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 = 0.0006)
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.
CONCLUSION This novel diagnostic approach presents an easy, non-invasive, and inexpensive method for leprosy screening,
which may be applicable in endemic areas.
