Although development of viral resistance linked to ineffective monitoring remains a concern in resource-poor settings, monitoring of clinical response (i.e., initial weight gain) and immune reconstitution (i.e., rise in CD4 cell counts) has been broadly used as a primary tool to assess success of therapy: there is a direct relationship between a lack of clinical response or a lack of a rise in CD4 count and risk of developing or not recovering from opportunistic infections. This evidence concerns the gene CD4 and Opportunistic infection.