ABSTRACT
Apical membrane antigen-1 (AMA1) is a conserved malarial vaccine candidate essential for the formation of tight junctions with the rhoptry neck protein (RON) complex, enabling Plasmodium parasites to invade human erythrocytes, hepatocytes, and mosquito salivary glands. Despite its critical role, extensive surface polymorphisms in AMA1 have led to strain-specific protection, limiting the success of AMA1-based interventions beyond initial clinical trials. Here, we identify an i-body, a humanised single-domain antibody-like molecule that recognises a conserved pan-species conformational epitope in AMA1 with low nanomolar affinity and inhibits the binding of the RON2 ligand to AMA1. Structural characterisation indicates that the WD34 i-body epitope spans the centre of the conserved hydrophobic cleft in AMA1, where interacting residues are highly conserved among all Plasmodium species. Furthermore, we show that WD34 inhibits merozoite invasion of erythrocytes by multiple Plasmodium species and hepatocyte invasion by P. falciparum sporozoites. Despite a short half-life in mouse serum, we demonstrate that WD34 transiently suppressed P. berghei infections in female BALB/c mice. Our work describes the first pan-species AMA1 biologic with inhibitory activity against multiple life-cycle stages of Plasmodium. With improved pharmacokinetic characteristics, WD34 could be a potential immunotherapy against multiple species of Plasmodium.
Subject(s)
Antigens, Protozoan , Erythrocytes , Liver , Membrane Proteins , Mice, Inbred BALB C , Protozoan Proteins , Animals , Protozoan Proteins/immunology , Protozoan Proteins/metabolism , Protozoan Proteins/genetics , Antigens, Protozoan/immunology , Antigens, Protozoan/metabolism , Female , Membrane Proteins/immunology , Membrane Proteins/metabolism , Mice , Humans , Erythrocytes/parasitology , Erythrocytes/immunology , Liver/parasitology , Liver/immunology , Liver/metabolism , Malaria Vaccines/immunology , Malaria/immunology , Malaria/parasitology , Malaria/prevention & control , Cross Reactions/immunology , Plasmodium falciparum/immunology , Plasmodium berghei/immunology , Epitopes/immunology , Hepatocytes/parasitology , Hepatocytes/immunology , Hepatocytes/metabolism , Plasmodium/immunology , Merozoites/immunology , Merozoites/metabolismABSTRACT
INTRODUCTION: Malaria continues to remain a major global health problem with nearly a quarter of a billion clinical cases and more than 600,000 deaths in 2022. There has been significant progress toward vaccine development, however, poor efficacy of approved vaccines requiring multiple immunizing doses emphasizes the need for continued efforts toward improved vaccines. Progress to date, nonetheless, has provided impetus for malaria elimination. AREAS COVERED: In this review we will focus on diverse immune mechanisms targeting gametocytes in the human host and gametocyte-mediated malaria transmission via the mosquito vector. EXPERT OPINION: To march toward the goal of malaria elimination it will be critical to target the process of malaria transmission by mosquitoes, mediated exclusively by the sexual stages, i.e. male, and female gametocytes, ingested from infected vertebrate host. Studies over several decades have established antigens in the parasite sexual stages developing in the mosquito midgut as attractive targets for the development of transmission blocking vaccines (TBVs). Immune clearance of gametocytes in the vertebrate host can synergize with TBVs and directly aid in maintaining effective transmission reducing immune potential.
Subject(s)
Malaria Vaccines , Malaria , Mosquito Vectors , Vaccine Development , Humans , Malaria Vaccines/immunology , Malaria Vaccines/administration & dosage , Animals , Malaria/prevention & control , Malaria/transmission , Malaria/immunology , Malaria/parasitology , Mosquito Vectors/parasitology , Mosquito Vectors/immunology , Plasmodium/immunologyABSTRACT
The Plasmodium parasites that cause malaria undergo asymptomatic development in the parenchymal cells of the liver, the hepatocytes, prior to infecting erythrocytes and causing clinical disease. Traditionally, hepatocytes have been perceived as passive bystanders that allow hepatotropic pathogens such as Plasmodium to develop relatively unchallenged. However, now there is emerging evidence suggesting that hepatocytes can mount robust cell-autonomous immune responses that target Plasmodium, limiting its progression to the blood and reducing the incidence and severity of clinical malaria. Here we discuss our current understanding of hepatocyte cell-intrinsic immune responses that target Plasmodium and how these pathways impact malaria.
