Malaria is a devastating disease caused by one of the world's most pathogenic parasites, Plasmodium. Five species of Plasmodium infect humans: P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi. P. falciparum is the most pathogenic and causes the greatest numbers of deaths. To date, no licensed vaccine against malaria is available, although there are numerous vaccine candidates in various stages of development. Pca 96 is a 96 kDa Plasmodium chabaudi adami protein shown to have a protective property in mice challenged with P. chabaudi adami. Thus, a P. falciparum orthologue of Pca 96 may be useful in vaccine development. BLAST searches with the Pca 96 amino acid and nucleotide sequences revealed proteins with high sequence identity to Pca 96 including the hypothetical P. falciparum PFC0760c and P. yoelii yoelii PY05757 proteins. A peptide sequence FKLGSCYLYIINRNLKEI was found to be conserved in all homologues of Pca 96, including PFC0760c, PY05757 and in the sequences of proteins from 5 other Plasmodium species. Bioinformatic approaches were explored to attempt to find a possible role of the protein and the possible importance of the conserved sequence. The conserved sequence was predicted to be an alpha helix and to contain possible HLA-DRB1*1101 and HLA-DRB1*0401(Dr4Dw4) T-cell epitopes (GSCYLYIINRNLKEI) in addition to a possible H2-Kd T-cell epitope (CYLYIINRNL). Protein-protein interaction predictions revealed that PFC0760c was likely to interact with proteins involved with nucleic acid binding. PFC0760c was predicted to have a domain found in proteins involved in the structural maintenance of chromosomes, which may suggest the protein is involved in chromatid cohesion during mitotic chromosome condensation. PFC0760c was also predicted to be located in the nucleus by the sub cellular prediction program, SubLoc. Anti-peptide antibodies were raised against the conserved amino acid sequence and against a peptide specific for PY05757 (SDDDNRQIQDFE). Both antibodies detected native antigens with immunofluorescence microscopy. The fluorescent signal appeared throughout the parasite cytoplasm and as an intense signal in the parasite nucleus. These immunofluorescence data supports the predicted nuclear location of the protein. A 822 bp portion of PFC0760c gene was expressed as a maltose-binding protein fusion protein (Pf33-MBP). Pf33-MBP was expressed and purified. Reducing SDS-PAGE and western blotting analysis revealed the fusion protein to be expressed at low levels as four bands (79, 60, 45 and 37 kDa). The purified fusion protein was cleaved with Factor Xa. MBP and Pf33 were of similar molecular mass after cleavage. To attempt to obtain better expression and purification, the 822 bp insert from pTS822 was sub-cloned into pGEX4T1. A glutathione-S-transferase (GST)-fusion protein (Pf33-GST) was expressed. The level of expression was poor and therefore not pursued. To take the study further, potential proteins that interact with PFC0760c and Pf33 need to be identified. In addition, immunisation of mice with the protein and subsequent Plasmodium challenge needs to be performed to ascertain the protective potential of the protein. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Human malaria, caused by four species of the intracellular protozoan parasite Plasmodium, is a major health and economic burden in the tropics where the disease is endemic. The biotindependent enzyme acetyl-CoA carboxylase catalyses the commitment step in de novo fatty acid biosynthesis in several organisms. Acetyl-CoA carboxylase is a target for anti-parasitic drug development due to its relevance in membrane biogenesis. This study describes the detection of acetyl-CoA carboxylase and the partial characterisation of the biotinoyl domain of the enzyme of the mouse malaria parasite, Plasmodium yoelii. Acetyl-CoA carboxylase mRNA was detected by RT-PCR performed on total RNA isolated from P. yoelii 17XL-infected mouse erythrocytes using primers designed from PY01695 ORF of the Plasmodb-published MALPY00458 gene of P. yoelii 17XNL. The RT-PCR was confirmed by sequencing and comparative analysis of the sequenced RT-PCR cDNA products. Northern blot analysis performed on total RNA using probes designed from a 1 kb region of the gene showed that the transcript was greater than the predicted 8.7 kb ORF. An immunogenic peptide corresponding to the P. yoelii theoretical acetyl-CoA carboxylase sequence was selected using epitope prediction and multiple sequence alignment algorithms. The