Novel human recombinant antibodies against Mycobacterium tuberculosis antigen 85B

Abstract

BackgroundTuberculosis is the leading cause of death due to bacterial infections worldwide, mainly caused by Mycobacterium tuberculosis. The antigen 85 complex comprises a set of major secreted proteins of M. tuberculosis, which are potential biomarkers for diagnostic.ResultsIn this work, the first human single chain fragment variable (scFv) antibodies specific for the tuberculosis biomarker 85 B were selected by phage display from naïve antibody gene libraries (HAL7/8). Produced as scFv-Fc in mammalian cells, these antibodies were further characterized and analysed for specificity and applicability in different tuberculosis antigen detection assays. Sandwich detection of recombinant 85 B was successful in enzyme linked immunosorbent assay (ELISA), lateral flow immunoassay and immunoblot. Whereas detection of M. tuberculosis cell extracts and culture filtrates was only possible in direct ELISA and immunoblot assays. It was found that the conformation of 85 B, depending on sample treatment, influenced antigen detection.ConclusionsRecombinant antibodies, selected by phage display, may be applicable for 85 B detection in various assays. These antibodies are candidates for the development of future point of care tuberculosis diagnostic kits. Using 85 B as a biomarker, the antigen conformation influenced by sample treatment is important.

Naïve Human Antibody Libraries for Infectious Diseases

“…A naïve human antibody library has also been used to isolate antibody fragments against tuberculosis (TB) antigens [141]. TB appears to be one of the leading fatal microbial infectious diseases worldwide caused by Mycobacterium tuberculosis [142].…”

“…Five scFv clones were successfully isolated and confirmed with DNA sequencing. Four clones have lambda light chain and one with kappa light chain [141].…”

Diagnosis of pulmonary and extrapulmonary tuberculosis based on detection of mycobacterial antigen 85B by immuno-PCR

“…Diagnosis of TB in most low-and middle-income countries continues to rely on smear microscopy, which detects 40-60% pulmonary TB (PTB) and 0-60% extrapulmonary TB (EPTB) cases (Fuchs et al, 2014;Mehta et al, 2012aMehta et al, , 2012b. Despite the considerable improvements in diagnostics for the last few decades, a simple and effective point-of-care TB diagnostic test is yet not available.…”

Early diagnosis and effective treatment regimens are the keys to tackle antimicrobial resistance in tuberculosis (TB): A report from Euroscicon's international TB Summit 2016

“…111 Another study used 5 human antibodies against Ag85B from the naive libraries, where 3 of them bound specifically to the 85B proteins as tested by ELISA. 112 Monitoring host response to TB treatment can identify the efficacy of treatment and predict the likelihood of relapse. The current method to validate treatment success is through bacteriological culture conversion at 2 months from the onset of therapy.…”