摘要：Because of wide variations in the methods used to assay the potency of pertussis vaccine, the effect of the type of challenge used in the mouse-protection test was studied. Eight laboratories took part in a collaborative investigation and the potencies of 4 pairs of vaccines were estimated. Two methods were used, a ”local method” using local strains and procedures for challenge, and a ”study method” using a distributed strain and a specified procedure. For both methods the challenge level (mouse LD50) and the number of colony-forming units per challenge dose varied greatly between laboratories. The results of the collaborative assay show that the use of a common challenge, Bordetella pertussis strain 18-323, and a uniform method for preparing the challenge did not reduce the heterogeneity of the results. Other factors influencing the results of potency assays, such as the use of different strains of mice and the effect of levels of challenge, have still to be investigated. Full text Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.2M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References . 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687
