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van der Boor SC, Alkema M, van Gemert GJ, Teelen K, van de Vegte-Bolmer M, Walk J, van Crevel R, de Mast Q, Ockenhouse CF, Sauerwein RW, McCall MBB. Whole sporozoite immunization with Plasmodium falciparum strain NF135 in a randomized trial. BMC Med 2023; 21:137. [PMID: 37024868 PMCID: PMC10079489 DOI: 10.1186/s12916-023-02788-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 02/15/2023] [Indexed: 04/08/2023] Open
Abstract
BACKGROUND Whole sporozoite immunization under chemoprophylaxis (CPS regime) induces long-lasting sterile homologous protection in the controlled human malaria infection model using Plasmodium falciparum strain NF54. The relative proficiency of liver-stage parasite development may be an important factor determining immunization efficacy. Previous studies show that Plasmodium falciparum strain NF135 produces relatively high numbers of large liver-stage schizonts in vitro. Here, we evaluate this strain for use in CPS immunization regimes. METHODS In a partially randomized, open-label study conducted at the Radboudumc, Nijmegen, the Netherlands, healthy, malaria-naïve adults were immunized by three rounds of fifteen or five NF135-infected mosquito bites under mefloquine prophylaxis (cohort A) or fifteen NF135-infected mosquito bites and presumptive treatment with artemether/lumefantrine (cohort B). Cohort A participants were exposed to a homologous challenge 19 weeks after immunization. The primary objective of the study was to evaluate the safety and tolerability of CPS immunizations with NF135. RESULTS Relatively high liver-to-blood inocula were observed during immunization with NF135 in both cohorts. Eighteen of 30 (60%) high-dose participants and 3/10 (30%) low-dose participants experienced grade 3 adverse events 7 to 21 days following their first immunization. All cohort A participants and two participants in cohort B developed breakthrough blood-stage malaria infections during immunizations requiring rescue treatment. The resulting compromised immunizations induced modest sterile protection against homologous challenge in cohort A (5/17; 29%). CONCLUSIONS These CPS regimes using NF135 were relatively poorly tolerated and frequently required rescue treatment, thereby compromising immunization efficiency and protective efficacy. Consequently, the full potential of NF135 sporozoites for induction of immune protection remains inconclusive. Nonetheless, the high liver-stage burden achieved by this strain highlights it as an interesting potential candidate for novel whole sporozoite immunization approaches. TRIAL REGISTRATION The trial was registered at ClinicalTrials.gov under identifier NCT03813108.
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Affiliation(s)
- Saskia C van der Boor
- Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Geert Grooteplein Zuid 28, 6525 GA, Nijmegen, The Netherlands
| | - Manon Alkema
- Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Geert Grooteplein Zuid 28, 6525 GA, Nijmegen, The Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Geert Grooteplein Zuid 28, 6525 GA, Nijmegen, The Netherlands
| | - Karina Teelen
- Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Geert Grooteplein Zuid 28, 6525 GA, Nijmegen, The Netherlands
| | - Marga van de Vegte-Bolmer
- Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Geert Grooteplein Zuid 28, 6525 GA, Nijmegen, The Netherlands
| | - Jona Walk
- Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Geert Grooteplein Zuid 28, 6525 GA, Nijmegen, The Netherlands
- Present affiliation: TropIQ Health Sciences, Transistorweg 5-C02, 6534 AT, Nijmegen, The Netherlands
| | - Reinout van Crevel
- Department of Internal Medicine, Radboud Center for Infectious Diseases, Radboud University Medical Centre, Geert Grooteplein Zuid 10, 6525 GA, Nijmegen, The Netherlands
| | - Quirijn de Mast
- Department of Internal Medicine, Radboud Center for Infectious Diseases, Radboud University Medical Centre, Geert Grooteplein Zuid 10, 6525 GA, Nijmegen, The Netherlands
| | | | - Robert W Sauerwein
- Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Geert Grooteplein Zuid 28, 6525 GA, Nijmegen, The Netherlands.
- Present affiliation: TropIQ Health Sciences, Transistorweg 5-C02, 6534 AT, Nijmegen, The Netherlands.
| | - Matthew B B McCall
- Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Geert Grooteplein Zuid 28, 6525 GA, Nijmegen, The Netherlands.
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Kuipers K, van Selm S, van Opzeeland F, Langereis JD, Verhagen LM, Diavatopoulos DA, de Jonge MI. Genetic background impacts vaccine-induced reduction of pneumococcal colonization. Vaccine 2017; 35:5235-41. [PMID: 28822643 DOI: 10.1016/j.vaccine.2017.08.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 08/04/2017] [Accepted: 08/09/2017] [Indexed: 01/08/2023]
Abstract
Vaccination has been one of the most successful strategies to reduce morbidity and mortality caused by respiratory infections. Recent evidence suggests that differences in the host genetic background and environmental factors may contribute to heterogeneity in the immune response to vaccination. During pre-clinical testing, vaccines are often evaluated in a single mouse inbred strain, which may not translate well to the heterogeneous human population. Here, we examined the influence of host genetic background on vaccine-induced protection against pneumococcal colonization in two commonly used inbred mouse strains, i.e. C57BL/6 and BALB/cas well as the F1 cross of these two strains. Groups of mice were vaccinated intranasally with a vaccine formulation containing a model pneumococcal antigen, i.e. pneumococcal surface protein A (PspA), adjuvanted with cholera toxin subunit B (CTB). Even in the absence of vaccination, differences in colonization density were observed between mouse strains. Although vaccination significantly reduced pneumococcal density in all mouse strains, differences were observed in the magnitude of protection. We therefore examined immunological parameters known to be involved in vaccine-induced mucosal clearance of S. pneumoniae. We found that PspA-specific IgG levels in nasal tissue differed between mouse strains, but in all cases it correlated significantly with a reduction in colonization. Furthermore, increased mucosal IL17A, but not IFNγ, IL10, or IL4, was found to be mouse strain specific. This suggests that the reduction of bacterial load may be accompanied by a Th17 response in all genetic backgrounds, although the cytokine dynamics may differ. Increased insight into the different immune mechanisms that affect pneumococcal carriage will contribute to development of future vaccines against S. pneumoniae.
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