RESUMEN
Malaria, babesiosis, trypanosomosis, and leishmaniasis are some of the most life-threatening parasites, but the range of drugs to treat them is limited. An effective, safe, and low-cost drug with a large activity spectrum is urgently needed. For this purpose, an aryl amino alcohol derivative called Alsinol was resynthesized, screened in silico, and tested against Plasmodium, Babesia, Trypanosoma, and Leishmania. In silico Alsinol follows the Lipinski and Ghose rules. In vitro it had schizontocidal activity against Plasmodium falciparum and was able to inhibit gametocytogenesis; it was particularly active against late gametocytes. In malaria-infected mice, it showed a dose-dependent activity similar to chloroquine. It demonstrated a similar level of activity to reference compounds against Babesia divergens, and against promastigotes, and amastigotes stages of Leishmania in vitro. It inhibited the in vitro growth of two African animal strains of Trypanosoma but was ineffective in vivo in our experimental conditions. It showed moderate toxicity in J774A1 and Vero cell models. The study demonstrated that Alsinol has a large spectrum of activity and is potentially affordable to produce. Nevertheless, challenges remain in the process of scaling up synthesis, creating a suitable clinical formulation, and determining the safety margin in preclinical models.
Asunto(s)
Amino Alcoholes/farmacología , Antiprotozoarios/farmacología , Amino Alcoholes/síntesis química , Amino Alcoholes/química , Animales , Antiprotozoarios/síntesis química , Antiprotozoarios/química , Babesia/efectos de los fármacos , Babesia/crecimiento & desarrollo , Supervivencia Celular/efectos de los fármacos , Chlorocebus aethiops , Modelos Animales de Enfermedad , Leishmania/efectos de los fármacos , Leishmania/crecimiento & desarrollo , Estadios del Ciclo de Vida/efectos de los fármacos , Ratones , Plasmodium/efectos de los fármacos , Plasmodium/crecimiento & desarrollo , Infecciones por Protozoos/tratamiento farmacológico , Infecciones por Protozoos/parasitología , Resultado del Tratamiento , Trypanosoma/efectos de los fármacos , Trypanosoma/crecimiento & desarrollo , Células VeroRESUMEN
Avian malaria is a mosquito-borne disease caused by Plasmodium spp. protozoa, and penguins are considered particularly susceptible to this disease, developing rapid outbreaks with potentially high mortality. We report on an outbreak of avian malaria in Magellanic penguins (Spheniscus magellanicus) at a rehabilitation center in Espírito Santo, southeast Brazil. In August and September 2015, a total of 89 Magellanic penguins (87 juveniles and 2 adults) received care at Institute of Research and Rehabilitation of Marine Animals. Over a period of 2 weeks, Plasmodium infections were identified in eight individuals (9.0%), four of which died (mortality = 4.5%, lethality = 50%). Blood smears and sequencing of the mitochondrial cytochrome b gene revealed the presence of Plasmodium lutzi SPMAG06, Plasmodium elongatum GRW06, Plasmodium sp. PHPAT01, Plasmodium sp. SPMAG10, and Plasmodium cathemerium (sequencing not successful). Two unusual morphological features were observed in individuals infected with lineage SPMAG06: (a) lack of clumping of pigment granules and (b) presence of circulating exoerythrocytic meronts. Hematological results (packed cell volume, plasma total solids, complete blood cell counts) of positive individuals showed differences from those of negative individuals depending on the lineages, but there was no overarching pattern consistently observed for all Plasmodium spp. The epidemiology of the outbreak and the phylogeography of the parasite lineages detected in this study support the notion that malarial infections in penguins undergoing rehabilitation in Brazil are the result of the spillover inoculation by plasmodia that circulate in the local avifauna, especially Passeriformes.
