Characterization of the gene encoding Mhp1 from Mycoplasma hyopneumoniae and examination of Mhp1's vaccine potential.

The gene encoding Mhp1, a 124 kDa protein from Mycoplasma hyopneumoniae, has been cloned, sequenced, and its product characterized. No significant homology to the gene or encoded polypeptide was found in the Genbank, NBRF, or PIR databases, though this protein appears similar to p97, a putative adhesin of M. hyopneumoniae described by Zhang et al. (Infect. Immun. 63, 1013-1019, 1995). Two repeated motifs were identified within the 3' end of the gene and encoded polypeptide. The mhp1 gene was fused to the glutathione S-transferase (GST) gene from Schistosoma japonicum, enabling high-level expression and purification of the protein. Both the authentic and recombinant proteins were recognized by sera from pigs infected with M. hyopneumoniae. In an induced-disease model in pigs, coughing was reduced in animals vaccinated with recombinant GST-Mhp1, although differences were not significant. Only minimal protection against lung lesion formation was provided, and again differences between the Mhpl-vaccinated and nonvaccinated groups were not significant.