Subject(s)
Hepatocytes , Malaria , Plasmodium , Plasmodium/immunology , Plasmodium/physiology , Humans , Malaria/immunology , Malaria/parasitology , Hepatocytes/parasitology , Hepatocytes/immunology , AnimalsABSTRACT
OBJECTIVE: Analyze the molecular mimicry between Plasmodium spp. and autoantigens associated with GBS, identifying possible antigenic epitopes. METHODS: PSI-Blast, Praline, Emboss, Protein Data Bank, Swiss Model Server, AlphaFold 2, Ellipro and PyMol 2.3 were used to search for homologies, perform alignments, obtain protein structures, and predict epitopes. RESULTS: 17 autoantigens and seven immunological targets of the peripheral nervous system were included, identifying 72 possible epitopes associated with GBS. From the proteome of Plasmodium spp. (298 proteins), only two showed similarities close to 30% with TRIM21 and BACE1, generating seven possible epitopes. CONCLUSION: No significant homologies were observed between the proteome of GBS and Plasmodium spp. The exploration of other mechanisms such as immune-mediated capillary damage, Epitope Spreading or Bystander Activation is suggested to explain the mentioned association. These findings underscore the need to clarify the etiology of autoimmune diseases and the role of pathogens. The need for experimental studies to validate these results is emphasized.
OBJETIVO: Analizar el mimetismo molecular entre Plasmodium spp. y autoantígenos asociados al SGB, identificando posibles epítopos antigénicos. MÉTODOS: Se emplearon PSI-Blast, Praline, Emboss, Protein Data Bank, Swiss Model Server, AlphaFold 2, Ellipro y PyMol 2.3 para buscar homologías, realizar alineamientos, obtener estructuras proteicas y predecir epítopos. RESULTADOS: Se incluyeron 17 autoantígenos y siete objetivos inmunológicos del sistema nervioso periférico, identificándose 72 posibles epítopos asociados al SGB. Del proteoma de Plasmodium spp. (298 proteínas), solo dos mostraron similitud cercana al 30% con TRIM21 y BACE1, generando siete posibles epítopos. CONCLUSIÓN: No se observaron homologías significativas entre el proteoma de SGB y Plasmodium spp. Se sugiere la exploración de otros mecanismos como el daño capilar inmunomediado, Epitope Spreading o Bystander Activation para explicar la asociación mencionada. Estos hallazgos subrayan la necesidad de aclarar la etiología de las enfermedades autoinmunes y el papel de los patógenos. Se enfatiza la necesidad de estudios experimentales para validar estos resultados.
Subject(s)
Guillain-Barre Syndrome , Molecular Mimicry , Molecular Mimicry/immunology , Guillain-Barre Syndrome/immunology , Humans , Plasmodium/immunology , Autoantigens/immunology , Epitopes/immunologyABSTRACT
Development of Plasmodium-specific humoral immunity is critically dependent on CD4 Th cell responses and germinal center (GC) reactions during blood-stage Plasmodium infection. IL-21, a cytokine primarily produced by CD4 T cells, is an essential regulator of affinity maturation, isotype class-switching, B cell differentiation, and maintenance of GC reactions in response to many infection and immunization models. In models of experimental malaria, mice deficient in IL-21 or its receptor IL-21R fail to develop memory B cell populations and are not protected against secondary infection. However, whether sustained IL-21 signaling in ongoing GCs is required for maintaining GC magnitude, organization, and output is unclear. In this study, we report that CD4+ Th cells maintain IL-21 expression after resolution of primary Plasmodium yoelii infection. We generated an inducible knockout mouse model that enabled cell type-specific and timed deletion of IL-21 in peripheral, mature CD4 T cells. We found that persistence of IL-21 signaling in active GCs had no impact on the magnitude of GC reactions or their capacity to produce memory B cell populations. However, the memory B cells generated in the absence of IL-21 exhibited reduced recall function upon challenge. Our data support that IL-21 prevents premature cellular dissolution within the GC and promotes stringency of selective pressures during B cell fate determination required to produce high-quality Plasmodium-specific memory B cells. These data are additionally consistent with a temporal requirement for IL-21 in fine-tuning humoral immune memory responses during experimental malaria.
Subject(s)
CD4-Positive T-Lymphocytes , Interleukins , Malaria , Plasmodium , Animals , Mice , B-Lymphocytes , CD4-Positive T-Lymphocytes/metabolism , Germinal Center/immunology , Germinal Center/metabolism , Malaria/immunology , Memory B Cells/immunology , Mice, Inbred C57BL , Plasmodium/immunologyABSTRACT
Naturally acquired immunity to the different types of malaria in humans occurs in areas of endemic transmission and results in asymptomatic infection of peripheral blood. The current study examined the possibility of naturally acquired immunity in Bornean orangutans, Pongo pygmaeus, exposed to endemic Plasmodium pitheci malaria. A total of 2140 peripheral blood samples were collected between January 2017 and December 2022 from a cohort of 135 orangutans housed at a natural forested Rescue and Rehabilitation Centre in West Kalimantan, Indonesia. Each individual was observed for an average of 4.3 years during the study period. Blood samples were examined by microscopy and polymerase chain reaction for the presence of plasmodial parasites. Infection rates and parasitaemia levels were measured among age groups and all 20 documented clinical malaria cases were reviewed to estimate the incidence of illness and risk ratios among age groups. A case group of all 17 individuals that had experienced clinical malaria and a control group of 34 individuals having an event of >2000 parasites µL−1 blood but with no outward or clinical sign of illness were studied. Immature orangutans had higher-grade and more frequent parasitaemia events, but mature individuals were more likely to suffer from clinical malaria than juveniles. The case orangutans having patent clinical malaria were 256 times more likely to have had no parasitaemia event in the prior year relative to asymptomatic control orangutans. The findings are consistent with rapidly acquired immunity to P. pitheci illness among orangutans that wanes without re-exposure to the pathogen.