immunogenic peptide was coupled to rabbit albumin carrier for immunisation in chickens and the affinity purified antibody titre was approximately 25 mg. The anti-peptide antibodies detected a 330 kD protein in P. yoelii lysate blot, which corresponds to the predicted size of the enzyme. The enzyme was also detected in situ by immunofluorescence microscopy using the anti-peptide antibodies. A 1 kb region of the P. yoelii acetyl-CoA carboxylase gene containing the biotinoyl domain was cloned and expressed in E. coli as 66 kD GST-tag and 45 kD His-tag protein. Both recombinant biotinoyl proteins were shown to contain bound biotin using peroxidaseconjugated avidin-biotin detection system. This suggested in vivo biotinylation of the recombinant P. yoelii biotinoyl protein, possibly by the E. coli biotin protein ligase. The Proscan™ and the NetPhos 2.0™ algorithms were used to predict protein kinase phosphorylation sites on the biotin carboxylase and the carboxyltransferase domains of the enzyme. The three-dimensional structure of the biotinoyl and the biotin carboxylase domains were predicted using the SWISS-MODEL™ homology modelling algorithm. Homology modelling revealed a similarity in the 3D conformation of the predicted P. yoelii biotinoyl domain and the E. coli biotinoyl protein with negligible root mean square deviation. The model also revealed the possibility of inhibiting P. yoelii and falciparum acetyl-CoA carboxylases with soraphen A based on the similarity in conformation with S. cerevisiae biotin carboxylase and the stereochemical properties of the residues predicted to interact with soraphen A. This study demonstrated that malaria parasite expresses acetyl-CoA carboxylase and, combined with data on other enzymes involved in fatty acid metabolism suggests that the parasite synthesizes fatty acids de novo. This enzyme could be a target for rational drug design. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

The Plasmodium falciparum parasite, carried by Anopheles mosquitoes, is currently a global problem due to the rising incidence of resistance of the parasite to available antimalaria drugs. Resistance and difficult treatment groups, including pregnant woman and young children, are pressing for the development of new, safe and effective prophylactic and treatment antimalarials. Because of the extensive process of developing new drugs, researchers and health care professionals have turned to combination therapy where a fast acting antimalarial is combined with slower acting drugs, such as antibiotics. The macrolide antibiotics, erytbromycin and azithromycin, have been studied to a limited extent for their potential antimalarial effect. Certain advantages, such as their safety profile (especially that of azithromycin) in pregnancy and administration to young children, motivates continual research into the advancement of the effect these drugs exude on malaria. Drug delivery systems contribute to the efficacy of medicines, conquering several difficulties of treatment with oral medication. Pheroid™ technology is a patented drug delivery system, mainly consisting of plant and essential fatty acids, and has been demonstrated to entrap, carry and deliver pharmacologically active compounds and other useful molecules. This study compared the in vitro effects of the macrolide antibiotics on the growth of a chloroquine-resistant strain (RSA 11) of Plasmodium falciparum to the effects of the macrolides entrapped in Pheroid™ vesicles on the same strain over and extended observation period of 144 hours. ELISA assays were conducted by analysing the HRP II (histidine-rich protein) levels on a pre-coated microtitre plate. The effects of the type of formulation, concentration and time were compared. The in vitro difference between erythromycin alone and entrapped in Pheroid™ vesicles were found to be statistically significant (p = 0.000000) while the effects of both formulations did not seem to be concentration dependant (p = 0.628424). Prolonged exposure was also statistically meaningful (p = 0.008268), though it seems that exposure need not exceed 96 hours. The type of formulation, in the case of azithromycin (azithromycin alone vs. azitbromycin entrapped in Pheroid™ vesicles), proved statistically significant (P = 0.002572), while neither formulation seemed concentration dependant (P = 0.427731). Prolonged exposure was found to be statistically insignificant for azithromycin (P = 0.221941). / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2010.

