YOKOHAMA, Japan _ French researchers presented a detailedanalysis of a new subtype HIV that is prevalent in West Africa and isoften not detected by HIV antibody tests.Called subtype O because it is an "outlier" or remotely related subtype,it is a genetically aberrant form of HIV-1 and antigenically distinctfrom other HIV-1 subtypes. It was first discovered in chimpanzees inCameroon, and now is believed to be the type of virus found in up to10 percent of HIV-1 infection in Cameroon.The subtype also has been identified in a handful of HIV-positivepeople from Cameroon now living in France and Belgium.HIV-1 has been divided into subtypes A through H, each of whichelicits a distinct antigen response in infected individuals. Until now, themost recent subtype identified was subtype H in Russia.Although subtype O appears to be limited almost entirely to WestAfrica, its features of diminished envelope bands makes it difficult todetect by most HIV antigen tests. More than half of the commerciallyavailable HIV antigen tests missed detection of nine subtype samples,at least once, said James George, an epidemiologist at the Centers forDisease Control and Prevention in Atlanta.George reported that the subtype O virus has not been reported in theU.S., dampening concerns that the virus could contaminate the bloodsupply. HIV antigen tests can be modified to make them sensitive tothe virus, but health officials from the U.S. and the World HealthOrganization said such action is not necessary except in the countrieswhere it has been identified.Research is continuing to determine the exact origin of the subtype andwhether it is more easily spread than other subtypes. One questionraised is why the subtype has arisen in a country with a moderateprevalence of the virus.In Other News From The Conferenceu Jay Levy, of the University of California at San Francisco's CancerResearch Institute, said baboons are a promising animal model forAIDS because they not only can be infected with HIV, but they alsodevelop AIDS.Levy said baboons have immune systems similar to humans and he isusing the animals to study how activated CD8+ cells prevent HIVinfection from progressing to full-blown AIDS. Levy added that whenAIDS develops only after CD8+ cells lose their anti-HIV activity.u The Community Programs for Clinical Research on AIDS, a branchof the National Institutes of Health, is conducting one of the largeststudies to date of oral ganciclovir for prevention of cytomegalovirusinfection (CMV), one of the most serious opportunistic diseasesacquired by HIV-infected patients.The study, which involves 995 CMV-infected volunteers at 16 sites inthe U.S., will be conducted through June 1995. Two-thirds of theparticipants will receive 12 capsules, or three grams, a day of oralganciclovir and the other third will receive a placebo.CMV normally causes a latent infection, but when AIDS is present, itcan cause blindness and gastrointestinal problems, such as diarrhea,wasting, severe pain and death. n081094HIV1

-- Skip Connett

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