Subject(s)
Ape Diseases , Malaria , Plasmodium , Pongo pygmaeus , Animals , Malaria/epidemiology , Malaria/immunology , Malaria/parasitology , Plasmodium/immunology , Indonesia/epidemiology , Pongo pygmaeus/parasitology , Male , Female , Ape Diseases/parasitology , Ape Diseases/epidemiology , Parasitemia/veterinary , Parasitemia/epidemiology , Parasitemia/parasitology , IncidenceABSTRACT
Resumen La malaria asociada al embarazo es un evento poco estudiado en América Latina. Los abundantes trabajos sobre el problema en África llevan a pensar que esta infección genera una modulación de la respuesta inmune y alteraciones en el ambiente placentario, eventos cruciales para el adecuado desarrollo del feto y el neonato. La inmunidad contra Plasmodium spp es compleja porque involucra diversos factores que amplían las posibilidades de desenlaces, los que finalmente conducen a los diferentes fenotipos clínicos de la enfermedad. Uno de los desenlaces inmunológicos en infecciones por Plasmodium spp es la modulación de la respuesta inmune hacía un perfil regulador. Esta regulación inducida por la infección malárica resulta ventajosa para la persistencia del parásito en el hospedero, y adicionalmente, podría generar eventos adversos en la respuesta inmune general de los individuos infectados. El objetivo de esta revisión es abordar los mecanismos con los cuales Plasmodium spp modula la respuesta inmune del hospedero y exponer las consecuencias de las infecciones maláricas en el contexto madre-neonato.
Pregnancy-associated malaria is an understudied event in Latin America. Most works about malaria in pregnancy have been conducted in Africa. These studies indicate that the infection generates immune response modulation and alterations in the placental environment, key factors for the proper development of the fetus and neonate. Immunity against Plasmodium spp is complex since involves several factors that increase the possible infection outcomes. One of these immunological outcomes is the immune response modulation towards a regulatory profile, which is advantageous for the persistence of the parasite in the host; additionally, it could generate adverse events in the general immune response of infected individuals. The objective of this review is to address the Plasmodium spp mechanisms of modulation in the host immune response and expose the consequences of malarial infections in the mother-neonate context.
Subject(s)
Humans , Female , Pregnancy , Infant, Newborn , Plasmodium/immunology , Pregnancy Complications, Parasitic/immunology , Immunomodulation/physiology , Malaria/immunology , Placenta/immunology , Placenta/parasitology , Plasmodium/physiology , Host-Parasite Interactions/immunology , Immune System/immunologyABSTRACT
Abstract The aim of this study was to identify Plasmodium spp. in blood samples from nonhuman primates (NHPs) in the state of Maranhão, using classical and alternative techniques for examination of human malaria. A total of 161 blood samples from NHPs were analyzed: 141 from captive animals at a Wildlife Screening Center (CETAS) and 20 from free-living animals in a private reserve. The techniques used were microscopy, rapid diagnostic test (RDT), Indirect fluorescent antibody test (IFAT) and molecular techniques (semi-nested PCR, quantitative real-time PCR and LAMP). Two serological methods (dot-ELISA and indirect ELISA) were also standardized with rhoptry protein-soluble antigen of P. falciparum and P. berghei. Trophozoite forms of Plasmodium sp. were identified on slides from five different animals. No samples were positive through RDT and LAMP. Four samples were seropositive for P. malariae through IFAT. The samples showed low reactivity to ELISA. Plasmodium sp. was detected in 34.16% (55/161) of the samples using qPCR based on the 18S rRNA gene. After sequencing, two samples showed 100% identityl to P. malariae, one showed 97% identity to Plasmodium sp. ZOOBH and one showed 99% identity to P. falciparum . PCR was shown to be the most sensitive technique for diagnosing Plasmodium in NHP samples.
