were present in a respective 58 percent, 38 percent and 13 percent of the samples. Seven percent of the samples had two of the mutations; 1 percent had all three of them.
The investigators concluded that much of transmitted drug resistance in the UK “is likely to be derived from untreated and likely undiagnosed individuals, and that it is mostly unlikely to have considerable impact on therapy outcomes.”
This finding may not hold for developing nations, however, where ARVs that are largely obsolete in wealthier countries are still widely used.