RESUMO
The immune response of Anopheles mosquitoes to Plasmodium invasion has been extensively studied and shown to be mediated mainly by the nitric oxide synthase (NOS), dual oxidase (DUOX), phenoloxidase (PO), and antimicrobial peptides activity. Here, we studied the correlation between a heat shock insult, transcription of immune response genes, and subsequent susceptibility to Plasmodium berghei infection in Anopheles albimanus. We found that transcript levels of many immune genes were drastically affected by the thermal stress, either positively or negatively. Furthermore, the transcription of genes associated with modifications of nucleic acid methylation was affected, suggesting an increment in both DNA and RNA methylation. The heat shock increased PO and NOS activity in the hemolymph, as well as the transcription of several immune genes. As consequence, we observed that heat shock increased the resistance of mosquitoes to Plasmodium invasion. The data provided here could help the understanding of infection transmission under the ever more common heat waves.
Assuntos
Anopheles/imunologia , Anopheles/parasitologia , Resposta ao Choque Térmico/imunologia , Hemolinfa/parasitologia , Malária/imunologia , Plasmodium berghei/imunologia , Animais , Anopheles/genética , Feminino , Resposta ao Choque Térmico/genética , Imunidade/genética , Malária/parasitologiaRESUMO
In invertebrates, "immunological priming" is considered as the ability to acquire a protective (adaptive) immune response against a pathogen due to previous exposure to the same organism. To date, the mechanism by which this type of adaptive immune response originates in insects is not well understood. In the Anopheles albimanus - Plasmodium berghei model, a DNA synthesis that probably indicates an endoreplication process during priming induction has been evidenced. This work aimed to know the transcriptomic profile in the midguts of An. albimanus after priming induction. Our analysis indicates the participation of regulatory elements of the cell cycle in the immunological priming and points out the importance of the cell cycle regulation in the mosquito midgut.
Assuntos
Imunidade Adaptativa , Anopheles/imunologia , Interações Hospedeiro-Parasita/imunologia , Plasmodium berghei/imunologia , Animais , Anopheles/parasitologia , Ciclo Celular/imunologia , Epigênese Genética/imunologia , Perfilação da Expressão Gênica , Interações Hospedeiro-Parasita/genética , Masculino , CamundongosRESUMO
Different evidences suggest that pericardial cells play an important role during the immune response against pathogens that invade the mosquito hemocoel. Previously, we identified two lysozyme genes in Anopheles albimanus heart transcriptome. The present study showed that one of these genes (IDVB: AALB004517) has high percentage of identity to mosquito lysozyme genes related to immunity, suggesting its possible participation during the mosquito immune response. This An. albimanus gen, constitutively expressed lysozyme c-1 mRNA (albLys c-1) in mosquito heart; however, it was overexpressed in bacteria-injected mosquitoes. In heart extract samples, we identified a protein of approximately 14 kDa (likely lysozyme c-1), which lysed M. luteus. In addition, mRNA-FISH assay in heart samples, showed specific fluorescent hybridization signal in pericardial cells from M. luteus-injected mosquitos. We conclude that for the first time an inducible immune factor (lysozyme c-1) is identified in Anopheles albimanus mosquito pericardial cells, which could be a key component in the response against pathogens that interact with the mosquito heart.
Assuntos
Anopheles/imunologia , Escherichia coli/fisiologia , Infecções por Bactérias Gram-Positivas/imunologia , Proteínas de Insetos/metabolismo , Micrococcus luteus/fisiologia , Muramidase/metabolismo , Pericárdio/metabolismo , Animais , Clonagem Molecular , Biologia Computacional , Proteínas de Escherichia coli/imunologia , Imunidade Inata , Proteínas de Insetos/genética , Muramidase/genética , Pericárdio/patologia , Filogenia , Transcriptoma , Regulação para CimaRESUMO
BACKGROUND: The humoral immune response against Anopheles salivary glands proteins in the vertebrate host can reflect the intensity of exposure to Anopheles bites and the risk of Plasmodium infection. In Colombia, the identification of exposure biomarkers is necessary due to the several Anopheles species circulating. The purpose of this study was to evaluate risk of malaria infection by measuring antibody responses against salivary glands extracts from Anopheles (Nyssorhynchus) albimanus and Anopheles (Nys.) darlingi and also against the gSG6-P1 peptide of Anopheles gambiae in people residing in a malaria endemic area in the Colombian Pacific coast. METHODS: Dried blood spots samples were eluted to measure the IgG antibodies against salivary gland extracts of An. albimanus strains STECLA (STE) and Cartagena (CTG) and An. darlingi and the gSG6-P1 peptide by ELISA in uninfected people and microscopic and submicroscopic Plasmodium carriers from the Colombia Pacific Coast. A multiple linear mixed regression model, Spearman correlation, and Mann-Whitney U-test were used to analyse IgG data. RESULTS: Significant differences in specific IgG levels were detected between infected and uninfected groups for salivary glands extracts from An. albimanus and for gSG6-P1, also IgG response to CTG and gSG6-P1 peptide were positively associated with the IgG response to Plasmodium falciparum in the mixed model. CONCLUSION: The CTG and STE An. albimanus salivary glands extracts are a potential source of new Anopheles salivary biomarkers to identify exposure to the main malaria vector and to calculate risk of disease in the Colombian Pacific coast. Also, the gSG6-P1 peptide has the potential to quantify human exposure to the subgenus Anopheles vectors in the same area.
