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1.
Ryan C Smith Joel Vega-Rodríguez Marcelo Jacobs-Lorena 《Memórias do Instituto Oswaldo Cruz》2014,109(5):644-661
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. 相似文献
2.
《International journal for parasitology》2022,52(1):23-33
Asymptomatic malaria parasite carriers do not seek anti-malarial treatment and may constitute a silent infectious reservoir. In order to assess the level of asymptomatic and symptomatic carriage amongst adolescents in a highly endemic area, and to identify the risk factors associated with such carriage, we conducted a cross-sectional survey of 1032 adolescents (ages 10–19 years) from eight schools located in Ibadan, southwestern Nigeria in 2016. Blood films and blood spot filter paper samples were prepared for microscopy and DNA analysis. The prevalence of asymptomatic malaria was determined using microscopy, rapid diagnostic tests and PCR for 658 randomly selected samples. Of these, we found that 80% of asymptomatic schoolchildren were positive for malaria parasites by PCR, compared with 47% and 9%, determined by rapid diagnostic tests and microscopy, respectively. Malaria parasite species typing was performed using PCR targeting the mitochondrial CoxIII gene, and revealed high rates of carriage of Plasmodium malariae (53%) and Plasmodium ovale (24%). Most asymptomatic infections were co-infections of two or more species (62%), with Plasmodium falciparum + P. malariae the most common (35%), followed by P. falciparum + P. malariae + P. ovale (21%) and P. falciparum + P. ovale (6%). Single infections of P. falciparum, P. malariae and P. ovale accounted for 24%, 10% and 4% of all asymptomatic infections, respectively. To compare the species composition of asymptomatic and symptomatic infections, further sample collection was carried out in 2017 at one of the previously sampled schools, and at a nearby hospital. Whilst the species composition of the asymptomatic infections was similar to that observed in 2016, the symptomatic infections were markedly different, with single infections of P. falciparum observed in 91% of patients, P. falciparum + P. malariae in 5% and P. falciparum + P. ovale in 4%. 相似文献
3.
Jessica Kehrer Pauline Formaglio Julianne Mendi Muthinja Sebastian Weber Danny Baltissen Christopher Lance Johanna Ripp Janessa Grech Markus Meissner Charlotta Funaya Rogerio Amino Friedrich Frischknecht 《EMBO reports》2022,23(7)
During transmission of malaria‐causing parasites from mosquitoes to mammals, Plasmodium sporozoites migrate rapidly in the skin to search for a blood vessel. The high migratory speed and narrow passages taken by the parasites suggest considerable strain on the sporozoites to maintain their shape. Here, we show that the membrane‐associated protein, concavin, is important for the maintenance of the Plasmodium sporozoite shape inside salivary glands of mosquitoes and during migration in the skin. Concavin‐GFP localizes at the cytoplasmic periphery and concavin(−) sporozoites progressively round up upon entry of salivary glands. Rounded concavin(−) sporozoites fail to pass through the narrow salivary ducts and are rarely ejected by mosquitoes, while normally shaped concavin(−) sporozoites are transmitted. Strikingly, motile concavin(−) sporozoites disintegrate while migrating through the skin leading to parasite arrest or death and decreased transmission efficiency. Collectively, we suggest that concavin contributes to cell shape maintenance by riveting the plasma membrane to the subtending inner membrane complex. Interfering with cell shape maintenance pathways might hence provide a new strategy to prevent a malaria infection. 相似文献
4.
Daniela Camargos Costa Vanessa Pecini da Cunha Gabriela Maria Pereira de Assis Júlio César de Souza Junior Zelinda Maria Braga Hirano Mércia Eliane de Arruda Flora Satiko Kano Luzia Helena Carvalho Cristiana Ferreira Alves de Brito 《Memórias do Instituto Oswaldo Cruz》2014,109(5):641-643
Blood infection by the simian parasite, Plasmodium simium, wasidentified in captive (n = 45, 4.4%) and in wild Alouatta clamitansmonkeys (n = 20, 35%) from the Atlantic Forest of southern Brazil. A single malariainfection was symptomatic and the monkey presented clinical and haematologicalalterations. A high frequency of Plasmodium vivax-specificantibodies was detected among these monkeys, with 87% of the monkeys testing positiveagainst P. vivax antigens. These findings highlight the possibilityof malaria as a zoonosis in the remaining Atlantic Forest and its impact on theepidemiology of the disease. 相似文献
5.
