Virulence genes in Moraxella spp. isolates from infectious bovine keratoconjunctivitis cases.

INTRODUCTION Infectious bovine keratoconjunctivitis (IBK) is an important ocular disease which affects cattle worldwide. To advance towards IBK effective prevention and treatment strategies, it is important to define the distribution and genetic diversity of potential virulence factors present in M. bovis and M. bovoculi. The objective of this work was to identify and to analyze Moraxella spp. potential virulence factor genes in a collection of clinical isolates. METHODOLOGY The presence and diversity of virulence factors in a collection of Moraxella spp. strains isolated since 1983 to 2009 in Uruguay was analyzed by PCR using primers for partial amplification of tolC, omp79, plb, fur and mbxA. The selection criterion of these genes was based on the fact that they encode virulence factors which could be present and conserved within strains, an important issue for the development of vaccines. RESULTS Differences in PCR amplification were observed within tolC (84%), omp79 (80%), plb (76%) and fur (44%) in M. bovis strains, whereas mbxA was amplified in all M. bovis and M. bovoculi strains. Regarding genetic diversity, the tolC nucleotide sequences were the less diverse within all M. bovis and mbxA were the less diverse within all M. bovis and M. bovoculi strains. CONCLUSIONS PCR amplifications suggest the occurrence of differences between both Moraxella species, related to evaluated genes within Moraxella spp. strains and suggests that both species may have different pathogenic attributes. MbxA and the outer membrane protein TolC might be considered for future studies to develop new vaccines against IBK.