Assuntos
Anopheles/imunologia , Imunoglobulina G/biossíntese , Malária/epidemiologia , Mosquitos Vetores/imunologia , Proteínas e Peptídeos Salivares/imunologia , Adolescente , Animais , Infecções Assintomáticas/epidemiologia , Criança , Pré-Escolar , Colômbia/epidemiologia , Estudos Transversais , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunoglobulina G/sangue , Estudos Longitudinais , Malária/imunologia , Malária/transmissão , Masculino , Razão de Chances , Oceano Pacífico , Fatores de RiscoRESUMO
INTRODUCTION: Malaria and leishmaniases are transmitted by vectors during blood-feeding. Vector-infected animals develop antibodies against the vector's saliva. This study evaluated IgY antibody detection in the chicken eggs exposed to bites from Migonemyia migonei, Lutzomyia longipalpis and Anopheles aquasalis. METHODS: We used ELISA to quantify the antibody levels in the sera and exposed chicken eggs. RESULTS: High IgY levels were observed following immunization; furthermore, higher reactivity was observed in the eggs and species-specific immune response was observed post final immunization. CONCLUSIONS: Chicken eggs can be used as sentinels to surveil vector saliva antibodies.
Assuntos
Anopheles/imunologia , Galinhas/parasitologia , Ovos/parasitologia , Imunoglobulinas/análise , Insetos Vetores/imunologia , Psychodidae/imunologia , Saliva/imunologia , Animais , Ensaio de Imunoadsorção Enzimática , Leishmaniose/transmissão , Malária/transmissão , Fatores de TempoRESUMO
Epigenetic mechanisms such as DNA methylation and histone post-translational modifications are fundamental for the phenotypic plasticity of insects during their interaction with the environment. In response to environmental cues, the methylation pattern in DNA is dynamically remodeled to achieve an epigenetic control of gene expression. DNA methylation is the focus of study in insects for its evolutionarily conserved character; however, there is scant knowledge about the epigenetic regulation in vector mosquitoes, especially during their infection by parasites. The aim of the present study was to evaluate the participation of DNA methylation in the immune response of Anopheles albimanus to a Plasmodium infection. For this, we first investigated the presence of a fully functional DNA methylation system in A. albimanus by assessing its potential role in larval development. Subsequently, we evaluated the transcriptional response to Plasmodium berghei of two mosquito phenotypes with different degrees of susceptibility to the parasite, in a scenario where their global DNA methylation had been pharmacologically inhibited. Our study revealed that A. albimanus has a functional DNA methylation system that is essential to larval viability, and that is also responsive to feeding and parasite challenges. The pharmacological erasure of the methylome with azacytidine or decitabine abolished the divergent responses of both mosquito phenotypes, leading to a transcriptionally similar response upon parasite challenge. This response was more specific, and the infection load in both phenotypes was lowered. Our findings suggest that DNA methylation may constitute a key factor in vector competence, and a promising target for preventing malaria transmission.