Asunto(s)
Enfermedades de las Aves/parasitología , Malaria Aviar/parasitología , Plasmodium/crecimiento & desarrollo , Spheniscidae/parasitología , Animales , Enfermedades de las Aves/sangre , Enfermedades de las Aves/epidemiología , Brasil/epidemiología , Brotes de Enfermedades , Femenino , Hematología , Malaria Aviar/sangre , Malaria Aviar/epidemiología , Masculino , Filogenia , Plasmodium/clasificación , Plasmodium/genética , Plasmodium/aislamiento & purificaciónRESUMEN
BACKGROUND: The merozoite surface protein 7 (MSP7) is a Plasmodium protein which is involved in parasite invasion; the gene encoding it belongs to a multigene family. It has been proposed that MSP7 paralogues seem to be functionally redundant; however, recent experiments have suggested that they could have different roles. RESULTS: The msp7 multigene family has been described in newly available Plasmodium genomes; phylogenetic relationships were established in 12 species by using different molecular evolutionary approaches for assessing functional divergence amongst MSP7 members. Gene expansion and contraction rule msp7 family evolution; however, some members could have had concerted evolution. Molecular evolutionary analysis showed that relaxed and/or intensified selection modulated Plasmodium msp7 paralogous evolution. Furthermore, episodic diversifying selection and changes in evolutionary rates suggested that some paralogous proteins have diverged functionally. CONCLUSIONS: Even though msp7 has mainly evolved in line with a birth-and-death evolutionary model, gene conversion has taken place between some paralogous genes allowing them to maintain their functional redundancy. On the other hand, the evolutionary rate of some MSP7 paralogs has become altered, as well as undergoing relaxed or intensified (positive) selection, suggesting functional divergence. This could mean that some MSP7s can form different parasite protein complexes and/or recognise different host receptors during parasite invasion. These results highlight the importance of this gene family in the Plasmodium genus.
Asunto(s)
Evolución Molecular , Proteínas de la Membrana/genética , Plasmodium/genética , Proteínas Protozoarias/genética , Animales , Conversión Génica , Merozoítos/metabolismo , Familia de Multigenes , Filogenia , Plasmodium/clasificación , Plasmodium/crecimiento & desarrollo , Selección GenéticaRESUMEN
Dendritic cells (DCs) play a central role in the initiation of adaptive immune responses, efficiently presenting antigens to T cells. This ability relies on the presence of numerous surface and intracellular receptors capable of sensing microbial components as well as inflammation and on a very efficient machinery for antigen presentation. In this way, DCs sense the presence of a myriad of pathogens, including Plasmodium spp., the causative agent of malaria. Despite many efforts to control this infection, malaria is still responsible for high rates of morbidity and mortality. Different groups have shown that DCs act during Plasmodium infection, and data suggest that the phenotypically distinct DCs subsets are key factors in the regulation of immunity during infection. In this review, we will discuss the importance of DCs for the induction of immunity against the different stages of Plasmodium, the outcomes of DCs activation, and also what is currently known about Plasmodium components that trigger such activation.
Asunto(s)
Células Dendríticas/inmunología , Malaria/inmunología , Presentación de Antígeno , Humanos , Pruebas Inmunológicas , Estadios del Ciclo de Vida , Malaria/parasitología , Plasmodium/crecimiento & desarrollo , Plasmodium/inmunología , Linfocitos T/inmunologíaRESUMEN
Numerous studies addressed the diversity of bird Plasmodium and Haemoproteus parasites. However, a few have been carried out in continental avian hotspot regions such as Brazil, a country with markedly different biomes, including Amazon, Brazilian Savanna, Atlantic Forest,Caatinga, Pantanal, and Pampas. We present the first study on hemosporidian (Haemosporida) parasites in free-living birds from an Atlantic Forest fragment where more than 80 avian species have been reported. Within this area, the São Paulo Zoo locates, and it is the fourth largest zoo in the world and the largest in Latin America. A total of 133 free-living bird samples representing 12 species were collected in the zoo, with the overall hemosporidian prevalence of 18 % by PCR based diagnostics. Twenty-four positive PCR signals were reported from four different bird species, including migratory ones. Columba livia, an urban species, considered nowadays a pest in big cities, showed 100% prevalence of Haemoproteusspp., mainly Haemoproteus columbae...
Asunto(s)
Animales , Haemosporida/crecimiento & desarrollo , Haemosporida/parasitología , Plasmodium/crecimiento & desarrollo , Plasmodium/parasitologíaRESUMEN
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...
