Aided by Amyloid

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Science  11 Jan 2008:
Vol. 319, Issue 5860, pp. 137
DOI: 10.1126/science.319.5860.137b

The role played by semen in the sexual transmission of HIV may be more than simply as an innocuous carrier. Münch et al. show that semen contains factors that can actually amplify the infectious potential of HIV by helping to promote the binding of the virus to target cells. Within semen, the enzyme prostatic acidic phosphatase can break down and form fragments that can, in turn, coalesce into amyloid-like fibrils. These fibrils can bind to HIV virions and enhance their binding to target cells—effectively amplifying the chance of successful viral infection by several orders of magnitude. Addition of the fibrils at physiological concentrations increased HIV infection in susceptible cell cultures, cultures of human tonsils, and in transgenic rats. It remains to be confirmed to what extent this mechanism is effective during human-to-human sexual transmission, but if it is an important factor, it may represent a valuable target in efforts to prevent transmission. — SMH

Cell 131, 1059 (2007).

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