The Plasmodium falciparum parasite, carried by Anopheles mosquitoes, is currently a global problem due to the rising incidence of resistance of the parasite to available antimalaria drugs. Resistance and difficult treatment groups, including pregnant woman and young children, are pressing for the development of new, safe and effective prophylactic and treatment antimalarials. Because of the extensive process of developing new drugs, researchers and health care professionals have turned to combination therapy where a fast acting antimalarial is combined with slower acting drugs, such as antibiotics. The macrolide antibiotics, erytbromycin and azithromycin, have been studied to a limited extent for their potential antimalarial effect. Certain advantages, such as their safety profile (especially that of azithromycin) in pregnancy and administration to young children, motivates continual research into the advancement of the effect these drugs exude on malaria. Drug delivery systems contribute to the efficacy of medicines, conquering several difficulties of treatment with oral medication. Pheroid™ technology is a patented drug delivery system, mainly consisting of plant and essential fatty acids, and has been demonstrated to entrap, carry and deliver pharmacologically active compounds and other useful molecules. This study compared the in vitro effects of the macrolide antibiotics on the growth of a chloroquine-resistant strain (RSA 11) of Plasmodium falciparum to the effects of the macrolides entrapped in Pheroid™ vesicles on the same strain over and extended observation period of 144 hours. ELISA assays were conducted by analysing the HRP II (histidine-rich protein) levels on a pre-coated microtitre plate. The effects of the type of formulation, concentration and time were compared. The in vitro difference between erythromycin alone and entrapped in Pheroid™ vesicles were found to be statistically significant (p = 0.000000) while the effects of both formulations did not seem to be concentration dependant (p = 0.628424). Prolonged exposure was also statistically meaningful (p = 0.008268), though it seems that exposure need not exceed 96 hours. The type of formulation, in the case of azithromycin (azithromycin alone vs. azitbromycin entrapped in Pheroid™ vesicles), proved statistically significant (P = 0.002572), while neither formulation seemed concentration dependant (P = 0.427731). Prolonged exposure was found to be statistically insignificant for azithromycin (P = 0.221941). / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2010.

The kinetics of production and role of tumor necrosis factor-alpha (TNF-$ alpha$) and nitric oxide (NO) during the early phase of blood-stage infection with Plasmodium chabaudi AS were investigated using two inbred strains of mice which differ in the level of resistance to this parasite. Analysis of the in vivo expression of TNF-$ alpha$ and inducible nitric oxide synthase (iNOS) revealed that, early during infection, resistant C57BL/6 mice, which clear the infection by 4 weeks, have higher levels of TNF-$ alpha$ and iNOS mRNA in the spleen and TNF-$ alpha$ mRNA in the liver than susceptible A/J mice which succumb to the disease 10 days after initiation of infection. Moreover, resistant mice expressed high levels of IFN-$ gamma$ (a Th1 marker) and low levels of IL-4 (a Th2 marker) mRNA in the spleen, whereas susceptible A/J mice had low levels of IFN-$ gamma$ but high levels of IL-4 mRNA in the spleen early during infection. Increased levels of NO$ sb3 sp-$ were detected in serum of resistant C57BL/6 mice only at the time of peak parasitemia. Furthermore, treatment of resistant C57BL/6 mice with anti-IFN-$ gamma$ and anti-TNF-$ alpha$ monoclonal antibody demonstrated that TNF-$ alpha$, either alone or in synergy with IFN-$ gamma$, plays a major role in the up-regulation of NO production during P. chabaudi AS malaria. Moreover, treatment with the iNOS inhibitor aminoguanidine, eliminated resistance of these mice to infection with P. chabaudi AS without affecting parasitemia, suggesting that NO may not be involved in parasite killing in vivo. Taken together, these results demonstrate that a Th1-associated increase in TNF-$ alpha$ early during infection, as occurs in resistant mice, leads to the up-regulation of NO production which is crucial for survival of the host. On the other hand, our results also suggest that a Th2 response, as occurs in susceptible mice, does not result in protective levels of TNF-$ alpha$ and NO. However, susceptible A/J mice were found to

