A component that is abundant in human semen can increase HIV's ability to cause infection by several orders of magnitude, according to findings reported by researchers from Germany, Spain, and the United States (Münch J et al. Cell. 2007;131:1059-1071).
The researchers demonstrated that naturally occurring fragments of prostatic acidic phosphatase form amyloid fibrils that capture HIV particles and promote their attachment to target cells, specifically CD4 T cells and macrophages. They also found that the fibrils, which they termed semen-derived enhancer of virus infection (SEVI),
reduced the amount of virus needed to infect human tonsillar tissue and enhanced infection of transgenic rats engineered to have human receptors for HIV-1 infection.
Stephenson J. Semen Boosts HIV Spread. JAMA. 2008;299(3):279. doi:10.1001/jama.299.3.279-c