HIV "superinfection," the term given to the phenomenon where a person is infected with two genetically different strains of HIV, is becoming more common, according to new research presented Monday at the International AIDS Society's Conference on HIV Pathogenesis and Treatment. Researchers at the Paris conference presented data from three new studies of HIV-positive people who became ill and were no longer able to suppress HIV replication after being infected with a second strain of HIV.
A study conducted in Switzerland showed that two HIV-positive injection-drug users who had maintained low viral loads without the use of anti-HIV drugs suddenly experienced surging viral loads and plunging T-cell counts. Blood tests showed that they had been infected a second time with a genetically different virus, leading to their immune system damage. Researchers in New York presented data from a study showing that an HIV-positive woman had become infected with two separate strains of the virus and that the two eventually combined to form a single hybrid virus in her body. The report was the first documented case showing the creating of a hybrid virus from two separate HIV strains.
AIDS researchers greeted the studies with disappointment, noting that superinfection could likely pose a challenge to creating effective anti-HIV vaccines that may not be able to target two separate HIV strains in the body. "Superinfection is sobering," said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. "That means that although you can mount an adequate response against one virus, the body still does not have the capability to protect you against new infection, which tells you that the development of a vaccine is going to be even more of a challenge."
Some researchers also suggested that superinfection--and the possibility of hybrid viruses emerging from superinfection--could result in an even more aggressive viral attack in those infected with HIV. Anton Pozniak of London's Chelsea and Westminster Hospital said that possibility "reinforces the message that we've got to stop HIV today so that we can deal with what we have now and not generate a whole load of new mutants that wouldn't have been there otherwise."