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Published on: February 7, 2013
Differences in protein expression of Haemophilus somnus grown under conditions of iron-restriction
A Wedderkopp1, S V Primal, S Silva
1Department of Pathology and Epidemiology, National Veterinary Laboratory, Copenhagen, Denmark.
Abstract:
Outer membrane protein profiles were compared in 14 H. somnus strains isolated from brain and lung lesions as well as from the genital tract of asymptomatic carriers during in vitro growth under iron-restricted conditions. Ethylenediamine-di-O-hydroxyphenyl acetic acid (EDDA) was used to obtain iron-restricted conditions in media used for this study. The outer membrane protein profiles were studied by the discontinuous sodium dodecyl sulfate-polyacrylamide gel electrophoretic system (SDS-PAGE), and the proteins were stained with silver or transferred to nitrocellulose sheets and western blots conducted. Growth under iron-restricted conditions resulted in the induction of outer membrane proteins in most H. somnus strains examined. Studies also indicated differences among H. somnus strains in the number of induced proteins and their molecular weights but the results did not indicate a specific relationship between these strain-dependent differences and tissue trophism. Western blot analysis revealed a high degree of immunological relatedness among strains of H. somnus in their iron-regulated proteins. However, hyperimmune serum used in these assays failed to recognize certain iron-regulated proteins expressed by some H. somnus strains, a finding which may have important implications for the induction of protective immunity in cattle against this bovine pathogen.
Insights
Outer membrane protein profiles of Haemophilus somnus (H. somnus) strains were analyzed under iron restriction. Differences in iron-regulated proteins were observed, impacting potential cattle immunity strategies.
Area of Science:
- Veterinary Microbiology
- Bacterial Pathogenesis
Background:
- Haemophilus somnus is a significant bovine pathogen causing various diseases.
- Understanding H. somnus outer membrane proteins is crucial for developing effective vaccines and treatments.
Purpose of the Study:
- To compare outer membrane protein (OMP) profiles of H. somnus strains under iron-restricted conditions.
- To investigate the immunological relatedness of iron-regulated proteins among different H. somnus strains.
- To assess the implications of protein variations for inducing protective immunity in cattle.
Main Methods:
- Isolation and in vitro cultivation of 14 H. somnus strains from diverse bovine tissues.
- Induction of iron-restricted conditions using Ethylenediamine-di-O-hydroxyphenyl acetic acid (EDDA).
- Analysis of outer membrane protein profiles via SDS-PAGE and Western blotting.
Main Results:
- Iron restriction induced outer membrane proteins in most H. somnus strains.
- Strain-dependent variations in the number and molecular weight of induced proteins were noted, but not linked to tissue tropism.
- Western blot analysis showed significant immunological relatedness of iron-regulated proteins, yet some proteins were not recognized by hyperimmune serum.
Conclusions:
- H. somnus exhibits iron-regulated outer membrane protein expression with inter-strain variability.
- The presence of non-recognized iron-regulated proteins suggests challenges in developing broadly protective vaccines for cattle against H. somnus infections.
