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 (Mr) 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 Mr protein appeared in 43 of the strains, and a 46,000 Mr in two. The 39,000 Mr protein remained unchanged, whereas the 33,000 Mr protein disappeared. The 30,000 and the 28,000 Mr proteins became more clearly separated. A faint 16,000 Mr 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.