Major outer membrane proteins of Pasteurella haemolytica serovars 1-15: comparison of separation techniques and surface-exposed proteins on selected serovars.

The Sarkosyl method of obtaining outer membrane proteins (OMPs) from Pasteurella haemolytica A1 was more efficient and less laborious than separating membranes by sucrose gradient centrifugation. More OMPs were recovered and major OMPs were present in greater concentrations in the Sarkosyl-derived preparations. Therefore, OMPs of P. haemolytica serovars 1-15 (serovars 3, 4, 10, and 15 being T biotypes and the remainder being A biotypes) were prepared by the Sarkosyl method and compared by SDS-PAGE. Serovars 1, 2, 5, 6, 7, 8, 11, and 12 which are A biovars had similar OMP profiles characterized by major OMPs of 30.5 and 43 kDa. Biovar T strains were characterized by doublet protein bands in the 26-28 kDa region and a major OMP in the 38-40 kDa range. Serovars 9, 13, and 14, which are also A biovars, had profiles similar, although not identical, to the T biovars. A 43 kDa protein was present in all serovars although concentration was greater in the A biovars. Surface-exposed proteins of P. haemolytica A1 determined by 125I-labeling of whole cells were 94, 84, 53.5, 49, 43, 41, 29.5, and 16 kDa. Iodine-labeling of serovars A2 and A6 which have similar OMP profiles by SDS-PAGE resulted in autoradiographs indistinguishable from A1. These studies expand our knowledge of P. haemolytica OMPs especially showing the utility of the Sarkosyl extraction procedure, variations in OMP profiles among some A biovar strains, and the similarities of OMP profiles and surface-labeled proteins among three of the most important serovars (1, 2, and 6).