An experimental live vaccine trial against contagious caprine pleuropneumonia

Live attenuated Mycoplasma capricolum subsp. capripneumoniae (Mccp) vaccine prepared from local isolate at the National Veterinary Institute (NVI), Ethiopia, was injected to 56 contagious caprine pleuropneumonia unexposed goats with the aim of determining level of seroconversion and safety compared to a killed commercial vaccine, produced by the NVI. The 56 goats were randomly allocated into three groups vaccinated with: candidate live vaccine (n=19) and Mccp killed vaccine (positive control) (n=19), and negative control (n=18). Antibody was detected by compliment fixation test (CFT). The candidate live vaccine induced seropositivity in higher proportion of inoculated goats than that of the killed vaccine in use. Moreover, the seroconversion occurred slightly earlier and for slightly prolonged period compared to the killed vaccine. Increase in body temperature was recorded in 4 of 19 (21.1%) goats inoculated by the killed vaccine. Back to seronegativity was rapid in both types of vaccines. In conclusion, absence of any post vaccination reaction, early appearance and longer persistence of antibodies made the live candidate Mccp vaccine better than the killed vaccine. However, further experimental and field trial of the vaccine is suggested and reversion to the attenuated virus to virulent form and carrier state should be considered.