Spam-busting tools have grabbed the limelight in the fight against a more insidious infection - HIV.

Microsoft Corp. computer scientists, in conjunction with bioengineers from the Royal Perth Hospital, WA, and the University of Washington are attempting to use features currently used in Outlook and Hotmail to reduce spam to map the mutation patterns of the HIV virus.

So what is an antispam tool doing in the fight against HIV? The tools used to separate spam from legitimate e-mail have evolved to the stage where they now seek out changing patterns in message structure.

Scientists are using the spam-busting algorithms to pinpoint the stable sequences throughout HIV strains so they can design vaccines to combat the variations.

So far, the vaccines are being tested at Royal Perth Hospital and the University of Washington using immune cells from HIV-infected patients, with results expected to be released at the end of this year.

The research could potentially be used to combat Hepatitis C and other viruses prone to mutation.

The catalyst for the alliance between Microsoft"s researchers and medical scientists was Viagra. Apparently, software designed to link the message "Viagra" and "V1agxa" might also be perfect for tracking DNA sequence mutations. Viagra, and Viagra-related products, are estimated to account for nearly one quarter of all spam.

Executive director of the Royal Perth Hospital"s Centre for Clinical Immunology and Biomedical Statistics, Simon Mallal credited Microsoft with enabling the medical research team to sift through patient data 10 times faster than any previous research technique. Fellow staffer Dr Corey Moore said the project involves classifying the HIV virus as a series of letters, AGCT, and they have already mapped the make-up of nearly 250 patients.

"HIV is represented as a string of four letters to represent the virus," Moore said.

"And so far from the virus (AGCT) we have strung together 9700 characters of mutation, which represents different parts of the string," Moore said.