Considerable effort has been directed toward controlling tuberculosis, which kills almost two million people yearly. High on the research agenda is the discovery of biomarkers of active tuberculosis (TB) for diagnosis and for monitoring treatment outcome. Rational biomarker discovery requires understanding host-pathogen interactions leading to biomarker expression. Here we report a systems immunology approach integrating clinical data and bacterial metabolic and regulatory information with high-throughput detection in human serum of antibodies to the entire Mycobacterium tuberculosis proteome. Sera from worldwide TB suspects recognized approximately 10% of the bacterial proteome. This result defines the M. tuberculosis immunoproteome, which is rich in membraneassociated and extracellular proteins. Additional analyses revealed that during active tuberculosis (i) antibody responses focused on an approximately 0.5% of the proteome enriched for extracellular proteins, (ii) relative target preference varied among patients, and (iii) responses correlated with bacillary burden. These results indicate that the B cell response tracks the evolution of infection and the pathogen burden and replicative state and suggest functions associated with B cell-rich foci seen in tuberculous lung granulomas. Our integrated proteome-scale approach is applicable to other chronic infections characterized by diverse antibody target recognition.biomarkers | humoral immunity | protein microarray | granuloma

In areas with low hepatitis B virus (HBV) endemicity such as most parts of Europe and the United States "anti-HBc alone" is found in 10-20% of all individuals with HBV markers, i.e., 1-4% of the population. In about 10% of these individuals HBV DNA is detected by PCR, the proportions varying greatly depending on the population studied, being highest in individuals coinfected with hepatitis C virus (HCV) (above 35%) and HIV (above 85%). A small proportion of individuals with "anti-HBc alone" are in the window phase of an HBV infection or in a stage of late HBV immunity. For the large proportion of these individuals this is not the case and they are thought to have an unresolved HBV-infection or a chronic infection in a late or "low grade" productive state. Currently, limited studies have been performed concerning the clinical aspects of individuals with "anti-HBc alone" and suspected chronic HBV infection. The majority of these individuals seem to be healthy. Some chronic carriers with "anti-HBc alone," however, do present signs of chronic hepatitis. Individuals with "anti-HBc alone" are potentially infectious. This is exemplified by a few case reports of HBV transmission to sexual contacts, perinatal transmission between mother and newborns and in blood recipients. Recommendations are given in relation to both the diagnostic and therapeutic procedures in the individuals with "anti-HBc alone" and in the blood banking and transplantation services.

The amino-terminal domain of the essential myosin light chain (MLC-1) binds to the carboxy terminus of the actin molecule. We studied the functional role of this interaction by two approaches: first, incubation of intact and chemically skinned human heart fibers with synthetic peptide corresponding to the sequences 5 through 14 (P5-14), 5 through 8 (P5-8), and 5 through 10 (P5-10) of the human ventricular MLC-1 (VLC-1) to saturate actin-binding sites, and second, incubation of skinned human heart fibers with a monoclonal antibody (MabVLC-1) raised against the actin-interacting N-terminal domain of human VLC-1 using P5-14 as antigen to deteriorate VLC-1 binding to actin. P5-14 increased isometric tension generation of skinned human heart fibers at both submaximal and maximal Ca2+ activation, the maximal effective peptide dosage being in the nanomolar range. A scrambled peptide of P5-14 with random sequence had no effects up to 10(-8) mol/L, ie, where P5-14 was maximally effective. P5-8 and P5-10 increased isometric force to the same extent as P5-14, but micromolar concentrations were required. Amplitude of isometric twitch contraction, rate of tension development, rate of relaxation, and shortening velocity at near-zero load of electrically driven intact human atrial fibers increased significantly on incubation with P5-14. These alterations were not associated with modulation of intracellular Ca2+ transients as monitored by fura 2 fluorescence measurements. Incubation of skinned human heart fibers with MabVLC-1 increased isometric tension at both submaximal and maximal Ca2+ activation levels, having a maximal effective concentration in the femtomolar range.

No abstract