In areas where malaria is endemic, pregnant women and children bear the main burden of severe and life-threatening malarial disease. The aim of this work was to study the impact of Plasmodium falciparum infection on inflammatory responses in pregnant women and children residing in African countries. In paper I we investigated peripheral blood samples from pregnant women, living in Tanzania, for potential biomarkers of P. falciparum infection during pregnancy. We found that IL-10 and IP-10 were potential candidates, which increased upon infection, irrespective of gestational age. In addition, increased IL-10 and IP-10 and decreased RANTES levels were predictive of an infection. In paper II we investigated frequencies of peripheral blood-cell types and biomarkers upon infection, in pregnant women living in Benin, and assessed the predictive values of variables measured at inclusion for pregnancy outcomes at delivery. Higher IL-10 levels distinguished quantitative PCR-detectable, sub-microscopic infections, at inclusion, but not at delivery. Maternal anaemia at delivery was associated with increased numbers of circulating monocytes, Treg cells and IL-10 levels measured at inclusion. In paper III we investigated neutrophil functions in the context of pregnancy malaria in vivo and in vitro. Numbers of circulating neutrophils and IL-8 levels were reduced in the infected women, whilst increased levels of IL-8 were found in placental blood of those infected. In vitro assays suggested migration of neutrophils to infected placentas, which also was supported by histological examinations showing the presence of neutrophils containing hemozoin (Hz), in the infected placenta. Stimulation of neutrophils with various Hz preparations revealed distinct patterns of neutrophil activation. In paper IV we investigated cytokines and malaria-specific antibody titres in children belonging to two African ethnic groups, living in Mali, with known different susceptibility to malaria. The Fulani showed increased cytokines (IL-6, IL-8, IL-12, IFN-α, IFN-γ) and higher titres of malaria-specific antibody subclasses (IgG, IgM and IgG1-IgG3), compared to the Dogon. Taken together, this thesis shows that host biomarkers in peripheral blood may represent useful diagnostic markers for malaria during pregnancy. The neutrophil population was shown to be highly affected by the presence of P. falciparum parasites, suggesting a role for neutrophils during malaria infections. The Fulani, showed increased pro-inflammatory and antibody responses against P. falciparum parasites, as compared to Dogon, and these differences are established already at an early age. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript.</p>

I denna avhandling presenteras arbete utfört med enzymet humant karboanhydras II (HCAII). Enzymer är en typ av proteiner som accelererar (katalyserar) kemiska reaktioner, vilket är nödvändigt för allt levande. Den naturliga funktionen för HCAII är att katalysera omvandlingen av gasen koldioxid till vätekarbonat, som är löslig i vätska. Detta är viktigt bl.a. för att koldioxid som bildas i kroppen, och fraktas i blodet i form av vätekarbonat, skall hinna över till utandningsluften under den korta tid blodet är i lungorna. Proteiner består av aminosyror som länkats samman i en lång kedja, där varje aminosyra är en av de 20 naturliga aminosyratyperna. Ett proteins struktur och egenskaper bestäms av aminosyrasekvensen, som i sin tur bestäms av genen för just det proteinet. Med genteknik kan ett proteins gen ändras (muteras), så att aminosyrasekvensen ändras, och det har här utnyttjats för att förändra HCAIIs katalytiska egenskaper. Förutom