RESUMO
The rhesus macaque provides a unique model of acquired immunity against schistosomes, which afflict >200 million people worldwide. By monitoring bloodstream levels of parasite-gut-derived antigen, we show that from week 10 onwards an established infection with Schistosoma mansoni is cleared in an exponential manner, eliciting resistance to reinfection. Secondary challenge at week 42 demonstrates that protection is strong in all animals and complete in some. Antibody profiles suggest that antigens mediating protection are the released products of developing schistosomula. In culture they are killed by addition of rhesus plasma, collected from week 8 post-infection onwards, and even more efficiently with post-challenge plasma. Furthermore, cultured schistosomula lose chromatin activating marks at the transcription start site of genes related to worm development and show decreased expression of genes related to lysosomes and lytic vacuoles involved with autophagy. Overall, our results indicate that enhanced antibody responses against the challenge migrating larvae mediate the naturally acquired protective immunity and will inform the route to an effective vaccine.
Assuntos
Schistosoma mansoni/fisiologia , Esquistossomose mansoni/imunologia , Animais , Anticorpos Anti-Helmínticos/imunologia , Anticorpos Anti-Helmínticos/farmacologia , Antígenos de Helmintos/imunologia , Modelos Animais de Doenças , Epigênese Genética/efeitos dos fármacos , Feminino , Genes de Helmintos/genética , Granulócitos/imunologia , Histonas/metabolismo , Interações Hospedeiro-Parasita/imunologia , Larva/efeitos dos fármacos , Larva/genética , Larva/crescimento & desenvolvimento , Linfócitos/imunologia , Macaca mulatta/imunologia , Macaca mulatta/parasitologia , Masculino , Contagem de Ovos de Parasitas , Reinfecção/imunologia , Esquistossomose mansoni/parasitologiaRESUMO
The rhesus macaque provides a unique model of acquired immunity against schistosomes, which afflict >200 million people worldwide. By monitoring bloodstream levels of parasite-gut-derived antigen, we show that from week 10 onwards an established infection with Schistosoma mansoni is cleared in an exponential manner, eliciting resistance to reinfection. Secondary challenge at week 42 demonstrates that protection is strong in all animals and complete in some. Antibody profiles suggest that antigens mediating protection are the released products of developing schistosomula. In culture they are killed by addition of rhesus plasma, collected from week 8 post-infection onwards, and even more efficiently with post-challenge plasma. Furthermore, cultured schistosomula lose chromatin activating marks at the transcription start site of genes related to worm development and show decreased expression of genes related to lysosomes and lytic vacuoles involved with autophagy. Overall, our results indicate that enhanced antibody responses against the challenge migrating larvae mediate the naturally acquired protective immunity and will inform the route to an effective vaccine.
RESUMO
The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was funded in 2008 to conduct research that would support country schistosomiasis control programs. As schistosomiasis prevalence decreases in many places and elimination is increasingly within reach, a sensitive and specific test to detect infection with Schistosoma mansoni and Schistosoma haematobium has become a pressing need. After obtaining broad input, SCORE supported Leiden University Medical Center (LUMC) to modify the serum-based antigen assay for use with urine, simplify the assay, and improve its sensitivity. The urine assay eventually contributed to several of the larger SCORE studies. For example, in Zanzibar, we demonstrated that urine filtration, the standard parasite egg detection diagnostic test for S. haematobium, greatly underestimated prevalence in low-prevalence settings. In Burundi and Rwanda, the circulating anodic antigen (CAA) assay provided critical information about the limitations of the stool-based Kato-Katz parasite egg-detection assay for S. mansoni in low-prevalence settings. Other SCORE-supported CAA work demonstrated that frozen, banked urine specimens yielded similar results to fresh ones; pooling of specimens may be a useful, cost-effective approach for surveillance in some settings; and the assay can be performed in local laboratories equipped with adequate centrifuge capacity. These improvements in the assay continue to be of use to researchers around the world. However, additional work will be needed if widespread dissemination of the CAA assay is to occur, for example, by building capacity in places besides LUMC and commercialization of the assay. Here, we review the evolution of the CAA assay format during the SCORE period with emphasis on urine-based applications.
