The AIDS-causing human immunodeficiency virus mutates in a way that can make it invisible to virus-fighting T-cells, complicating efforts to design an effective vaccine, researchers said Wednesday.
The envelope protein, or outer shell, of the virus contains amino acid chains that apparently change over time, evading T-cells that fight viruses, according to researchers Rodney Phillips and colleagues at Oxford University, England.Phillips studied the virus in six HIV-infected hemophiliacs. In one patient, changes in part of the envelope protein were observed in December 1989, less than six months after an initial analysis. Further changes were seen in a subsequent observation in February 1990.
Because of the mutations, the immune system T-cells did not recognize HIV as their target. Similar observations were made in two other patients, the researchers reported in the journal Nature.
"We have detected variant viral sequences that were not recognized by (T-cells,)" said the researchers.