A technique called sperm washing, a laboratory process that removes HIV from semen, has dramatically lowered the odds of transmitting HIV from an HIV-positive prospective father to his female partner or to their unborn child through in vitro fertilization. But now Japanese researchers have found a way to lower the HIV risks even further.
Sperm washing works by separating sperm from HIV genetic material in a test tube. HIV sinks to the bottom of the tube, while HIV-free sperm swim to the top. But the current method entails a very small risk of HIV infection, since minute amounts of HIV proviral DNA can exist in seminal cells. In the journal AIDS scientists reported having developed a genetic test that can detect a single piece of proviral material in a pool of 1.8 million sperm. The test allows doctors to reject sperm samples with even the slightest trace of virus present. They also have improved the test-tube separation method to lessen the chances of HIV mixing with human genetic material.
The new techniques were used in a study of 52 HIV-positive men and their female partners in Japan. No HIV RNA or proviral DNA were detected in any of the sperm samples that underwent sperm washing. Twenty of the women conceived through in vitro fertilization by using the washed sperm; none of the women or their babies contracted HIV.