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《英国医生杂志》
Controversy over a possible "super strain" of HIV has been burgeoning in the United States since the case of a man with a multidrug resistant virus with rare characteristics and very rapid disease progression was discussed at a high profile news conference in New York city last month. A report, by Marc Santora et al, was published in the New York Times (2005 Feb 12; www.nytimes.com/).
The first scientific presentation of the case came in a poster at the 12th retroviral conference in Boston. The organisers added a special session on drug resistance and rapid disease progression on the last evening of the conference to provide context for interpreting data from the poster.
Dr David Ho, director of the Aaron Diamond AIDS Research Center at Rockefeller University, New York, described the patient as a homosexual man aged 46 who acknowledges having had anonymous unprotected anal sex with hundreds of men, often while using crystal methamphetamine.
Dr Ho believes that the man became infected with HIV in October 2004, and by January 2005 his CD4 cell count had declined to 80. Laboratory tests detected viral RNA mutations that confer resistance to 19 of the 20 drugs commonly used to treat HIV.
About 60% of the virus used the CCR5 coreceptor to enter cells, and 40% could use either CCR5 or the CXCR4 coreceptor. The second variant is rarely transmitted sexually; it is characteristic of late stage disease and rapid clinical decline.
Dr Ho feared the possible public health implications of these findings and notified the New York city抯 public health commissioner, Thomas Frieden. The ensuing news conference set off a frenzy of media coverage.
The other presenters at the conference抯 special session saw the case as rare and worthy of investigation but not cause for a public health warning. They believe the rapid progression was more likely to be the result of unique host factors, not the virus. Ongoing contact tracing has yet to find evidence of another person infected with a similar virus.
But one leading HIV/AIDS expert said that researchers looking at the case were hampered by lack of relevant information. Dr Harold Jaffe, former director of HIV prevention programmes at the US Centers for Disease Control and Prevention and now at Oxford University, said it was not known for certain when the patient in question was infected, who infected him, or if he had infected others. He said, "If lack of fear has really become a driver of the epidemic, we have to ask ourselves, cases like this . . . to scare people at risk? I personally don抰 think so."
Two researchers pointed out that the rapid progression from infection to full blown AIDS in the patient in question was not unique.
Dr Stephen Gange, a professor at Johns Hopkins University, Baltimore, is the principal statistician for ongoing HIV cohort studies of homosexual men and of women, totalling more than 10 000 participants dating back to 1984. He said that data from the cohorts and from modelling indicate that 7 in 10 000 will progress to AIDS in the first six months after infection. "They are consistent with the rates reported in the literature," he said.
He also noted two examples within one cohort of cases similar to the one under discussion, where patients with rapidly progressing disease had been infected with a dual tropic CCR5/CXCR4 virus.
Dr Matthew Dolan reported a similar range of disease progression from the US military cohort of 4500. He offered a snapshot of the impact of host genetic variations on disease progression and concluded, "While therapy has been very beneficial, it still does not overcome the genetic bias that people."
Although it was generally agreed that the emergence of a strain of HIV that was highly drug resistant would be worrying, researcher Dr Andrew Leigh Brown, a professor at the University of Edinburgh, pointed out that viruses that were drug resistant were usually transmitted less easily.(Boston Bob Roehr)
The first scientific presentation of the case came in a poster at the 12th retroviral conference in Boston. The organisers added a special session on drug resistance and rapid disease progression on the last evening of the conference to provide context for interpreting data from the poster.
Dr David Ho, director of the Aaron Diamond AIDS Research Center at Rockefeller University, New York, described the patient as a homosexual man aged 46 who acknowledges having had anonymous unprotected anal sex with hundreds of men, often while using crystal methamphetamine.
Dr Ho believes that the man became infected with HIV in October 2004, and by January 2005 his CD4 cell count had declined to 80. Laboratory tests detected viral RNA mutations that confer resistance to 19 of the 20 drugs commonly used to treat HIV.
About 60% of the virus used the CCR5 coreceptor to enter cells, and 40% could use either CCR5 or the CXCR4 coreceptor. The second variant is rarely transmitted sexually; it is characteristic of late stage disease and rapid clinical decline.
Dr Ho feared the possible public health implications of these findings and notified the New York city抯 public health commissioner, Thomas Frieden. The ensuing news conference set off a frenzy of media coverage.
The other presenters at the conference抯 special session saw the case as rare and worthy of investigation but not cause for a public health warning. They believe the rapid progression was more likely to be the result of unique host factors, not the virus. Ongoing contact tracing has yet to find evidence of another person infected with a similar virus.
But one leading HIV/AIDS expert said that researchers looking at the case were hampered by lack of relevant information. Dr Harold Jaffe, former director of HIV prevention programmes at the US Centers for Disease Control and Prevention and now at Oxford University, said it was not known for certain when the patient in question was infected, who infected him, or if he had infected others. He said, "If lack of fear has really become a driver of the epidemic, we have to ask ourselves, cases like this . . . to scare people at risk? I personally don抰 think so."
Two researchers pointed out that the rapid progression from infection to full blown AIDS in the patient in question was not unique.
Dr Stephen Gange, a professor at Johns Hopkins University, Baltimore, is the principal statistician for ongoing HIV cohort studies of homosexual men and of women, totalling more than 10 000 participants dating back to 1984. He said that data from the cohorts and from modelling indicate that 7 in 10 000 will progress to AIDS in the first six months after infection. "They are consistent with the rates reported in the literature," he said.
He also noted two examples within one cohort of cases similar to the one under discussion, where patients with rapidly progressing disease had been infected with a dual tropic CCR5/CXCR4 virus.
Dr Matthew Dolan reported a similar range of disease progression from the US military cohort of 4500. He offered a snapshot of the impact of host genetic variations on disease progression and concluded, "While therapy has been very beneficial, it still does not overcome the genetic bias that people."
Although it was generally agreed that the emergence of a strain of HIV that was highly drug resistant would be worrying, researcher Dr Andrew Leigh Brown, a professor at the University of Edinburgh, pointed out that viruses that were drug resistant were usually transmitted less easily.(Boston Bob Roehr)