Protective effect of vaccination against Mycoplasma pulmonis respiratory disease in rats

Abstract

I.v. vaccination of rats with viable or formalin-inactivated M. pulmonis reduced the incidence and severity of lower respiratory tract lesions after intranasal challenge with viable organisms. Intranasal vaccination with killed organisms reduced the severity of rhinitis, but did not affect lesions in any other region of the respiratory tract. The maximum protection against upper tract lesions (rhinitis, otitis and laryngotracheitis) was provided by i.v. immunization with viable organisms. Dual vaccination (i.p. plus intranasal) with killed organisms provided no significant protection in any segment of the tract. However, these ineffective vaccine regimens did not potentiate the lesions. Vaccination of rats against mycoplasma respiratory disease is feasible. Systemic vaccination may provide greater protection for the lungs than intranasal vaccination, at least when equivalent antigen doses are used.