Assuntos
Anopheles/genética , Anopheles/imunologia , Anopheles/parasitologia , Resistência à Doença/genética , Malária/veterinária , Plasmodium berghei/imunologia , Animais , Metilação de DNA , Resistência à Doença/imunologia , Intestinos/imunologia , Malária/genética , Malária/imunologiaRESUMO
Abstract INTRODUCTION: Malaria and leishmaniases are transmitted by vectors during blood-feeding. Vector-infected animals develop antibodies against the vector's saliva. This study evaluated IgY antibody detection in the chicken eggs exposed to bites from Migonemyia migonei, Lutzomyia longipalpis and Anopheles aquasalis. METHODS: We used ELISA to quantify the antibody levels in the sera and exposed chicken eggs. RESULTS: High IgY levels were observed following immunization; furthermore, higher reactivity was observed in the eggs and species-specific immune response was observed post final immunization. CONCLUSIONS: Chicken eggs can be used as sentinels to surveil vector saliva antibodies.
Assuntos
Animais , Psychodidae/imunologia , Saliva/imunologia , Imunoglobulinas/análise , Galinhas/parasitologia , Ovos/parasitologia , Insetos Vetores/imunologia , Anopheles/imunologia , Fatores de Tempo , Ensaio de Imunoadsorção Enzimática , Leishmaniose/transmissão , Malária/transmissãoRESUMO
Endoreplication is a cell cycle program in which cells replicate their genomes without undergoing mitosis and cytokinesis. For the normal development of many organisms (from fungi to humans) and the formation of their organs, endoreplication is indispensable. The aim of the present study was to explore whether endoreplication and DNA synthesis are relevant processes during the induction of trained innate immunity in human monocytes and in the Anopheles albimanus mosquito cell line. During the induction of trained immunity in both models, endoreplication markers were overexpressed and we observed an increase in DNA synthesis with an augmented copy number of genes essential for trained immunity. Blocking DNA synthesis prevented trained immunity from being established. Overall, these findings suggest that DNA synthesis and endoreplication are important mechanisms involved in inducing innate immune memory. They have probably been conserved throughout evolution from invertebrates to humans.
Assuntos
Anopheles , DNA , Imunidade Inata , Memória Imunológica , Modelos Imunológicos , Monócitos , Animais , Anopheles/imunologia , Anopheles/metabolismo , DNA/biossíntese , DNA/imunologia , Humanos , Monócitos/imunologia , Monócitos/metabolismoRESUMO
Innate immunity is an ancient and conserved defense system that provides an early effective response against invaders. Many immune genes of Anopheles mosquitoes have been implicated in defense against a variety of pathogens, including plasmodia. Nevertheless, only recent work identified some immune genes of Anopheles aquasalis mosquitoes upon P. vivax infection. Among these was a GATA transcription factor gene, which is described here. This is an ortholog of GATA factor Serpent genes described in Drosophila melanogaster and Anopheles gambiae. Gene expression analyses showed an increase of GATA-Serpent mRNA in P. vivax-infected A. aquasalis and functional RNAi experiments identified this transcription factor as an important immune gene of A. aquasalis against both bacteria and P. vivax. Besides, we were able to identify an effect of GATA-Serpent knockdown on A. aquasalis hemocyte proliferation and differentiation. These findings expand our understanding of the poorly studied A. aquasalis-P. vivax interactions and uncover GATA-Serpent as a key player of the mosquito innate immune response.
Assuntos
Anopheles/imunologia , Bactérias/imunologia , Fatores de Transcrição GATA/metabolismo , Imunidade Inata , Plasmodium/imunologia , Animais , Anopheles/genética , Diferenciação Celular , Proliferação de Células , Feminino , Fatores de Transcrição GATA/genética , Perfilação da Expressão Gênica , Inativação Gênica , Hemócitos/imunologia , Hemócitos/fisiologiaRESUMO
BACKGROUND: Malaria parasites are transmitted by Anopheles mosquitoes. Although several studies have identified mosquito midgut surface proteins that are putatively important for Plasmodium ookinete invasion, only a few have characterized these protein targets and demonstrated transmission-blocking activity. Molecular information about these proteins is essential for the development of transmission-blocking vaccines (TBV). The aim of the present study was to test three monoclonal antibodies (mAbs), A-140, A-78 and A-10, for their ability to recognize antigens and block oocyst infection of the midgut of Anopheles albimanus, a major malaria vector in Latin America. METHOD: Western-blot of mAbs on antigens from midgut brush border membrane vesicles was used to select antibodies. Three mAbs were tested by membrane feeding assays to evaluate their potential transmission-blocking activity against Plasmodium berghei. The cognate antigens recognized by mAbs with oocyst-reducing activity were determined by immunoprecipitation followed by liquid chromatography tandem mass spectrometry. RESULTS: Only one mAb, A-140, significantly reduced oocyst infection intensity. Hence, its probable protein target in the Anopheles albimanus midgut was identified and characterized. It recognized three high-molecular mass proteins from a midgut brush border microvilli vesicle preparation. Chemical deglycosylation assays confirmed the peptide nature of the epitope recognized by mAb A-140. Immunoprecipitation followed by proteomic identification with tandem mass spectrometry revealed five proteins, presumably extracted together as a complex. Of these, AALB007909 had the highest mascot score and corresponds to a protein with a myosin head motor domain, indicating that the target of mAb A-140 is probably myosin located on the microvilli of the mosquito midgut. CONCLUSION: These results provide support for the participation of myosin in mosquito midgut invasion by Plasmodium ookinetes. The potential inclusion of this protein in the design of new multivalent vaccine strategies for blocking Plasmodium transmission is discussed.
