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

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.

Avaliação de biomarcadores para diagnóstico e monitoramento do tratamento da tuberculose pulmonar / Biomarker assessment for diagnosis and monitoring of treatment of pulmonary tuberculosis

INTRODUÇÃO: A tuberculose (TB), doença crônica infecciosa causada por Mycobacterium tuberculosis, é considerada um grave problema de saúde pública no país. A caracterização de antígenos protéicos e/ou lipídios que induzem uma resposta imunológica no hospedeiro, torna-se um importante passo para o desenvolvimento de novas ferramentas de diagnóstico e resposta terapêutica. Dentre os diferentes antígenos, em especial a mammalian cell entry protein 1A (proteína Mce1A), e os fosfolipídios da parede celular do bacilo como a cardiolipina (CL), os fosfatidilinositol (FI), fosfatidilcolina (FC), fosfatidiletanolamina (FE) e o sulfatide (SL), são, em sua maioria altamente imunogênicos, podendo então ser úteis no sorodiagnóstico. Portanto, o objetivo do estudo é avaliar a produção de anticorpos anti- Mce1A...

INTRODUCTION: Tuberculosis (TB), chronic infectious disease caused by Mycobacterium tuberculosis, is still a serious public health problem in the country. The characterization of protein and/or lipids antigens that induce an immune response in the host, it is an important step in the development of new diagnostic tools and monitoring TB treatment response. Among the different antigens, particularly mammalian cell entry protein 1A (Mce1A protein), and phospholipids from the cell wall of bacillus such as cardiolipin (CL), phosphatidylinositol (PI), phosphatidylcholine (PTC), phosphatidylethanolamine (PE) and sulfatide (SL), are highly immunogenic and can be used for improvement of the serodiagnosis. Therefore, the aim of the study is to evaluate the production of anti-Mce1A...

Avaliação IgG total anti-MCE1A como potencial biomarcado da tuberculose ativa e latente / Total IgG anti-MCE1A evaluation as potential biomarker of active and latent tuberculosis

Introdução: A tuberculose (TB), doença crônica causada por Mycobacterium tuberculosis (Mtb), é uma das doenças infecciosas que mais acomete a população brasileira, com 2.832 óbitos em 2010. Na infecção causada pelo Mtb, a interação das células T com os macrófagos (MØs) infectados é fundamental na imunidade protetora contra o bacilo. A Mce1A é uma proteína da parede celular do Mtb que confere grande capacidade de aderência, invasão e sobrevivência em MØs. Contudo, a caracterização da proteína Mce1A pode fornecer um biomarcador para diagnóstico e monitoramento do tratamento. Nosso objetivo é avaliar a produção de IgG total anti-Mce1A em pacientes com TB e seus comunicantes domiciliares (CDTB). Material e métodos: Indivíduos diagnosticados com TB pulmonar e CDTB foram submetidos a coleta de sangue por punção venosa. O diagnóstico da TB foi baseado em quadro clínico e/ou radiografia sugestiva e/ou baciloscopia do escarro positiva. Nos CDTB, a infecção foi determinada a partir da reação do teste tuberculínico (TT) e avaliação radiográfica. Soro dos três grupos foi coletado e armazenado a -20ºC, até a determinação dos níveis de IgG total anti-Mce1A por meio de um ensaio imunoenzimático (ELISA). Resultados: Entre janeiro de 2012 e outubro de 2013 foram identificados 50 pacientes com TB pulmonar e 50 CDTB, dentre os quais 23 foram TT positivo e 27 foram TT negativo. A média de idade da população estudada foi de 37,8 anos (DP ± 20,4). O gênero masculino prevaleceu entre os pacientes com TB (68%), porém nos CDTB, o gênero feminino prevaleu (62%)...

Introduction: Tuberculosis (TB), a chronic disease caused by Mycobacterium tuberculosis (Mtb), is an infectious disease that affects the Brazilian population, with 2,832 deaths in 2010. In Mtb infection, the interaction of T cells with infected macrophages (MØs) is critical in protective immunity against the bacillus. The Mce1A is a cell wall protein of Mtb which gives great adhesion characteristics, invasion and survival in MØs. However, the characterization of protein Mce1A can provide a biomarker for diagnosis and monitoring of treatment. Our goal is to evaluate the production of total IgG anti-Mce1A TB patients and their household contacts (HHC). Material and Methods: Individuals diagnosed with pulmonary TB and HHC were subjected to blood collection by venipuncture. The diagnosis of TB was based on clinical and/or suggestive radiography and/or positive sputum smear. In HHC, infection was determined from the reaction of the tuberculin skin test (TST) and radiographic evaluation. Three groups of serum was collected and stored at -20 ° C until determination of the levels of anti-Mce1A total IgG by an enzyme-linked immunosorbent assay (ELISA). Results: Between January 2012 and October 2013, 50 patients were identified with pulmonary TB and 50 HHC, of which 23 were positive TST and 27 were negative TST. The average age of the study population was 37.8 years (SD ± 20.4). The males predominated among patients with TB (68%), but the HHC, the prevailed females (62%)...