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AIDS/SARS guru `hopeful for vaccine'

Saturday, Dec 18, 2004, Page 4

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.

"The HIV effort will be a struggle for the next ten years. But in the case of SARS, all the data and results suggest that we should be able to protect against the virus."

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.

TT: You noted that the AIDS is difficult to treat because of the HIV's mysterious ability to mutate. Do you notice any similar property in SARS coronavirus?

Ho: The SARS coronavirus will also change. Many of the so-called RNA viruses make mutations when they divide and replicate. But what is different is that SARS virus only replicates for a few weeks, whereas HIV virus replicates for years and years. This is why you [HIV vaccine developers] keep making mistakes and changes. Since SARS only allows the virus to replicate for a short amount of time, it probably won't change as fast as HIV.

TT: The SARS vaccine is now proven to be safe and effective in the monkey trial you conducted with the Chinese Academy of Medical Science. What will be the next step and what are the challenges?

Ho: We now need to figure out how to bring this to testing in people. The clinical trial part will be very difficult. You have to come up with the funding to make a [vaccine] product. You also need funds to support the clinical trial. All these things cost a fair amount of money, ranging from US$5 million to US$10 million. The problem is -- who is going to invest in them when there is no SARS right now?

TT: Do you think Taiwan is equipped with the technology to conduct the clinical trial and develop the SARS vaccine?

Ho: Yes, I think if Taiwan pools the right people and groups together, it could make the vaccine. Once again, the difficult part to determine is who -- the private sector or the government -- is going to make an investment. I don't see the private sector gambling with their money. It is almost the government's responsibility to invest in the vaccine research and development process. It's a question of political will. So that when the next SARS epidemic comes, whenever it is, you are at least prepared with vaccines.

TT: Compared to Hong Kong, Singapore, China and other Asian countries, do you think Taiwan is a preferable place to develop a SARS vaccine?

Ho: Comparing Taiwan, Hong Kong, and Singapore, I think Taiwan is just as good as any of them. Taiwan is probably better than Hong Kong in terms of environment. Singapore is very focused and trying to do something, too.

TT: Is there a possibility that you will work together with a certain regional government?

Ho: We want to cooperate with any government -- whoever wants to develop the vaccine.

TT: What are future challenges facing scientists in the HIV vaccine and SARS vaccine research areas?

Ho: I think HIV is going to be very tough. The vaccine still has a long road ahead. It will take years and years to determine whether these vaccines work. The HIV effort will be a struggle for the next 10 years. But in the case of SARS, all the data and results suggest that we should be able to protect ourselves against the virus. I am much more optimistic about the SARS vaccine, should there be enough investment to allow some of the vaccine candidates to be developed and tested. I am hopeful for an effective SARS vaccine.
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