02731nas a2200277   4500000000100000008004100001653001400042653001000056653001200066653001500078653001000093653001400103653001100117653001500128100001200143700001500155700001800170700001200188700001300200245014300213856007300356300001200429490000800441520199000449022001402439       2017                            d10aScreening10aMce1A10aleprosy10aImmunology10aELISA10adiagnosis10aBrazil10aAntibodies1 aLima FR1 aTakenami I1 aCavalcanti MA1 aRiley L1 aArruda S00aELISA-based assay of immunoglobulin G antibodies against mammalian cell entry 1A (Mce1A) protein: a novel diagnostic approach for leprosy.  uhttp://www.scielo.br/pdf/mioc/v112n12/0074-0276-mioc-112-12-0844.pdf  a844-8490 v1123 a<p><strong>BACKGROUND: </strong>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.</p>

<p><strong>OBJECTIVE: </strong>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.</p>

<p><strong>METHODS: </strong>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.</p>

<p><strong>RESULTS: </strong>The median anti-Mce1A IgA was significantly higher in multibacillary (MB) and paucibacillary (PB) cases than in EC (p &lt; 0.0001). A similar trend was observed in IgM levels, which were significantly higher in both MB (p &lt; 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 &lt; 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.</p>

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