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Plasmodium falciparum parasites causing cerebral malaria share variant surface antigens, but are they specific?

Kheliouen N, Viwami F, Lalya F, Tuikue-Ndam N, Moukoko EC, Rogier C, Deloron P, Aubouy A - Malar. J. (2010)

Bottom Line: The reactivity of plasma samples from each clinical group was measured by flow cytometry against parasites isolated from individuals from each clinical group.In conclusion, this study suggests the existence of serologically distinct VSACM and VSAUM.CM isolates were shown to share common epitopes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut de Recherche pour le Développement (IRD) UMR216, Mother and Child faced with tropical infections Unit, Paris, 75006, France.

ABSTRACT

Background: Variant surface antigens (VSA) expressed on the surface of Plasmodium falciparum-infected red blood cells constitute a key for parasite sequestration and immune evasion. In distinct malaria pathologies, such as placental malaria, specific antibody response against VSA provides protection. This study investigated the antibody response specifically directed against VSA expressed by parasites isolated from individuals presenting a given type of clinical presentation.

Methods: Plasma and isolates were obtained from four groups of Beninese subjects: healthy adults, patients presenting uncomplicated malaria (UM), cerebral malaria (CM), or pregnancy-associated malaria (PAM). The reactivity of plasma samples from each clinical group was measured by flow cytometry against parasites isolated from individuals from each clinical group.

Results: Antibody responses against VSAUM were predominant in CM, UM and HA plasmas. When analysed according to age in all plasma groups, anti-VSACM and -VSAUM antibody levels were similar until six years of age. In older groups (6-18 and >19 years of age), VSAUM antibody levels were higher than VSACM antibody levels (P = .01, P = .0008, respectively). Mean MFI values, measured in all plasmas groups except the PAM plasmas, remained low for anti-VSAPAM antibodies and did not vary with age. One month after infection the level of anti-VSA antibodies able to recognize heterologous VSACM variants was increased in CM patients. In UM patients, antibody levels directed against heterologous VSAUM were similar, both during the infection and one month later.

Conclusions: In conclusion, this study suggests the existence of serologically distinct VSACM and VSAUM. CM isolates were shown to share common epitopes. Specific antibody response to VSAUM was predominant, suggesting a relative low diversity of VSAUM in the study area.

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Related in: MedlinePlus

Mean levels of anti-VSA IgG in Beninese plasma with age, according to the type of isolate tested. The adjacent table specifies the number of different plasma donors, isolates and the total combinations tested for each age group by type of isolate. For UM and CM isolates, the plasma included come from CM, UM, PAM patients and healthy adults. For PAM isolates, the plasma analysed do not include plasmas from PAM women. Error bars indicate standard errors. Homologous samples are not included in the analysis.
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Figure 2: Mean levels of anti-VSA IgG in Beninese plasma with age, according to the type of isolate tested. The adjacent table specifies the number of different plasma donors, isolates and the total combinations tested for each age group by type of isolate. For UM and CM isolates, the plasma included come from CM, UM, PAM patients and healthy adults. For PAM isolates, the plasma analysed do not include plasmas from PAM women. Error bars indicate standard errors. Homologous samples are not included in the analysis.

Mentions: The level of anti-VSA antibodies was analysed at different ages in all plasma groups, except for anti-VSAPAM Abs that were measured only in UM, CM, and HA plasmas (Figure 2). Anti-VSAUM antibodies levels remained at baseline level until 6 years of age, then increased until 12. From that time, a plateau was reached and maintained until 54 with a mean MFI value around 3.5. Overall, MFI levels for anti-VSAUM Abs increased with age (ANCOVA, P < .0001). Anti-VSACM antibodies gradually increased until 18 years then decreased, although values did not vary statistically. Mean MFI values remained low for anti-VSAPAM Abs (max. 1.5) and did not vary with age. VSAUM and VSACM antibody levels were then compared according to three age groups: until 6 years old, between 6 and 18, older than 18. Until 6 years old, levels were similar (t-test). In both other age groups, VSAUM antibody levels were higher than VSACM antibody levels (P = .01, P = .0008, respectively).