Resumo Neste estudo objetivamos identificar Plasmodium spp. em amostras sangue de primatas não humanos (PNH) do estado do Maranhão, utilizando técnicas clássicas e alternativas para o exame da malária humana. Foram analisadas 161 amostras de sangue de PNH, sendo 141 de CETAS (cativeiro) e 20 de reserva particular (vida livre), utilizando microscopia, teste de diagnóstico rápido (RDT), imunofluorescência indireta (IFI) e técnicas moleculares (semi-nested PCR, PCR em tempo real quantitativo e LAMP). Dois métodos sorológicos (dot-ELISA e ELISA indireto) também foram padronizados com antígenos solúveis de roptrias de P. falciparum e P. berghei. Formas trofozoíticas de Plasmodium sp. foram identificadas em lâminas de cinco animais diferentes. Nenhuma amostra foi positiva em TDR e LAMP. Quatro amostras foram soropositivas para P. malariae na IFI. Os soros de PNH mostraram baixa reatividade pelo ELISA indireto. Plasmodium sp. foi detectado em 34,16% (55/161) das amostras utilizando a qPCR baseada no gene 18S rRNA. No sequenciamento, duas amostras mostraram identidade com P. malariae (100%), uma com Plasmodium sp. ZOOBH (97%) e uma com P. falciparum (99%). A PCR mostrou ser a técnica mais sensível para diagnósticos de Plasmodium em amostras de PNH.
Subject(s)
Animals , Male , Plasmodium/genetics , Plasmodium/immunology , Platyrrhini/parasitology , Malaria/veterinary , Antibodies, Protozoan/blood , RNA, Ribosomal, 18S/blood , DNA, Protozoan/blood , Fluorescent Antibody Technique, Indirect , Real-Time Polymerase Chain Reaction , Malaria/diagnosis , Malaria/parasitologyABSTRACT
INTRODUÇÃO: A malária é uma das doenças infecciosas de maior incidência e que mais leva a óbito no mundo. Os medicamentos disponíveis são capazes de combater o parasita no ciclo intraeritrocítico, no entanto há cepas resistentes ao tratamento com quinolinas e temisininas. Além disso, os medicamentos em uso clínico não eliminam as formas sexuadas do parasita, responsáveis pela transmissão, nem os hipnozoítos, fase hepática latente causadora das recidivas da doença. Em virtude disso, é necessário identificar novos fármacos antimaláricos. Dentre as classes de moléculas com potencial terapêutico antimalárico, os complexos com metais de transição se destacam como possíveis candidatos...
Subject(s)
Humans , Malaria/diagnosis , Malaria/epidemiology , Malaria/prevention & control , Malaria/transmission , Plasmodium/growth & development , Plasmodium/immunology , Plasmodium/microbiology , Plasmodium/parasitology , Plasmodium/pathogenicityABSTRACT
No disponible
Subject(s)
Plasmodium/immunology , Plasmodium/isolation & purification , Antibiotic Prophylaxis/methods , Antibiotic Prophylaxis , Military Medicine/organization & administration , Military Medicine/standards , World Health Organization/organization & administration , Health Classifications/methodsABSTRACT
Asymptomatic Plasmodium infection carriers represent a major threat to malaria control worldwide as they are silent natural reservoirs and do not seek medical care. There are no standard criteria for asymptomaticPlasmodium infection; therefore, its diagnosis relies on the presence of the parasite during a specific period of symptomless infection. The antiparasitic immune response can result in reducedPlasmodium sp. load with control of disease manifestations, which leads to asymptomatic infection. Both the innate and adaptive immune responses seem to play major roles in asymptomatic Plasmodiuminfection; T regulatory cell activity (through the production of interleukin-10 and transforming growth factor-β) and B-cells (with a broad antibody response) both play prominent roles. Furthermore, molecules involved in the haem detoxification pathway (such as haptoglobin and haeme oxygenase-1) and iron metabolism (ferritin and activated c-Jun N-terminal kinase) have emerged in recent years as potential biomarkers and thus are helping to unravel the immune response underlying asymptomatic Plasmodium infection. The acquisition of large data sets and the use of robust statistical tools, including network analysis, associated with well-designed malaria studies will likely help elucidate the immune mechanisms responsible for asymptomatic infection.
Subject(s)
Humans , Asymptomatic Infections , Antigens, Protozoan/immunology , Carrier State/immunology , Malaria, Falciparum/immunology , Malaria, Vivax/immunology , Plasmodium/immunology , Adaptive Immunity/physiology , Biomarkers , Carrier State/parasitology , Disease Reservoirs/parasitology , Ferritins/immunology , Haptoglobins/immunology , Heme Oxygenase-1/immunology , Immunity, Innate/physiology , /immunology , JNK Mitogen-Activated Protein Kinases/immunology , Malaria, Falciparum/prevention & control , Malaria, Vivax/prevention & control , Parasitemia/immunology , Plasmodium/isolation & purification , Transforming Growth Factor beta/immunologyABSTRACT
The states that make up the Legal Amazon Region, which include the state of Maranhão, account for 99% of registered cases of human malaria in Brazil. It is also believed that transmission of malaria from nonhuman primates (NHP) to humans occurs in this region, because of current reports of seroepidemiological results from samples from humans and NHP coexisting in the same areas. This study aimed to make morphological, serological and molecular diagnoses of Plasmodium spp. in neotropical primates on the island of São Luís, state of Maranhão, Brazil. The diagnostic techniques used were optical microscopy, the polymerase chain reaction (PCR) and the indirect immunofluorescence assay (IFA). From June 2009 to April 2010, 70 NHP were sampled: 50 at the Wild Animal Screening Center (CETAS), located in the municipality of São Luís and 20 free-living individuals that were caught in a private reserve located in the municipality of São Jose de Ribamar, state of Maranhão. Under an optical microscope, 140 slides (two from each animal) were evaluated and five animals (7.1%) were found to be positive. IFA did not detect anti-Plasmodium spp. From PCR on the 70 animals sampled, amplified Plasmodium spp. products were observed in 13 samples, of which eight (61.5%) were from free-living animals and five (38.5%) were from animals at CETAS.
