Association of apoptosis-related variants to malaria infection and parasite density in individuals from the Brazilian Amazon.

BACKGROUND: In malaria infection, apoptosis acts as an important immunomodulatory mechanism that leads to the elimination of parasitized cells, thus reducing the parasite density and controlling immune cell populations. Here, it was investigated the association of INDEL variants in apoptotic genes-rs10562972 (FAS), rs4197 (FADD), rs3834129 and rs59308963 (CASP8), rs61079693 (CASP9), rs4647655 (CASP3), rs11269260 (BCL-2), and rs17880560 (TP53)-and the influence of genetic ancestry with susceptibility to malaria and parasite density in an admixed population from the Brazilian Amazon. METHODS: Total DNA was extracted from 126 malaria patients and 101 uninfected individuals for investigation of genetic ancestries and genotypic distribution of apoptosis-related variants by Multiplex PCR. Association analyses consisted of multivariate logistic regressions, considering the following comparisons: (i) DEL/DEL genotype vs. INS/DEL + INS/INS; and (ii) INS/INS vs. INS/DEL + DEL/DEL. RESULTS: Individuals infected by Plasmodium falciparum had significantly higher African ancestry proportions in comparison to uninfected controls, Plasmodium vivax, and mixed infections. The INS/INS genotype of rs3834129 (CASP8) seemed to increase the risk for P. falciparum infection (P = 0.038; OR = 1.867; 95% CI 0.736-3.725), while the DEL/DEL genotype presented a significant protective effect against infection by P. falciparum (P = 0.049; OR = 0.446; 95% CI 0.185-0.944) and mixed infection (P = 0.026; OR = 0.545; 95% CI 0.281-0.996), and was associated with lower parasite density in P. falciparum malaria (P = 0.009; OR = 0.383; 95% CI 0.113-1.295). Additionally, the INS/INS genotype of rs10562972 (FAS) was more frequent among individuals infected with P. vivax compared to P. falciparum (P = 0.036; OR = 2.493; 95% CI 1.104-4.551), and the DEL/DEL genotype of rs17880560 (TP53) was significantly more present in patients with mono-infection by P. vivax than in individuals with mixed infection (P = 0.029; OR = 0.667; 95% CI 0.211-1.669). CONCLUSIONS: In conclusion, variants in apoptosis genes are associated with malaria susceptibility and parasite density, indicating the role of apoptosis-related genetic profiles in immune responses against malaria infection.

Mixed Plasmodium malariae Infections Were Underdetected in a Malaria Endemic Area in the Amazon Region, Brazil.

Plasmodium malariae infections are often asymptomatic and long-lasting. Mixed infections are often underdetected in areas where P. malariae, P. vivax, and P. falciparum are coendemic. In this study, we described the occurrence of these species circulating as single or mixed infections in Pará state, Brazil, in the Amazon region, with the purpose of clarifying the impact of misidentification of parasite species based only on morphological description using thick blood smear. By using real-time polymerase chain reaction based on the amplification of the mitochondrial DNA, we detected a prevalence of 46% (58/126) mixed infections with 33.3% P. malariae/P. vivax which were read as P. vivax monoinfections by microscopy detection. Our findings confirmed the high circulation of P. malariae in a malaria endemic area in the Brazilian Amazon region.

Plasmodium vivax AMA1: Implications of distinct haplotypes for immune response.

In Brazil, Plasmodium vivax infection accounts for around 80% of malaria cases. This infection has a substantial impact on the productivity of the local population as the course of the disease is usually prolonged and the development of acquired immunity in endemic areas takes several years. The recent emergence of drug-resistant strains has intensified research on alternative control methods such as vaccines. There is currently no effective available vaccine against malaria; however, numerous candidates have been studied in the past several years. One of the leading candidates is apical membrane antigen 1 (AMA1). This protein is involved in the invasion of Apicomplexa parasites into host cells, participating in the formation of a moving junction. Understanding how the genetic diversity of an antigen influences the immune response is highly important for vaccine development. In this study, we analyzed the diversity of AMA1 from Brazilian P. vivax isolates and 19 haplotypes of P. vivax were found. Among those sequences, 33 nonsynonymous PvAMA1 amino acid sites were identified, whereas 20 of these sites were determined to be located in predicted B-cell epitopes. Nonsynonymous mutations were evaluated for their influence on the immune recognition of these antigens. Two distinct haplotypes, 5 and 16, were expressed and evaluated for reactivity in individuals from northern Brazil. Both PvAMA1 variants were reactive. Moreover, the IgG antibody response to these two PvAMA1 variants was analyzed in an exposed but noninfected population from a P. vivax endemic area. Interestingly, over 40% of this population had antibodies recognizing both variants. These results have implications for the design of a vaccine based on a polymorphic antigen.

The effect of SNPs in CYP450 in chloroquine/primaquine Plasmodium vivax malaria treatment.