Asunto(s)
Humanos , Malaria/diagnóstico , Malaria/epidemiología , Malaria/prevención & control , Malaria/transmisión , Plasmodium/crecimiento & desarrollo , Plasmodium/inmunología , Plasmodium/microbiología , Plasmodium/parasitología , Plasmodium/patogenicidadRESUMEN
Anopheles darlingi Root is the principal vector of Plasmodium in Brazil, but its biological variability is notwell known. Morphometric analyses of scanning electron microscopy images of the eggs of An. darlingiwere conducted using individuals collected in nine states of Brazil (Acre, Amapá, Espírito Santo, Pará,Paraná, Rio de Janeiro, Rondônia, São Paulo, and Tocantins). Ten attributes of the eggs (seven continuous variables and three discrete variables) were respectively measured or counted and analyzed to determine if populations from different geographical regions or biomes could be distinguished. Univariate analysisshowed that the eggs from Espírito Santo were the narrowest where as representatives from Tocantins populations had the smallest floats. Results of multivariate analyses of continuous variables showed that the first principal component (PC1), mainly represented by all four float attributes, helped to differentiate populations. The second principal component (PC2) comprised roughly the length and width of the egg. PC1 of discrete variables corresponded to the number of ribs on the float where as PC2 was approximately equivalent to the number of discs on the micropyle. Based on those variables (continuous and discrete separately), multivariate discriminant analysis indicated that eggs from individuals collected in Tocantins were distinct from the other populations. Among sampled localities, the one from the state of Tocantins was situated within the Cerrado biome whereas the locality from São Paulo state was at the border of Cerrado, within a transition zone of the Atlantic Forest biome...
Asunto(s)
Animales , Anopheles/crecimiento & desarrollo , Anopheles/genética , Plasmodium/crecimiento & desarrolloRESUMEN
Nearly one million people are killed every year by the malaria parasite Plasmodium. Although the disease-causing forms of the parasite exist only in the human blood, mosquitoes of the genus Anopheles are the obligate vector for transmission. Here, we review the parasite life cycle in the vector and highlight the human and mosquito contributions that limit malaria parasite development in the mosquito host. We address parasite killing in its mosquito host and bottlenecks in parasite numbers that might guide intervention strategies to prevent transmission.
Asunto(s)
Anopheles/parasitología , Insectos Vectores/parasitología , Estadios del Ciclo de Vida/fisiología , Plasmodium/crecimiento & desarrollo , Animales , Anopheles/clasificación , Interacciones Huésped-Parásitos/fisiología , Humanos , Insectos Vectores/clasificación , Malaria/transmisión , Plasmodium/fisiologíaRESUMEN
Nearly one million people are killed every year by the malaria parasite Plasmodium. Although the disease-causing forms of the parasite exist only in the human blood, mosquitoes of the genus Anopheles are the obligate vector for transmission. Here, we review the parasite life cycle in the vector and highlight the human and mosquito contributions that limit malaria parasite development in the mosquito host. We address parasite killing in its mosquito host and bottlenecks in parasite numbers that might guide intervention strategies to prevent transmission.
Asunto(s)
Animales , Humanos , Anopheles/parasitología , Insectos Vectores/parasitología , Estadios del Ciclo de Vida/fisiología , Plasmodium/crecimiento & desarrollo , Anopheles/clasificación , Interacciones Huésped-Parásitos/fisiología , Insectos Vectores/clasificación , Malaria/transmisión , Plasmodium/fisiologíaRESUMEN
Plasmodium (Novyella) nucleophilum was identified using microscopy and PCR, in an Egyptian Goose(Alopochen aegyptiacus) that died in São Paulo Zoo, Brazil. This parasite is characterized by elongated gametocytes, small meronts with scant cytoplasm, less than eight merozoites and mainly for having all the stages appressed to the nuclei of infected erythrocytes. Additionally, Plasmodium (Haemamoeba)sp. was identified by microscopy in the same blood sample. The latter parasite lacks nucleophilic blood stages and is characterized by large roundish trophozoites, each with a large prominent centrally collated vacuole. This co-infection was not confirmed by PCR amplification of the mitochondrial cytochrome b(cytb) gene and sequencing; only one Plasmodium sp. cytb sequence was detected in the blood sample. Since parasitemia of P. nucleophilum (2.4%) was much higher than that of P. (Haemamoeba) sp. (0.2%),PCR may have favored the amplification of the cytb sequence of the former. Phylogenetic analysis is inagreement with this conclusion because the reported cytb sequence was positioned in the same branch of sequences of several Novyella species. This is the first assignment of the mitochondrial cytb gene sequence to P. nucleophilum...