Os Estados que compõem a Amazônia Legal, entre eles o Estado do Maranhão, respondem a 99% dos casos registrados de malária humana no Brasil. Também se acredita que nessa região ocorra a transmissão de malária de primatas não humanos (PNH) para humanos, devido a relatos atuais de resultados soroepidemiológicos de amostras de humanos e PNH que coexistem nas mesmas áreas. O presente estudo objetivou realizar o diagnóstico morfológico, sorológico e molecular de Plasmodium spp. em primatas neotropicais na Ilha de São Luís, Estado do Maranhão, Brasil. Foram utilizadas como técnicas de diagnóstico: a microscopia de luz, a reação em cadeia pela polimerase (PCR) e a imunofluorescência indireta (RIFI). No período de junho de 2009 a abril de 2010, foram amostrados 70 PNH, sendo 50 provenientes do Centro de Triagem de Animais Silvestres (CETAS), localizado no município de São Luís, e 20 de vida livre, capturados em reserva particular localizada no município de São José de Ribamar, Estado do Maranhão. Foram avaliadas pela microscopia de luz 140 lâminas (duas de cada animal), das quais cinco animais (7,1%) foram positivos. Pela RIFI não se detectou anticorpos anti-Plasmodium spp. Pela PCR, dos 70 animais amostrados, foi possível observar produtos amplificados para Plasmodium spp. em 13 amostras, das quais oito (61,5%) eram de animais de vida livre e cinco (38,5%) de CETAS.
Subject(s)
Animals , Primates , Malaria/veterinary , Plasmodium/immunology , Brazil , Antibodies, Protozoan/blood , Fluorescent Antibody Technique, Indirect , Malaria/diagnosis , Malaria/bloodABSTRACT
O peptídeo sinal é um motivo encontrado, geralmente, na extremidade N-terminal deproteínas e a sua presença determina a entrada na via clássica de transporte intracelular,após a translocação da proteína para o lúmen do retículo endoplasmático. Portanto, apresença ou ausência do peptídeo sinal influencia a função biológica de uma proteína ao serum fator determinante da sua localização subcelular. Como a conservação de função entreproteínas ortólogas é esperada, foi hipotetizado que a localização subcelular e,consequentemente, a presença do peptídeo sinal deveriam, também, se apresentarconservadas. Partindo desta premissa, as predições de peptídeo sinal em proteínasortólogas de cinco espécies de Plasmodium foram analisadas.Predições de peptídeo sinal (SignalP) e informações de ortologia (OrthoMCL-DB)para proteínas de cinco espécies do gênero Plasmodium (Plasmodium falciparum,Plasmodium vivax, Plasmodium knowlesi, Plasmodium berguei e Plasmodium yoelii) foramcombinadas em uma estratégia inovadora, visando a identificação de grupos de proteínasortólogas que apresentam predições de peptídeo sinal divergentes (grupos Mistos).
Asproteínas pertencentes a estes grupos foram submetidas a uma análise comparativabaseada na inspeção visual de alinhamentos múltiplos e de modelos gênicos e regiõesgenômicas flanqueadoras da extremidade N-terminal. Novos modelos gênicos foramsugeridos para aquelas proteínas que apresentavam prováveis erros de anotação desequência, especialmente na região N-terminal. Alguns dos novos modelos gênicos foramvalidados por RT-PCR. Os resultados da inspeção visual foram usados para treinar umaMáquina de Suporte de Vetores (Support Vector Machine) com o objetivo de classificargrupos Mistos em: (1) Com erros de anotação ou (2) Sem erros de anotação. O SVM foiaplicado para classificar os grupos Mistos de cinco bancos de dados, montados a partir devinte e duas espécies.Os grupos contendo proteínas com predições de peptídeo sinal divergentesapresentaram uma alta taxa de erros de anotação. Um total de 478 proteínas dePlasmodium foram reanotadas sendo que a maioria apresentou inversões das suaspredições de peptídeo sinal originais, representando um impacto significativo no conjuntofinal de proteínas destinadas à via clássica de transporte intracelular, principalmente paraPlasmodium vivax e Plasmodium yoelii. O classificador baseado nos dados da inspeçãovisual se mostrou bastante flexível e robusto, apresentando uma performance boa econsistente mesmo frente a cenários variados de agrupamento de espécies.A metodologia proposta introduz uma abordagem simples, porém promissora, para arealização de tarefas de curadoria e controle de qualidade dos dados de anotação desequências proteicas em uma escala genômica. Os resultados do classificador definem a base para seu desenvolvimento em uma ferramenta computacional e os resultados dasreanotações em Plasmodium impactarão a busca por novos alvos vacinais equimioterápicos.
