Subtyping of Danish Haemophilus Influenzae Type B by Their 45000 and 46000 Molecular Weight Proteins

In order to obtain a way of subtyping Haemophilus influenzae type b strains, outer‐membrane protein patterns were investigated. Outer‐membrane proteins from 45 different Haemophilus influenzae type b strains were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The non‐heated sarkosyl insoluble outer‐membrane preparations all contained four major proteins with molecular weights (M r ) of 39,000, 33,000, 30,000, and 28,000, except for one strain which possessed a protein weighing approximately 32,000. After heating the samples a 45,000 M r protein appeared in 43 of the strains, and a 46,000 M r in two. The 39,000 M r protein remained unchanged, whereas the 33,000 M r protein disappeared. The 30,000 and the 28,000 M r proteins became more clearly separated. A faint 16,000 M r band was observed in both heated and non‐heated samples. 42 strains with the light heat‐modified protein band had identical protein patterns and could not be subdivided by the methods used and may therefore constitute a clone. The remaining strains had individual patterns.