HIV replication at low copy number and its correlation with the HIV reservoir: A clinical perspective

The efficacy of combination therapy (antiretroviral therapy--ARV) is demonstrated by the high rates of viral suppression achieved in most treated HIV patients. Whereas contemporary treatments may continuously suppress HIV replication, they do not eliminate the latent reservoir, which can reactivate HIV infection if ARV is discontinued. The persistence of HIV proviral DNA and infectious viruses in CD4+ T cells and others cells has long been considered a major obstacle in eradicating the HIV virus in treated patients. Moreover, recent studies have demonstrated the persistence of HIV replication at low copies in most patients on suppressive ARV. The source of this 'residual viraemia' and whether it declines over years of therapy remain unknown. Similarly, little is known regarding the biological relationships between the HIV reservoir and viral replication at low copies. The question of whether this 'residual viraemia' represents active replication or the release of non-productive virus from the reservoir has not been adequately resolved. From a clinical perspective, both the quantification of the HIV reservoir and the detection of low levels of replication in full-responder patients on prolonged ARV may provide important information regarding the effectiveness of treatment and the eradication of HIV. To date, the monitoring of these two parameters has been conducted only for research purposes; the routine use of standardised tests procedure is lacking. This review aims to assess the current data regarding the correlation between HIV replication at low copies and the HIV reservoir and to provide useful information for clinicians.