Subject(s)
Male , Female , Humans , Malaria/genetics , Peptides/immunology , Plasmodium/immunologyABSTRACT
O peptídeo sinal é um motivo encontrado, geralmente, na extremidade N-terminal deproteínas e a sua presença determina a entrada na via clássica de transporte intracelular,após a translocação da proteína para o lúmen do retículo endoplasmático. Portanto, apresença ou ausência do peptídeo sinal influencia a função biológica de uma proteína ao serum fator determinante da sua localização subcelular. Como a conservação de função entreproteínas ortólogas é esperada, foi hipotetizado que a localização subcelular e,consequentemente, a presença do peptídeo sinal deveriam, também, se apresentarconservadas. Partindo desta premissa, as predições de peptídeo sinal em proteínasortólogas de cinco espécies de Plasmodium foram analisadas.Predições de peptídeo sinal (SignalP) e informações de ortologia (OrthoMCL-DB)para proteínas de cinco espécies do gênero Plasmodium (Plasmodium falciparum,Plasmodium vivax, Plasmodium knowlesi, Plasmodium berguei e Plasmodium yoelii) foramcombinadas em uma estratégia inovadora, visando a identificação de grupos de proteínasortólogas que apresentam predições de peptídeo sinal divergentes (grupos Mistos).
Asproteínas pertencentes a estes grupos foram submetidas a uma análise comparativabaseada na inspeção visual de alinhamentos múltiplos e de modelos gênicos e regiõesgenômicas flanqueadoras da extremidade N-terminal. Novos modelos gênicos foramsugeridos para aquelas proteínas que apresentavam prováveis erros de anotação desequência, especialmente na região N-terminal. Alguns dos novos modelos gênicos foramvalidados por RT-PCR. Os resultados da inspeção visual foram usados para treinar umaMáquina de Suporte de Vetores (Support Vector Machine) com o objetivo de classificargrupos Mistos em: (1) Com erros de anotação ou (2) Sem erros de anotação. O SVM foiaplicado para classificar os grupos Mistos de cinco bancos de dados, montados a partir devinte e duas espécies.Os grupos contendo proteínas com predições de peptídeo sinal divergentesapresentaram uma alta taxa de erros de anotação. Um total de 478 proteínas dePlasmodium foram reanotadas sendo que a maioria apresentou inversões das suaspredições de peptídeo sinal originais, representando um impacto significativo no conjuntofinal de proteínas destinadas à via clássica de transporte intracelular, principalmente paraPlasmodium vivax e Plasmodium yoelii. O classificador baseado nos dados da inspeçãovisual se mostrou bastante flexível e robusto, apresentando uma performance boa econsistente mesmo frente a cenários variados de agrupamento de espécies.A metodologia proposta introduz uma abordagem simples, porém promissora, para arealização de tarefas de curadoria e controle de qualidade dos dados de anotação desequências proteicas em uma escala genômica. Os resultados do classificador definem a base para seu desenvolvimento em uma ferramenta computacional e os resultados dasreanotações em Plasmodium impactarão a busca por novos alvos vacinais equimioterápicos.
Subject(s)
Humans , Male , Female , Malaria/genetics , Peptides/immunology , Plasmodium/immunologyABSTRACT
A study was carried out in the area of influence of the Porto Primavera Hydroelectric Power Station, in western São Paulo State, to investigate ecological and epidemiological aspects of malaria in the area and monitor the profile of the anopheline populations following the environmental changes brought about by the construction of the lake. Mosquitoes captured were analyzed by standardized indicator species analysis (ISA) before and during different flooding phases (253 m and 257 m elevations). The local human population was studied by means of parasitological (thin/thick blood smears), molecular (PCR) and serological tests. Serological tests consisted of Enzyme Linked Immunosorbent Assay (ELISA) with synthetic peptides of the circumsporozoite protein (CSP) from classic Plasmodium vivax, P. vivax variants (VK247 and "vivax-like"), P. malariae and P. falciparum and Indirect Immunofluorescence Assay (IFA) with asexual forms of P. vivax, P. malariae and P. falciparum. The results of the entomological survey indicated that, although the Anopheles darlingi population increased after the flooding, the population density remained very low. No malaria, parasite infection or DNA was detected in the inhabitants of the study area. However, there was a low frequency of antibodies against asexual forms and a significant prevalence of antibodies against P. vivax, P. vivax variants, P. falciparum and P. malariae; the presence of these antibodies may result from recent or less recent contact with human or simian Plasmodium (a parallel study in the same area revealed the existence of a sylvatic cycle) ...
