Various collagenous lectins involved in innate immunity bind to surface oligosaccharides of bacteria and other microorganisms. We have been characterizing porcine plasma lectins that bind in a carbohydrate-dependent manner to surfaces of important bacterial pig pathogens including Actinobacillus suis (AS), A. pleuropneumoniae (APP), and Haemophilus parasuis (HP). A plasma protein with 32kDa subunits (pI 5.4 and 5.75) bound most isolates of HP, AS, and some APP. Partial amino acid sequences of this protein were similar to mammalian mannan-binding lectins (MBLs). The corresponding MBL-A cDNA sequences obtained by RT-PCR on liver tissue from pigs and cattle were homologous to the MBL1 gene of mice, rats and the MBL1P1 pseudogene of humans and chimpanzees. While human MBL-C, the product of the MBL2 gene, is known to bind various microorganisms, our studies in pigs provide the first direct evidence that MBL-A has bacteria-binding properties, and suggest it may have antibacterial functions in pigs.
Porcine mannan-binding lectin A binds to Actinobacillus suis and Haemophilus parasuis. Publishing Authors By Initials
