Failure of a novel surface polysaccharide-targeting vaccine to prevent Tritrichomonas infection in beef cattle
Tritrichomonas foetus (T. foetus) is the causative agent of bovine trichomoniasis that has a major impact on production costs for beef cattle producers. Immunization strategies to effectively protect against T. foetus are a high priority. Tritrichomonas foetus expresses a surface polysaccharide, beta 1-6 poly-N-acetyl glucosamine (PNAG), that is synthesized by a broad range of microbial pathogens. Vaccination with a PNAG-specific vaccine has demonstrated protection in pigs and horses. This study attempted to protect pregnant cows from an experimental T. foetus infection by prior vaccination with a PNAG-specific vaccine. Acceptable PNAG-specific antibody titers were achieved after vaccination, but antibodies elicited were non-protective against experimental challenge with T. foetus and in in vitro antibody functional bacterial killing assays.