It has been recently recognized that vaccination for influenza, tetanus, and cholera can modulate HIV population dynamics, at least in the short term. In vitro tests have identified many other agents, predominantly of the herpes family of viruses, that also increase HIV production from infected cells. In addition, there is a question of susceptibility to infection being varied by the presence of certain agents or conditions (e.g. transmission from mother to child increased if vitamin deficiencies are present). Here, the model of Root-Bernstein & Merrill (1997), is used to investigate the potential effect of infective cofactors on HIV infectivity and progression to AIDS.
The model suggests that 1) presence of cofactors prior to HIV exposure can make infection by HIV more likely; 2) treatment of cofactors present concurrent with HIV could produce an environment where HIV could not thrive; and 3) long-term progression is affected by the (prior) presence of cofactors. The argument for the third point also involves an increase in viral diversity.