Omaira Vera Lizcano Sarah Stela Resende Yonne F Chehuan Marcus VG Lacerda Cristiana FA Brito Mariano G Zalis 《Memórias do Instituto Oswaldo Cruz》2014,109(7):948-951
The molecular basis of Plasmodium vivax chloroquine (CQ) resistance
is still unknown. Elucidating the molecular background of parasites that are
sensitive or resistant to CQ will help to identify and monitor the spread of
resistance. By genotyping a panel of molecular markers, we demonstrate a similar
genetic variability between in vitro CQ-resistant and sensitive phenotypes of
P. vivax parasites. However, our studies identified two
loci (MS8 and MSP1-B10) that could be used to discriminate
between both CQ-susceptible phenotypes among P. vivax isolates in
vitro. These preliminary data suggest that microsatellites may be used to identify
and to monitor the spread of P. vivax-resistance around the
world. 相似文献
6.
Manuela Herrera-Varela Lorena I Orjuela Cilia Pe?alver Jan E Conn Martha L Qui?ones 《Memórias do Instituto Oswaldo Cruz》2014,109(7):952-956
Malaria in La Guajira, the most northern state of Colombia, shows two different
epidemiological patterns. Malaria is endemic in the municipality of Dibulla whereas
in Riohacha it is characterised by sporadic outbreaks. This study aimed to establish
whether differences in transmission patterns could be attributed to different vector
species. The most abundant adult female species were Anopheles
aquasalis, exclusive to Riohacha, and Anopheles darlingi,
restricted to Dibulla. Anopheles mosquitoes were identified
using morphology and the molecular markers internal transcribed spacer 2 and
cytochrome c oxidase I. All specimens (n = 1,393) were tested by ELISA to determine
natural infection rates with Plasmodium falciparum and
Plasmodium vivax. An. darlingi was positive for P. vivax
210, with an infection rate of 0.355% and an entomological inoculation rate
of 15.87 infective bites/person/year. Anopheles albimanus larvae
were the most common species in Riohacha, found in temporary swamps; in contrast, in
Dibulla An. darlingi were detected mainly in permanent streams.
Distinctive species composition and larval habitats in each municipality may explain
the differences in Plasmodium transmission and suggest different
local strategies should be used for vector control. 相似文献
7.
Jiraprapa Wipasa Chaisuree Suphavilai Lucy C. Okell Jackie Cook Patrick H. Corran Kanitta Thaikla Witaya Liewsaree Eleanor M. Riley Julius Clemence R. Hafalla 《PLoS pathogens》2010,6(2)
Antibodies constitute a critical component of the naturally acquired immunity that develops following frequent exposure to malaria. However, specific antibody titres have been reported to decline rapidly in the absence of reinfection, supporting the widely perceived notion that malaria infections fail to induce durable immunological memory responses. Currently, direct evidence for the presence or absence of immune memory to malaria is limited. In this study, we analysed the longevity of both antibody and B cell memory responses to malaria antigens among individuals who were living in an area of extremely low malaria transmission in northern Thailand, and who were known either to be malaria naïve or to have had a documented clinical attack of P. falciparum and/or P. vivax in the past 6 years. We found that exposure to malaria results in the generation of relatively avid antigen-specific antibodies and the establishment of populations of antigen-specific memory B cells in a significant proportion of malaria-exposed individuals. Both antibody and memory B cell responses to malaria antigens were stably maintained over time in the absence of reinfection. In a number of cases where antigen-specific antibodies were not detected in plasma, stable frequencies of antigen-specific memory B cells were nonetheless observed, suggesting that circulating memory B cells may be maintained independently of long-lived plasma cells. We conclude that infrequent malaria infections are capable of inducing long-lived antibody and memory B cell responses. 相似文献
8.
