Seleção e caracterização de biomarcadores aplicáveis em plataformas nanotecnológicas para o diagnóstico da tuberculose

Abstract

Tuberculosis (TB) is a bacterial disease of high mortality, caused by Mycobacterium tuberculosis, transmitted by the patient through the respiratory tract. TB is a serious public health problem. It is estimated that one third of the world population is infected with M. tuberculosis in the form of latent infection, which may as well stay for the entire life, until a drop of immunity will develop characterizing the active infection. Brazil, despite the mass immunization of newborns, is among the 22 countries that represent 80% of those infected. To control the spread and disease progression is necessary, and monitor patients to ensuring the treatment and cure, rapid diagnosis. The diagnostic methods currently used do not meet the need and the speed and sensitivity, and are not able to differentiate infection from active disease. Some studies have demonstrated the importance of proteins secreted by virulent strains for use in diagnostic platforms. In recent decades, many authors have called attention to the promising features of saliva as a biological sample ideal for testing various types of diseases. The objective of this work was to select and characterize high-affinity ligands to immunoglobulins A present in the saliva of individuals with tuberculosis. We used the technology libraries displayed on phage, phage display to identify mimetic peptides to proteins of M. tuberculosis, IgA saliva from patients with tuberculosis. Twenty clones were selected and analyzed for similarity and alignment with proteins deposited in the database. Five showed similarity and aligned with antigenic proteins related to virulence of M. tuberculosis, CFP-10/ESAT-6, rpf and PE-family of proteins encoded in the Region of Differentiation (RD1). The clones were subjected to ELISA tests to evaluate the immunoreactivity against IgA in saliva from healthy individuals, or non-reactive with PPD and tuberculosis patients with treatment time range 0-6 months. Statistical analyzes showed that the clones differed significantly from negative to positive salivas (p<0.05), with 100% sensitivity and specificity averaged 73%. The analysis of the regression curve of absorbance values versus time of treatment tended to decline. Our clones are potential markers for diagnosis and possibly treatment control, being able to differentiate between latent infection and active disease.