Foi realizada pesquisa na área de influência do lago da Usina Hidrelétrica de Porto Primavera, região oeste do Estado de São Paulo, para estudar aspectos ecológicos e epidemiológicos da malária na localidade e acompanhar o perfil das populações de anofelinos frente às mudanças decorrentes do impacto ambiental pela formação do lago. Mosquitos capturados foram analisados pelo Índice de Abundância de Espécies Padronizado (IAEP), antes e durante o enchimento do reservatório (cotas 253 e 257 m). A população humana local foi estudada por meio de teste parasitológico (gota espessa e esfregaço sangüíneo), testes moleculares (PCR) e testes sorológicos. A sorologia consistiu na reação de ELISA com peptídeos sintéticos correspondentes à porção repetitiva da proteína circumsporozoíta (CSP) de Plasmodium vivax clássico, e suas variantes VK247 e "vivax-like", P. malariae e P. falciparum; e reação de Imunofluorescência Indireta (RIFI) com formas assexuadas de P. vivax, P. malariae e P. falciparum. Os resultados do estudo entomológico indicaram que, embora a população de Anopheles darlingi tenha aumentando após o enchimento, permaneceu em baixa densidade. Não foi detectada malária nem a presença de parasitos ou de DNA parasitário nos habitantes estudados. No entanto, foi observada baixa freqüência de anticorpos contra formas assexuadas e significativa prevalência de anticorpos contra esporozoítos de P. vivax e suas variantes, P. falciparum e P. malariae, que poderiam decorrer de contatos prévios, recentes ou não, com plasmódios humanos ou símios (o ciclo silvestre foi evidenciado em estudo paralelo realizado na mesma área)...
Subject(s)
Animals , Humans , Culicidae/classification , Insect Vectors/classification , Malaria/epidemiology , Brazil/epidemiology , Culicidae/parasitology , Ecosystem , Insect Vectors/parasitology , Malaria/diagnosis , Plasmodium/classification , Plasmodium/immunology , Plasmodium/isolation & purification , Population Density , Power Plants , PrevalenceABSTRACT
Malaria emerges from a disequilibrium of the system 'human-plasmodium-mosquito' (HPM). If the equilibrium is maintained, malaria does not ensue and the result is asymptomatic plasmodium infection. The relationships among the components of the system involve coadaptive linkages that lead to equilibrium. A vast body of evidence supports this assumption, including the strategies involved in the relationships between plasmodium and human and mosquito immune systems, and the emergence of resistance of plasmodia to antimalarial drugs and of mosquitoes to insecticides. Coadaptive strategies for malaria control are based on the following principles: (1) the system HPM is composed of three highly complex and dynamic components, whose interplay involves coadaptive linkages that tend to maintain the equilibrium of the system; (2) human and mosquito immune systems play a central role in the coadaptive interplay with plasmodium, and hence, in the mainten-ance of the system's equilibrium; the under- or overfunction of human immune system may result in malaria and influence its severity; (3) coadaptation depends on genetic and epigenetic phenomena occurring at the interfaces of the components of the system, and may involve exchange of infectrons (genes or gene fragments) between the partners; (4) plasmodia and mosquitoes have been submitted to selective pressures, leading to adaptation, for an extremely long while and are, therefore, endowed with the capacity to circumvent both natural (immunity) and artificial (drugs, insecticides, vaccines) measures aiming at destroying them; (5) since malaria represents disequilibrium of the system HPM, its control should aim at maintaining or restoring this equilibrium; (6) the disequilibrium of integrated systems involves the disequilibrium of their components, therefore the maintenance or restoration of the system's equilibrium depend on the adoption of integrated and coordinated measures acting on all components,...
