Identification of a heparin-binding hemagglutinin present in mycobacteria.

Abstract

SummaryAdherence to mammalian host tissues is an important virulence trait in microbial pathogenesis, yet little is known about the adherence mechanisms of mycobacteria. Here, we show that binding ofmycobacteria to epithelial cells but not to macrophages can be specifically inhibited by sulfated carbohydrates. Using heparin-Sepharose chromatography, a 28-kD heparin-binding protein was purified from culture supematants and cell extracts ofMycobacterium bovis and Mycobacterium tuberculosis. This protein, designated heparin-binding hemagglutinin (HBHA), promotes the agglutination of rabbit erythrocytes, which is specifically inhibited by sulfated carbohydrates. HBHA also induces mycobacterial aggregation, suggesting that it can mediate bacteria-bacteria interactions as well. Hemagglutination, mycobacterial aggregation, as well as attachment to epithelial cells are specifically inhibited in the presence of anti-HBHA antibodies. Immunoelectron microscopy using anti-HBHA monoclonal antibodies revealed that the protein is surface exposed, consistent with a role in adherence. Immunoblot analyses using antigen-specific antibodies indicated that HBHA is different from the fibronectin-binding proteins of the antigen 85 complex and p55, and comparison of the NH2-terminal amino acid sequence of purified HBHA with the protein sequence data bases did not reveal any significant similarity with other known proteins. Sera from tuberculosis patients but not from healthy individuals were found to recognize HBHA, indicating its immunogenicity in humans during mycobacterial infections. Identification of putative mycobacterial adhesins, such as the one described in this report, may provide the basis for the development of new therapeutic and prophylactic strategies against mycobacterial diseases.

Antigen-43-mediated autoaggregation impairs motility in Escherichia coli

“…Many bacteria, including Bordetella pertussis (Menozzi et al, 1994), Mycobacterium tuberculosis (Menozzi et al, 1996), Staphylococcus aureus (McDevitt et al, 1994) and Streptococcus pyogenes (Frick et al, 2000), form aggregates. This confers an ability to resist various host defences, e.g.…”

Broad heparin‐binding haemagglutinin‐specific cytokine and chemokine response in infants following Mycobacterium bovis BCG vaccination

“…Membranes were cut into strips and each strip blocked in 1% BSA then probed with a 1/100 dilution of infant serum in TBS-T. Antibody binding was detected using alkaline phosphatase visualisation (ProtoBlot II AP system, Promega, Madison, WI, USA). The HBHA-specific mouse E4 monclonal antibody [8] was used to confirm detection of HBHA on separate western blot strips.…”

Mycobacterium tuberculosis adhesins: potential biomarkers as anti-tuberculosis therapeutic and diagnostic targets

“…HBHA-mediated aggregation is instrumental in the formation of bacterial clumps, allowing for more effective adherence and invasion (Esposito et al, 2012;Lebrun et al, 2012). A definitive role for HBHA in the facilitation of host adherence was shown by Menozzi et al (1996), in which antibodies directed against HBHA inhibited attachment of mycobacteria to epithelial cells. In support of this, patients with active TB have been shown to produce anti-HBHA antibodies, suggesting HBHA expression during human infection (Menozzi et al, 1998 in recognizing heparan sulphate-containing receptors on epithelial cells (Delogu & Brennan, 1999;Pethe et al, 2000).…”

“…This surface-exposed protein is a virulence factor that facilitates the dissemination of M. tuberculosis from the site of primary infection by initiating interaction with host epithelial cells (Menozzi et al, 1996(Menozzi et al, , 1998(Menozzi et al, , 2006Pethe et al, 2001;Esposito et al, 2011). The two crucial steps in TB pathogenesis, namely bacterial aggregation and cell adhesion, are facilitated by HBHA (Menozzi et al, 1998;Esposito et al, 2012).…”