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Vaccine Effective Against Avian Flu
FiReaNGeL writes "Researchers announced they have genetically engineered an avian flu vaccine from the critical components of the deadly H5N1 virus that completely protected mice and chickens from infection. This virus has thus far killed 80 people, devastated bird populations in Southeast Asia and Europe and caused for billions in damage through the world." Here's hoping it works on us, too.
University of Pittsburgh researchers announced they have genetically engineered an avian flu vaccine from the critical components of the deadly H5N1 virus that completely protected mice and chickens from infection. Avian flu has devastated bird populations in Southeast Asia and Europe and so far has killed more than 80 people.
Because this vaccine contains a live virus, it may be more immune-activating than avian flu vaccines prepared by traditional methods, say the researchers. Furthermore, because it is grown in cells, it can be produced much more quickly than traditional vaccines, making it an extremely attractive candidate for preventing the spread of the virus in domestic livestock populations and, potentially, in humans, according to the study, published in the Feb 15 issue of the Journal of Virology and made available early online.
"The results of this animal trial are very promising, not only because our vaccine completely protected animals that otherwise would have died, but also because we found that one form of the vaccine stimulates several lines of immunity against H5N1," said Andrea Gambotto, M.D., assistant professor in the departments of surgery and molecular genetics and biochemistry, University of Pittsburgh School of Medicine, and lead author of the study.
Dr. Gambotto and his colleagues constructed the vaccine by genetically engineering a common cold virus, called adenovirus, to express either all or parts of an avian influenza protein called hemagglutinin (HA) on its surface. Found on the surface of all influenza viruses, HA allows the virus to attach to the cell that is being infected and is, therefore, critical to the influenza virus' ability to cause illness and death.
Since the late 1990s, a number of outbreaks of the avian influenza H5N1 in poultry have occurred in Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand and Vietnam. Outbreaks recently have been reported in Turkey and Romania. To date, H5N1 has caused the most large-scale and widespread bird deaths in known history--an estimated 150 to 200 million birds have either died in the outbreaks or been killed as part of infection control actions in the last eight years.
The H5N1 virus does not usually infect humans. However, in 1997, the first case of spread from a bird to a human occurred in Hong Kong during an outbreak of bird flu in poultry. The virus caused severe respiratory illness in 18 people, six of whom died. Since that time, more than 170 cases of known H5N1 infection have occurred among humans worldwide, approximately half of whom died.
Based on the published sequence of the Vietnam strain of the H5N1 avian influenza virus, members of the University of Pittsburgh Vector Core Facility, led by Wentao Gao, Ph.D., research instructor in the School of Medicine's department of surgery, constructed several adenovirus "vectors"--viruses that have been modified to serve as a vector, or delivery vehicle, for foreign genes or DNA--containing either the full genetic sequence of the HA protein or sequences for only parts, or subunits, of HA. They also constructed a vector containing sequences for a portion of the HA protein from the H5N1 Hong Kong strain.
Collaborating with investigators Xiuhua Lu, Ph.D., Doan C. Nguyen, M.D., Yumi Matsuoka, Ph.D., Ruben O. Donis, Ph.D., and Jaquelin M. Katz, Ph.D., of the Influenza Branch of the Centers for Disease Control and Prevention, Dr. Gambotto's team tested the ability of their slightly different vaccines to protect mice from infection by wild-type H5N1 by comparing its performance to an adenovirus vector containing no H5N1 genes, or an "empty vector." The investigators then observed the H5NI-exposed mice for any signs of illness, including weight loss and death, and also checked their blood for anti-viral antibodies and other markers of H5N1-specific immunity.
All of the mice immunized with the empty vector vaccine experienced substantial weight loss beginning about three days after exposure to wild-type H5N1, and all were dead withi