4.10 TRANSMISSION OF DRUG RESISTANT HIV VARIATIONS
The utilization of mix combinations of antiretroviral medications has been strikingly effective in suppressing HIV infection; all things considered, such advantages can be bargained by the development of drug resistance and, likewise, by the transmission of drug-resistance HIV strains. HIV imperviousness to antiretroviral medications is classified as primary resistance when there is no history of antiretroviral treatment or as secondary resistance, when it develops after the exposure to antiretroviral drugs. An explanation for the primary resistance of HIV is the transmitted resistance or infection with a drug-resistant HIV strain that may happen through parental, sexual, and vertical courses of HIV acquisition. The transmitted HIV drug resistance is a developing concern, in light of the fact that the existence of low-frequency or minority HIV drug-resistance mutations which may negatively influence response to antiretroviral treatment (Jayaraman et al., 2006). Generally, in Western Europe and North America, where the historical backdrop of the usage of antiretroviral treatment is extensive, the prevalence of transmitted medication resistance has been evaluated to be between 4-16% among HIV infected patients (Little et al., 2002; Pillay, 2004; Shet et al., 2006; Descamps et al., 2010).

The majority of transmitted HIV resistance mutations’ cases include both NRTIs and NNRTIs. Transmitted HIV resistance patterns are continually changing, reflecting the advancement of therapeutic strategies and procedures, and the introduction of new antiretroviral agents. Transmitted resistance cases were initially described with NRTI drugs that were antiretroviral agents’ first class in widespread use (Erice et al., 1993). As antiretroviral medication uses extended, a shift towards more transmitted NNRTI resistance followed after extensive usage of this class of medications (Shet et al., 2006). Transmitted protease inhibitor resistance is still uncommon, happening in less than ~5% of cases regardless of far reaching using of this class (Bonura et al., 2010). Most accessible information on transmitted HIV resistance mutations are from HIV B subtype. It has been suggested this could be clarified by a longer time of antiretroviral treatment use among patients with infections of B subtype instead of any inherent transmission advantage or disadvantage concerning non-subtype B. Interestingly, it has as well been recommended that some HIV subtypes can build up specific mutations at differential rates contrasted with subtype B viruses’ origin. Brenner et al (2006) demonstrated that subtype C display a more prominent propensity than subtype B to choose the K65R mutation in reverse tr