Assuntos
Antígenos de Helmintos/imunologia , Glicoproteínas/imunologia , Proteínas de Helminto/imunologia , Schistosoma/imunologia , Esquistossomose/diagnóstico , Animais , Biomarcadores , Burundi/epidemiologia , Criança , Testes Diagnósticos de Rotina , Fezes/parasitologia , Feminino , Humanos , Testes Imunológicos , Masculino , Modelos Animais , Papio/parasitologia , Contagem de Ovos de Parasitas , Prevalência , Ruanda/epidemiologia , Santa Lúcia/epidemiologia , Schistosoma/isolamento & purificação , Schistosoma haematobium/imunologia , Schistosoma haematobium/isolamento & purificação , Schistosoma japonicum/imunologia , Schistosoma japonicum/isolamento & purificação , Schistosoma mansoni/imunologia , Schistosoma mansoni/isolamento & purificação , Esquistossomose/epidemiologia , Sensibilidade e Especificidade , Tanzânia/epidemiologia , Urina/parasitologiaRESUMO
Saint Lucia at one time had levels of schistosomiasis prevalence and morbidity as high as many countries in Africa. However, as a result of control efforts and economic development, including more widespread access to sanitation and safe water, schistosomiasis on the island has practically disappeared. To evaluate the current status of schistosomiasis in Saint Lucia, we conducted a nationally representative school-based survey of 8-11-year-old children for prevalence of Schistosoma mansoni infections using circulating antigen and specific antibody detection methods. We also conducted a questionnaire about available water sources, sanitation, and contact with fresh water. The total population of 8-11-year-old children on Saint Lucia was 8,985; of these, 1,487 (16.5%) provided urine for antigen testing, 1,455 (16.2%) provided fingerstick blood for antibody testing, and 1,536 (17.1%) answered the questionnaire. Although a few children were initially low positives by antigen or antibody detection methods, none could be confirmed positive by follow-up testing. Most children reported access to clean water and sanitary facilities in or near their homes and 48% of the children reported contact with fresh water. Together, these data suggest that schistosomiasis transmission has been interrupted on Saint Lucia. Additional surveys of adults, snails, and a repeat survey among school-age children will be necessary to verify these findings. However, in the same way that research on Saint Lucia generated the data leading to use of mass drug administration for schistosomiasis control, the island may also provide the information needed for guidelines to verify interruption of schistosomiasis transmission.
Assuntos
Anticorpos Anti-Helmínticos/sangue , Esquistossomose/epidemiologia , Esquistossomose/transmissão , Criança , Feminino , Humanos , Masculino , Fatores de Risco , Santa Lúcia/epidemiologia , Saneamento , Esquistossomose/prevenção & controle , Testes Sorológicos , Inquéritos e QuestionáriosRESUMO
Techniques with high sensitivity and specificity are required for an accurate diagnosis in low-transmission settings, where the conventional parasitological methods are insensitive. We determined the accuracy of an up-converting phosphor-lateral flow circulating anodic antigen (UCP-LF CAA) assay in urine and serum for Schistosoma mansoni diagnosis in low-prevalence settings in Ceará, Brazil, before and after praziquantel treatment. Clinical samples of a total of 258 individuals were investigated by UCP-LF CAA, point-of-care-circulating cathodic antigen (POC-CCA), soluble worm antigen preparation (SWAP)-ELISA and Kato-Katz (KK); a selection of 128 stools by real-time PCR technique. Three and 6-weeks after treatment, samples were collected and evaluated by detection Schistosoma circulating antigens (CAA and CCA). The UCP-LF CAA assays detected 80 positives (31%) with urine and 82 positives (31.8%) with serum. The urine POC-CCA and serum SWAP-ELISA assays detected 30 (11.6%) and 107 (40.7%) positives, respectively. The Kato-Katz technique revealed only 4 positive stool samples (1.6%). Among the 128 individuals with complete data records, 19 cases were identified by PCR (14.8%); Sensitivities and specificities of the UCP-LF CAA assays, determined versus a combined reference standard based on CCA/KK/PCR positivity, ranged from 60-68% to 68-77%, respectively. In addition only for comparative purposes, sensitivities of the different assays were determined vs. a comparative reference based on CAA/KK/PCR positivity, showing the highest sensitivity for the urine CAA assay (80%), followed by the serum CAA (70.9%), SWAP-ELISA (43.6%), PCR (34.5%), POC-CCA (29.1%), whilst triplicate Kato-Katz thick smears had a very low sensitivity (3.6%). CAA concentrations were higher in serum than in urine and were significantly correlated. There was a significant decrease in urine and serum CAA levels 3 and 6-weeks after treatment. The UCP-LF CAA assays revealed 33 and 28 S. mansoni-infected patients at the 3- and 6-week post-treatment follow-up, respectively. The UCP-LF CAA assays show high sensitivity for the diagnosis of S. mansoni in low-endemicity settings. It detects a considerably higher number of infections than microscopy, POC-CCA or PCR. Also it shows to be very useful for evaluating cure rates after treatment. Hence, the UCP-LF CAA assay is a robust and promising diagnostic approach in low-transmission settings.