Plasmodium falciparum parasites causing cerebral malaria share variant surface antigens, but are they specific?

Kheliouen N, Viwami F, Lalya F, Tuikue-Ndam N, Moukoko EC, Rogier C, Deloron P, Aubouy A - Malar. J. (2010)

Mean levels of anti-VSA IgG in Beninese plasma with age, according to the type of isolate tested. The adjacent table specifies the number of different plasma donors, isolates and the total combinations tested for each age group by type of isolate. For UM and CM isolates, the plasma included come from CM, UM, PAM patients and healthy adults. For PAM isolates, the plasma analysed do not include plasmas from PAM women. Error bars indicate standard errors. Homologous samples are not included in the analysis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2921079&req=5

Figure 2: Mean levels of anti-VSA IgG in Beninese plasma with age, according to the type of isolate tested. The adjacent table specifies the number of different plasma donors, isolates and the total combinations tested for each age group by type of isolate. For UM and CM isolates, the plasma included come from CM, UM, PAM patients and healthy adults. For PAM isolates, the plasma analysed do not include plasmas from PAM women. Error bars indicate standard errors. Homologous samples are not included in the analysis.
Mentions: The level of anti-VSA antibodies was analysed at different ages in all plasma groups, except for anti-VSAPAM Abs that were measured only in UM, CM, and HA plasmas (Figure 2). Anti-VSAUM antibodies levels remained at baseline level until 6 years of age, then increased until 12. From that time, a plateau was reached and maintained until 54 with a mean MFI value around 3.5. Overall, MFI levels for anti-VSAUM Abs increased with age (ANCOVA, P < .0001). Anti-VSACM antibodies gradually increased until 18 years then decreased, although values did not vary statistically. Mean MFI values remained low for anti-VSAPAM Abs (max. 1.5) and did not vary with age. VSAUM and VSACM antibody levels were then compared according to three age groups: until 6 years old, between 6 and 18, older than 18. Until 6 years old, levels were similar (t-test). In both other age groups, VSAUM antibody levels were higher than VSACM antibody levels (P = .01, P = .0008, respectively).

Bottom Line: The reactivity of plasma samples from each clinical group was measured by flow cytometry against parasites isolated from individuals from each clinical group.In conclusion, this study suggests the existence of serologically distinct VSACM and VSAUM.CM isolates were shown to share common epitopes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut de Recherche pour le Développement (IRD) UMR216, Mother and Child faced with tropical infections Unit, Paris, 75006, France.

ABSTRACT

Background: Variant surface antigens (VSA) expressed on the surface of Plasmodium falciparum-infected red blood cells constitute a key for parasite sequestration and immune evasion. In distinct malaria pathologies, such as placental malaria, specific antibody response against VSA provides protection. This study investigated the antibody response specifically directed against VSA expressed by parasites isolated from individuals presenting a given type of clinical presentation.

Methods: Plasma and isolates were obtained from four groups of Beninese subjects: healthy adults, patients presenting uncomplicated malaria (UM), cerebral malaria (CM), or pregnancy-associated malaria (PAM). The reactivity of plasma samples from each clinical group was measured by flow cytometry against parasites isolated from individuals from each clinical group.

Results: Antibody responses against VSAUM were predominant in CM, UM and HA plasmas. When analysed according to age in all plasma groups, anti-VSACM and -VSAUM antibody levels were similar until six years of age. In older groups (6-18 and >19 years of age), VSAUM antibody levels were higher than VSACM antibody levels (P = .01, P = .0008, respectively). Mean MFI values, measured in all plasmas groups except the PAM plasmas, remained low for anti-VSAPAM antibodies and did not vary with age. One month after infection the level of anti-VSA antibodies able to recognize heterologous VSACM variants was increased in CM patients. In UM patients, antibody levels directed against heterologous VSAUM were similar, both during the infection and one month later.

Conclusions: In conclusion, this study suggests the existence of serologically distinct VSACM and VSAUM. CM isolates were shown to share common epitopes. Specific antibody response to VSAUM was predominant, suggesting a relative low diversity of VSAUM in the study area.

Show MeSH
Related in: MedlinePlus