Identification of Moraxella bovis by using a monoclonal antibody to a lipopolysaccharide epitope

Membrane-associated and cytosolic species-specific antigens of Mycoplasma bovis recognized by monoclonal antibodies

Mycoplasma bovis is a causative agent of bovine mastitis, arthritis, and pneumonia. Six monoclonal antibodies (MAbs) against M. bovis were prepared and used to characterize specific antigens of the mycoplasma. Reactivity of the MAbs to six M. bovis strains was tested by IFA, ELISA, and immunoblotting. The specificity of these MAbs was tested by the same methods against 8 other species of bovine mycoplasmas and 1 mycoplasma species of sheep and goats (Mycoplasma agalactiae) that is highly cross-reactive with M. bovis. Three of the MAbs were used on Western blots of trypsin-treated whole organisms to determine if the antigens were exposed on the surface of M. bovis By isotyping, MAbs were identified as kappa chain IgG1 (3 MAbs), and IgM (3MAbs). The MAbs reacted with all six M. bovis strains in IFA, ELISA, and Western blots. Four of the antigens recognized were highly specific for M. bovis in ELISA, and 3 were cross-reactive with M. agalactiae or other bovine mycoplasmas in Western blots. One MAb reacted with multiple bands with all M. bovis strains, indicating recognition of a size-variant antigen. The size-variant antigen and one of the M. bovis-specific antigens were recognized as surface proteins. A large M. bovis-specific antigen was a conserved cytosolic protein. The M. bovis antigens discovered may be used for specific detection of the organism or measurement of antibody responses, particularly if used in tests with nondenatured alkali-treated antigen, such as ELISA.

Iron sequestration by macrophages decreases the potential for extracellular hydroxyl radical formation

Alveolar macrophages (AM) from smokers contain a much higher quantity of intracellular iron than AM from nonsmokers. Since some forms of iron will catalyze the formation of hydroxyl radical (.OH) from superoxide and hydrogen peroxide, the ability of AM derived from smokers and nonsmokers to generate .OH was assessed. No detectable .OH was produced by AM from either source, suggesting that iron sequestration by AM may limit the potential for .OH-mediated lung injury. Consistent with this hypothesis, the ability of bronchoalveolar lavage fluid (BAL) from smokers and nonsmokers to act as an .OH catalyst decreased after exposure to AM. We found that, like AM, human monocyte-derived macrophages (MDM) have the ability to acquire large quantities of iron from small low molecular weight iron chelates as well as decrease the ability of BAL to act as a .OH catalyst. When MDM or AM were exposed to the iron chelates or BAL they were then able to generate .OH after phorbol myristate acetate stimulation. However, when acutely iron-loaded or BAL-exposed MDM were placed in culture, their ability to produce .OH decreased with time to the level of non-iron-exposed controls. This process correlated with iron translocation from the plasma membrane to the cytosol as well as a 3-9-fold increase in cellular ferritin. No increase in antioxidant enzyme levels or induction of the heat shock response was observed. Iron sequestration by macrophages may protect nearby cells from exposure to potentially cytotoxic iron-catalyzed oxidants such as .OH.

Production of a monoclonal antibody that recognizes the lipopolysaccharide of a Campylobacter-like organism

A monoclonal antibody was produced to a Campylobacter-like organism (RMIT 32A) which was isolated from the terminal ileum of a pig with proliferative enteritis. Isotyping of the antibody revealed that it was an IgG2a with kappa light chains. Immunoblots using the antibody against proteinase-K-treated whole cell lysates of RMIT 32A, a selection of Campylobacter species and other enteric bacteria showed that the antibody was specific for RMIT 32A and was directed against the lipopolysaccharide. This antibody can be used for the specific detection of RMIT 32A.

Generation of monoclonal antibodies against surface antigens of Moraxella bovis

Six hybridoma lines producing monoclonal antibodies (MAbs) against Moraxella bovis were established from fusions between the SP2/0 myeloma cells and BALB/c mice splenocytes. Three antibodies were of the IgG1 isotype, two were IgG2a, and one was IgG2b. The specificity of the antibodies was determined by indirect enzyme-linked immunosorbent assay (ELISA) using whole cells of M. bovis and of other Gram-negative bacteria, and lipopolysaccharide (LPS) from M. bovis JUR2 and E. coli as antigens. Ascitic fluid produced by the six hybridoma lines inhibited hemagglutination by M. bovis GF9. One MAb (35F) reacted specifically with purified M. bovis LPS in the ELISA test. The MAb panel detected heterogeneity among the isolates recovered from different geographical regions.