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Animales , Plasmodium/crecimiento & desarrollo , Plasmodium/genética , Plasmodium/parasitologíaRESUMEN
This study investigated Plasmodium spp. infection in free-ranging neotropical primates from Brazilian Amazon regions under the impact of major anthropogenic actions. Blood samples from 19 new world primates were collected and analyzed with microscopic and molecular procedures. The prevalence of Plasmodium infection was 21.0% (4/19) and PCR positive samples were identified as P. brasilianum. Considering the social-economic changes that the Amazon is facing, the prevalence of P. brasilianum infection highlights the necessity to closely monitor the movement of both human and non-human primate populations, in order tomitigate pathogen exposure and the introduction of new agents into previously...
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Animales , Ecosistema Amazónico , Plasmodium/crecimiento & desarrollo , Primates/crecimiento & desarrolloRESUMEN
This paper is an overview of vaccine antigens against malaria produced in plants. Plant-based expression systems represent an interesting production platform due to their reduced manufacturing costs and high scalability. At present, different Plasmodium antigens and expression strategies have been optimized in plants. Furthermore, malaria antigens are one of the few examples of eukaryotic proteins with vaccine value expressed in plants, making plant-derived malaria antigens an interesting model to analyze. Up to now, malaria antigen expression in plants has allowed the complete synthesis of these vaccine antigens, which have been able to induce an active immune response in mice. Therefore, plant production platforms offer wonderful prospects for improving the access to malaria vaccines.
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Antígenos de Plantas/inmunología , Vacunas contra la Malaria/inmunología , Malaria/inmunología , Malaria/prevención & control , Plantas/metabolismo , Plasmodium/inmunología , Animales , Humanos , Estadios del Ciclo de Vida , Plasmodium/crecimiento & desarrolloRESUMEN
Infections caused by resistant microorganisms often fail to respond to conventional therapy, resulting in prolonged illness, increased treatment costs and greater risk of death. Consequently, the development of novel antimicrobial drugs is becoming more demanding every day since the existing drugs either have too many side-effects or they tend to lose effectiveness due to the selection of resistant strains. In view of these facts, a number of new strategies to obstruct vital biological processes of a microbial cell have emerged; one of these is focused on the use of metal-chelating agents, which are able to selectively disturb the essential metal metabolism of the microorganism by interfering with metal acquisition and bioavailability for crucial reactions. The chelation activity is able to inhibit the biological role of metal-dependent proteins (e.g., metalloproteases and transcription factors), disturbing the microbial cell homeostasis and culminating in the blockage of microbial nutrition, growth and development, cellular differentiation, adhesion to biotic (e.g., extracellular matrix components, cell and/or tissue) and abiotic (e.g., plastic, silicone and acrylic) structures as well as controlling the in vivo infection progression. Interestingly, chelating agents also potentiate the activity of classical antimicrobial compounds. The differences between the microorganism and host in terms of the behavior displayed in the presence of chelating agents could provide exploitable targets for the development of an effective chemotherapy for these diseases. Consequently, metal chelators represent a novel group of antimicrobial agents with potential therapeutic applications. This review will focus on the anti-fungal and anti-protozoan action of the most common chelating agents, deciphering and discussing their mode of action.
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Antiinfecciosos/farmacología , Antiprotozoarios/farmacología , Quelantes/farmacología , Hongos/efectos de los fármacos , Animales , Hongos/crecimiento & desarrollo , Hongos/patogenicidad , Humanos , Plasmodium/efectos de los fármacos , Plasmodium/crecimiento & desarrollo , Plasmodium/patogenicidad , Trypanosoma/efectos de los fármacos , Trypanosoma/crecimiento & desarrollo , Trypanosoma/patogenicidadRESUMEN
A delayed vector-bias model for malaria transmission with incubation period in mosquitoes is studied. The delay t corresponds to the time necessary for a latently infected vector to become an infectious vector. We prove that the global stability is completely determined by the threshold parameter, R0(τ). If R0(τ) ≥ 1, the disease-free equilibrium is globally asymptotically stable. If R0(τ) > 1 a unique endemic equilibrium exists and is globally asymptotically stable. We apply our results to Ross-MacDonald malaria models with an incubation period (extrinsic or intrinsic).
