Viral quasispecies population dynamics between monocytes and T-lymphocytes were 
analyzed in patients after highly active antiretroviral therapy (HAART) 
interruption, during a follow-up of 3-6 months. V3 env region underwent 
ultra-deep pyrosequencing. Co-receptor usage prediction was performed by 
Position Specific Score Matrix Analysis. Phylogenetic trees were constructed to 
evaluate the relationships between the variants. Gene flow was also 
investigated. Even though at the moment of therapy interruption monocyte-derived 
HIV-1 genomes presented higher genetic heterogeneity than that of T-lymphocytes, 
at subsequent times, this difference in genetic heterogeneity disappeared, due 
to different waves of expansion and reduction of quasispecies variability 
associated with monocytes and T-lymphocytes. Phylogenetic analysis and gene flow 
evaluation supported the hypothesis of extensive interchange of variants between 
cellular compartments of the infection. A spread of proviral X4 lineages hidden 
in monocytes to T cells was observed, but this was not associated with an 
overall shift towards CXCR4 using variants during the observation period.