Abstract
Recent field studies of immunization against pertussis have yielded conflicting evidence. This is not altogether surprising in view of the fact that there is no standard method of preparing vaccines of Hemophilus pertussis. Recently isolated, toxic, Phase 1 strains 1 of H. pertussis have been used in the majority of recent trials. 2-5 Stock strains, however, are still used in preparing vaccine. 6 Although the newer knowledge of the antigenic changes of H. pertussis contra-indicates the use of stock strains, it is obvious that a proposed immunizing agent must be judged only by careful clinical trial. Such trials as have been made with stock strain vaccines 7 , 8 have not been sufficiently comprehensive to permit comparison.
Vaccines made from recently isolated, toxic, Phase 1 strains have differed principally in the amount of washing to which they were subjected. It is a current view 9 that the efficiency of any bacterial vaccine depends on (a) its production from virulent, smooth bacteria, and (b) the presence of the surface antigens of the virulent, smooth bacteria. Furthermore, Lawson 10 has reported that Phase 1 strains have a capsule, demonstrable only when smeared directly without emulsification in an aqueous solution. The amount of washing to which an H. pertussis vaccine is subjected would therefore seem to influence its antigenic potency.
The following data were obtained when H. pertussis vaccine washings were tested for the presence of specific substance.
Rabbits were given intravenous injections of an unwashed suspension of Phase 1 H. pertussis in 0.85% NaCl containing 0.5% phenol. The vaccine contained approximately 11 billion organisms per cc. The strains used were less than one month old and were grown on Bordet-Gengou media containing either horse or human blood.
Get full access to this article
View all access options for this article.