Microbial interaction between HIV-1 and anaerobic bacteria producing butyric acid: its potential implication in AIDS progression

Abstract

Microbial coinfection has great impact on the course of disease progression of HIV-1 and the development of AIDS-related deaths. In fact, progression of AIDS development is more rapid in individuals with concomitant infections. Although it is well known that immunosuppression due to HIV-1 infection leads to AIDS-associated opportunistic infections, it has also become apparent that opportunistic infection often promotes the disease progression of HIV-1 infection by enhancing viral transmission or replication, or by modulating host immune responses. We have focused on such microbial interaction between HIV-1 and butyrate-producing anaerobic bacteria and explored the effects of these bacterial culture supernatants containing butyric acid in upregulating HIV-1 gene expression and thus inducing viral replication from the latently infected cells. Since butyric acid inhibits histone deacetylases, these findings suggest that the HIV latency is maintained in ‘recessive’ chromatin, where histone proteins are largely deacetylated, and that concomitant infection of butyrate-producing bacteria could obviously be a risk factor for HIV-1 reactivation in infected individuals, and might contribute to AIDS progression. Moreover, it is possible that therapeutic elimination of such bacterial infection could conceivably prevent the clinical development of AIDS and its epidemiological transmission. Widespread epidemiological surveys are warranted in order to elucidate the role of concomitant infection of such bacteria.