dess naturliga funktion kan HCAII även klyva (hydrolysera) vissa estrar. Mutationer gjordes så att en ’ficka’ i HCAIIs struktur, där molekylerna (substraten) som skall klyvas binder, fick en större volym. På så sätt skapades varianter med en kraftigt ökad kapacitet för att hydrolysera långa estersubstrat jämfört med icke-muterat HCAII. Som en utveckling av detta projekt skapades en mutant av HCAII, som kan hydrolysera ett än mer skrymmande substrat. I ett annat projekt har en ny katalytisk aktivitet skapats i HCAII, som inte utnyttjar enzymets naturliga katalytiska förmåga. Ett nytt estersubstrat konstruerades, med en del som binder kraftigt till HCAII, så att en stark substratbindning erhölls. Sedan muterades vissa aminosyror till en reaktiv aminosyra som heter histidin. Valet av positioner för mutation baserades på en datormodell av enzymet med bundet substrat. Eftersom histidin kan delta i hydrolysreaktioner, får det muterade enzymet möjlighet att klyva substratet. Flera olika mutanter testades, och den effektivaste innehöll ett nära kopplat par av histidiner. Denna mutant undersöktes mer noggrannt, vilket gav viss information om den katalytiska mekanismen. Det långsiktiga målet med detta arbete är att konstruera muterade enzymer som kan klyva giftiga ämnen, eller användas vid framställning av kemikalier. Det finns behov av nya enzymer för olika typer av substrat, och att med rationella metoder skapa nya katalytiska aktiviteter i proteiner är ett svårt vetenskapligt problem som ännu är i ett tidigt utvecklingsskede. / The main part of this thesis describes results from protein engineering experiments, in which the catalytic activity of the enzyme human carbonic anhydrase II (HCAII) is engineered by mutagenesis. This enzyme, which catalyzes the interconversion between CO2 and HCO3- in the body, also has the ability to hydrolyze ester bonds. In one project, the specificity of HCAII towards a panel of para-nitrophenyl ester substrates, with acyl chain lengths ranging from one to five carbon atoms, was changed by enlarging the substrate binding hydrophobic pocket. A variant was identified that has highly increased specificity towards substrates with long acyl chains. The mutant V121A/V143A hydrolyzes pNPV, which has four carbon atoms in the acyl chain, with an efficiency that is increased by a factor of 3000 compared to HCAII. Further, transition state analogues (TSAs) were docked to HCAII and mutant variants, and the results were correlated to the results from kinetic measurements. This indicated that automated docking could be used to some extent to construct HCAII variants with a designed specificity. Using this approach, a HCAII mutant that can hydrolyze a model benzoate ester was created. Interestingly, the resulting variant V121A/V143A/T200A was found to be highly active with other ester substrates as well. For pNPA, a kcat/KM of 1*105 M-1s-1 was achieved, which is the highest efficiency for hydrolysis of carboxylic acid esters reported for any HCAII variant. In another project, the strong affinity between the active site zinc ion and sulfonamide was used to achieve binding of a designed substrate. Thus, the natural Zn-OH- site of HCAII was not used for catalysis, but for substrate binding. The substrate contains a benzenesulfonamide part in one end, with a para-nitrophenyl ester connected via a linker. The linker was chosen to ensure that the scissile bond is positioned close to His-64 and histidine residues introduced by mutagenesis in other positions. Using this approach, an enzyme was designed with a distinctly new two-histidine catalytic site for ester hydrolysis. The mutant, F131H/V135H, has a kcat/KM of approximately 14000 M-1s-1, which corresponds to a rate enhancement of 107 compared to a histidine mimic. Finally, results are reported on a project aimed at cloning and producing a putative carbonic anhydrase from the malaria parasite Plasmodium falciparum. The gene was cloned by PCR and the construct was overexpressed in E. coli. However, the resulting protein was not soluble, and initial attempts to refold it are also reported.

