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PAGES: DOI: 10.1590/0074-02760170467 Full paper
Utility of immunoglobulin isotypes against LID-1 and NDO-LID for, particularly IgG1, confirming the diagnosis of multibacillary leprosy

Pedro Henrique Ferreira Marçal1, Lúcia Alves de Oliveira Fraga2, Ana Márcia Menezes de Mattos1, Laura Menegati1, Angélica da Conceição Oliveira Coelho3, Roberta Olmo Pinheiro4, Euzenir Nunes Sarno4, Malcolm S Duthie5, Henrique Couto Teixeira1,+

1Universidade Federal de Juiz de Fora, Instituto de Ciências Biológicas, Departamento de Parasitologia, Microbiologia e Imunologia, Juiz de Fora, MG, Brasil
2Universidade Federal de Juiz de Fora, Instituto de Ciências da Vida, Governador Valadares, MG, Brasil
3Universidade Federal de Juiz de Fora, Faculdade de Enfermagem, Departamento de Enfermagem Básica, Juiz de Fora, MG, Brasil
4Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório de Hanseníase, Rio de Janeiro, RJ, Brasil
5Infectious Disease Research Institute, Seattle, WA, USA


BACKGROUND Leprosy remains a health problem in many countries, with difficulties in diagnosis resulting in delayed treatment and more severe disabilities. Antibodies against several Mycobacterium leprae antigens have, however, shown value as diagnostic and/or prognostic markers.

OBJECTIVES The objective of this study was to evaluate serum immunoglobulin (Ig) IgM and IgG subclass reactivity against three M. leprae specific antigens: NDO-HSA, a conjugate formed by natural octyl disaccharide bound to human serum albumin; LID-1, the fusion protein product of the ml0405 and ml2331 genes; and NDO-LID, a combination of LID-1 and NDO.

METHODS Sera from healthy controls, paucibacillary (PB) and multibacillary (MB) leprosy patients, and their respective household contacts, were evaluated for the presence of antigen-specific IgM, IgG, and IgG subclass antibodies by enzyme-linked immunosorbent assay (ELISA). The sensitivity and specificity of each ELISA were evaluated by receiver operating characteristic (ROC) curve analysis.

FINDINGS Our data confirm that serum IgM antibodies against NDO-HSA and IgG antibodies against LID-1, as well as IgG/M antibodies against NDO-LID, are markedly increased in MB patients. For the first time, our data reveal a selective increase in IgG1 and IgG3 antibodies against LID-1 and NDO-LID in MB patients, demonstrating that these antibody isotypes are suitable for differentiation between MB and PB patients. ROC curve analysis indicates an improved capacity for diagnosing MB leprosy patients using the detection of IgG antibodies, particularly the IgG1 isotype, specific to LID-1 and NDO-LID over the performance levels attained with NDO-HSA.

CONCLUSIONS Our findings indicate that serological tests based on the detection of antigen-specific IgG1 antibodies are a useful tool to differentiate MB from PB patients, and indicate the enhanced performance of the LID-1 and NDO-LID antigens in the serodiagnosis of leprosy.

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Financial support: CNPq (31036/2015-5), FAPEMIG (RED-00313-16,
APQ-02504-17). PHFM received a doctoral fellowship from UFJF.
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Received 27 October 2017
Accepted 18 January 2018