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Ho team makes H5N1 vaccines

Researchers at Academia Sinica working on developing new vaccines for the avian flu virus have determined that DNA-based vaccines can provide protection against various strains of H5N1, researchers said on Wednesday.

A team of researchers also established that once a new strain of the virus is identified, its genetic composition can be incorporated into a vaccine database to produce new vaccines against the virus, an academic said.

The team, led by David Ho (何大一) of Rockefeller University and Wong Chi-huey (翁啟惠) of Academia Sinica’s Genomics Research Center, published the findings on Tuesday in the online edition of the Proceedings of the National Academy of Sciences.

The team began its research two years ago with a focus on hemagglutinin (HA) — a type of glycoprotein molecule that is found on the surface of all H5N1 viruses and plays a vital role in the viral infection mechanism, Academia Sinica said in a press release.

After analyzing hundreds of hemagglutinin samples collected from various H5N1 strains, researchers found that a specific gene sequence known as “Consensus HA” was found in all specimens.

The sequence was then genetically engineered to produce the prototype vaccines.

Experiments showed that lab mice inoculated with the vaccines had developed immunity against various strains of the H5N1 virus, including those found in Vietnam, Indonesia, Turkey and southern China.

“After infection with the Indonesian strain of H5N1, 80 percent of the subject mice survived,” said Rachel Cheng (鄭婷仁) of the Genomics Research Center.

“Meanwhile, 100 percent survival rates were found among all mice that were exposed to the other three strains,” she said.

DNA-based vaccines, however, have a major drawback.

“Based on the experiments and research conducted by other scientists, DNA-based vaccines tend to elicit a weak immune response,” said Chen Ming-wei, a post-graduate student at National Yang-Ming University and the lead author of the paper.

The team therefore sought to enhance the vaccines’ potency by using an electroporation device developed by Ho, Chen said.

The device injects the vaccine into a muscle while generating a brief electrical pulse to “push” the DNA into the cells, Chen said.

“Delivered in this fashion, DNA-based vaccines induce quite drastic immune responses and protect mice against most of the avian flu strains tested,” he said.

The vaccines have been transferred to the Development Center for Biotechnology, a Taiwan-based non-profit organization, for animal safety tests, Academia Sinica said.

Testing should be completed by the end of the year, whereupon the vaccines will be submitted to the US Department of Health and the Food and Drug Administration as a new drug awaiting human trial.

Once approved, phase-I clinical trial in humans could commence.
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