Severe anemia is the most prevalent life-threatening complication of malaria infection. In addition to destruction of red blood cells (RBC), decreased RBC production or erythropoietic suppression has been shown to contribute to malarial anemia. The mechanism of this suppression is unknown, but it is considered to be multifactorial since erythropoietic suppression can be observed in the presence of both inflammatory mediators and parasite-derived factors. Experiments presented in this thesis aimed at determining the role of host cytokines released in response to blood-stage malaria infection and parasite-derived factors in erythropoietic suppression underlying the development of malarial anemia. Pro-inflammatory cytokines released during malaria infection have been proposed to play a central role in erythroid suppression. To dissect the discrete roles of these cytokines in the processes leading to anemia, mice were treated with CpG-oligodeoxynucleotides (CpG-ODN) which, like malaria infection in humans and experimental mouse models, induces an acute type 1 pro-inflammatory response. CpG-ODN treatment induced anemia, which was associated with suppressed erythropoiesis and reduced RBC survival. Importantly, CpG-ODN-induced IFN-gamma was found to be the major factor mediating erythropoietic suppression but not decreased RBC survival. We also studied the roles of Th1, Th2 and anti-inflammatory cytokines produced in response to Plasmodium chabaudi AS infection in the development of erythropoietic suppression during blood-stage malaria. Signal transducer and activator of transcription (STAT)6, required for signaling of the Th2 cytokines IL-4 and IL-13, was shown to play a critical role in malarial anemia by inhibiting the proliferation and differentiation of erythroid cells. We also observed that suppressed erythropoiesis is a general feature in mice infected with various rodent Plasmodium species that differ in their clinical manifestations and immune responses. Since parasite-derived factors have been shown to contribute to malarial pathogenesis including anemia, the contribution of P. falciparum - and P. yoelii-derived products to erythropoietic suppression was investigated. Both Plasmodium-derived and synthetic hemozoin (Hz) suppressed the proliferation but not the maturation of erythroid progenitor cells in vitro. However, P. yoelii-derived Hz but not synthetic Hz induced transient anemia in mice. These findings provide novel insights into the complex interactions between the parasite and host immune system and the regulation of erythropoiesis during severe malarial anemia.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 108-129). / Microfiche. / xi, 129 leaves, bound ill., maps, photos. 29 cm

Malaria is caused by protozoan parasites of the genus Plasmodium, Plasmodiidae family, transmitted to humans through the bite of infected female Anopheles.spp mosquitoes. It is one of the major global public health problems and an important cause of death in young children in Subsaharian Africa.Malaria is both a cause and a consequence of poverty. It best represents the paradigm of the vicious circle of disease and poverty. Recent estimates suggest that malaria alone costs about 12 billion US dollars to the endemic countries of Africa, and therefore represents a major constraint to economic progress. Today, Africa continues to carry the brunt of the global malaria burden with around 350-550 million clinical episodes and between 700.000 and 1.6 million deaths annually, representing 80-90% of the all malaria deaths in the world, mostly in children younger than five years and pregnant women. Estimates of malaria mortality are rather imprecise. However, describing the contribution of malaria to under five mortality is a very important and relevant objective. It improves the precision of our burden estimate, and helps prioritize and guide control efforts, as well as evaluate its impact. However in rural areas of Africa such as Mozambique, many children are born and die without ever being registered, and a significant proportion of all deaths take place outside health facilities. In this scenario, the only way of estimating the likely cause of death is through an interview of a witness of the final illness. This is called a verbal autopsy (VA).The last decades have witnessed the establishment of a network of centres throughout the continent that include continuous demographic surveillance of defined populations, the so called Demographic Surveillance Sites (DSS). The DSS have been established to record prospectively demographic information, including births and deaths, to investigate epidemiological and social determinants, and to provide a platform on which to undertake large-scale community interventions trials.The first article of this thesis describes 10 year data from the Manhiça DSS on the most frequent causes of mortality in children under 15 years of age, between 1997 and 2006. During this period, 10037 deaths were recorded, of which 3730 were recorded in children under 15 years old. Verbal autopsy interviews were conducted for 3002 (80.4%) of these deaths. According to respondents, 54% of deaths occurred outside a health facility. Overall, malaria accounted for 22% of