A unified serotyping scheme for Moraxella bovis

Area of Science:

• Veterinary Microbiology
• Bacterial Pathogenesis
• Immunology

Background:

• Moraxella bovis is an important cause of infectious bovine keratoconjunctivitis (IBK).
• Fimbrial antigens of M. bovis are crucial for host-protective immunity and serological classification.
• Previous serological classifications have varied between regions.

Purpose of the Study:

• To classify international Moraxella bovis isolates into serogroups based on fimbrial antigens.
• To compare different serological methods for M. bovis classification.
• To propose an updated, amalgamated serogroup classification system.

Main Methods:

• Serological classification of 53 Australian, 7 British, 2 American, and 2 New Zealand M. bovis isolates.
• Utilized whole cell slide agglutination (SA), enzyme-linked immunosorbent assays (ELISA), and tandem-crossed immunoelectrophoresis (TCIE).
• Compared and reconciled discrepancies between SA and ELISA results using TCIE.

Main Results:

• Identified seven distinct serogroups based on fimbrial antigen variability.
• SA and ELISA yielded identical results for 68.7% of isolates, with TCIE resolving discrepancies.
• Results indicate potentially limited worldwide variation in M. bovis fimbrial antigens.

Conclusions:

• The study proposes an amalgamated classification of British and Australian M. bovis serogroups, designated A to G.
• A protocol for future serotyping of M. bovis is suggested.
• Limited global variation in fimbrial antigens may simplify vaccine development and epidemiological studies.