Natural antibody response to Plasmodium falciparum merozoite antigens MSP5, MSP9 and EBA175 is associated to clinical protection in the Brazilian Amazon

BACKGROUND: Antibodies have an essential role in the acquired immune response against blood stage P. falciparum infection. Although several antigens have been identified as important antibody targets, it is still elusive which antigens have to be recognized for clinical protection. Herein, we analyzed antibodies from plasmas from symptomatic or asymptomatic individuals living in the same geographic area in the Western Amazon, measuring their recognition of multiple merozoite antigens. METHODS: Specific fragments of genes encoding merozoite proteins AMA1 and members of MSP and EBL families from circulating P. falciparum field isolates present in asymptomatic and symptomatic patients were amplified by PCR. After cloning and expression of different versions of the antigens as recombinant GST-fusion peptides, we tested the reactivity of patients’ plasmas by ELISA and the presence of IgG subclasses in the most reactive plasmas. RESULTS: 11 out of 24 recombinant antigens were recognized by plasmas from either symptomatic or asymptomatic infections. Antibodies to MSP9 (X(2)(DF=1) = 9.26/p = 0.0047) and MSP5 (X(2)(DF=1) = 8.29/p = 0.0069) were more prevalent in asymptomatic individuals whereas the opposite was observed for MSP1 block 2-MAD20 (X(2)(DF=1) = 6.41/p = 0.0206, Fisher’s exact test). Plasmas from asymptomatic individuals reacted more intensely against MSP4 (U = 210.5, p < 0.03), MSP5 (U = 212, p < 0.004), MSP9 (U = 189.5, p < 0.002) and EBA175 (U = 197, p < 0.014, Mann-Whitney’s U test). IgG1 and IgG3 were predominant for all antigens, but some patients also presented with IgG2 and IgG4. The recognition of MSP5 (OR = 0.112, IC(95%) = 0.021-0.585) and MSP9 (OR = 0.125, IC(95%) = 0.030-0.529, cross tab analysis) predicted 8.9 and 8 times less chances, respectively, to present symptoms. Higher antibody levels against MSP5 and EBA175 were associated by odds ratios of 9.4 (IC(95%) = 1.29-69.25) and 5.7 (IC(95%) = 1.12-29.62, logistic regression), respectively, with an asymptomatic status. CONCLUSIONS: Merozoite antigens were targets of cytophilic antibodies and antibodies against MSP5, MSP9 and EBA175 were independently associated with decreased symptoms

Avaliação da incidência da deficiência de Glicose-6-Fosfato Desidrogenase (G6PD) e perfil hematológico em indivíduos de uma região de Rondônia

O estudo compreendeu a avaliação da deficiência de Glicose-6-Fosfato Desidrogenase (G6PD) e perfil hematológico em 122 indivíduos (69 homens e 53 mulheres), com idade variando entre 3 a 84 anos, selecionados conforme a aceitação em participação no estudo, residentes na área urbana e rural do município de Porto Velho, Rondônia, Brasil, no período de julho de 2003 a agosto de 2004. A análise foi realizada utilizando-se o método da glicose NaNO2, e hemograma completo. Foram detectados quatro indivíduos do sexo masculino com deficiência da G6PD, sendo 5,8% entre os homens e 3,3% do total analisado. Dos indivíduos com deficiência da G6PD nenhum apresentava malária, através de diagnóstico realizado pela gota espessa corado pelo Giemsa. Entre os homens, 19 (27,5%) apresentaram malária, sendo 15 por Plasmodium vivax e quatro por Plasmodium falciparum; 48 (69,5%) apresentaram valores de hemoglobina abaixo de 14,0 g/dl, e 26 (37,6%) apresentaram valores eritrocitários abaixo do 4,5 milhões/mm³. Entre as mulheres apenas duas (3,7%) apresentaram malária por Plasmodium vivax; 24 (45,2%) apresentaram valores de hemoglobina abaixo de 12,0 g/dl, e 12 (22,6%) apresentaram massa eritrocitária abaixo de 4,0 milhões/mm³. A eosinofilia esteve presente em 47 (68,1%) dos homens e em 34 (64,1%) das mulheres. A incidência de deficiência da G6PD foi significativa na população masculina que procurou assistência médica devido a sintomas febris. Considerando que a primaquina é utilizada para o tratamento da malária vivax e falciparum, o risco de ocorrência de hemólise intravascular grave entre os indivíduos é significante. O teste utilizado é muito simples e de baixo custo e sugerimos a adoção desta metodologia na rotina dos laboratórios de atendimento público em áreas endêmicas de malária.This study consisted of evaluations of glucose-6-phosphate dehydrogenase (G6PD) deficiency and the hematologic profile of 122 individuals (69 men and 53 women) with ages varying between 3 and 83 years old. The individuals, all of whom were residents of the rural and urban areas of Porto Velho, Rondonia, Brazil, were selected according to their acceptance to participate in the study. The data of this study were collected in the period from July 2003 to August 2004. The analyses consisted of using the glucose NaNO2 method and complete Blood Cell count. Four men had G6PD deficiency (5.8% among the men and 3.3% of the total cases analyzed). None of the individuals with G6PD deficiency presented malaria tested using a thick smear stained with Giemsa stain 20. Among the men, 19 individuals (27.5%) presented malaria with 15 infected by Plasmodium vivax and 4 infected by Plasmodium falciparum. Forty-eight men (69.5%) presented with haemoglobin values of less than 14.0 g/dL and 26 (37.6%) presented erythrocytary values of less than 4.5 millions/mm³. Among the women, just 2 (3.2%) presented with malaria, caused by Plasmodium vivax and 24 (45.2%) presented haemoglobin values less than 12.0 g/dL. Twelve (22.6%) presented erithrocytary values less than 4.0 millions/mm³. Eosinophilia was seen in 47 (68.1%) men and 34 (64.1%) women. The incidence of G6PD deficiency was significant among the male population who sought medical assistance due to fever. As primaquine is used in the radical treatment of malaria caused by both vivax and falciparum infections, the risk of serious intravascular hemolysis is significant among these individuals. The test used is very simple and has a low cost so we suggest its adoption in routine public service laboratories in endemic areas

