Abstract INTRODUCTION Mutations in the propeller domain of the Plasmodium falciparum kelch13 (k13) gene are associated with artemisinin resistance. METHODS: We developed a PCR protocol to sequence the pfk13 gene and determined its sequence in a batch of 50 samples collected from 2003 to 2016 in Brazil. RESULTS: We identified 1 K189T substitution located outside the propeller domain of the PfK13 protein in 36% of samples. CONCLUSIONS: Although the sample size is relatively small, these results suggest that P. falciparum artemisinin-resistant mutants do not exist in Brazil, thereby supporting the continuation of current treatment programs based on artemisinin-based combination therapy.

OBJETIVOS: avaliar a resposta de anticorpos IgG anti-P. vivax (IgG anti-PV) e suas subclasses citofílicas (IgG1 e IgG3) e não citofílicas (IgG2), em 34 crianças com malária por P. vivax, de 0 a 15 anos de idade. MÉTODOS: os níveis de anticorpos IgG foram mensurados pela técnica de imunofluorescência indireta, durante a fase aguda e de controle de cura. Os pacientes foram distribuídos em dois grupos, de priminfectados e pacientes com história de malária anterior. Os níveis de anticorpos no dia do início do tratamento (ou dia zero) e no último dia de tratamento (ou D7) foram comparados (teste t de Student) e correlacionados com a parasitemia assexuada nos dois grupos (Correlação de Spearman). RESULTADOS E CONCLUÕES : foi observado aumento inicial significativo dos títulos de IgG anti-PV no início e no final do tratamento. As médias geométricas dos títulos de subclasses de IgG anti-PV encontradas nos pacientes com história prévia de malária foram IgG1 (806,35) > IgG3 (28,28) > IgG2 (20). Nos pacientes priminfectados as respostas obtidas foram IgG1 (709,21) > IgG3 (39,3) > IgG2 (10,7). Não ocorreu associação entre parasitemia assexuada e títulos de IgG anti-PV no primeiro dia de tratamento. Houve predominância de anticorpos citofílicos (IgG1> IgG3) sobre os não citofílicos.

OBJECTIVE: To assess the IgG antibody response against P. vivax (IgG anti-PV), and cytophilic (IgG1 and IgG3) and noncytophilic (IgG2) IgG subclasses in 34 children aged 0 to 15 years old infected with P. vivax malaria. METHODS: IgG levels were determined by indirect fluorescent antibody technique during the acute and therapeutic control phase. Patients were distributed into 2 groups according to the presence or absence of a previous malaria episode. IgG anti-PV levels were measured on the first and last day of treatment, and compared by Student's t test. Antibody levels were correlated with asexual parasitemia (Spearman's correlation test). RESULTS AND CONCLUSIONS : Increased IgG levels were observed on the first and on the last day of treatment. The geometric means for IgG subclass titers found in patients with previous history of malaria were: IgG1 (806.35) > IgG3 (28.28) > IgG2 (20). In patients infected for the first time, the responses obtained were: IgG1 (709.21) > IgG3 (39.3) > IgG2 (10.7). There was no association between asexual parasitemia and antibody levels on the first day of treatment. Cytophilic antibodies (IgG1, IgG3) predominated over noncytophilic antibodies (IgG2).