Protective effects of an oral microencapsulated Mycoplasma hyopneumoniae vaccine against experimental infection in pigs.

Oral microencapsulated Mycoplasma hyopneumoniae vaccines were tested for their ability to prevent mycoplasmal pneumonia in pigs. Eighteen four-week-old specific pathogen free pigs were divided into six groups of three. Each pig of groups 1 to 4 was inoculated intramuscularly with formalin-inactivated M hyopneumoniae in adjuvant and boosted orally 14 days later with four different microencapsulated vaccine microspheres. Group 5 was used as a positive control. All 15 pigs of groups 1 to 5 were challenged at 28 days after the first vaccination by an intratracheal inoculation of pneumonic lung suspension. The three pigs of group 6 were used as a negative control. All four vaccinated groups showed some protection when challenged, but the protection was more solid in pigs boosted with vaccine D (group 4) which contained less porcine serum in the microsphere. The study indicates that oral vaccination with M hyopneumoniae could play a role in prevention and eradication of mycoplasmal pneumonia in the pig.