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16-08-2011 | General practice | Article

Candidate vaccine against chikungunya virus developed

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MedWire News: Researchers have developed a live candidate vaccine to combat the mosquito-borne chikungunya virus, which is characterized by painful and often chronic arthritic symptoms, and has recently caused large urban outbreaks in Asia and Africa.

Scott Weaver (University of Texas, Galveston, USA) and colleagues report in the journal PLoS Pathogens that a single dose (104 plaque-forming units) of the "recombinant live-attenuated vaccine" protected laboratory mice from being infected with the disease.

"Currently, we have no approved treatment or vaccine for chikungunya, and there's a real need for an effective vaccine to protect against this debilitating and economically devastating infection," said Weaver. "Everything we've seen so far suggests this vaccine candidate could fill that need."

To develop the vaccine, Weaver and team used a rational attenuation mechanism that also stops infection of mosquito vectors.

They replaced the subgenomic promoter in a copyDNA chikungunya clone with the internal ribosome entry site from the encephalomyocarditis virus. This changed the levels and host-specific mechanism of structural protein gene expression in the pathogen.

Testing in normal and interferon-response defective laboratory mice showed the vaccine to be highly effective at preventing infection with the chikungunya virus after one dose.

The team notes that the genetic modification carried out during vaccine development means that the modified virus is incapable of infecting mosquitoes or replicating in mosquito cells.

This type of live vaccine is relatively cheap to produce in large amounts, write the authors, which could be an important factor as the areas worst affected by the chikungunya virus have limited resources.

"We need to slow this virus down in India and Southeast Asia, not just to protect the people there but to reduce the very real risk that it might become endemic here after an infected traveler arrives," Weaver commented.

"The best way to do that is with a vaccine, and if you're going to make a vaccine you have to look at where it's going to be used and what they can afford."

The investigators explain that the next stage of vaccine testing is currently being carried out in nonhuman primates to assess whether it is suitable for trialling in humans.

By Helen Albert

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