Location: Virus and Prion ResearchTitle: Evaluation of the zoonotic potential of transmissible mink encephalopathy Author
|Torres, Juan Maria|
Submitted to: Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2013
Publication Date: 7/30/2013
Citation: Comoy, E.E., Mikol, J., Ruchoux, M., Durand, V., Luccantoni-Freire, S., Dehen, C., Correia, E., Casalone, C., Richt, J.A., Greenlee, J.J., Torres, J.M., Brown, P., Deslys, J. 2013. Evaluation of the zoonotic potential of transmissible mink encephalopathy. Pathogens. 2:(3)520-532. Interpretive Summary: Cases of bovine spongiform encephalopathy (BSE) or mad cow disease can be subclassified into at least 3 distinct disease forms with the predominate form known as classical BSE and the others collectively referred to as atypical BSE. Atypical BSE can be further subdivided into H-type and L-type cases that are distinct from classical BSE and from each other. Both of the atypical BSE subtypes are believed to occur spontaneously, whereas classical BSE is spread through feeding contaminated meat and bone meal to cattle. Transmissible mink encephalopathy (TME) is another prion disease that transmits to cattle and show similarities to L-type BSE when subjected to laboratory testing. The purpose of this study was to use non-human primates (cynomologous macaque) and transgenic mice expressing the human prion protein to determine if TME could represent a potential risk to human health. TME from two sources (cattle and raccoons) was able to infect non-human primates and transgenic mice after exposure by the intracranial route. This result suggest that humans may be able to replicate TME prions after an exposure that allows infectious material access to brain tissue. At this time, it is unknown whether non-human primates or transgenic mice would be susceptible to TME prions after oral exposure. The results obtained in these animal models were similar to those obtained for L-type BSE. Although rare, the existence of TME and that it transmits to cattle, non-human primates, and transgenic mice suggest that feed bans preventing the feeding of mammalian tissues to cattle should stay in place and that regular prion surveillance during the slaughter should remain in place. Parties with interest in the cattle and beef industries and regulatory officials responsible for safe feeding practices of cattle will be interested in this work.
Technical Abstract: Successful transmission of Transmissible Mink Encephalopathy (TME) to cattle supports the bovine hypothesis to the still controversial origin of TME outbreaks. Human and primate susceptibility to classical Bovine Spongiform Encephalopathy (c-BSE) and the transmissibility of L-type BSE to macaques assume a low cattle-to-primate species barrier: we therefore evaluated the zoonotic potential of cattle-adapted TME. In less than two years, this strain induced in cynomolgus macaques a neurological disease similar to L-BSE and distinct from c-BSE. TME derived from another donor species (raccoon) induced a similar disease with shorter incubation periods. L-BSE and cattle-adapted TME were also transmissible to transgenic mice expressing human PrP. Interestingly, secondary transmissions to transgenic mice expressing bovine PrP showed the maintenance of prion strain features for the three tested bovine prion strains (cattle TME, c-BSE and L-BSE) regardless of intermediate host. Thus, TME is the third animal prion strain transmissible to both macaques and humanized transgenic mice, suggesting zoonotic potentials that should be considered in the risk analysis of animal prion diseases for human health. Moreover, the similarities between TME and L-BSE are highly suggestive of a link between those strains, and of the presence of L-BSE decades prior to its identification in USA and Europe.