An electrophoretic characterization of iron-transporting proteins in Mannheimia haemolytica A1

Abstract

Iron-regulated outer membrane proteins (IROMPs) in Mannheimia haemolytica A1, which function as a receptor for complexes containing iron ions, are induced by iron deficiency in the growth environment of the bacteria. Densitometric analysis of SDS-PAGE separation showed expression of IROMPs of 71, 77, and 100 kDa in the case of bacteria grown in a medium with 2,2-dipyridyl. The electrophoregrams obtained in 2-DE separations confirmed the presence of protein fractions with these molecular weights and isoelectric points ranging from 5.4 to 6.4. The results of the study also confirmed the ability of M. haemolytica A1 proteins involved in iron uptake to induce a protective immune response. In Western blot with serum from convalescent calves naturally infected with M. haemolytica A1, distinct reactions were obtained for IROMPs of 71, 77, and 100 kDa.

Mannheimia haemolyticain bovine respiratory disease: immunogens, potential immunogens, and vaccines

“…Iron acquisition from transferrin is a major mechanism used by M. haemolytica, and three IROMPs (approximately 70, 77, and 105 kDa) involved in transferrin binding were identified in bacteria grown in vitro under iron-restricted conditions or in vivo within an intraperitoneal implanted chamber (Deneer and Potter, 1989; Ogunnariwo and Schryvers, 1990; Morck et al ., 1991; Yu et al ., 1992; Geschwend et al ., 1997; Ogunnariwo et al ., 1997). Western blots using convalescent sera from M. haemolytica -infected calves demonstrated antibodies against the three proteins (Deneer and Potter, 1989; Puchalski et al ., 2013). We demonstrated antibody responses to the 70 and 77 kDa proteins to be significantly higher in live M. haemolytica -vaccinated calves than in control calves; however, there was no significant correlation between antibody responses to those proteins and lesion scores following challenge (Confer et al ., 1995).…”