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A vaccine for bovine mastitis, tested under challenge
Staphylococcus aureus mastitis is chronic, recurrent, and largely unresponsive to antibiotic therapy once established. It drives milk loss, somatic cell count penalties, culling decisions, and a large share of on-farm antibiotic use.
Chronic, recurrent, and hard to treat
Chronic S. aureus infection persists inside the mammary gland, where antibiotics reach poorly. Cure rates for established infections are low, and treatment failure often ends in culling. Every course of intramammary antibiotic adds to withdrawal periods, cost, and resistance pressure. There is no highly effective licensed vaccine.
A live challenge in dairy cattle
In a small preclinical cow study, vaccinated animals received a prime and a boost during the dry period, followed by a direct intramammary challenge with live S. aureus. Milk and blood were sampled through day 30.
Readouts: antigen-specific IgG in milk and serum, somatic cell count, bacterial shedding, rectal temperature, and milk production.
Four findings
Antigen-specific IgG
Vaccinated cattle produced higher antigen-specific IgG in both milk and serum than unvaccinated controls, and held that difference through the study period.
Inflammatory cell influx
After challenge, vaccinated animals showed a lower inflammatory cell influx into milk than controls — the readout that tracks udder inflammation and milk quality.
Bacterial shedding
Vaccinated animals shed less S. aureus across the challenge period — the readout that matters for herd-level control.
Safety
Rectal temperature stayed in the normal range, with no adverse events attributable to vaccination.
Results from a small preclinical cow study, conducted under a USDA NIFA STTR Phase I award (2023–2025). Detailed data are shared with partners under confidentiality.
A dairy cow is not a model organism standing in for a person. It is a large outbred animal with a real S. aureus disease, challenged with live organism under field conditions — the closest thing to a clinical trial that a preclinical platform can run. What it demonstrates about the CTA2/B carrier, and about the antigens, applies directly to the human programme.
Human Health →Development status
BoStaph™ is an investigational intramammary vaccine for S. aureus mastitis in dairy cows, given at dry-off. It is in development under a USDA NIFA STTR Phase I award (2023–2025) and a Phase II award (2026–2028), and is not licensed by the USDA.
Regulatory pathway: planned USDA Center for Veterinary Biologics (CVB) licensure.
The ask
We are seeking dairy producers, veterinary partners, and animal-health companies for herd-scale evaluation and licensing discussions.
Investigational use. This vaccine is investigational. It is not licensed or approved for commercial veterinary use.