Natural antibody response to Plasmodium falciparum merozoite antigens MSP5, MSP9 and EBA175 is associated to clinical protection in the Brazilian Amazon

Abstract Background Antibodies have an essential role in the acquired immune response against blood stage P. falciparum infection. Although several antigens have been identified as important antibody targets, it is still elusive which antigens have to be recognized for clinical protection. Herein, we analyzed antibodies from plasmas from symptomatic or asymptomatic individuals living in the same geographic area in the Western Amazon, measuring their recognition of multiple merozoite antigens. Methods Specific fragments of genes encoding merozoite proteins AMA1 and members of MSP and EBL families from circulating P. falciparum field isolates present in asymptomatic and symptomatic patients were amplified by PCR. After cloning and expression of different versions of the antigens as recombinant GST-fusion peptides, we tested the reactivity of patients’ plasmas by ELISA and the presence of IgG subclasses in the most reactive plasmas. Results 11 out of 24 recombinant antigens were recognized by plasmas from either symptomatic or asymptomatic infections. Antibodies to MSP9 (X2 DF=1 = 9.26/p = 0.0047) and MSP5 (X2 DF=1 = 8.29/p = 0.0069) were more prevalent in asymptomatic individuals whereas the opposite was observed for MSP1 block 2-MAD20 (X2 DF=1 = 6.41/p = 0.0206, Fisher’s exact test). Plasmas from asymptomatic individuals reacted more intensely against MSP4 (U = 210.5, p < 0.03), MSP5 (U = 212, p < 0.004), MSP9 (U = 189.5, p < 0.002) and EBA175 (U = 197, p < 0.014, Mann-Whitney’s U test). IgG1 and IgG3 were predominant for all antigens, but some patients also presented with IgG2 and IgG4. The recognition of MSP5 (OR = 0.112, IC95% = 0.021-0.585) and MSP9 (OR = 0.125, IC95% = 0.030-0.529, cross tab analysis) predicted 8.9 and 8 times less chances, respectively, to present symptoms. Higher antibody levels against MSP5 and EBA175 were associated by odds ratios of 9.4 (IC95% = 1.29-69.25) and 5.7 (IC95% = 1.12-29.62, logistic regression), respectively, with an asymptomatic status. Conclusions Merozoite antigens were targets of cytophilic antibodies and antibodies against MSP5, MSP9 and EBA175 were independently associated with decreased symptoms

Natural Plasmodium infection in monkeys in the state of Rondônia (Brazilian Western Amazon)