Assuntos
Anopheles/imunologia , Anticorpos Monoclonais/imunologia , Insetos Vetores/imunologia , Malária/transmissão , Miosinas/imunologia , Plasmodium berghei/crescimento & desenvolvimento , Animais , Anopheles/parasitologia , Sistema Digestório/imunologia , Sistema Digestório/parasitologia , Feminino , Insetos Vetores/parasitologia , Malária/parasitologia , Oocistos , ProteômicaRESUMO
Anopheles darlingi is the main malaria vector in humans in South America. In the Amazon basin, it lives along the banks of rivers and lakes, which responds to the annual hydrological cycle (dry season and rainy season). In these breeding sites, the larvae of this mosquito feed on decomposing organic and microorganisms, which can be pathogenic and trigger the activation of innate immune system pathways, such as proteins Gram-negative binding protein (GNBP). Such environmental changes affect the occurrence of polymorphic inversions especially at the heterozygote frequency, which confer adaptative advantage compared to homozygous inversions. We mapped the GNBP probe to the An. darlingi 2Rd inversion by fluorescent in situ hybridization (FISH), which was a good indicator of the GNBP immune response related to the chromosomal polymorphic inversions and adaptative evolution. To better understand the evolutionary relations and time of divergence of the GNBP of An. darlingi, we compared it with nine other mosquito GNBPs. The results of the phylogenetic analysis of the GNBP sequence between the species of mosquitoes demonstrated three clades. Clade I and II included the GNBPB5 sequence, and clade III the sequence of GNBPB1. Most of these sequences of GNBP analyzed were homologous with that of subfamily B, including that of An. gambiae (87 %), therefore suggesting that GNBP of An. darling belongs to subfamily B. This work helps us understand the role of inversion polymorphism in evolution of An. darlingi.
Assuntos
Anopheles/genética , Evolução Biológica , Inversão Cromossômica , Genes de Insetos , Animais , Anopheles/imunologia , Insetos Vetores/genética , Insetos Vetores/imunologia , Filogenia , Mapeamento Físico do Cromossomo , Cromossomos Politênicos , América do SulRESUMO
BACKGROUND: During blood meal, the female mosquito injects saliva able to elicit an immune response in the vertebrate. This immune response has been proven to reflect the intensity of exposure to mosquito bites and risk of infection for vector transmitted pathogens such as malaria. The peptide gSG6-P1 of An. gambiae saliva has been demonstrated to be antigenic and highly specific to Anopheles as a genus. However, the applicability of gSG6-P1 to measure exposure to different Anopheles species endemic in the Americas has yet to be evaluated. The purpose of this pilot study was to test whether human participants living in American countries present antibodies able to recognize the gSG6-P1, and whether these antibodies are useful as a proxy for mosquito bite exposure and malaria risk. METHODS: We tested human serum samples from Colombia, Chile, and the United States for the presence of IgG antibodies against gSG6-P1 by ELISA. Antibody concentrations were expressed as delta optical density (ΔOD) of each sera tested in duplicates. The difference in the antibody concentrations between groups was tested using the nonparametric Mann Whitney test (independent groups) and the nonparametric Wilcoxon matched-pairs signed rank test (dependent groups). All differences were considered significant with a P < 0.05. RESULTS: We found that the concentration of gSG6-P1 antibodies was significantly correlated with malaria infection status and mosquito bite exposure history. People with clinical malaria presented significantly higher concentrations of IgG anti-gSG6-P1 antibodies than healthy controls. Additionally, a significant raise in antibody concentrations was observed in subjects returning from malaria endemic areas. CONCLUSION: Our data shows that gSG6-P1 is a suitable candidate for the evaluation of exposure to Anopheles mosquito bites, risk of malaria transmission, and effectiveness of protection measures against mosquito bites in the Americas.