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Culicidae/parasitología , Insectos Vectores/parasitología , Malaria/parasitología , Modelos Biológicos , Plasmodium/crecimiento & desarrollo , Animales , Número Básico de Reproducción , Humanos , Malaria/transmisiónRESUMEN
In some states of the Brazilian extra-Amazonian region, such as the Atlantic Forest area, autochthonous human cases of malaria were related to simian malarias and vice versa. METHODS:To verify the presence of Plasmodium, 50 blood samples of howler monkeys (Alouatta guariba clamitans) rescued from the Metropolitan Region of São Paulo city, where the Atlantic Forest is present, were analyzed. The samples were submitted to microscopy (thin and thick blood smears), enzyme-linked immunosorbent assays (ELISA), indirect immunofluorescent assay (IFA), and polymerase chain reaction (PCR)...
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Humanos , Animales , Malaria/diagnóstico , Malaria/epidemiología , Malaria/transmisión , Plasmodium/crecimiento & desarrolloRESUMEN
Our ongoing search for a fully-effective vaccine against the Plasmodium falciparum parasite (causing the most lethal form of human malaria) has been focused on identifying and characterising proteins' amino acid sequences (high activity binding peptides or HABPs) involved in parasite invasion of red blood cells (RBC) by the merozoite and hepatocytes by the sporozoite. Many such merozoite HABPs have been recognised and molecularly and structurally characterised; however, native HABPs are immunologically silent since they do not induce any immune response or protection against P. falciparum malaria infection and they have to be structurally modified to allow them to fit perfectly into immune system molecules. A deeply structural analysis of these conserved merozoite HABPs and their modified analogues has led to rules or principles becoming recognised for constructing a logical and rational methodology for a minimal subunit-based, multi-epitope, multi-stage, chemically-synthesised vaccine. The same in-depth analysis of the most relevant sporozoite proteins involved in sporozoite cell-traversal and hepatocyte invasion as well as the hepatic stage is shown here. Specifically modifying these HABPs has resulted in a new set of potential pre-erythrocyte targets which are able to induce high, longlasting antibody titres in Aotus monkeys, against their corresponding recombinant proteins and the complete parasite native molecules. This review shows how these rules may be applied against the first stage of parasite invasion (i.e. the sporozoite) to mount the first line of defence against the malarial parasite, which may indeed be the most effective one. Our results strongly support including some of these modified sporozoite HABPs in combination with the previously-described modified merozoite HABPs for obtaining the aforementioned fully-protective, multiepitope, multi-stage, minimal subunit-based, chemically-synthesized, antimalarial vaccine.
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Vacunas contra la Malaria/química , Vacunas contra la Malaria/inmunología , Malaria/prevención & control , Péptidos/química , Péptidos/inmunología , Plasmodium/crecimiento & desarrollo , Secuencia de Aminoácidos , Animales , Antimaláricos , Humanos , Malaria/inmunología , Vacunas contra la Malaria/uso terapéutico , Modelos Moleculares , Datos de Secuencia Molecular , Péptidos/uso terapéutico , Plasmodium/inmunología , Proteínas Protozoarias/química , Proteínas Protozoarias/inmunologíaRESUMEN
Enolase is the eighth enzyme in the glycolytic pathway, a reaction that generates ATP from phosphoenol pyruvate in cytosolic compartments. Enolase is essential, especially for organisms devoid of the Krebs cycle that depend solely on glycolysis for energy. Interestingly, enolase appears to serve a separate function in some organisms, in that it is also exported to the cell surface via a poorly understood mechanism. In these organisms, surface enolase assists in the invasion of their host cells by binding plasminogen, an abundant plasma protease precursor. Binding is mediated by the interaction between a lysine motif of enolase with Kringle domains of plasminogen. The bound plasminogen is then cleaved by specific proteases to generate active plasmin. Plasmin is a potent serine protease that is thought to function in the degradation of the extracellular matrix surrounding the targeted host cell, thereby facilitating pathogen invasion. Recent work revealed that the malaria parasite Plasmodium also expresses surface enolase, and that this feature may be essential for completion of its life cycle. The therapeutic potential of targeting surface enolases of pathogens is discussed.
