Lab Canada

Ozone sterilizer developer reschedules plans for testing on prions

Qubec City, QC – Before reaching the planned end of the third phase of testing on prions underway at the National Research Council of Canada (NRC) facilities in Winnipeg, TSO3 said it had not obtained the results anticipated. The company is a developer of ozone sterilization systems.

The aim of the third phase of testing, launched in April this year, was to confirm the capacity of the company’s 125L ozone sterilizer to deactivate strains of prions. The experiments are being carried out on transgenic mice from the laboratory of Dr Stanley Prusiner (a 1997 Nobel Prize winner for his research on prions). The protocol utilized compares ozone sterilization to the usual steam sterilization, and to a steam cycle that is much hotter which is considered as the only option available that could reduce some of the risk of prions, without guaranteeing the total disappearance of infectiousness. The testing was to have concluded at the end of this month.

The company says that the partial deactivation of prions has generated symptoms of the disease in certain subjects inoculated with substances extracted from plaques sterilized with ozone. This partial deactivation is not concordant with the results obtained in previous studies where ozone showed a capacity to deactivate prions superior to the level observed during the current phase of testing.

"These partial results are disappointing, however the recognized oxidizing power of ozone, as well as the results of our previous studies, moves us to re-evaluate our current protocols and to maintain our research program. We still believe in the superior capacity of ozone to deactivate prions," says Simon Robitaille, the company’s vice president, operations, and director of research.

The company says that after the start of the program’s third phase, new scientific publications utilizing a different methodology impelled it to re-evaluate its protocols so that the results can be compared to those obtained through other sterilization technologies. The measuring technique for residual infectious capability utilized in the recent studies in question has the advantage of corresponding more closely to established practices in hospitals.

The phase three testing consisted of taking the brains from sick mice and making a homogenate that was spread on plaques and left to dry, then sterilized in the ozone sterilizer, while other samples were sterilized with steam, in order to compare the effectiveness of ozone to the autoclave. The residual matter was then recovered and injected into the brains of mice. This phase was planned to take six months, scheduled to conclude at the end of October 2004. TSO3 intends to initiate a new phase of testing, with new protocols, at the end of 2004.