Assuntos
Anopheles/imunologia , Anticorpos/imunologia , Mordeduras e Picadas de Insetos/imunologia , Proteínas de Insetos/imunologia , Insetos Vetores/imunologia , Malária/imunologia , Proteínas e Peptídeos Salivares/imunologia , Adolescente , Animais , Anopheles/parasitologia , Anopheles/fisiologia , Anticorpos/sangue , Chile , Colômbia , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Mordeduras e Picadas de Insetos/sangue , Mordeduras e Picadas de Insetos/parasitologia , Insetos Vetores/parasitologia , Insetos Vetores/fisiologia , Malária/sangue , Malária/parasitologia , Masculino , North Carolina , Projetos Piloto , Plasmodium/fisiologia , Estações do Ano , Viagem , Adulto JovemRESUMO
INTRODUCTION: The saliva of mosquitoes has an important role in the transmission of several diseases, including malaria, and contains substances with vasomodulating and immunomodulating effects to counteract the host physiological mechanisms and enhance pathogen transmission. As immunomodulatory components, salivary gland proteins can induce the generation of specific IgG antibodies in the host, which can be used as specific biomarkers of exposure to Anopheles sundaicus . The objective of this study was to identify immunogenic proteins from the salivary glands of Anopheles sundaicus by reaction with sera from individuals living in malaria-endemic areas who are thus exposed to Anopheles mosquitoes. METHODS: IgG antibodies targeting salivary gland proteins in serum samples from individuals living in malaria-endemic areas were measured by enzyme-linked immunosorbent assay (ELISA). Sera from healthy individuals living in non-endemic areas were used as negative controls. Determination of the presence of salivary gland immunogenic proteins was carried out by western blotting. RESULTS: Sixteen bands appeared in sodium dodecyl sulfate polyacrylamide gel electrophoresis, with molecule weights ranging from 22 to 144kDa. Among the exposed individuals, IgG responses to salivary gland proteins were variable. Protein bands with molecular weights of 46, 41, 33, and 31kDa were the most immunogenic. These immunogenic proteins were consistently recognized by pooled serum and individual samples from people living in malaria-endemic areas but not by negative controls. CONCLUSIONS: These results support the potential use of immunogenic proteins from the salivary glands of Anopheles as candidate markers of bite exposure or in malaria vaccines.
Assuntos
Anopheles/imunologia , Proteínas de Insetos/imunologia , Glândulas Salivares/imunologia , Adulto , Animais , Anopheles/química , Biomarcadores/análise , Estudos de Casos e Controles , Eletroforese em Gel de Poliacrilamida , Feminino , Humanos , Imunoglobulina G/análise , Imunoglobulina G/imunologia , Proteínas de Insetos/análise , Proteínas e Peptídeos Salivares/análiseRESUMO
The saliva of mosquitoes has an important role in the transmission of several diseases, including malaria, and contains substances with vasomodulating and immunomodulating effects to counteract the host physiological mechanisms and enhance pathogen transmission. As immunomodulatory components, salivary gland proteins can induce the generation of specific IgG antibodies in the host, which can be used as specific biomarkers of exposure to
IgG antibodies targeting salivary gland proteins in serum samples from individuals living in malaria-endemic areas were measured by enzyme-linked immunosorbent assay (ELISA). Sera from healthy individuals living in non-endemic areas were used as negative controls. Determination of the presence of salivary gland immunogenic proteins was carried out by western blotting.
Sixteen bands appeared in sodium dodecyl sulfate polyacrylamide gel electrophoresis, with molecule weights ranging from 22 to 144kDa. Among the exposed individuals, IgG responses to salivary gland proteins were variable. Protein bands with molecular weights of 46, 41, 33, and 31kDa were the most immunogenic. These immunogenic proteins were consistently recognized by pooled serum and individual samples from people living in malaria-endemic areas but not by negative controls.
