Detection of anti-listeriolysin O and Listeria monocytogenes in experimentally infected buffaloes (Bubalus bubalis).

The kinetics of antibody production against listeriolysin O (ALLO) and the recovery pattern of Listeria monocytogenes from bacteriological samples were studied following oral infection of buffalo calves with 3 x 10(9) cells each of pathogenic L. monocytogenes. Antibodies to LLO appeared by 7-10 days post infection (PI), with a shallow peak between days 16 and 36 PI, when tested by indirect plate-ELISA. The titres of ALLO in all the animals then declined slowly but remained detectable up to day 70 PI. In dot-ELISA, ALLO could be detected by days 5 to 7 PI, and with higher titres than with the plate-ELISA. The pathogen was recovered at low rates as ALLO first appeared but was absent in the faecal, nasal and blood cultures as production of ALLO peaked.