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Non-O ABO blood group genotypes differ in their associations with Plasmodium falciparum rosetting and severe malaria.

ABSTRACT: Blood group O is associated with protection against severe malaria and reduced size and stability of P. falciparum-host red blood cell (RBC) rosettes compared to non-O blood groups. Whether the non-O blood groups encoded by the specific ABO genotypes AO, BO, AA, BB and AB differ in their associations with severe malaria and rosetting is unknown. The A and B antigens are host RBC receptors for rosetting, hence we hypothesized that the higher levels of A and/or B antigen on RBCs from AA, BB and AB genotypes compared to AO/BO genotypes could lead to larger rosettes, increased microvascular obstruction and higher risk of malaria pathology. We used a case-control study of Kenyan children and in vitro adhesion assays to test the hypothesis that "double dose" non-O genotypes (AA, BB, AB) are associated with increased risk of severe malaria and larger rosettes than "single dose" heterozygotes (AO, BO). In the case-control study, compared to OO, the double dose genotypes consistently had higher odds ratios (OR) for severe malaria than single dose genotypes, with AB (OR 1.93) and AO (OR 1.27) showing most marked difference (p = 0.02, Wald test). In vitro experiments with blood group A-preferring P. falciparum parasites showed that significantly larger rosettes were formed with AA and AB host RBCs compared to OO, whereas AO and BO genotypes rosettes were indistinguishable from OO. Overall, the data show that ABO genotype influences P. falciparum rosetting and support the hypothesis that double dose non-O genotypes confer a greater risk of severe malaria than AO/BO heterozygosity.

SUBMITTER: Opi DH

PROVIDER: S-EPMC10522014 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature

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Non-O ABO blood group genotypes differ in their associations with Plasmodium falciparum rosetting and severe malaria.

Opi D Herbert DH Ndila Carolyne M CM Uyoga Sophie S Macharia Alex W AW Fennell Clare C Ochola Lucy B LB Nyutu Gideon G Siddondo Bethseba R BR Ojal John J Shebe Mohammed M Awuondo Kennedy O KO Mturi Neema N Peshu Norbert N Tsofa Benjamin B Band Gavin G Maitland Kathryn K Kwiatkowski Dominic P DP Rockett Kirk A KA Williams Thomas N TN Rowe J Alexandra JA

PLoS genetics 20230914 9

Blood group O is associated with protection against severe malaria and reduced size and stability of P. falciparum-host red blood cell (RBC) rosettes compared to non-O blood groups. Whether the non-O blood groups encoded by the specific ABO genotypes AO, BO, AA, BB and AB differ in their associations with severe malaria and rosetting is unknown. The A and B antigens are host RBC receptors for rosetting, hence we hypothesized that the higher levels of A and/or B antigen on RBCs from AA, BB and AB ...[more]

PMID: 37708213

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Project description:Background: The cytoadherence of Plasmodium falciparum is thought to be mediated by variant surface antigens (VSA), encoded by var, rif, stevor and pfmc-2tm genes. The last three families have rarely been studied in the context of cytoadherence. As most VSA genes are unique, the variability among sequences has impeded the functional study of VSA across different P. falciparum strains. However, many P. falciparum genomes have recently been sequenced, allowing the development of specific microarray probes to each VSA gene. Methods: All VSA sequences from the HB3, Dd2 and IT/FCR3 genomes were extracted using HMMer. Oligonucleotide probes were designed with OligoRankPick and added to the 3D7-based microarray chip. As a proof of concept, IT/R29 parasites were selected for and against rosette formation and the transcriptomes of isogenic rosetting and non-rosetting parasites were compared by microarray. Results: From each parasite strain 50-56 var genes, 125-132 rif genes, 26-33 stevor genes and 3-8 pfmc-2tm genes were identified. The ability of the VSA-supplemented microarray chip to detect cytoadherence-related genes was assessed using P. falciparum clone IT/R29, in which rosetting is known to be mediated by PfEMP1 encoded by ITvar9. Whole transcriptome analysis showed that the most highly upregulated gene in rosetting parasites was ITvar9 (19 to 429-fold upregulated over six time points). Only one rif gene (IT4rifA_042) was upregulated by more than 4-fold (5-fold at 12 hours post-invasion), and no stevor or pfmc-2tm genes were upregulated by more than 2-fold. 49 non-VSA genes were upregulated in rosetting parasites by more than 3-fold in at least two time-points, although none as markedly as ITvar9. Conclusions: We demonstrate that the VSA of newly sequenced P. falciparum strains can be added to the 3D7-based microarray chip, allowing the analysis of the entire transcriptome of multiple strains. For the rosetting clone IT/R29, the striking transcriptional upregulation of ITvar9 was confirmed, and the data did not support the involvement of other VSA families in rosette formation.

Dataset Information

Non-O ABO blood group genotypes differ in their associations with Plasmodium falciparum rosetting and severe malaria.

Publications

Non-O ABO blood group genotypes differ in their associations with Plasmodium falciparum rosetting and severe malaria.

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