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  • Cao, Jun  (3)
  • Lu, Feng  (3)
  • 2020-2024  (3)
  • 1
    Online Resource
    Online Resource
    Elicitation of T-cell-derived IFN-γ-dependent immunity by highly conserved Plasmodium ovale curtisi Duffy binding protein domain region II (PocDBP-RII)
    Springer Science and Business Media LLC ; 2023
    In:  Parasites & Vectors Vol. 16, No. 1 ( 2023-08-08)
    Details
    In: Parasites & Vectors, Springer Science and Business Media LLC, Vol. 16, No. 1 ( 2023-08-08)
    Abstract: Infections with Plasmodium ovale are widely distributed but rarely investigated, and the resulting burden of disease has been underestimated. Plasmodium ovale curtisi Duffy binding protein domain region II ( PocDBP-RII ) is an essential ligand for reticulocyte recognition and host cell invasion by P. ovale curtisi . However, the genomic variation, antigenicity and immunogenicity of PocDBP-RII remain major knowledge gaps. Methods A total of 93 P. ovale curtisi samples were collected from migrant workers who returned to China from 17 countries in Africa between 2012 and 2016. The genetic polymorphism, natural selection and copy number variation (CNV) were investigated by sequencing and real-time PCR. The antigenicity and immunogenicity of the recombinant PocDBP-RII (rPocDBP-RII) protein were further examined, and the humoral and cellular responses of immunized mice were assessed using protein microarrays and flow cytometry. Results Efficiently expressed and purified rPocDBP-RII (39 kDa) was successfully used as an antigen for immunization in mice. The haplotype diversity (Hd) of PocDBP-RII gene was 0.105, and the nucleotide diversity index (π) was 0.00011. No increased copy number was found among the collected isolates of P. ovale curtisi . Furthermore, rPocDBP-RII induced persistent antigen-specific antibody production with a serum IgG antibody titer of 1: 16,000. IFN-γ-producing T cells, rather than IL-10-producing cells, were activated in response to the stimulation of rPocDBP-RII. Compared to PBS-immunized mice (negative control), there was a higher percentage of CD4 + CD44 high CD62L − T cells (effector memory T cells) and CD8 + CD44 high CD62L + T cells (central memory T cells) in rPocDBP-RII‑immunized mice. Conclusions PocDBP-RII sequences were highly conserved in clinical isolates of P. ovale curtisi . rPocDBP-RII protein could mediate protective blood-stage immunity through IFN-γ-producing CD4 + and CD8 + T cells and memory T cells, in addition to inducing specific antibodies. Our results suggested that rPocDBP-RII protein has potential as a vaccine candidate to provide assessment and guidance for malaria control and elimination activities. Graphical Abstract
    Type of Medium: Online Resource
    ISSN: 1756-3305
    URL: Article
    DOI: 10.1186/s13071-023-05897-9
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2409480-8
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  • 2
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    Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivax
    Springer Science and Business Media LLC ; 2022
    In:  Parasites & Vectors Vol. 15, No. 1 ( 2022-11-15)
    Details
    In: Parasites & Vectors, Springer Science and Business Media LLC, Vol. 15, No. 1 ( 2022-11-15)
    Abstract: Plasmodium vivax rhoptry-associated membrane antigen (RAMA) is a glycophosphatidylinositol-anchored membrane protein currently under consideration as a malaria vaccine candidate. Immunoglobulin G (IgG) antibodies induced by P. vivax RAMA (PvRAMA) have been proved to persist over 12 months in the sera of people infected with P. vivax. It has also been shown that through stimulation of peripheral blood mononuclear cells with PvRAMA in vitro, the antigen can induce CD4 + T cells to produce interleukin-10. However, the genetic diversity of the RAMA gene in isolates of P. vivax ( pvrama ) and the immunogenicity of PvRAMA in animals remain unclear. Methods Genomic DNA was extracted from blood samples ( n  = 25) of patients in Jiangsu Province, China with imported infections of P. vivax from endemic countries in South and Southeast Asia. The extract genomic DNA was used as templates to amplify the P. vivax rama gene ( pvrama ) by PCR, and the PCR products were then sequenced and analyzed by the DnaSP, MEGA, and GeneDoc software packages. Recombinant PvRAMA (rPvRAMA) protein