UC Davis shelves WNV vaccine for now

Dec 01, 2002

The University of California, Davis, (UC Davis) Center for Equine Health has shelved blueprints for a new West Nile Virus (WNV) vaccine.

The university concedes that Fort Dodge Animal Health owns the market for the equine WNV vaccine and has no plans to steal anyone's thunder yet, according to one school official.

But its work continues.

Dr. Greg Ferraro of UC Davis, who is helping raise funds for the school's vaccine development, says researchers at UC Davis have developed a construct for a recombinant-type vaccine.

The recombinant vaccine is a new generation of vaccines where a piece of DNA or RNA is removed from the virus and used to create protection.

The vaccine in the works has already been used for equine infectious anemia with proven effectiveness. Researchers are confident it can be modified for West Nile Virus.

Old kid on block

Ferraro says the university has been conducting research on the recombinant vaccine since WNV's first appearance in Queens in 1999. Of late, the university finished a study that was conducted on horses in South Africa where WNV is endemic.

Although South Africa's WNV strain is slightly different, "possibly we could take the part of the virus DNA that causes horses to get immunity from the nonpathogenic strain and protect against the pathogenic strain," he explains. "The advantage is that 1) it's much more specific in getting your immunogenic response and 2) you don't have to worry about properly killed virus vaccine or modified live virus in any kind of viral drift.

"If you're working with DNA of the viruses you should be able to create a specific immunity that is more reliable."

Yet the work remains on hold for one, to allow Fort Dodge the chance to prove efficacy, and secondly, for economic reasons.

"The problem with it is recombinant vaccines are more sophisticated vaccines and much more expensive to produce than traditional killed or modified live virus vaccines," says Ferraro.

"When you have a conditionally licensed killed vaccine out there, if that is effective we probably wouldn't go forward with designing or developing this other vaccine, because it would cost more money."

In light of a recent Fort Dodge abstract paper citing preliminary efficacy results, Ferraro says the university's decision is to "wait and see" if there is still a need for the vaccine. A decision will not likely be made until next year.

The Maurice Stans Foundation is the primary financer of the UC Davis project.

Looming threat

While the country reacts to the devastation of WNV, Ferraro says he keeps one eye on the horizon.

Through cooperative work with the University of Pretoria in South Africa, he says researchers are also studying African horse sickness, a pathogenic disease.

"That's the one we really need to worry about - that's a much more serious disease. West Nile is serious and we're taking it seriously and working on it, but really we're looking at it as a preparatory thing for more serious diseases down the road."