Subject(s)
Humans , Animals , Anopheles , Adaptation, Physiological/genetics , Insect Vectors , Malaria , Plasmodium , Adaptation, Physiological/immunology , Adaptation, Physiological/physiology , Anopheles/genetics , Anopheles/immunology , Anopheles/parasitology , Antimalarials/pharmacology , Biological Evolution , Drug Resistance/genetics , Host-Parasite Interactions/genetics , Host-Parasite Interactions/immunology , Insect Vectors/genetics , Insect Vectors/immunology , Insect Vectors/parasitology , Malaria/immunology , Malaria/parasitology , Plasmodium/drug effects , Plasmodium/genetics , Plasmodium/immunology , Plasmodium/physiologyABSTRACT
Nitric oxide (NO) is thought to be an important mediator and critical signaling molecule for malaria immunopathology; it is also a target for therapy and for vaccine. Inducible nitric oxide synthase (iNOS) is synthesized by a number of cell types under inflammatory conditions. The most relevant known triggers for its expression are endotoxins and cytokines. To date, there have been conflicting reports concerning the clinical significance of NO in malaria. Some researchers have proposed that NO contributes to the development of severe and complicated malaria, while others have argued that NO has a protective role. Infection with parasites resistant to the microbicidal action of NO may result in high levels of NO being generated, which could then damage the host, instead of controlling parasitemia. Consequently, the host-parasite interaction is a determining factor for whether the parasite is capable of stimulating NO production; the role of NO in resistance to malaria appears to be strain specific. It is known that NO and/or its related molecules are involved in malaria, but their involvement is not independent of other immune events. NO is an important, but possibly not an essential contributor to the control of acute-phase malaria infection. The protective immune responses against malaria parasite are multifactorial; however, they necessarily involve final effector molecules, including NO, iNOS and RNI.
Subject(s)
Animals , Humans , Malaria/immunology , Nitric Oxide/immunology , Host-Parasite Interactions , Malaria/enzymology , Nitric Oxide Synthase Type II/metabolism , Plasmodium/immunology , Plasmodium/physiologyABSTRACT
Malaria is an infectious disease caused by the protist Plasmodium spp. and it currently kills more than one million people annually. The burden of malaria is concentrated in sub-Saharan Africa, India, and Southeast Asia. The parasites resistance to commonly used anti-malarial drugs has worsened the situation in the poorest countries. The World Health Organization (WHO) estimates that more than 100 countries suffer from endemic malaria episodes. In addition to numerous control measures and treatments, several vaccines are at different research stages and trials. We have assayed RTS,S/AS02A, a pre-erythrocytic candidate vaccine that has shown promising protection levels in phase IIb trials in Mozambique. The vaccine is directed against the sporozoite form of the parasite, which is injected by the mosquito Anopheles spp. The vaccine induces a strong antibody response and stimulates Th1 cells-a subset of helper T cells that participates in cell-mediated immunity. Recent interest by international funding agencies has provided new inputs into initiatives and programs to fight malaria, which, under normal welfare and adequate social development conditions, is a curable disease (AU)
La malaria, una enfermedad infecciosa causada por el protista Plasmodium spp. causa anualmente más de un millón de muertes. Las regiones más afectadas son África subsahariana, India y el sudeste asiático. La resistencia del parásito a los fármacos antimaláricos más comunes ha empeorado la situación en los países más pobres. La Organización Mundial de la Salud (OMS) calcula que son más de 100 los países donde la enfermedad es endémica. Además de las numerosas medidas de control y de los tratamientos a los afectados, varias vacunas se encuentran en diferentes fases de prueba. Nuestro grupo ha ensayado la RTS,S/AS02A, una vacuna candidata pre-eritrocítica que ha dado niveles de protección esperanzadores en ensayos de fase IIb en Mozambique. La vacuna está dirigida contra el esporozoito, la forma del parásito inyectada por el mosquito Anopheles spp. La vacuna induce una fuerte producción de anticuerpos y células Th1 (el tipo de células T que intervienen en la inmunidad mediada por células). El reciente interés de organizaciones internacionales patrocinadoras ha supuesto un renovado estímulo a iniciativas y programas para combatir la malaria, una enfermedad curable en condiciones adecuadas de desarrollo social (AU)
Subject(s)
Animals , Humans , Malaria/prevention & control , Malaria Vaccines/therapeutic use , Insect Vectors/parasitology , Anopheles/parasitology , Malaria/immunology , Malaria/parasitology , Malaria/transmission , Malaria Vaccines/immunology , Plasmodium/immunology , Clinical Trials as TopicABSTRACT
A Amazônia é conhecida pela elevada prevalência de infeccão pelo vírus da hepatite B, contribui também com mais de 90 por cento dos casos de malária do país. É proposto que a ocorrência de co-infeccões seja importante e que na associacão ocorram alteracões na história natural dessas enfermidades. O estudo avalia 545 pacientes com malária, em Coari, AM: 333 (61,1 por cento) pelo Plasmodium vivax, 193 (35,4 por cento) pelo Plasmodium falciparum e 19 (3,5 por cento) com infeccão mista. A prevalência do AgHBs foi 4,2 por cento e a do anti-HBc total 49,7 por cento. Os pacientes sororreativos para o VHB, não apresentaram diferencas clínicas dos outros pacientes com malária, nem associacão a sinais clássicos de comprometimento hepático. Apesar de não ter sido detectada associacão estatisticamente significativa, os indivíduos AgHBs reativos apresentaram baixas parasitemias e índices de reatividade de anticorpos mais elevados, sugerindo a possibilidade da resposta imune em um indivíduo co-infectado ser diferenciada e favorecer variacões em relacão à parasitemia e producão de anticorpos.