Honors Program


Date of this Version


Document Type



Schmit, A. 2024. Association of Moraxella bovis Genotype with Geographic Location and Host Factors in Cattle from the United States. Undergraduate Honors Thesis. University of Nebraska-Lincoln.


Copyright Anna Schmit 2024


Infectious bovine keratoconjunctivitis (IBK) is the most common ocular disease in cattle. Moraxella bovis, a gram-negative coccobacillus, is the main cause of IBK in cattle. Moraxella bovis is an opportunistic pathogen which causes infection when irritation to the cornea occurs. Recently, a study has found two different genotypes of Moraxella bovis. This research focuses on identifying relationships between the genotype of the Moraxella bovis isolated from field cases of IBK and the host factors of the animal from which the strains were obtained.

667 strains of Moraxella bovis were collected, grown, and ran through matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in order to create spectra for each strain. The spectra were then ran through two classifier tools (genetic algorithm [GA] and quick classifier [QC] software) as previously described. These software identified the strains as genotype 1, genotype 2, or excluded. The excluded strains were analyzed by hand to determine the genotype using a specific peak at 6854 m/z. Once the genotypes of each strain were determined, the strains were arranged based on location, breed, sex, age, and year.

Genotype 2 was represented by 75.7% of the strains while Genotype 1 was only represented by 24.3% of the strains. Nebraska was represented by the majority of the strains (251 isolates), followed by Wisconsin (72 isolates) and Iowa (58 isolates). In 2011, the United States was represented by 40.56% genotype 1, but this difference was not seen in Nebraska (where 23.077% of the strains collected in 2011 classified as genotype 1).