Scientists develop more effective bird flu vaccine for flocks

By Ahmed ElAmin

- Last updated on GMT

Related tags: Influenza, Influenza vaccine

US scientists claimed yesterday to have genetically engineered an
avian flu vaccine that is more effective in protecting chickens
from infection.

Vaccination could be a tool to help prevent the spread of the disease further into Europe.A vaccination programme might calm fears about the transfer of the disease to the human population and about the safety of the bloc's poultry.

The EU has generally been reluctant to mass vaccinate its flocks against bird flu. The treatment can mask the occurance of the disease, thus delaying efforts to quarantine flocks and prevent its spread.

Now University of Pittsburgh scientists say they have genetically engineered a more effective vaccine for poultry.

"The vaccine can be made quickly and induced a strong immune response in the animals, making it a potentially useful tool for preventing the spread of the virus,"​ the scientists stated.

This vaccine contains a live virus, so it activates immune responses better than avian flu vaccines prepared by traditional methods, the researchers stated.

"Because it appears to be so successful in immunizing chickens against H5N1, widespread inoculation of susceptible poultry populations could provide a barrier to the spread of the virus in countries where bird flu has not appeared,"​ the scientists stated.

The study, to published in the 15 February issue of the "Journal of Virology" was made available online yesterday.

"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,"​ stated Andrea Gambotto, an assistant professor in the departments of surgery and molecular genetics and biochemistry at the university.

Rather than replacing traditional inactivated influenza vaccines, Gambotto and his colleagues suggest that their adenovirus-based vaccine could be a critically important complement to them.

However Reuters yesterday reported that the European Commission is now considering allowing mass vaccination of flocks throughout the bloc. The EU's health and food safety officials were not immediately available for comment on the report. The Netherlands, one of the world's top poultry exporters, is considering launching a preventive vaccination campaign.

Currently, flu vaccines are prepared in fertilized chicken eggs, a process developed more than 50 years ago that requires millions of fertilized eggs that would be in short supply if a pandemic were to occur. The recombinant vaccine approach grows the vaccine in cell cultures, which are unlimited in supply, the researchers stated.

"It takes a little over a month for us to develop a recombinant vector vaccine compared to a minimum of several months via traditional methods,"​ Gambotto stated. "This capacity will be particularly invaluable if the virus begins to mutate rapidly, a phenomenon that often limits the ability of traditional vaccines to contain outbreaks of mutant strains."

The study's release comes at a time when Turkey is battling the disease in its flocks through a culling programme that has resulted in the killing of about 1.6 million birds.

Four people have died of the disease in the country so far, the first ocurrances of the human form of H5N1 infection outside of Asia. This weekend the European Union banned live animals and animal products from Northern Cyprus after H5N1 was detected in wild birds on the island.

Since the latest outbreak began in December 2003, avian flu has killed more than 80 people in four Southeast Asian countries and killed or led to culling of an estimated 200 million birds across the region and in Turkey and Russia.

Poultry sales in Turkey have dropped by 70 per cent since bird flu was reported in humans earlier this month, according to a report in Turkey's Hurriyet newspaper. Kemal Akman, head of the union of poultry producers, is quoted as saying the industry would suffer losses amounting to $30 million per month.

Indonesia vaccinated 114 million poultry against avian flu with traditionally made vaccine in 2004.

In other related news:

A UK laboratory yesterday confirmed 12 of the 21 cases of H5N1 avian influenza previously announced by the Turkish ministry of health. All four fatalities are among the 12 confirmed cases. Samples from the remaining nine patients, confirmed as H5 positive in an Ankara laboratory, are undergoing further joint investigation.

The Food and Agriculture Organisation (FAO) has warned that the virus could become entrenched in the Black Sea, Caucasus and Near East regions through trade and movement of people and animals and it could be further spread by migratory birds particularly coming from Africa in the spring.

"Fighting the avian influenza virus in animals is the most effective and cost-effective way to reduce the likelihood of H5N1 mutating or reassorting to cause a human flu pandemic,"​ the FAO stated. "Containing bird flu in domestic animals - mostly chickens and ducks - will significantly reduce the risk to humans. Avian influenza should not only be considered as a human health issue, but as a human and animal health issue."

Related topics: Food Safety & Quality

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