Submitted by Luciane Willcox ([email protected]) on 2016-09-19T17:56:42Z No. of bitstreams: 1 Natural Plasmodium infection in monkeys.pdf: 788264 bytes, checksum: b2ed5ea62837cac50a01899b4f821875 (MD5)Approved for entry into archive by Luciane Willcox ([email protected]) on 2016-09-19T18:07:01Z (GMT) No. of bitstreams: 1 Natural Plasmodium infection in monkeys.pdf: 788264 bytes, checksum: b2ed5ea62837cac50a01899b4f821875 (MD5)Made available in DSpace on 2016-09-19T18:07:01Z (GMT). No. of bitstreams: 1 Natural Plasmodium infection in monkeys.pdf: 788264 bytes, checksum: b2ed5ea62837cac50a01899b4f821875 (MD5) Previous issue date: 2013-06-03MCT/CNPq/CT AmazôniaFundação Oswaldo Cruz. Instituto de Pesquisa em Patologias Tropicais. Porto Velho, RO, Brasil.Universidade Federal de Rondônia. Departamento de Biologia. Porto Velho, RO, Brasil.Embrapa Amazônia Oriental. Belém, PA, Brasil.Fundação Oswaldo Cruz. Instituto de Pesquisa em Patologias Tropicais. Porto Velho, RO, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto de Pesquisa em Patologias Tropicais. Porto Velho, RO, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto de Pesquisa em Patologias Tropicais. Porto Velho, RO, Brasil.Virginia Commonwealth University. Life Sciences. Center for the Study of Biological Complexity. Richmond, USA. / Department of Microbiology and Immunology. Richmond, USA.BACKGROUND: Simian malaria is still an open question concerning the species of Plasmodium parasites and species of New World monkeys susceptible to the parasites. In addition, the lingering question as to whether these animals are reservoirs for human malaria might become important especially in a scenario of eradication of the disease. To aid in the answers to these questions, monkeys were surveyed for malaria parasite natural infection in the Amazonian state of Rondônia, Brazil, a state with intense environmental alterations due to human activities, which facilitated sampling of the animals. METHODS: Parasites were detected and identified in DNA from blood of monkeys, by PCR with primers for the 18S rRNA, CSP and MSP1 genes and sequencing of the amplified fragments. Multiplex PCR primers for the 18S rRNA genes were designed for the parasite species Plasmodium falciparum and Plasmodium vivax, Plasmodium malariae/Plasmodium brasilianum and Plasmodium simium. RESULTS: An overall infection rate of 10.9% was observed or 20 out 184 monkey specimens surveyed, mostly by P. brasilianum. However, four specimens of monkeys were found infected with P. falciparum, two of them doubly infected with P. brasilianum and P. falciparum. In addition, a species of monkey of the family Aotidae, Aotus nigriceps, is firstly reported here naturally infected with P. brasilianum. None of the monkeys surveyed was found infected with P. simium/P. vivax. CONCLUSION: The rate of natural Plasmodium infection in monkeys in the Brazilian state of Rondônia is in line with previous surveys of simian malaria in the Amazon region. The fact that a monkey species was found that had not previously been described to harbour malaria parasites indicates that the list of monkey species susceptible to Plasmodium infection is yet to be completed. Furthermore, finding monkeys in the region infected with P. falciparum clearly indicates parasite transfer from humans to the animals. Whether this parasite can be transferred back to humans and how persistent the parasite is in monkeys in the wild so to be efficient reservoirs of the disease, is yet to be evaluated. Finding different species of monkeys infected with this parasite species suggests indeed that these animals can act as reservoirs of human malaria

Open Access Natural Plasmodium infection in monkeys in the state of Rondônia (Brazilian Western Amazon)

Background: Simian malaria is still an open question concerning the species of Plasmodium parasites and species of New World monkeys susceptible to the parasites. In addition, the lingering question as to whether these animals are reservoirs for human malaria might become important especially in a scenario of eradication of the disease. To aid in the answers to these questions, monkeys were surveyed for malaria parasite natural infection in the Amazonian state of Rondônia, Brazil, a state with intense environmental alterations due to human activities, which facilitated sampling of the animals. Methods: Parasites were detected and identified in DNA from blood of monkeys, by PCR with primers for the 18S rRNA, CSP and MSP1 genes and sequencing of the amplified fragments. Multiplex PCR primers for the 18S rRNA genes were designed for the parasite species Plasmodium falciparum and Plasmodium vivax, Plasmodium malariae/Plasmodium brasilianum and Plasmodium simium. Results: An overall infection rate of 10.9 % was observed or 20 out 184 monkey specimens surveyed, mostly by P. brasilianum. However, four specimens of monkeys were found infected with P. falciparum, two of them doubly infected with P. brasilianum and P. falciparum. In addition, a species of monkey of the family Aotidae, Aotus nigriceps, is firstly reported here naturally infected with P. brasilianum. None of the monkeys surveyed was found infected with P. simium/P. vivax. Conclusion: The rate of natural Plasmodium infection in monkeys in the Brazilian state of Rondônia is in line with previou