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Membrana Celular/enzimología , Fosfopiruvato Hidratasa/metabolismo , Plasmodium/enzimología , Animales , Fibrinolisina/metabolismo , Estadios del Ciclo de Vida , Plasminógeno/metabolismo , Plasmodium/crecimiento & desarrollo , Plasmodium/patogenicidadRESUMEN
Enolase is the eighth enzyme in the glycolytic pathway, a reaction that generates ATP from phosphoenol pyruvate in cytosolic compartments. Enolase is essential, especially for organisms devoid of the Krebs cycle that depend solely on glycolysis for energy. Interestingly, enolase appears to serve a separate function in some organisms, in that it is also exported to the cell surface via a poorly understood mechanism. In these organisms, surface enolase assists in the invasion of their host cells by binding plasminogen, an abundant plasma protease precursor. Binding is mediated by the interaction between a lysine motif of enolase with Kringle domains of plasminogen. The bound plasminogen is then cleaved by specific proteases to generate active plasmin. Plasmin is a potent serine protease that is thought to function in the degradation of the extracellular matrix surrounding the targeted host cell, thereby facilitating pathogen invasion. Recent work revealed that the malaria parasite Plasmodium also expresses surface enolase, and that this feature may be essential for completion of its life cycle. The therapeutic potential of targeting surface enolases of pathogens is discussed.
Asunto(s)
Animales , Membrana Celular/enzimología , Fosfopiruvato Hidratasa , Plasmodium/enzimología , Fibrinolisina , Estadios del Ciclo de Vida , Plasminógeno , Plasmodium/crecimiento & desarrollo , PlasmodiumRESUMEN
Evolutionary theory predicts that the sex ratio of Plasmodium gametocytes will be determined by the number of gametes produced per male gametocyte (male fecundity), parasite clonal diversity and any factor that reduces male gametes' ability to find and combine with female gametes. Despite the importance of male gametocyte fecundity for sex ratio theory as applied to malaria parasites, few data are available on gamete production by male gametocytes. In this study, exflagellating gametes, a measure of male fecundity, were counted for 866 gametocytes from 26 natural infections of the lizard malaria parasite, Plasmodium mexicanum. The maximum male fecundity observed was 8, but most gametocytes produced 2-3 gametes, a value consistent with the typical sex ratio observed for P. mexicanum. Male gametocytes in infections with higher gametocytaemia had lower fecundity. Male fecundity was not correlated with gametocyte size, but differed among infections, suggesting genetic variation for fecundity. Fecundity and sex ratio were correlated (more female gametocytes with higher fecundity) as predicted by theory. Results agree with evolutionary theory, but also suggest a possible tradeoff between production time and fecundity, which could explain the low fecundity of this species, the variation among infections, and the correlation with gametocytaemia.
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Enfermedades de los Animales/parasitología , Fertilidad/fisiología , Células Germinativas , Lagartos/parasitología , Malaria/parasitología , Plasmodium/crecimiento & desarrollo , Animales , Colorantes Azulados , Evolución Biológica , Tamaño de la Célula , Femenino , Variación Genética , Células Germinativas/citología , Células Germinativas/fisiología , Masculino , Microscopía , Plasmodium/genética , Razón de MasculinidadRESUMEN
Vertebrate hosts of malaria parasites (Plasmodium) often harbour two or more genetically distinct clones of a single species, and interaction among these co-existing clones can play an important role in Plasmodium biology. However, how relative clonal proportions vary over time in a host is still poorly known. Experimental mixed-clone infections of the lizard malaria parasite, Plasmodium mexicanum, were followed in its natural host, the western fence lizard using microsatellite markers to determine the relative proportions of two to five co-existing clones over time (2-3 months). Results for two markers, and two PCR primer pairs for one of those, matched very closely, supporting the efficacy of the method. Of the 54 infections, 67% displayed stable relative clonal proportions, with the others showing a shift in proportions, usually with one clone outpacing the others. Infections with rapidly increasing or slowly increasing parasitemia were stable, showing that all clones within these infections reproduced at the same rapid or slow rate. Replicate infections containing the same clones did not always reveal the same growth rate, final parasitemia or dominant clone; thus there was no clone effect for these life history measures. The rate of increase in parasitemia was not associated with stable versus unstable relative proportions, but infections with four to five clones were more likely to be unstable than those with two to three clones. This rare look into events in genetically complex Plasmodium infections suggests that parasite clones may be interacting in complex and unexpected ways.