Jenny S. Carlson Juan E. Martínez‐Gómez Anthony Cornel Claire Loiseau Ravinder N. M. Sehgal 《Journal of vector ecology》2011,36(1):213-220
Avian malaria (Plasmodium spp.) has been implicated in the decline of avian populations in the Hawaiian Islands and it is generally agreed that geographically isolated and immunologically naïve bird populations are particularly vulnerable to the pathogenic effects of invasive malaria parasites. In order to assess the potential disease risk of malaria to the avifauna of Socorro Island, México, we surveyed for Plasmodium isolates from 1,300 resident field‐caught mosquitoes. Most of them were identified as Aedes (Ochlerotatus) taeniorhynchus (Wiedemann, 1821), which were abundant in the salt marshes. We also collected Culex quinquefasciatus Say, 1823 close to human dwellings. Mitochondrial ND5 and COII gene sequences of Ae. taeniorhynchus were analyzed and compared to corresponding sequences of mosquitoes of the Galápagos Islands, Latin America, and the North American mainland. Aedes lineages from Socorro Island clustered most closely with a lineage from the continental U.S. Plasmodium spp. DNA was isolated from both species of mosquitoes. From 38 positive pools, we isolated 11 distinct mitochondrial Cytb lineages of Plasmodium spp. Seven of the Plasmodium lineages represent previously documented avian infective strains while four were new lineages. Our results confirm a potential risk for the spread of avian malaria and underscore the need to monitor both the mosquito and avian populations as a necessary conservation measure to protect endangered bird species on Socorro Island. 相似文献
9.
Jaymin C. Patel Jenna Oberstaller Maniphet Xayavong Jothikumar Narayanan Jeremy D. DeBarry Ganesh Srinivasamoorthy Leopoldo Villegas Ananias A. Escalante Alexandre DaSilva David S. Peterson John W. Barnwell Jessica C. Kissinger Venkatachalam Udhayakumar Naomi W. Lucchi 《PloS one》2013,8(1)
Plasmodium vivax infections remain a major source of malaria-related morbidity and mortality. Early and accurate diagnosis is an integral component of effective malaria control programs. Conventional molecular diagnostic methods provide accurate results but are often resource-intensive, expensive, have a long turnaround time and are beyond the capacity of most malaria-endemic countries. Our laboratory has recently developed a new platform called RealAmp, which combines loop-mediated isothermal amplification (LAMP) with a portable tube scanner real-time isothermal instrument for the rapid detection of malaria parasites. Here we describe new primers for the detection of P. vivax using the RealAmp method. Three pairs of amplification primers required for this method were derived from a conserved DNA sequence unique to the P. vivax genome. The amplification was carried out at 64°C using SYBR Green or SYTO-9 intercalating dyes for 90 minutes with the tube scanner set to collect fluorescence signals at 1-minute intervals. Clinical samples of P. vivax and other human-infecting malaria parasite species were used to determine the sensitivity and specificity of the primers by comparing with an 18S ribosomal RNA-based nested PCR as the gold standard. The new set of primers consistently detected laboratory-maintained isolates of P. vivax from different parts of the world. The primers detected P. vivax in the clinical samples with 94.59% sensitivity (95% CI: 87.48–98.26%) and 100% specificity (95% CI: 90.40–100%) compared to the gold standard nested-PCR method. The new primers also proved to be more sensitive than the published species-specific primers specifically developed for the LAMP method in detecting P. vivax. 相似文献
10.
