New Compound T-705 Better Than Tamiflu for Bird Flu, H1N1

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Scientists have developed a new compound, called T-705, which may be more potent and safer for treating bird flu than the antiviral drug known as Tamiflu. T-705 also appears to be effective against seasonal flu and H1N1 virus.

The possibility of another outbreak of bird flu is on the minds of many experts. Also known as H5N1, the bird flu virus “is so pathogenic even Tamiflu doesn’t protect all the infected animals,” according to Yoshihiro Kawaoka, senior author of the new study and a University of Wisconsin-Madison virologist.

T-705 is on the threshold of final testing in humans. In the current study, the results of which appear in the Proceedings of the National Academy of Sciences, the researchers conducted their tests in mice and found that T-705 was effective and safe against H5N1, seasonal flu, and swine flu, H1N1. The compound has already been tested against seasonal flu in human subjects in Japan.

The discovery of this new compound is exciting for several reasons. One is that it works even three days after individuals have become infected. This ability is important because bird flu is nearly always diagnosed after symptoms have become apparent. Thus T-705 provides an opportunity to save people who are already along in the disease course.

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Development of T-705 is also critical because cases of Tamiflu-resistant strains of H5N1 have been reported recently, which increases concerns among scientists about the ability of currently available antiviral drugs to handle a pandemic of bird flu. Currently there are few drugs that have demonstrated effectiveness against bird flu.

Bird flu is an influenza A virus subtype that occurs mostly in birds and is highly contagious among them. Humans have little pre-existing natural immunity to H5N1 virus, according to the Centers for Disease Control and Prevention, and the CDC notes that if H5N1 viruses “gain the ability for efficient and sustained transmission among humans, an influenza pandemic could result,” with the possibility of high rates of death worldwide. Currently there are no vaccines available for human use against H5N1.

Cases of bird flu have occurred in Asia, Africa, the Pacific, Europe, North America, and the Near East. Indonesia and Vietnam have reported the greatest number of H5N1 cases to date. Among reported H5N1 cases, overall mortality is about 60 percent.

Dr. Kawaoka notes that the activity of T-705 “is considerably higher than Tamiflu,” and that it is very specific to an enzyme that enables the H5N1 virus to copy its genetic material. The new compound disables the enzyme, rendering the bird flu virus unable to make new virus particles and continue its course of infection.

SOURCES:
Centers for Disease Control and Prevention
University of Wisconsin-Madison news release, Dec. 21, 2009

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