A MORAXELLA-BOVIS PILI VACCINE PRODUCED BY RECOMBINANT-DNA TECHNOLOGYFOR THE PREVENTION OF INFECTIOUS BOVINE KERATOCONJUNCTIVITIS

Pili (fimbriae) were prepared from Moraxella bovis strain Dalton 2d (D al2d) and from a derivative of Pseudomonas aeruginosa K/2PfS that cont ained a plasmid-borne Dal2d pilin gene and produced pili having,serogr oup-specific identity to Dal2d. Nine calves were vaccinated with two d oses each of 30 mug authentic M. bovis Dal2d pili in oil adjuvant and 10 calves were vaccinated with a similar dose of P. aeruginosa-derived Dal2d pili in the same formulation. All 19 calves and 10 non-vaccinat ed controls were challenged by instillation of 1 X 10(9) virulent M. b ovis Dal2d cells into both conjunctival sacs 19 days after the second vaccine dose. The serological response to vaccination and the degree o f protection against experimentally induced infectious bovine keratoco njunctivitis (IBK) were assessed. None of the nine calves vaccinated w ith authentic M. bovis Dal2d pili developed IBK while two of those vac cinated with P. aeruginosa-derived Dal2d pili developed lesions which accounted for a mean group lesion score of 0.3. In contrast, 9 of the 10 non-vaccinated calves developed IBK lesions, the majority of which were progressive, required early treatment and accounted for a mean gr oup lesion score of 1.5. These results demonstrate the potential of a relatively low dose of pili produced by recombinant DNA technology for development of an effective vaccine against IBK.