The Return of the Virion

Via ProMED-mail: Yale Daily News reports on research by Dr. Laura Manuelidis, the head of neuropathology at Yale's School of Medicine, into viral explanations for Creutzfeldt-Jakob and related diseases:

The research team’s goal was to try to identify viral particles in infected cells. They infected cell lines with either scrapie (a sheep disease related to mad cow) or CJD agents and found virus-like particles that did not contain prion protein. An abundance of these particles was related to high levels of infectivity, which was not true of the presence of prion proteins.
“People hypothesize that prion proteins are infectious, but they’re probably part of the disease, not the infectious agent itself,” Manuelidis said.
The virus-like particles had been found by other researchers but were largely ignored. They were first identified in 1968 in synaptic regions of scrapie-infected brain and later found in many other animals with different TSEs. But Manuelidis said that researchers apparently forgot about them once the prion hypothesis became dominant.