SERUM AND MUCOSAL ANTIBODY-RESPONSES AND PROTECTION IN PIGS VACCINATED AGAINST MYCOPLASMA-HYOPNEUMONIAE WITH VACCINES CONTAINING A DENATURED MEMBRANE ANTIGEN POOL AND ADJUVANT

Objective To investigate the protective efficacy of a pool oi denature d membrane protein antigens of Mycoplasma hyopneumoniae (J strain) in the molecular size range 70 to 85 kDa (F3 antigen) in combination with adjuvants for pigs challenged with M hyopneumoniae. Design A vaccine efficacy experiment with assessment of serum and respiratory tract ant ibody responses. Procedure F3 antigens were emulsified with five diffe rent adjuvants. To groups of three pigs per vaccine, four vaccines wer e given by intramuscular injection, and two vaccines, including one of those given intramuscularly, were given by intraperitoneal injection. Results Compared to six unvaccinated pigs, animals vaccinated with F3 antigen displayed significantly reduced pneumonia (54% reduction in m ean lung score) following experimental challenge. Analysis of post-vac cination, pre-challenge IgG and IgA ELISA antibody absorbances in seru m and respiratory tract washings revealed no correlation with lung sco re. Six weeks after challenge, pigs previously vaccinated intramuscula rly mostly demonstrated greater IgG and IgA responses in respiratory t ract washings, and greater IgG serum antibody responses, than those va ccinated by intraperitoneal injection. Conclusion Pigs vaccinated with M hyopneumoniae antigens in the molecular size range of 70 to 85 kDa showed a significant reduction in lung lesions compared with unvaccina ted control animals after experimental challenge. IgG and IgA antibody concentrations in serum and respiratory tract washings after vaccinat ion do not provide a useful prognostic indicator of protection from en zootic pneumonia.