New AIDS test may be more sensitive

A new test for the AIDS virus that detects proteins inside the microbe may be more sensitive than existing tests, U.S. researchers said on Monday.

The test, which can also be adapted to detect the misshapen prions that cause mad cow disease and related sicknesses, may be useful for screening donated blood and monitoring patients, the developers at the University of Maryland's Institute of Human Virology said.

They said it is 25 times more sensitive than the best technology currently available.

"This new ultra-sensitive testing method, known as Real-Time Immuno-PCR, will allow us to detect HIV earlier and at much lower levels," said Dr. Niel Constantine, who helped develop the test.

Writing in the July issue of the American Journal of Clinical Pathology, Constantine's team said the new test detects an inner protein of the virus known as p24, rather than detecting antibodies or viral nucleic acids, as current tests do.

"Each virus particle contains about 3,000 molecules of p24 as compared with only two copies of nucleic acid, so there's a greater amount of target to detect," Constantine said.

"It's an advance over current methods in that we can detect down to the equivalent of two copies of RNA as compared with current methods which have been validated to only 50 copies," his colleague, Janet Barletta, added in a statement.

The human immunodeficiency virus is a retrovirus, meaning it uses RNA rather than DNA to replicate itself.

Current methods do not detect HIV in the blood until a person has been infected for 12 to 14 days. Theoretically, the new test should catch an infection sooner, although the researchers have been unable to test this.

"We have submitted a patent for this test for the prion protein," Constantine said in a telephone interview. Prions are the protein particles that cause bovine spongiform encephalopathy or mad cow disease and the related human version, Creutzfeldt Jakob disease or CJD.

Constantine hopes his team can partner with a drug company to develop the test commercially.

He believes it could be used to screen blood for CJD or HIV.

"If you could save 4 to 5 infected units a year, it would be important to do that," Constantine said. "You could further protect the blood supply."

It should also be useful for monitoring a patient's response to drug cocktails that can suppress the fatal and incurable AIDS virus.

The research team is also developing a low-cost, battery-operated version of the test that could be used in developing countries.