The response of the 22A strain of scrapie agent to microwave irradiation compared with boiling.

The 22A strain of scrapie agent was exposed to boiling or microwave irradiation. Subsequent bioassay in IM and VM mice showed that neither treatment had inactivated the agent. Although IM and VM mice are homozygous for the p7 allele of the Sinc gene which controls the incubation period of scrapie in mice, the incubation period for unheated 22A was 22 days longer in IM compared with VM mice. This suggests that other unidentified genes can have a more minor effect on incubation period. The difference between the IM and VM incubation period with microwave-irradiated 22A was much the same as for the unheated control but was increased to 68 days after boiling. The conclusion is that the agent is modified in some way by boiling but not by microwave irradiation such that it is more subject to the influence of genes other than Sinc which affect incubation period.