RESUMO
Plasmodium falciparum-infected erythrocytes (PfE) were collected from acutely infected children in The Gambia and Tanzania and cultured for more than 30 hr until the parasites were mature trophozoites. Sera collected from these countries, other African countries, Asia, and South America were used in the PfE microagglutination test to determine whether PfE from East and West Africa share surface antigens. From the patterns of agglutination reactivity, we identified extensive antigenic diversity in surface antigens, but obtained no evidence for greater differences between isolates from East or West Africa and those within one region. The majority of sera from immune adults from The Gambia, Tanzania, Sudan, Nigeria, or Ghana were pan-agglutinating, and agglutinated all PfE isolates from The Gambia and Tanzania. Some sera from immune adults of Irian Jaya also agglutinated each of the seven African isolates, while others agglutinated many but not all of the isolates, similar to sera from immune adults of Flores, Indonesia. In contrast, sera from nonimmune adults from Colombia agglutinated few of the African isolates. It was remarkable, however, that sera from nonimmune Colombians agglutinated any African isolates. Our results are consistent with the following conclusions: some PfE surface antigen(s) are very diverse; this diversity is a feature of the parasite worldwide; the repertoire of isolate-specific surface antigens, although large, includes antigens that are either identical or antigenically cross-reactive in geographically very distant parasite populations; and African adults have pan-agglutinating antibodies that may contribute to protective immunity. Such pan-agglutinating antibodies could reflect the accumulation of a large repertoire of isolate-specific antibodies. The contribution of antibody against any shared PfE surface antigen to the pan-agglutinating reactivities is unknown and awaits development of the appropriate reagents.
Assuntos
Antígenos de Protozoários/imunologia , Antígenos de Superfície/imunologia , Testes de Hemaglutinação , Malária Falciparum/imunologia , Plasmodium falciparum/imunologia , Adolescente , Adulto , África Oriental , África Ocidental , Animais , Sudeste Asiático , Criança , Colômbia , Eritrócitos/parasitologia , Humanos , Malária Falciparum/sangue , Pessoa de Meia-Idade , Plasmodium falciparum/classificaçãoRESUMO
Epidemiologic and immunologic factors determine the impact of malaria on the demography and economics of human communities. Where malaria is epidemiologically stable, its effects are most obvious in young children; adults, because of acquired immunity, are much less affected and remain an economically viable workforce. Where the disease is unstable, it affects all age groups and may incapacitate adults enough to impede food production seriously. Three areas are identified in which malaria may adversely affect host nutrition: low birth weight, the development of protein energy malnutrition, and the pathogenesis of anemia. The influence of host nutrition on malarial infections is considered. The view is expressed that, although deficiencies of some dietary factors may potentiate the resistance to malaria conferred by some genetic traits, there is as yet little convincing evidence that malnutritional states in humans materially enhance the severity or lethality of plasmodial infections.