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Research: More effective bird flu vaccine

University of Guelph scientists have made a discovery that may lead to more effective vaccines to protect poultry and humans from the avian influenza virus.

"We have found one of the molecular determinants of the H5N1 avian influenza virus that can induce immune responses in chickens," said Prof. Shayan Sharif, a researcher in the Department of Pathobiology and lead author of the study published recently in the journal PLoS ONE.

“This molecular structure may be used in the future for protecting chickens against avian flu and possibly for control of transmission of the virus from birds to humans,” said Sharif.

Public concern about this year’s H1N1 flu pandemic has overshadowed the potential threat of its close cousin – H5N1 avian influenza virus, reports the University of Guelph. But scientists and public health officials have been keeping a close watch on a deadly strain of H5N1 virus. The World Health Organization reports that since 2003, there have been 442 confirmed cases of people being infected with H5N1 virus; of those, 262 have died.

While the numbers seem small in comparison to the thousands of people infected by H1N1 worldwide, H5N1 is far more lethal, reports state. While most H1N1 infections result in only mild illness, about 60% of people infected by the H5 virus have died. Luckily, so far the virus cannot be easily transmitted from person to person, Sharif said. But that could change.

“Influenza viruses are constantly changing and it is possible that the H5 virus could develop into something that is more efficiently transmitted from birds to humans and, more importantly, from person to person,” he said. “If that happens, then we may face a pandemic of massive proportions.”

The H5 avian influenza virus is commonly found in wild birds such as migratory waterfowl that are usually unaffected by the virus. They can, however, transmit the virus to a variety of domestic birds including chickens, in which it can cause a range of illness from no signs of disease at all to a severe epidemic that kills all infected birds.

Vaccines are available to protect domestic poultry from H5N1 virus. However, very little is known about how the chicken’s immune system interacts with the virus.

The molecular region identified by Sharif’s research team is a small peptide contained in the hemagglutinin (HA) antigen, a protein found on the surface of the flu virus. The researchers showed that the peptide is recognized by the chicken’s T-cells, which attack the virus directly and also trigger the production of antibodies that help the immune system fight the infection. This is the first time scientists have identified a T-cell epitope of an influenza virus– a protein on a virus particle recognized by the immune system – in chickens.

“This is an important step toward developing more efficacious vaccines against H5 avian influenza in chickens,” said Sharif. “We may be able to use this epitope in future vaccines to not only protect domestic flocks but also to prevent or control the spread of the virus from birds to humans. However, this still needs to be confirmed experimentally and that will be the focus of our future research.”

 Source: University of Guelph

Natalie Berkhout

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