http://www.reutershealth.com/archive/2001/04/09/business/links/20010409drgd005.html
Drug & Device Development
Human trials of West Nile vaccine may begin in 2002
Last Updated: 2001-04-09 14:58:00 EDT (Reuters Health)
WHITE PLAINS, NY (Reuters Health) - A human vaccine
against West Nile virus is still years away, although human trials on such a
vaccine could begin as early as next year, according to experts speaking at an
international conference this past weekend.
The best candidates for a vaccine, according to Dr. Alan
T. Barrett of the University of Texas Medical Branch in Houston, are a killed
virus being developed by the US Army and a chimeric product under development
at Boston-based Acambis. Barrett spoke on the current status of flavivirus vaccines
Saturday at the International Conference on the West Nile Virus in White
Plains, New York.
The Acambis product, ChimeriVax-West Nile, is a live attenuated
vaccine based on the 60-year-old yellow fever vaccine. The envelope proteins of
the original vaccine have been replaced with envelope proteins from the West Nile
virus. The company used a similar strategy for a vaccine against Japanese
encephalitis, which is currently in clinical trials.
ChimeriVax-West Nile has been tested in mice, with good
results, Dr. Thomas P. Monath, Acambis’ vice president of research and medical
affairs, told Reuters Health. A clinical trial in horses is also underway, with
data expected in May or early June.
The company expects to begin manufacturing materials for a
human vaccine in early 2002 and to begin clinical trials later in the year, he
said. The earliest that the vaccine would reach the market, Monath speculated,
is 4 or 5 years from now.
“I don’t think this is going to be a vaccine that would be
part of a public health program,” Monath added. Instead, he expects people may
choose to be immunized against West Nile if they live in areas where the virus
is endemic-such as New York City-and are at high risk.
“We don’t really know what the epidemiology of West Nile
virus is going to be in the next 5 years,” he added.
For horses, however, the product should come to market
soon. Monath noted that West Nile-which previously was identified in horses in
New Jersey-has severely disrupted the US “equine economy.” Other animal
candidates for vaccination include zoo animals and domestic birds, he added.
The military vaccine effort involves a killed vaccine and
has not yet entered clinical trials, Barrett told Reuters Health.
Dr. Jeffrey Chang, of the Arbovirus Disease Branch of the
US Centers for Disease Control and Prevention in Fort Collins, Colorado, reported
Saturday on his efforts to develop a DNA-based vaccine against West Nile. He
and his colleagues have been working on flavivirus vaccines for the past 5
years and began working on West Nile in the past year.
The researchers have begun studies in mice and horses.
With doses of 10 to 100 micrograms in mice, and 1 milligram in horses, the
vaccines have shown 100% seroconversion, Chang said.
·
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