was expressed and purified, and then used to immunize mice. Levels of total IgG and different IgG subclasses of rPvRAMA-immunized mice were evaluated by enzyme-linked immunosorbent assay. Also, spleen cells of rPvRAMA-immunized mice were stimulated with rPvRAMA in vitro and levels of T cells were measured by flow cytometry. Results The average pairwise nucleotide diversity ( π ) of the pvrama gene was 0.00190, and the haplotype diversity ( Hd ) was 0.982. The C-terminal of PvRAMA showed lower haplotype diversity compared to the N-terminal and was completely conserved at amino acid sites related to erythrocyte binding. To further characterize immunogenicity of the C-terminal of PvRAMA, mice were immunized with rPvRAMA antigen. The rPvRAMA protein induced antibody responses, with the end-point titer ranging from 1:10,000 to 1:5,120,000. IgG1 was the predominant IgG subclass in rPvRAMA-immunized mice, followed by IgG2b. In addition, levels of CD4 + and CD8 + T cells in the rPvRAMA-stimulated group were significantly higher than those in the phosphate-buffered saline-stimulated group (normal control group). Conclusions The high conservation at specific amino acid sites and the high immunogenicity of the C-terminal of PvRAMA indicate the presence of conserved epitopes able to generate broadly reactive humoral and cellular immune responses. These findings support the potential of PvRAMA to serve as a vaccine candidate against P. vivax infection. Graphical Abstract
    Type of Medium: Online Resource
    ISSN: 1756-3305
    URL: Article
    DOI: 10.1186/s13071-022-05561-8
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2409480-8
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  • 3
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    Online Resource
    Prevalence of pvmrp1 Polymorphisms and Its Contribution to Antimalarial Response
    MDPI AG ; 2022
    In:  Microorganisms Vol. 10, No. 8 ( 2022-07-22), p. 1482-
    Details
    In: Microorganisms, MDPI AG, Vol. 10, No. 8 ( 2022-07-22), p. 1482-
    Abstract: As more sporadic cases of chloroquine resistance occur (CQR) in Plasmodium vivax (P. vivax) malaria, molecular markers have become an important tool to monitor the introduction and spread of drug resistance. P. vivax multidrug resistance-associated protein 1 (PvMRP1), as one of the members of the ATP-binding cassette (ABC) transporters, may modulate this phenotype. In this study, we investigated the gene mutations and copy number variations (CNVs) in the pvmrp1 in 102 P. vivax isolates from China, the Republic of Korea (ROK), Myanmar, Papua New Guinea (PNG), Pakistan, the Democratic People’s Republic of Korea (PRK), and Cambodia. And we also obtained 72 available global pvmrp1 sequences deposited in the PlasmoDB database to investigate the genetic diversity, haplotype diversity, natural selection, and population structure of pvmrp1. In total, 29 single nucleotide polymorphisms reflected in 23 non-synonymous, five synonymous mutations and one gene deletion were identified, and CNVs were found in 2.9% of the isolates. Combined with the antimalarial drug susceptibility observed in the previous in vitro assays, except the prevalence of S354N between the two CQ sensitivity categories revealed a significant difference, no genetic mutations or CNVs associated with drug sensitivity were found. The genetic polymorphism analysis of 166 isolates worldwide found that the overall nucleotide diversity (π) of pvmrp1 was 0.0011, with 46 haplotypes identified (Hd = 0.9290). The ratio of non-synonymous to synonymous mutations (dn/ds = 0.5536) and the neutrality tests statistic Fu and Li’s D* test (Fu and Li’s D* = −3.9871, p 〈 0.02) suggests that pvmrp1 had evolved under a purifying selection. Due to geographical differences, genetic differentiation levels of pvmrp1 in different regions were different to some extent. Overall, this study provides a new idea for finding CQR molecular monitoring of P. vivax and provides more sequences of pvmrp1 in Asia for subsequent research. However, further validation is still needed through laboratory and epidemiological field studies of P. vivax samples from more regions.
    Type of Medium: Online Resource
    ISSN: 2076-2607
    URL: Article
    DOI: 10.3390/microorganisms10081482
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2720891-6
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