Expression, purification and X-ray crystallographic analysis of the Helicobacter pylori blood group antigen-binding adhesin BabA

Helicobacter pylori is a human pathogen that colonizes about 50% of the world's population, causing chronic gastritis, duodenal ulcers and even gastric cancer. A steady emergence of multiple antibiotic resistant strains poses an important public health threat and there is an urgent requirement for alternative therapeutics. The blood group antigen-binding adhesin BabA mediates the intimate attachment to the host mucosa and forms a major candidate for novel vaccine and drug development. Here, the recombinant expression and crystallization of a soluble BabA truncation (BabA^25-460) corresponding to the predicted extracellular adhesin domain of the protein are reported. X-ray diffraction data for nanobody-stabilized BabA^25-460 were collected to 2.25Å resolution from a crystal that belonged to space group P21, with unit-cell parameters a = 50.96, b = 131.41, c = 123.40Å, α = 90.0, β = 94.8, γ = 90.0°, and which was predicted to contain two BabA^25-460-nanobody complexes per asymmetric unit.

Differential T and B cell responses against Mycobacterium tuberculosis heparin-binding hemagglutinin adhesin in infected healthy individuals and patients with tuberculosis.

Because only 10% of individuals infected with Mycobacterium tuberculosis will eventually develop disease, antigens that are recognized differently by the immune systems of infected healthy and diseased subjects may constitute potential vaccine candidates. Here, the heparin-binding hemagglutinin adhesin (HBHA) is identified as such an antigen. Lymphocytes from 60% of healthy infected individuals (n=25) produced interferon (IFN)-gamma after stimulation with HBHA, compared with only 4% of patients with active tuberculosis (n=24). In the responders, both CD4(+) and CD8(+) cells secreted HBHA-specific IFN-gamma, and the antigen was presented by both major histocompatibility complex class I and II molecules. In contrast to the reduced ability of patients with tuberculosis to produce HBHA-specific IFN-gamma, most of them (82%) produced anti-HBHA antibodies, compared with 36% of the infected healthy subjects. These observations indicate that HBHA is recognized differently by the immune systems of patients with tuberculosis and infected healthy individuals and might provide a marker for protection against tuberculosis.