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Better Vaccines Against Rift Valley Fever Outbreak

19 February 2010

GLOBAL - The Central Veterinary Institute (CVI) has developed two candidate vaccines to protect animals, and probably humans, against the Rift Valley Fever virus. This virus can be fatal for ruminants and people, and is threatening to spread from Africa to Europe.

'It's better to take measures before the outbreak of a new disease than react to its consequences, as in the current situation of the Q Fever', says researcher Rob Moormann.

The Rift Valley Fever virus is transmitted by mosquitoes to ruminants, such as cows and sheep, and to humans. Recent outbreaks in East Africa have claimed many victims among ruminants and humans. It is feared that the virus will spread to Europe via North Africa or Saudi Arabia. It's only a question of time before the virus reaches Europe, says Mr Moormann, who considers Rift Valley Fever to be as dangerous as Q Fever. 'Climate changes, international trade and tourism can cause the virus to find its way here. The mosquitoes currently responsible for the spread of the virus are also found in the Netherlands'.

He has in the meantime introduced a protein produced by the Rift Valley Fever virus in the vaccine against the chicken disease Newcastle Disease, also a viral disease. Therefore, this vaccine is the carrier of the Rift Valley Fever protein. Mr Moormann's group reports in this month's Vaccine that this vaccine sparks an immune response in calves against the virus protein. He suspects that just one vaccination is enough to protect ruminants against the virus. A trial among sheep later this year could confirm his suspicion.

The CVI has applied for a patent for this discovery and will liaise with pharmaceutical companies interested in further developing the vaccine. Vaccines against Rift Valley Fever do already exist in the market. One vaccine is based on a living but weakened Rift Valley Fever virus. This vaccine is not safe for young and pregnant animals. A second vaccine, based on an inactivated virus, is not powerful enough.

'No vaccines are available for humans yet', says Mr Moormann. In another article in Vaccine, his research group and researchers from the Faculty of Veterinary Medicine of Utrecht University report on the development of a vaccine against Rift Valley Fever using insect cells. This type of vaccine is probably the most suitable for use in humans.

There are no medicines against the virus. As in the case of Q Fever, humans develop mostly flu-like symptoms when they have contracted Rift Valley Fever, but they can also die from it. Infected pregnant animals face abortions, and possible death.

Mr Moormann expects the approval of the vaccine for veterinary use in Europe to take four years because of a complex registration process, but it could be approved faster in Africa. 'The vaccine is simple to produce, also in Africa. It can be easily cultivated in incubated eggs. It would benefit us too if we can control the Rift Valley Fever in Africa.'

TheCattleSite News Desk



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