Comparisons of the major outer membrane protein (MOMP) gene sequences from seven unrelated strains of Histophilus somni revealed that the genes from four MOMP type 1 strains were highly conserved in length and sequence. However, two MOMP type 3c strains and one MOMP type 3a strain differed markedly from the MOMP type 1 strains in their 3’-terminal halves. Their deduced MOMP amino acid sequences differed in sequence (3c, 80.5% and 82.7% identity; 3a, 62.4% identity) and in length (3c, 384 and 376; 3a, 316), indicating that the molecular differences are the basis of the antigenicity and molecular mass differences of H. somni MOMP. In the predicted MOMP secondary structure, the variable sequences primarily mapped to putative surface-exposed loops, and a variable and surface-exposed epitope of an MOMP-specific antibody was identified in the seventh-largest loop. These findings are useful for understanding the structural and immunological characteristics of H. somni.
(Research Team for Bacterial/Parasitic Diseases, TEL +81-29-838-7739)
Reference:
Khan et al. (2005) Vet. Microbiol. 107:179-192.
