BARCELONA, SPAIN -. Discourage new data presented at the XIV International AIDS Conference can significantly increase the bar for developers of vaccines against HIV
researchers took heart in the long observation that people with HIV seem able to repel infection with a second strain or subtype of the virus. This resistance to so-called superinfection makes a compelling argument that although the immune system can not clear an established HIV infection, it can go up sufficient immunity "cross reaction" to counter new strains. But immunologist Bruce Walker of Massachusetts General Hospital of Harvard reported today strong evidence that the patient is co-infected with a second strain of HIV.
"It is terrible news," said Brigitte Autran, immunologist of the Pitié-Salpêtrière Hospital in Paris, France.
The patient was part of a study of people who started treatment with anti-HIV drugs soon after infection. When the human virus fell below the most sensitive test for the detection level, he stopped taking drugs. he stayed drugs until the virus became detectable again. the third time its enriched viral levels, the researchers found that it had become infected with a new virus that was of the same subtype, called clade B.
most disturbing of all, they found that he had produced high levels of killer cells - so-called cytotoxic lymphocytes (CTL) that the clear cells infected with HIV. - his first against strain "We can not extrapolate from a single case, but we were really struck this cross-reactivity was not enough to protect against another clade B virus, "said Walker. His team was particularly surprised to find that although the genes of the two viruses B clade differed only by 12%, both viruses showed substantial difference in one essential characteristic: the parts of the virus that trigger the production killer cell. This indicates that the CTL responses that lack scale can not provide enough cross-reactivity necessary to protect people in the real world.
The finding made many researchers do a double take, especially those like Autran, who are trying to stimulate NK cells to attack HIV. But Emilio Emini virologist has warned his colleagues not to over-interpret this single case. "This observation indicates simply that you superinfection is possible," said Emini, who heads the vaccine program at Merck & Co. Rahway, Pennsylvania, which attempts to make a vaccine based killer cells. "What it does not tell you is the probability of that happening. "
Related Sites
Description Walker's research
Website of the XIV International AIDS conference
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