Anti-NANP antibody and treatment efficacy in patients with acute uncomplicated falciparum malaria attacks.
African patients originating from the hypoendemic, urban area of Greater Dakar (Senegal, West Africa) who presented with an acute Plasmodium falciparum infection were studied using an in-vivo chloroquine sensitivity assay for 28 days. Forty-seven patients with acute malaria infections were treated with 25 mg/body weight of chloroquine. Adequate responses to treatment were observed in 24 patients (51%), whereas 23 (49%) were resistant. On the day of admission, these two groups of patients were comparable with respect to age, level of parasitemia and delay before initiation of treatment, but not with respect to gametocyte prevalence which was higher in patients resistant to therapy (48%) than in those who responded to treatment (17%). In order to evaluate whether the therapeutic response was associated with any given specific immune response, antibody activities against different stages of the parasite cycle were evaluated: anti-NANP repeats (i.e. antisporozoite stage antigen), anti-Pfs 45 kDa (i.e. antigametocyte stage antigen), and anti-MSP3 (i.e. antimerozoite stage antigen) antibodies were measured by ELISA at day 0 (i.e. on the day of admission and before initiation of treatment), day 7 and day 28. No significant differences between treatment-sensitive and treatment-resistant infections were observed for antibody prevalences and optical densities, except at day 0, when the prevalence of antibodies against NANP repeats was 2.4 times more frequent in the group of patients with a propitious response to treatment: 62.5% of the patients with an infection sensitive to chloroquine had anti-NANP antibodies, whereas only 26.1% of the patients resistant to chloroquine treatment had such a humoral response. These observations are discussed in relation to (1) the finding that gametocyte prevalence was markedly increased at a time when resistance to antimalarial treatment was observed; (2) the possibility that the efficacy of the therapeutic response could be the result of the combined effects of treatment and the individual immune status of the patients at the time of drug cure; and (3) the presence of detectable anti-NANP activity as potential indicator of the level of premunition acquired in an area of low and seasonal malaria transmission.
Robert
V
V
Institut de Recherche pour le Développement (ex-Orstom), Laboratoire de Paludologie, Dakar, Sénégal. robert@pasteur.mg
Roeffen
W
W
Brasseur
P
P
Aribot
G
G
Verhave
J P
JP
Roussilhon
C
C
D000293:Adolescent; D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000276:immunology*; D000962:Antimalarials / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D002738:Chloroquine / Q000627:therapeutic use*; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy* / Q000469:parasitology; D008562:Membrane Glycoproteins / Q000276:immunology; D010963:Plasmodium falciparum / Q000187:drug effects / Q000254:growth & development / Q000276:immunology; D015800:Protozoan Proteins / Q000276:immunology; D016896:Treatment Outcome
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D000962:Antimalarials; D008562:Membrane Glycoproteins; D015800:Protozoan Proteins; C089133:merozoite surface protein 3, Plasmodium; C084847:pfs48-45 protein, Plasmodium falciparum; D002738:Chloroquine