ELISA-based assay of immunoglobulin G antibodies against mammalian cell entry 1A (Mce1A) protein: a novel diagnostic approach for leprosy

Abstract

BACKGROUNDLeprosy is a chronic infectious disease caused by the obligate intracellular bacillus Mycobacterium leprae. Because leprosy diagnosis is complex and requires professional expertise, new tools and methodologies are needed to detect cases in early stages and prevent transmission. The M. leprae genome contains mce1A, which encodes a putative mammalian cell entry protein (Mce1A). We hypothesised that the presence of Mce1A on the cell surface could be detected by the host's immune system.OBJECTIVEThe aim of this study was to evaluate antibody responses against the Mce1A protein in leprosy patients, household contacts of patients, and the general population to present an addition tool for leprosy diagnosis.METHODSA cross-sectional study involving 89 volunteers [55 leprosy cases, 12 household contacts (HHC) and 22 endemic controls (EC)] was conducted at Couto Maia Hospital, in Salvador, Bahia (BA), Brazil.RESULTSThe median anti-Mce1A IgA was significantly higher in multibacillary (MB) and paucibacillary (PB) cases than in EC (p < 0.0001). A similar trend was observed in IgM levels, which were significantly higher in both MB (p < 0.0001) and PB (p = 0.0006) groups compared to in EC individuals. The greatest differences were observed for IgG class-specific antibodies against Mce1A. The median levels of MB and PB were significantly higher compared to both controls HHC and EC (MB or PB vs EC, MB vs HHC p < 0.0001; PB vs HHC, p = 0.0013). Among leprosy cases, IgG enzyme-linked immunosorbent assay sensitivity and specificity were 92.7% and 97.1%, respectively. IgG positivity was confirmed in 92.1% and 94.1% of MB and PB patients, respectively.CONCLUSIONThis novel diagnostic approach presents an easy, non-invasive, and inexpensive method for leprosy screening, which may be applicable in endemic areas.

In search of biomarkers for leprosy by unraveling the host immune response to Mycobacterium leprae

“…[50][51][52] Mce1A-specific antibodies have been detected in leprosy patients, especially IgG antibodies were significantly higher in both MB and PB patients compared to controls. 53 This is in contrast to the general assumption that antibodies are predominant in the MB side of the leprosy spectrum only, and Mce1A-specific antibodies therefore show potential for the identification of PB patients as well. The four cell types that can internalize M leprae via Mce1A will be discussed next.…”

“…These four cell types are most likely the first line of defense against M leprae, and tropism for these cells is potentially mediated via mammalian cell entry protein 1A (Mce1A) 50‐52 . Mce1A‐specific antibodies have been detected in leprosy patients, especially IgG antibodies were significantly higher in both MB and PB patients compared to controls 53 . This is in contrast to the general assumption that antibodies are predominant in the MB side of the leprosy spectrum only, and Mce1A‐specific antibodies therefore show potential for the identification of PB patients as well.…”

Serological Immunoassay for Hansen’s Disease Diagnosis and Monitoring Treatment: Anti-Mce1A Antibody Response Among Hansen’s Disease Patients and Their Household Contacts in Northeastern Brazil

“…Quantitative assessment of IgA, IgM and IgG antibodies against the Mce1A protein was performed by indirect ELISA ( 15 ). Purified recombinant Mce1A protein was provided by Dr. LW Riley (University of California, Berkeley, CA, United States).…”

“…The mammalian cell-entry 1A (Mce1A) protein, first described in M. tuberculosis , is present in the cell wall of M. leprae and it is associated with the entry of the bacillus into nasal epithelial cells and skin cells ( 13 , 14 ). Previous studies have shown the potential of using serum biomarkers such as antibodies against Mce1A in the diagnosis of HD ( 15 ). Therefore, because it plays a role in the invasion and maintenance of M. leprae infection, Mce1A represents a potential target for the development of new diagnostic tests to diagnose HD, monitor treatment, and screen for contacts of index cases of HD.…”

Recombinant polypeptide of Mycobacterium leprae as a potential tool for serological detection of leprosy

“…The immunoreactivity of anti-rMLP15 IgG in patient sera was assessed using a modified ELISA protocol of Lima et al (2017). In polystyrene 96-well ELISA plates (Kasvi™), 1 µg/well of rMLP15 in 100 μL of 0.1 M sodium carbonate buffer (pH 9.6) was coated and incubated for 16–18 h at 4 °C.…”