Sat, Dec 18, 2004 - Page 4 News List

AIDS/SARS guru `hopeful for vaccine'

David D. Ho, a Taiwanese American AIDS researcher, earned international fame and worldwide respect for devising a 'cocktail therapy' that has dramatically reduced AIDS-associated mortality since 1996. Ho and his research team at Rockefeller University's Aaron Diamond AIDS Research Center are now working on two HIV vaccine candidates that could save tens of millions in sub-Saharan Africa and Southeast Asia. During his stay in Taipei, Ho yesterday took the time to talk with 'Taipei Times' reporter Wang Hsiao-wen about his most recent work

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Academia Sinica member David Ho calls on the government to pay greater attention to the prevention of AIDS during a meeting held in Taichung in July.

PHOTO: SU MENG-CHUAN, TAIPEI TIMESN

Taipei Times: What is the life-saving potential of an HIV vaccine?

David Ho (何大一): Each year, there will be another 5 million new infections, at least. Each day, there are about 14,000 newly-infected people. Unfortunately, you cannot use drugs to lower this. You could use education, you could use behavioral modification, but those things have not worked very well. So, I think the only way to block the [disease's] spread is to come up with a vaccine. The impact will be huge if you have a 100 percent effective vaccine. You can give it to the whole world, control the epidemic, and get rid of the disease for a long time.

TT: From a clinical perspective, is there any possibility that we can produce large doses of vaccines in a cheap way?

Ho: Yes, I think most vaccines we and other people are working on are not very expensive. They will be more affordable than drugs. Many people who are working on the vaccines are doing it not because of profit. We are doing science and we want to make a contribution. If we have a vaccine that works, we don't intend to make a profit.

TT: How do your two vaccines, the DNA and MVA vaccines, work to prevent AIDS?

Ho: The DNA vaccine is composed of two plasmids that can express five HIV genes. This kind of multivalent vaccine will enhance the immune system's ability to detect the rapidly changing HIV virus and trigger a cell-mediated immune response to protect the body. The second vaccine under research is the MVA vaccine. We used a specific strain of modified vaccinia called Ankara, and inserted the same set of five HIV genes as in the DNA vaccine.

TT: How do these two vaccine developments progress? Can you describe the design of the clinical trials you have been conducting?

Ho: Our trials are still very premature. Trials are in Phase I, II, and III. Phase I is primary. The first trial is to make sure the product is safe. We have been doing the DNA vaccine for about a year. This month, we conducted a human clinical trial involving 45 subjects from New York City, and so far it seems to be safe. We'd like to move on to Phase II to test the immune response in people who received the vaccine. We have been working on the second one, the MVA vaccine, for four years. It's very close to beginning the Phase I study. We think it [Phase I human clinical trial] will come in the next few weeks. We are very excited to be able to take two products all the way from the lab to the clinic in four years' time.

TT: Your DNA vaccine candidate has gained approval from the US' FDA (Food and Drug Administration), yet another MVA vaccine hasn't. When do you think the permission will come?

Ho: We expect the second one very soon. In fact, we expect the approval to come any day. Hopefully, by January next year we could do the Phase I trial with the MVA vaccine.

TT: In your speech on Thursday (Dec. 16), you mentioned that you used similar platform technology to develop a SARS vaccine. Can you briefly talk about the mechanics and effect of the SARS vaccine?

Ho: We develop a SARS vaccine using vaccinia, like the MVA vaccine. So far, it's worked quite well in Chinese macaques. We are able to raise antibodies that could block the infection of the SARS virus in the laboratory. Then we put these [antibodies] into monkeys. All vaccinated monkeys are protected from infection. It's a very promising outcome.

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