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PAGES: 844-849 DOI: 10.1590/0074-02760160549 Full paper
ELISA-based assay of immunoglobulin G antibodies against mammalian cell entry 1A (Mce1A) protein: a novel diagnostic approach for leprosy

Filipe R Lima1,2,+, Iukary Takenami1, Maurílio AL Cavalcanti3, Lee W Riley4, Sérgio Arruda1,2

1Fundação Oswaldo Cruz-Fiocruz, Centro de Pesquisas Gonçalo Moniz, Laboratório Avançado de Saúde Pública, Salvador, BA, Brasil
2Escola Bahiana de Medicina e Saúde Pública, Salvador, BA, Brasil
3Hospital Couto Maia, Secretaria de Saúde do Estado da Bahia, Salvador, BA, Brasil
4University of California, School of Public Health, Division of Infectious Diseases and Vaccinology, Berkeley, CA, USA


BACKGROUND Leprosy 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.

OBJECTIVE The 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.

METHODS A 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.

RESULTS The 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 = 0.006) groups compared to in EC individuals. The greatest differences were obsrved 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.

CONCLUSION This novel diagnostic approach presents an easy, non-invasive, and inexpensive method for leprosy screening, which may be applicable in endemic areas.

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Financial support: CNPq
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Received 22 December 2016
Accepted 11 July 2017