all deaths, but the relative frequency was highest in children 1 to 4 years of age, accounting for 34% of all deaths corresponding to a mortality rate of 6.1 deaths/1000 pyrs.The last decade has witnessed a renewed effort in the study and control of this disease. New tools are becoming available, and the development of a vaccine is considered a potentially key component for improved control.GlaxoSmithKline (GSK) Biological's RTS,S,AS02A is a currently the world's most clinically-advanced malaria vaccine candidate. RTS,S/AS02A specifically targets the pre-erythrocytic stage of P. falciparum, and has been shown to confer protection against P. falciparum infection, delivered via laboratory-reared infected mosquitoes, in immunised malaria naive volunteers and against natural infection in semi-immune adult and immune children.As part of the clinical development plan, we conducted a Proof of Concept randomised, controlled, phase IIb trial of RTS,S/AS02A in 2022 Mozambican children aged 1-4 years living in a rural endemic area of Mozambique. The initial double blind phase included study months 0 to 8.5 and the single blind phase from study months 8.5 to 21. The open phase included study months 21 to 45. Children were randomised in a 1:1 ratio to receive RTS,S/AS02A or the control vaccines. The RTS,S/AS02A was administered intramuscularly in the deltoid region according to a 0, 1, and 2 month schedule. Children aged 24 months and older in the control group received three paediatric doses (0.5 ml) of Engerix-B . Children under 24 months received two paediatric doses of Prevenar , administered at the first and third vaccinations and one dose of Hiberix , at the second vaccination. Good safety profile and immunogenicity has been confirmed. Considering the entire follow up period of 45 months, Vaccine Efficacy (VE)(2.5-45) against first or only episode of clinical malaria disease was 30.5% (95% CI 18.9-40.4; p=<0.001), and VE against severe malaria was 38.3% (95% CI 3.4 to 61.3; p=0.045).These results highlight the feasibility of developing a malaria vaccine that may protect children against malaria, and may therefore be a useful component of the strategies to improve malaria control. / EN CASTELLANO: La malaria es causada por un parásito protozoario del género "Plasmodium", de la familia "Plasmodium Plasmodiiade", transmitido a los humanos a través de la picadura de un mosquito Anófeles.spp hembra infectado. Es uno de los mayores problemas de salud pública en el África Subsahariana y una de las causas más importantes de muerte en niños pequeños en la región.La malaria es tanto una causa como una consecuencia de la pobreza. Recientes estimaciones sugieren que la malaria cuesta aproximadamente 12.000 millones de dólares americanos a los países endémicos de África, y por consiguiente, representa un constreñimiento mayor al progreso económico de dichos países. Actualmente, África continúa soportando la mayor carga de malaria del mundo, con aproximadamente 350-550 millones de episodios clínicos y entre 700.000 y 1.6 millones de muertes anuales. Así, representa el 80-90% de la malaria en el mundo, la mayoría en niños menores de 5 años y mujeres embarazadas. Las últimas décadas han sido testimonio del establecimiento de una red de centros a lo largo del continente, que incluye a vigilancia demográfica continuada de poblaciones definidas, los llamados Sistemas de Vigilancia Demográficos (DSS). Los DSS han sido creados para registrar prospectivamente informaciones demográficas, incluyendo los nacimientos y las muertes, para investigar los determinantes epidemiológicos y sociales, y para proveer con una plataforma en la cual se puedan llevar a cabo ensayos de intervención comunitaria a gran escala.Durante los últimos diez años se ha asistido a un esfuerzo renovado en el estudio y el control de esta enfermedad. Se dispone de nuevas herramientas y en concreto se está avanzando en el desarrollo de una vacuna como componente potencialmente importante para un mejor control. Actualmente, la RTS,S/AS02A GlaxoSmithKline (GSK) Biological es la vacuna candidata contra la malaria más avanzada del mundo. Su objetivo específico es la actuación en el estado pre-eritrocítrico del "P.falciparum" y ha demostrado su validez a la hora de conferir protección contra la infección experimental por P.falciparum, administrada via mosquitos infectados criados en el laboratorio, en voluntarios nunca expuestos previamente y contra la infección natural en adultos semi inmunes y niños inmunes.Como parte del plan de desarrollo clínico, realizamos un estudio prueba de concepto, aleatorizado, controlado, de fase IIb de RTS,S/AS02A en 2022 niños mozambiqueños de 1 a 4 años de edad viviendo en una área rural endémica. Los resultados demostraron un buen perfil de seguridad y una buena respuesta inmunitaria. Durante el periodo de vigilancia, la eficacia de la vacuna (VE) (2.5-45) contra un primer o único episodio de malaria clínica fue del 30.5% (95% CI 18.9-40.4; p=<0.001) y contra malaria severa fue del 38.3% (95% CI 3.4 - 61.3;p=0.045).Estos resultados resaltan la viabilidad del desarrollo de una vacuna contra la malaria y puede ser, por consiguiente, un componente útil entre las estrategias para mejorar su control.