Rinderpest research restarts

Rinderpest has been eradicated, but vigilance and surveillance are needed to ensure it doesn’t come back. Research is set to resume on the rinderpest virus, the cause of a deadly cattle disease that was declared eradicated in 2011 and has been off limits for study ever since. The moratorium — part of efforts to guard against accidental or intentional release of virus that could reintroduce the disease — was lifted on 10 July and replaced by a new international oversight system for such research. In its heyday, the disease — the only one other than smallpox to be eradicated from nature — killed hundreds of millions of cattle, mainly in Europe, Asia and Africa, often leaving famine in its wake. Under the new oversight system, run by the Food and Agriculture Organization of the United Nations (FAO) in Rome and the Paris-based World Organisation for Animal Health (OIE), the risks and benefits of research proposals will be assessed by a joint advisory committee, and then the FAO and the OIE will decide on approvals. Eligible research must show potential for substantial practical or scientific benefits and be conducted under stringent biosafety and biosecurity conditions. The first project that has garnered approval will test whether vaccines developed against a closely related virus — peste des petits ruminants (PPR), which causes disease in sheep and goats — might also protect cattle against rinderpest. Led by Michael Baron, a rinderpest researcher at the Institute for Animal Health in Pirbright, UK, the project, if successful, would eliminate the need to retain stocks of live-attenuated rinderpest vaccine. That would contribute to the goal of reducing the number of labs worldwide holding rinderpest material, thus decreasing the risk of reintroduction.

Some 55 labs in 35 countries still hold some kind of rinderpest virus, according to a 2011 survey published in January 2012 in the journal Emerging Infectious Diseases: 37% of them in Asia, 29% in Africa and 26% in Europe (G. Fournié et al. Emerging Infect. Dis.; 2013). The identities of the labs remain confidential. The most dangerous stocks are of live field strains of virus, estimated to be kept in at least 16 labs in 14 countries, and samples of blood and tissues from infected herds, kept in at least 10 labs in 10 countries. Stocks of live-attenuated vaccine, currently held in at least 53 labs in 34 countries, are deemed less problematic, although some could, in theory, revert to disease-causing forms. The FAO and the OIE hope to eventually reduce the number of sites holding live wild viruses to a handful of officially designated labs, ideally located outside regions where accidental releases could have devastating consequences, says David Ulaeto, a virologist and member of the joint advisory committee. Conversely, the agencies plan to centralize stocks of vaccines in a few high-containment repositories in regions at highest risk of disease, so that they can be deployed within hours of any confirmed recurrence of rinderpest. No siting decisions have been made, but one might imagine a repository in Africa, one or two in Asia and one in Europe, says Juan Lubroth, the FAO’s chief veterinary officer. The process of destroying virus or shipping it to centres with high biosafety levels must be done in a way that does not risk its release, says Ulaeto. The FAO and the OIE are working on high-security protocols for shipping the virus and ways to ensure that autoclaves in labs holding it are certified to function at levels guaranteed to provide a 100% kill. Many countries are reluctant to give up their vaccine stocks in case the disease should reappear and threaten their food supply. They worry about becoming dependent on the willingness of the international community to swiftly provide them with needed vaccines. “The challenge is political,” says Bernard Vallat, director general of the OIE. He says that the FAO and the OIE are drafting agreements and international contingency plans that should help reassure countries that swift help would be forthcoming and that they would have guaranteed access to vaccine from FAO–OIE repositories. Vallat notes that if Baron proves that PPR vaccines can protect cattle against rinderpest, it would provide an elegant way around such political issues: there would no longer be any need to hold onto rinderpest vaccines. Baron says that he hopes to start the vaccine-challenge trials next spring and complete them by the end of 2014.

August 6, 2013

Original web page at Nature