Acquired resistant viruses establish themselves as the dominant viral population at primary infection and persist over time even if antiretroviral treatment is initiated and is associated with therapeutic success. Ghosn et al.  recently reported that HIV-1-resistant strains acquired at the time of primary infection massively fuel the cellular reservoir, and their prolonged persistence is supported by the early expansion of a dominant homogenous and resistant viral population.
Over time, a rare genetic event occurred because only one stepwise back mutation in the protease gene at codon 84 (patient A) and one at codon 46 (patient B) to wild-type codon were observed during 5 years of follow-up. In both cases, these genetic changes were probably associated with an increase in viral replicative capacity because this was temporally correlated with a marked decrease in CD4 cell numbers, as shown previously in primary and chronically infected patients [12,13].
There is concern that the transmission of MDR viruses in primary HIV-1 infection may limit future therapeutic options. It is accepted that treatment failure has been observed in several individuals harbouring MDR infections [13–17]. In most cases, empirical treatment began before the results of genotypic resistance testing were obtained, and may have been suboptimal, resulting in the acquisition of additional mutations in these already MDR viruses, as shown in a large cohort of HAART-treated patients at the time of HIV primary infection [6,16]. French guidelines recommend performing resistance testing prospectively in patients with HIV primary infection, so that the results are available soon after the initiation of HAART.
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