HUMORAL IMMUNE-RESPONSES TO MYCOPLASMA-HYOPNEUMONIAE IN SOWS AND OFFSPRING FOLLOWING AN OUTBREAK OF MYCOPLASMOSIS

Previously healthy sows, seropositive to Mycoplasma hyopneumoniae, dev eloped clinical signs of mycoplasmosis, as well as increasing amounts of antibodies to M. hyopneumoniae during an outbreak of the disease in a herd. During the early phase of the outbreak, young piglets (2 week s) with maternal antibodies remained healthy while older seronegative piglets (4-7 weeks) developed the disease. The duration of the materna l antibodies to M. hyopneumoniae varied between litters and was relate d to the amount of antibodies in the serum of the dam. In sows, the le vel of serum antibodies decreased continuously from 4 weeks ante partu m to partus, and the level of antibodies in the whey of colostrum was comparable to that in serum 4 weeks ante partum. After loss of materna l antibodies to M. hyopneumoniae, seropositive animals were not found among piglets younger than 9 weeks. Therefore peripheral blood mononuc lear cells (PBMC) were collected from various age categories of piglet s in order to measure the ability to produce antibodies to M. hyopneum oniae in vitro. PBMC obtained from piglets aged 1 and 3 weeks produced few antibodies to M. hyopneumoniae. Significantly higher levels of an tibodies to M. hyopneumoniae were produced by PBMC obtained from pigs aged 5-9 weeks. Thus, the ability of PBMC to produce antibodies to M. hyopneumoniae in vitro seemed to be age-dependent. (C) 1998 Elsevier S cience B.V.