BACKGROUND: Chloroquine/primaquine is the current therapy to eliminate Plasmodium vivax infection in the Amazon region. AIMS: This study investigates CYP1A2, CYP2C8, CYP2C9, CYP3A4 and CYP3A5 genetic polymorphisms influence on cloroquine/primaquine treatment. PATIENTS & METHODS: Generalized estimating equations analyses were performed to determine the genetic influence in parasitemia and/or gametocytemia clearance over treatment time in 164 patients. RESULTS: An effect of CYP2C8 low-activity alleles on treatment was observed (p = 0.01). From baseline to first day of treatment, wild-type individuals achieved greater reduction of gametocytes than low-activity allele carriers. CYP2C9 and CYP3A5 genes showed a trend for gametocytemia and parasitemia clearance rates. CONCLUSION: Future studies should be performed to access the extent of CYP2C8, CYP2C9 and CYP3A5 gene polymorphisms influence on cloroquine/primaquine treatment.

Malária por Plasmodium vivax em crianças e adolescentes - aspectos epidemiológicos, clínicos e laboratoriais / Plasmodium vivax malaria in children and adolescents - epidemiological, clinical and laboratory features

Objetivo: Avaliaçäo dos aspectos epidemiológicos, clínicos e laboratoriais da malária por Plasmodium vivax em crianças e adolescentes. Métodos: No ambulatório do Programa de Malária do Instituto Evandro Chagas (Belém-Pará), no período de janeiro de 1995 a novembro de 1996, foram estudadas de modo aleatório 100 crianças e adolescentes com diagnóstico positivo por gota espessa para malária por P. vivax. Elaborou-se um protocolo para avaliaçäo dos aspectos epidemiológicos, clínicos e laboratoriais dessa patologia. Resultados: Acometimento de ambos os sexos, com predomínio entre os adolescentes (37 por cento). As crianças e adolescentes em sua maioria (92 por cento) adquiriram a infecçäo no Pará. Os casos autóctones, área metropolitana de Belém, representaram 34 por ceneto da amostra. Primoinfecçäo ocorreu em 80 por cento dos pacientes. Febre foi a manifestaçäo clínica inicial mais freqüênte (88 por cento). Relato de paroxismo febril típico (febre terçä) foi obtido em somente 25 por cento da casuística. No 1§ dia de tratamento (DO) febre (97 por cento), calafrio (91 por cento), palidez (85 por cento), esplenomegalia (46 por cento) e hepatomegalia (29 por cento) foram alguns dos sinais e sintomas observados. Houve significância estatística (p=0,0004) na correlaçäo entre palidez (avaliaçäo clínica) e anemia (taxa de hemoglobina). Verificou-se uma correlaçäo negativa altamente significativa (p=0,0001) entre o retardo diagnóstico (média de 12,5 dias) e os níveis de hemoglobina. Em relaçäo ao exame parasitológico de fezes, somente crianças e adolescentes com resultado positivo para ancilostomídeos foram significativamente mais anêmicas (p=0,0133,p=0,0075) quando comparadas com aquelas com exame coprológico positivo para outros helmintos e/ou protozoários. Conclusöes: A malária acometeu crianças e adolescentes de ambos os sexos. A valorizaçäo de dados epidemiológicos e clínicos contribui para o diagnóstico precoce da doença. O retardo diagnóstico influenciou no agravamento da anemia

Eficácia de quatro esquemas terapêuticos para malaria vivax em crianças / Clinical efficacy of four schemes for vivax malaria treatment in children

Objetivo: A cura da malaria vivax permanece dificultada por um fator determinante de recaídas: a duraçäo do tratamento. Em Belém, a observaçäo de que um grande número de pacientes com malária vivax curava-se, a despeito do abandono do tratamento, levou à concretizaçäo deste estudo objetivando avaliar a eficácia de esquemas mais operacionais para malária em crianças. Métodos: Foi realizado ensaio clínico prospectivo e randomizado, em 200 crianças com malária vivax, atendidas ambulatorialmente. Variáveis observadas: velocidade de negativaçäo da parasitemia e respostas a quatro esquemas: a) cloroquina 10mg/kg - dose única (cloroquina DU) + primaquina 0,50/kg/dia por 7 dias; b) cloroquina DU + primaquina 0,25/kg/dia por 7 dias; c) cloroquina DU + primaquina 0,50/kg/dia por 5 dias; e d) cloroquina DU + primaquina 0,25/kg/dia por 5 dias. Para comparaçäo das resposwtas obtidas foi utilizado o teste exato de Fisher. Resultados: Todas as 144 crianças que completaram o estudo apresentaram negativaçäo da parasitemia até o quarto dia de tratamento. A comparaçäo das respostas aos esquemas, mostrou resultados significativos entre os esquemas A e D (p=0,022), e entre os esquemas C e D (p=0,005). Quanto à dose diária e ao tempo de duraçäo, a comparaçäo mostrou resultados significativos nos esquemas de doses duplicadas em relaçäo aos de dose padräo(p=0,0042)...