Title

Serum Resistance in Bartonella Species

Presentation Type

Poster

Abstract

Bartonella are widespread bacterial pathogens of vertebrates that have been found in virtually every type of mammal surveyed. Of the 31 validated species in the genus Bartonella, 11 are agents of serious infectious diseases of humans, including Carrión’s disease, trench fever, cat-scratch disease, and bacillary angiomatosis in AIDS patients. As facultative intracellular parasites that employ hemotrophy (infection of red blood cells), the key to survival depends on the ability to replicate within the bloodstream of the vertebrate host or reservoir. It has been demonstrated that bartonellae are resistant to the effects of complement proteins in serum, the primary effector of the humoral innate immune system. Although this effect has been characterized in other pathogens, the molecular basis of Bartonella’s serum resistance is undetermined. The overall objective of this research was to examine the genetic and molecular components of complement resistance in bartonellae using Bartonella bacilliformis (Bb) as a model. Complement resistance was demonstrated in Bb by complement assays with human serum. Using a far-Western blot, a ~90-kDa Bb protein was identified as a potential human factor H binding protein (Fhbp). Immunofluorescence microscopy demonstrated a Fhbp on the surface of intact bacterial cells. Genomic analyses based on molecular mass were used to identify two candidate Fhbp genes (KC583_0512 and _0314) which are currently being cloned for further analysis. Results of this study will allow us to analyze complement resistance in Bartonella and increase our understanding of serum resistance in other pathogenic bacteria.

Category

Life Sciences

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Apr 15th, 11:00 AM Apr 15th, 12:00 PM

Serum Resistance in Bartonella Species

Bartonella are widespread bacterial pathogens of vertebrates that have been found in virtually every type of mammal surveyed. Of the 31 validated species in the genus Bartonella, 11 are agents of serious infectious diseases of humans, including Carrión’s disease, trench fever, cat-scratch disease, and bacillary angiomatosis in AIDS patients. As facultative intracellular parasites that employ hemotrophy (infection of red blood cells), the key to survival depends on the ability to replicate within the bloodstream of the vertebrate host or reservoir. It has been demonstrated that bartonellae are resistant to the effects of complement proteins in serum, the primary effector of the humoral innate immune system. Although this effect has been characterized in other pathogens, the molecular basis of Bartonella’s serum resistance is undetermined. The overall objective of this research was to examine the genetic and molecular components of complement resistance in bartonellae using Bartonella bacilliformis (Bb) as a model. Complement resistance was demonstrated in Bb by complement assays with human serum. Using a far-Western blot, a ~90-kDa Bb protein was identified as a potential human factor H binding protein (Fhbp). Immunofluorescence microscopy demonstrated a Fhbp on the surface of intact bacterial cells. Genomic analyses based on molecular mass were used to identify two candidate Fhbp genes (KC583_0512 and _0314) which are currently being cloned for further analysis. Results of this study will allow us to analyze complement resistance in Bartonella and increase our understanding of serum resistance in other pathogenic bacteria.