Tanaka N Nakanishi M Kusakabe Y Shiraiwa K Yabe S Ito Y Kitade Y Nakamura KT 《Journal of molecular biology》2004,343(4):1007-1017
The human malaria parasite Plasmodium falciparum is responsible for the death of more than a million people each year. The emergence of strains of malarial parasite resistant to conventional drug therapy has stimulated searches for antimalarials with novel modes of action. S-Adenosyl-L-homocysteine hydrolase (SAHH) is a regulator of biological methylations. Inhibitors of SAHH affect the methylation status of nucleic acids, proteins, and small molecules. P.falciparum SAHH (PfSAHH) inhibitors are expected to provide a new type of chemotherapeutic agent against malaria. Despite the pressing need to develop selective PfSAHH inhibitors as therapeutic drugs, only the mammalian SAHH structures are currently available. Here, we report the crystal structure of PfSAHH complexed with the reaction product adenosine (Ado). Knowledge of the structure of the Ado complex in combination with a structural comparison with Homo sapiens SAHH (HsSAHH) revealed that a single substitution between the PfSAHH (Cys59) and HsSAHH (Thr60) accounts for the differential interactions with nucleoside inhibitors. To examine roles of the Cys59 in the interactions with nucleoside inhibitors, a mutant PfSAHH was prepared. A replacement of Cys59 by Thr results in mutant PfSAHH, which shows HsSAHH-like nucleoside inhibitor sensitivity. The present structure should provide opportunities to design potent and selective PfSAHH inhibitors. 相似文献
11.
André M Siqueira Lucas I Coutinho Rafael L Gurgel Willian CS Su Luiz M Carvalho Silvana G Benzecry Aline CC Alencar Márcia AA Alexandre Maria Gra?as C Alecrim Marcus VG Lacerda 《Memórias do Instituto Oswaldo Cruz》2014,109(5):540-545
Plasmodium vivax is the most widespread parasite causing malaria, being
especially prevalent in the Americas and Southeast Asia. Children are one of the
most affected populations, especially in highly endemic areas. However, there are
few studies evaluating the therapeutic response of infants with vivax malaria.
This study retrospectively evaluated the parasitaemia clearance in children
diagnosed with vivax malaria during the first five days of exclusive treatment
with chloroquine (CQ). Infants aged less than six months old had a significantly
slower parasitaemia clearance time compared to the group of infants and children
between six months and 12 years old (Kaplan-Meier survival analysis; Wilcoxon
test; p = 0.004). The impaired clearance of parasitaemia in younger children with
vivax malaria is shown for the first time in Latin America. It is speculated that
CQ pharmacokinetics in young children with vivax malaria is distinct, but this
specific population may also allow the detection of CQ-resistant parasites during
follow-up, due to the lack of previous immunity. 相似文献
12.
13.
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. 相似文献
14.
Paulo Renato Rivas Totino Raquel Alves Pinna Ana Cecilia Amado Xavier De-Oliveira Dalma Maria Banic Cláudio Tadeu Daniel-Ribeiro Maria de Fátima Ferreira-da-Cruz 《Memórias do Instituto Oswaldo Cruz》2013,108(6):686-690
Recently, while studying erythrocytic apoptosis during Plasmodiumyoelii infection, we observed an increase in the levels ofnon-parasitised red blood cell (nRBC) apoptosis, which could be related tomalarial anaemia. Therefore, in the present study, we attempted to investigatewhether nRBC apoptosis is associated with the peripheral RBC count, parasiteload or immune response. To this end, BALB/c mice were infected with P.yoelii 17XL and nRBC apoptosis, number of peripheral RBCs,parasitaemia and plasmatic levels of cytokines, nitric oxide and anti-RBCantibodies were evaluated at the early and late stages of anaemia. The apoptosisof nRBCs increased at the late stage and was associated with parasitaemia, butnot with the intensity of the immune response. The increased percentage of nRBCapoptosis that was observed when anaemia was accentuated was not related to areduction in peripheral RBCs. We conclude that nRBC apoptosis in P.yoelii malaria appears to be induced in response to a high parasiteload. Further studies on malaria models in which acute anaemia develops duringlow parasitaemia are needed to identify the potential pathogenic role of nRBCapoptosis. 相似文献
15.
16.
17.
