Researchers have, for the first time, discovered a patient infected with two similar but separate strains of the virus that causes AIDS. Researchers at Massachusetts General Hospital say the patient's second infection developed more than a year after the first infection was successfully controlled. They also said they were surprised to find that the immune system cells that worked against the first strain were powerless against the second infection.
The report in the journal "Nature" says no one knows yet what the ramifications of a dual infection may be, but they say the finding highlights the importance of protected sex - even between partners who are both HIV positive.
Other research has shown dual infection in HIV patients, but those cases all involved vastly different strains of the virus. Experts say the patient had successfully managed the first strain of the virus for about a year before becoming infected with the second. Researchers performed genetic tests on the individual viruses to discover they were both from a group of closely related viruses called a "clade". This is the first finding of a patient infected with two viruses from the same clade.