(New Vision) A small fraction of Ugandans have been able to naturally knock off HIV from their body, a development that could lead to an HIV vaccine, scientists have said.
Dr. Pontiano Kaleebu, an immunologist heading the Basic Sciences Programme of the MRC/UVRI Uganda Research Unit on AIDS at the Uganda Virus Research Institute (UVRI), told Saturday Vision that an ongoing study and a previous one at the institute had unearthed signs that some Ugandans may be resistant to HIV.
They have special white blood cells that can only be produced when the virus attacks the body. However, even with the most sophisticated tests, HIV could not be found in these individuals, implying that the virus had tried to infect them but the immune system kicked it out.
"We are seeing some immune responses but it is still too early to see if there is a lot of meaning to these responses," said Kaleebu.
"Such people are of interest to many researchers worldwide."
At the AIDS Information Centre in Kampala, the UVRI scientists are studying 70 discordant couples to see if some of them are indeed resistant to HIV. These are couples that have had unprotected sex for more than a year, one partner has had HIV for long while the other has not become infected. "We have set up a clinic in Kampala where doctors and counsellors do a lot of counselling and give them condoms to reduce risky sexual behaviour," Kaleebu said.
Despite early signs of resistance to HIV, Kaleebu said meaningful results can only be released at the end of the study. The five-year research, expected to be completed in 2010, is sponsored by the US National Institutes of Health through the British Medical Research Council (MRC). It is part of a multi-country study coordinated by the US-based Center for HIV/AIDS Vaccine Immunology (CHAVI) and involving Oxford University of UK.
Prof. Heiner Grosskurth, the Director of the MRC/UVRI Uganda Research Unit on AIDS, said: "A lack of ability to becoming HIV infected is extremely rare, but there is evidence meanwhile that people who have this characteristic exist worldwide, although in very small numbers."
Although they are so few, he said, studying them could generate new knowledge that would enable scientists to develop a vaccine. "Such work is going on with a lot of speed and effort in many countries, but there is no breakthrough yet! I think it will still take years until we have good vaccine candidates."
Earlier in 2002, Prof. Andrew Mc Michael of the University of Oxford and the late Dr. Anthony Kebba of UVRI announced that they had identified some eight Ugandans in Kampala and Entebbe, who were exposed to HIV but remained uninfected. One fifth of the discordant couples they studied showed some signs of resistance to HIV, but this required further confirmation. Mc Michael is involved with Kaleebu in the new study. Similar studies are going on in Kenya and the Gambia.
Kaleebu cautioned that nearly all people are vulnerable to HIV and Ugandans should not relax simply because a few individuals seem to be resistant to the virus. "It has to be clear that this apparent resistance is not a common thing. If you are HIV negative and your partner is HIV positive we cannot say you are resistant and you cannot become infected. If you continue to have unprotected sex you might become infected in the long run," said Kaleebu.
Indeed, in the late 1990s some people in Rakai were reported to have become infected with HIV after being discordant for many years. On discovering that they were discordant, scientists had advised them to begin using condoms. Later, some of those who declined to use condoms became infected. (more).
Dr. Pontiano Kaleebu, an immunologist heading the Basic Sciences Programme of the MRC/UVRI Uganda Research Unit on AIDS at the Uganda Virus Research Institute (UVRI), told Saturday Vision that an ongoing study and a previous one at the institute had unearthed signs that some Ugandans may be resistant to HIV.
They have special white blood cells that can only be produced when the virus attacks the body. However, even with the most sophisticated tests, HIV could not be found in these individuals, implying that the virus had tried to infect them but the immune system kicked it out.
"We are seeing some immune responses but it is still too early to see if there is a lot of meaning to these responses," said Kaleebu.
"Such people are of interest to many researchers worldwide."
At the AIDS Information Centre in Kampala, the UVRI scientists are studying 70 discordant couples to see if some of them are indeed resistant to HIV. These are couples that have had unprotected sex for more than a year, one partner has had HIV for long while the other has not become infected. "We have set up a clinic in Kampala where doctors and counsellors do a lot of counselling and give them condoms to reduce risky sexual behaviour," Kaleebu said.
Despite early signs of resistance to HIV, Kaleebu said meaningful results can only be released at the end of the study. The five-year research, expected to be completed in 2010, is sponsored by the US National Institutes of Health through the British Medical Research Council (MRC). It is part of a multi-country study coordinated by the US-based Center for HIV/AIDS Vaccine Immunology (CHAVI) and involving Oxford University of UK.
Prof. Heiner Grosskurth, the Director of the MRC/UVRI Uganda Research Unit on AIDS, said: "A lack of ability to becoming HIV infected is extremely rare, but there is evidence meanwhile that people who have this characteristic exist worldwide, although in very small numbers."
Although they are so few, he said, studying them could generate new knowledge that would enable scientists to develop a vaccine. "Such work is going on with a lot of speed and effort in many countries, but there is no breakthrough yet! I think it will still take years until we have good vaccine candidates."
Earlier in 2002, Prof. Andrew Mc Michael of the University of Oxford and the late Dr. Anthony Kebba of UVRI announced that they had identified some eight Ugandans in Kampala and Entebbe, who were exposed to HIV but remained uninfected. One fifth of the discordant couples they studied showed some signs of resistance to HIV, but this required further confirmation. Mc Michael is involved with Kaleebu in the new study. Similar studies are going on in Kenya and the Gambia.
Kaleebu cautioned that nearly all people are vulnerable to HIV and Ugandans should not relax simply because a few individuals seem to be resistant to the virus. "It has to be clear that this apparent resistance is not a common thing. If you are HIV negative and your partner is HIV positive we cannot say you are resistant and you cannot become infected. If you continue to have unprotected sex you might become infected in the long run," said Kaleebu.
Indeed, in the late 1990s some people in Rakai were reported to have become infected with HIV after being discordant for many years. On discovering that they were discordant, scientists had advised them to begin using condoms. Later, some of those who declined to use condoms became infected. (more).
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