90% (36/40) of the serum samples from Farm B (vaccine inoculation) were IgG antibody positive by commercial IgG-ELISA kit, however, only 12.5% (5/40) of swab samples from the same pigs were positive for M.hyopneumoniae infection according to the SIgA-ELISA.
Nested-PCR data also suggested low infection rates (4/40)on Farm B, which supports the results of SIgA-ELISA.