The comparison between field trials and mouse protection tests against intranasal and intracerebral challenges with Bordetella pertussis

Abstract

Fourteen vaccines, ten of which had been tested in the field in the M.R.C. trials, were assayed in the laboratory by the intracerebral (IC) and the intranasal (IN) routes. The IC test arranged the vaccines in quite a different order of potency to the IN test.

A satisfactory and reproducible assay can be made by either method, though the dose response curves about the 50 per cent protection point have very different slopes.

The field trails have shown that whereas the mouse potency test using the IC challenge corresponds remarkably well with the field results (M.R.C. Report), potency tests with the IN challenge do not.

Experiments with four different vaccines were consistent in showing that the IC antigen is heat labile and will not stand 100° for 1 hr., the IN antigen is heat stable and can be so heated for relatively small loss of potency.

Our results with vaccine K205 are similar to those reported by Fisher (1955), except that we were more fortunate in getting a graded dose response with the heated vaccine against the IN challenge, probably owing to the larger number of assays we carried out. We would agree with Fisher that individual experiments may give very odd results, and on the whole the dose response curves of individual IN assays are not as consistent as IC assays; this may be due either to differences in the antigens involved, for two different antigens must be responsible, or to differences in the course of infection in the lung and brain.