Identification and carbohydrate specificity of a chicken serum mannan-binding protein reactive with a Ra chemotype strain of Salmonella typhimurium.

To compare a chicken serum mannan-binding protein (MBP) with a chicken Ra-reactive factor (RaRF), both serum proteins were isolated by combination of different chromatography. In SDS-PAGE, both purified proteins were resolved into a major protein band with a molecular weight of 34,000 and a few minor protein bands. In Western blotting with both purified proteins, only a single band with a molecular weight of 34,000 was detected with anti-chicken serum MBP antibody, indicating that the major protein band of chicken serum MBP and RaRF are antigenically identical. The combining sites of these two proteins were most reactive with N-acetylmannosamine followed by mannose, N-acetylglucosamine, and L-fucose. These findings suggest that chicken serum MBP may be identical to its corresponding bactericidal factor RaFR in terms of antigenicity and monosaccharide specificity.