These results support the potential use of immunogenic proteins from the salivary glands of
Assuntos
Adulto , Animais , Feminino , Humanos , Anopheles/imunologia , Proteínas de Insetos/imunologia , Glândulas Salivares/imunologia , Anopheles/química , Biomarcadores/análise , Estudos de Casos e Controles , Eletroforese em Gel de Poliacrilamida , Imunoglobulina G/análise , Imunoglobulina G/imunologia , Proteínas de Insetos/análise , Proteínas e Peptídeos Salivares/análiseRESUMO
Transmission of malaria parasites from humans to Anopheles mosquitoes can be inhibited by specific antibodies elicited during malaria infection, which target surface Plasmodium gametocyte/gamete proteins. Some of these proteins may have potential for vaccine development. Pvs48/45 is a P. vivax gametocyte surface antigen orthologous to Pfs48/45, which may play a role during parasite fertilization and thus has potential for transmission blocking (TB) activity. Here we describe the expression of a recombinant Pvs48/45 protein expressed in Escherichia coli as a â¼60kDa construct which we tested for antigenicity using human sera and for its immunogenicity and transmission blocking activity of specific anti-mouse and anti-monkey Pvs48/45 antibodies. The protein reacted with sera of individuals from malaria-endemic areas and in addition induced specific IgG antibody responses in BALB/c mice and Aotus l. griseimembra monkeys. Sera from both immunized animal species recognized native P. vivax protein in Western blot (WB) and immunofluorescence assays. Moreover, sera from immunized mice and monkeys produced significant inhibition of parasite transmission to An. Albimanus mosquitoes as shown by membrane feeding assays. Results indicate the presence of reactive epitopes in the Pvs48/45 recombinant product that induce antibodies with TB activity. Further testing of this protein is ongoing to determine its vaccine potential.
Assuntos
Anopheles/imunologia , Antígenos de Protozoários/imunologia , Vacinas Antimaláricas/administração & dosagem , Malária Vivax/prevenção & controle , Malária Vivax/transmissão , Plasmodium vivax/genética , Animais , Anopheles/parasitologia , Anticorpos Antiprotozoários/metabolismo , Antígenos de Protozoários/genética , Aotidae/imunologia , Aotidae/parasitologia , Epitopos/imunologia , Escherichia coli/genética , Escherichia coli/metabolismo , Haplorrinos , Humanos , Imunoglobulina G/metabolismo , Vacinas Antimaláricas/genética , Vacinas Antimaláricas/imunologia , Malária Vivax/veterinária , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Plasmodium vivax/imunologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologiaRESUMO
In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Anopheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.
Assuntos
Anopheles/parasitologia , Insetos Vetores/parasitologia , Malária/transmissão , Plasmodium/classificação , Animais , Anopheles/classificação , Anopheles/genética , Anopheles/imunologia , Anopheles/ultraestrutura , Modelos Animais de Doenças , Insetos Vetores/classificação , Insetos Vetores/genética , Insetos Vetores/imunologia , Insetos Vetores/ultraestrutura , Malária/imunologia , Controle de Mosquitos , Carga Parasitária , Floresta ÚmidaRESUMO
Plasmodium falciparum originated in Africa, dispersed around the world as a result of human migration and had to adapt to several different indigenous anopheline mosquitoes. Anophelines from the New World are evolutionary distant form African ones and this probably resulted in a more stringent selection of Plasmodium as it adapted to these vectors. It is thought that Plasmodium has been genetically selected by some anopheline species through unknown mechanisms. The mosquito immune system can greatly limit infection and P. falciparum evolved a strategy to evade these responses, at least in part mediated by Pfs47, a highly polymorphic gene. We propose that adaptation of P. falciparum to new vectors may require evasion of their immune system. Parasites with a Pfs47 haplotype compatible with the indigenous mosquito vector would be able to survive and be transmitted. The mosquito antiplasmodial response could be an important determinant of P. falciparum population structure and could affect malaria transmission in the Americas.
Assuntos
Anopheles/parasitologia , Insetos Vetores/parasitologia , Plasmodium falciparum/fisiologia , Adaptação Fisiológica/genética , Adaptação Fisiológica/imunologia , Animais , Anopheles/classificação , Anopheles/imunologia , Interações Hospedeiro-Parasita/genética , Humanos , Evasão da Resposta Imune , Insetos Vetores/classificação , Glicoproteínas de Membrana/genética , Plasmodium falciparum/genética , Proteínas de Protozoários/genéticaRESUMO
Plasmodium falciparum originated in Africa, dispersed around the world as a result of human migration and had to adapt to several different indigenous anopheline mosquitoes. Anophelines from the New World are evolutionary distant form African ones and this probably resulted in a more stringent selection of Plasmodium as it adapted to these vectors. It is thought that Plasmodium has been genetically selected by some anopheline species through unknown mechanisms. The mosquito immune system can greatly limit infection and P. falciparum evolved a strategy to evade these responses, at least in part mediated by Pfs47, a highly polymorphic gene. We propose that adaptation of P. falciparum to new vectors may require evasion of their immune system. Parasites with a Pfs47 haplotype compatible with the indigenous mosquito vector would be able to survive and be transmitted. The mosquito antiplasmodial response could be an important determinant of P. falciparum population structure and could affect malaria transmission in the Americas.
