HIV-1 Superinfection: Evidence and Impact

Superinfection is defined as infection by a second virus during an immunologic steady state, following infection by a primary virus. It is now well established that superinfection with HIV-1 occurs in humans. Detection of an increasing number of circulating recombinant forms, which result from infection of a cell by two or more clades, suggests that superinfection occurs more frequently than previously thought. The second virus (from a different clade or the same clade as the primary virus) can superinfect some time after the first and this is associated with rapid viral rebound and immune decline. Primary infection with a specific clade appears not to provide cross-protection against superinfection with a different clade or the same clade. Estimating the overall impact of HIV-1 superinfection on pathogenesis and attempts to create a broadly protective prophylactic HIV-1 vaccine is complicated by our inability to quantify the true incidence and prevalence.