Search

The goal of this study was to characterize serum immunoglobulin G (IgG) antibody responses during experimental immunization of laboratory mice by purified recombinant proteins MPT63, MPT83 of M. tuberculosis and artificial fusion protein MPT83-MPT63 and obtain the recombinant single chain variable fragments of antibodies (scFv) against these antigens. This study demonstrates that the humoral immune response to MPT63, MPT83, MPT83-MPT63 fusion protein and equimolar set of MPT63 and MPT83 was highly different. For each antigen, serum antibody levels were evaluated by a cutoff value based on optical density index. A crucial role of MPT83 for immunogenicity of chimeric protein and/or cocktail of individual antigens under conditions of immunization of laboratory animals. We obtained also specific scFv antibodies against MPT63 and MPT83. These antibodies can be used for the development of the system for quantitative determination of antigens as well as for their biological properties investigation. Thereby, based on the results of the immune response and mycobacterial proteins antigenicity we showed highly immunogenicity properties of N-terminal part of MPT83 antigen for enhencement of ELISA sensitivity. We suggest MPT83-MPT63 fusion protein as a potential candidate on the role of antigenic substance for the serological diagnosis of tuberculosis.

Macrophages (MΦ) are the most described and characterized target and host of mycobacteria. Like other cells of innate immunity MΦ have a wide range of receptor molecules which interact with different pathogen associated molecular patterns (PAMPs). Immunodominant proteins MPT63 and MPT83 that are synthesized in abundance by Mycobacterium bovis or Mycobacterium tuberculosis strains could be involved in development of tuberculosis infection. The aim of this study was to search for effects of these mycobacterial antigens on target cells. For this aim full-sized sequences of MPT83 (rMPT83full) and MPT63 antigens were cloned into plasmid pET24a(+). The increase of phagocytic activity of murine peritoneal macrophages was demonstrated, but not of macrophage-like cells from J774 cell line, which were treated by rMPT63 and rMPT83full proteins for 24 h. This effect of such antigens can be considered as a way to facilitate the consumption of mycobacterial cells by macrophages to avoid other effector mechanisms of innate and adaptive immunity.