Assuntos
Animais , Humanos , Anopheles/parasitologia , Insetos Vetores/parasitologia , Plasmodium falciparum/fisiologia , Adaptação Fisiológica/genética , Adaptação Fisiológica/imunologia , Anopheles/classificação , Anopheles/imunologia , Interações Hospedeiro-Parasita/genética , Evasão da Resposta Imune , Insetos Vetores/classificação , Glicoproteínas de Membrana/genética , Plasmodium falciparum/genética , Proteínas de Protozoários/genéticaRESUMO
The induction of DNA synthesis in various tissues of Anopheles albimanus, in response to challenge with Saccharomyces cerevisiae, Micrococcus luteus, and Serratia marcescens, was analyzed by 5-bromo-2-deoxy-uridine (BrdU) incorporation. Microorganism-inoculated mosquitoes were fed with a sucrose solution containing BrdU and maintained alive for 5 days. Alternatively, abdominal carcasses of microorganisms-inoculated mosquitoes were cultivated in Roswell Park Memorial Institute (RPMI) medium supplemented with BrdU for 5 days. Control groups were inoculated with RPMI alone. In both experiments, DNA synthesis, evidenced by epifluorescence with an anti-BrdU fluorescein-labeled antibody, occurred in fat body, epithelial cells of pleural membranes, dorsal vessel, and the oviducts. Relative quantification of DNA synthesis, evaluated by ELISA using an anti-BrdU peroxidase-labeled antibody, was higher in abdomen tissues of microorganisms-inoculated mosquitoes than controls in in vitro and in vivo experiments. The intensity of DNA synthesis varied among the different microorganism challenges, but was higher in in vivo experiments, compared to cultured samples. These differences in DNA synthesis suggest a compartmentalization of the immune response, probably mediated by different signaling pathways.
Assuntos
Anopheles/imunologia , Anopheles/metabolismo , DNA/biossíntese , Animais , Anopheles/genética , Anopheles/microbiologia , Bromodesoxiuridina/metabolismo , Ensaio de Imunoadsorção Enzimática , Feminino , Imunofluorescência , Micrococcus luteus/fisiologia , Especificidade de Órgãos , Saccharomyces cerevisiae/fisiologia , Serratia marcescens/fisiologia , Especificidade da EspécieRESUMO
Malaria affects 300 million people worldwide every year and 450,000 in Brazil. In coastal areas of Brazil, the main malaria vector is Anopheles aquasalis, and Plasmodium vivax is responsible for the majority of malaria cases in the Americas. Insects possess a powerful immune system to combat infections. Three pathways control the insect immune response: Toll, IMD, and JAK-STAT. Here we analyze the immune role of the A. aquasalis JAK-STAT pathway after P. vivax infection. Three genes, the transcription factor Signal Transducers and Activators of Transcription (STAT), the regulatory Protein Inhibitors of Activated STAT (PIAS) and the Nitric Oxide Synthase enzyme (NOS) were characterized. Expression of STAT and PIAS was higher in males than females and in eggs and first instar larvae when compared to larvae and pupae. RNA levels for STAT and PIAS increased 24 and 36 hours (h) after P. vivax challenge. NOS transcription increased 36 h post infection (hpi) while this protein was already detected in some midgut epithelial cells 24 hpi. Imunocytochemistry experiments using specific antibodies showed that in non-infected insects STAT and PIAS were found mostly in the fat body, while in infected mosquitoes the proteins were found in other body tissues. The knockdown of STAT by RNAi increased the number of oocysts in the midgut of A. aquasalis. This is the first clear evidence for the involvement of a specific immune pathway in the interaction of the Brazilian malaria vector A. aquasalis with P. vivax, delineating a potential target for the future development of disease controlling strategies.