Microsatellite loci are generally assumed to evolve via a stepwise mutational process and a battery of statistical techniques has been developed in recent years based on this or related mutation models. It is therefore important to investigate the appropriateness of these models in a wide variety of taxa. We used two approaches to examine mutation patterns in the malaria parasite Plasmodium falciparum: (i) we examined sequence variation at 12 tri-nucleotide repeat loci; and (ii) we analysed patterns of repeat structure and heterozygosity at 114 loci using data from 12 laboratory parasite lines. The sequencing study revealed complex patterns of mutation in five of the 12 loci studied. Alleles at two loci contain indels of 24 bp and 57 bp in flanking regions, while in the other three loci, blocks of imperfect microsatellites appear to be duplicated or inserted; these loci essentially consist of minisatellite repeats, with each repeat unit containing four to eight microsatellites. The survey of heterozygosity revealed a positive relationship between repeat number and microsatellite variability for both di- and trinucleotides, indicating a higher mutation rate in loci with longer repeat arrays. Comparisons of levels of variation in different repeat types indicate that the mutation rate of dinucleotide-bearing loci is 1.6-2.1 times faster than trinucleotides, consistent with the lower mean number of repeats in trinucleotide-bearing loci. However, despite the evidence that microsatellite arrays themselves are evolving in a manner consistent with stepwise mutation model in P. falciparum, the high frequency of complex mutations precludes the use of analytical tools based on this mutation model for many microsatellite-bearing loci in this protozoan. The results call into question the generality of models based on stepwise mutation for analysing microsatellite data, but also demonstrate the ease with which loci that violate model assumptions can be detected using minimal sequencing effort. 相似文献
18.
Srdjan M. Dragovic Tolulope A. Agunbiade Marianna Freudzon Jing Yang Andrew K. Hastings Tyler R. Schleicher Xia Zhou Sam Craft Yu-Min Chuang Floricel Gonzalez Youquan Li Gabriela Hrebikova Abhai Tripathi Godfree Mlambo Lionel Almeras Alexander Ploss George Dimopoulos Erol Fikrig 《Cell host & microbe》2018,23(4):523-535.e5
19.
Cross-reactive antibodies to mycoplasmas found in human sera by the enzyme-linked immunosorbent assay (ELISA) 总被引:1,自引:0,他引:1
Antibodies against Mycoplasma pneumoniae in patients' sera with M. pneumoniae infection were measured by the complement fixation (CF) test and enzyme-linked immunosorbent assay (ELISA). Many patients' sera cross-reacted with heterologous mycoplasmal ELISA antigens such as M. hominis, M. hyorhinis, M. orale, M. pulmonis and M. salivarium. The sera with high CF (CF greater than or equal to 40) titers gave significantly higher ELISA values to M. hyorhinis (P less than 0.001) and M. pulmonis (P less than 0.001), which are not parasitic for humans, than those with low CF (CF less than 20) titer. Human normal immunoglobulin G (human normal IgG) containing 98% or more IgG, prepared from pooled plasma of at least 500 normal human donors, showed ELISA reactions with all mycoplasmal strains used. The nonspecific adsorption of human normal IgG on the surface of plate wells and on medium components which might contaminate mycoplasmal ELISA antigens could be disregarded. These results suggest that cross-reactive antibodies to mycoplasmas exist in human sera, and they affect the results of ELISA for serodiagnosis of M. pneumoniae infection. 相似文献
20.
Reptile and bird hosts of malaria parasites (Plasmodium) have nucleated erythrocytes. Infected blood thus contains a mix of abundant host and scant parasite DNA which has prevented identification of Plasmodium microsatellites. We developed a protocol for isolation of microsatellite markers for Plasmodium mexicanum, a parasite of lizards. The ATT repeat was common in the genome of P. mexicanum, but most (87%) of these repeats were exceptionally long (50–206 + repeats). Seven microsatellite markers with polymerase chain reaction primers are described. The protocol should allow discovery of microsatellites of malaria parasites (with AT‐rich genomes) infecting bird and reptile hosts. 相似文献