Journal of Clinical and Cellular Immunology
Open Access

Abstract

From Individuals to Populations: Immunological and Epidemiological Significance of Co-infection in the Dynamics of HIV

Diego F. Cuadros and Laith J. Abu-Raddad

Immunological activation in response to an invading organism is essential in order to support an effective host response to an invading pathogen. Paradoxically, it also provides an optimal immunological environment for the viral replication in HIV-positive individuals. Indeed, the life cycle of HIV is closely related to the activation state of its host cells since it depends on host cell surface receptor expression for entry, and also on many cellular pathways and transcription machinery for viral gene expression. In this review, we focused on the overall impact of immune activations generated by co-infection in the viral life cycle at host level leading to increases in HIV replication. Moreover, we discussed the epidemiological implications of this increment on the HIV viral load generated by coinfection. Here, we described how the intimate relationship between HIV and the activation state of the host immune system supporting viral replication results in a synergistic interaction between HIV and concurrent infections such as herpes simplex virus type 2 and malaria. A common denominator of these co-infections is the systemic immune activation resulting in an enhancement of the HIV viral load that ultimately might facilitate the transmission of the virus. There is a need, however, for more population-based studies of concurrent infections, and microbe-microbe interaction at the host level to better understand the impact of co-infections on the natural history of HIV.