Assuntos
Antígenos de Helmintos/imunologia , Testes Imunológicos , Schistosoma mansoni/imunologia , Esquistossomose mansoni/diagnóstico , Esquistossomose mansoni/imunologia , Adolescente , Adulto , Idoso , Animais , Antígenos de Helmintos/sangue , Brasil/epidemiologia , Criança , Pré-Escolar , Humanos , Testes Imunológicos/métodos , Testes Imunológicos/normas , Estudos Longitudinais , Pessoa de Meia-Idade , Vigilância da População , Prevalência , Reprodutibilidade dos Testes , Schistosoma mansoni/genética , Esquistossomose mansoni/epidemiologia , Esquistossomose mansoni/parasitologia , Sensibilidade e Especificidade , Adulto JovemRESUMO
Leprosy remains persistently endemic in several low- or middle income countries. Transmission is still ongoing as indicated by the unabated rate of leprosy new case detection, illustrating the insufficiency of current prevention methods. Therefore, low-complexity tools suitable for large scale screening efforts to specifically detect M. leprae infection and diagnose disease are required. Previously, we showed that combined detection of cellular and humoral markers, using field-friendly lateral flow assays (LFAs), increased diagnostic potential for detecting leprosy in Bangladesh compared to antibody serology alone. In the current study we assessed the diagnostic performance of similar LFAs in three other geographical settings in Asia, Africa and South-America with different leprosy endemicity. Levels of anti-PGL-I IgM antibody (humoral immunity), IP-10, CCL4 and CRP (cellular immunity) were measured in blood collected from leprosy patients, household contacts and healthy controls from each area. Combined detection of these biomarkers significantly improved the diagnostic potential, particularly for paucibacillary leprosy in all three regions, in line with data obtained in Bangladesh. These data hold promise for the use of low-complexity, multibiomarker LFAs as universal tools for more accurate detection of M. leprae infection and different phenotypes of clinical leprosy.
Assuntos
Anticorpos Antibacterianos/sangue , Antígenos de Bactérias/imunologia , Testes Imunológicos/métodos , Hanseníase/diagnóstico , Mycobacterium leprae/imunologia , Adolescente , Adulto , Idoso , Brasil , Proteína C-Reativa/metabolismo , Estudos de Casos e Controles , Quimiocina CCL4/sangue , Quimiocina CXCL10/sangue , Criança , China , Doenças Endêmicas , Etiópia , Feminino , Humanos , Imunidade Celular , Imunidade Humoral , Hanseníase/sangue , Hanseníase/imunologia , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade , Fatores Socioeconômicos , Adulto JovemRESUMO
Early detection of leprosy is key to reduce the ongoing transmission. Antibodies directed against M. leprae PGL-I represent a useful biomarker for detecting multibacillary (MB) patients. Since efficient leprosy diagnosis requires field-friendly test conditions, we evaluated two rapid lateral flow assays (LFA) for detection of Mycobacterium leprae-specific antibodies: the visual immunogold OnSite Leprosy Ab Rapid test [Gold-LFA] and the quantitative, luminescent up-converting phosphor anti-PGL-I test [UCP-LFA]. Test performance was assessed in independent cohorts originating from three endemic areas. In the Philippine cohort comprising patients with high bacillary indices (BI; average:4,9), 94%(n = 161) of MB patients were identified by UCP-LFA and 78%(n = 133) by Gold-LFA. In the Bangladeshi cohort, including mainly MB patients with low BI (average:1), 41%(n = 14) and 44%(n = 15) were detected by UCP-LFA and Gold-LFA, respectively. In the third cohort of schoolchildren from a leprosy hyperendemic region in Brazil, both tests detected 28%(n = 17) seropositivity. Both rapid tests corresponded well with BI(p < 0.0001), with a fairly higher sensitivity obtained with the UCP-LFA assay. However, due to the spectral character of leprosy, additional, cellular biomarkers are required to detect patients with low BIs. Therefore, the UCP-LFA platform, which allows multiplexing with differential biomarkers, offers more cutting-edge potential for diagnosis across the whole leprosy spectrum.