1
|
van Schuijlenburg R, Azargoshasb S, de Korne CM, Sijtsma JC, Bezemer S, van der Ham AJ, Baalbergen E, Geurten F, de Bes-Roeleveld LM, Chevalley-Maurel SC, van Oosterom MN, van Leeuwen FWB, Franke-Fayard B, Roestenberg M. Ageing of Plasmodium falciparum malaria sporozoites alters their motility, infectivity and reduces immune activation in vitro. Malar J 2024; 23:111. [PMID: 38641838 PMCID: PMC11027264 DOI: 10.1186/s12936-024-04946-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 04/12/2024] [Indexed: 04/21/2024] Open
Abstract
BACKGROUND Sporozoites (SPZ), the infective form of Plasmodium falciparum malaria, can be inoculated into the human host skin by Anopheline mosquitoes. These SPZ migrate at approximately 1 µm/s to find a blood vessel and travel to the liver where they infect hepatocytes and multiply. In the skin they are still low in number (50-100 SPZ) and vulnerable to immune attack by antibodies and skin macrophages. This is why whole SPZ and SPZ proteins are used as the basis for most malaria vaccines currently deployed and undergoing late clinical testing. Mosquitoes typically inoculate SPZ into a human host between 14 and 25 days after their previous infective blood meal. However, it is unknown whether residing time within the mosquito affects SPZ condition, infectivity or immunogenicity. This study aimed to unravel how the age of P. falciparum SPZ in salivary glands (14, 17, or 20 days post blood meal) affects their infectivity and the ensuing immune responses. METHODS SPZ numbers, viability by live/dead staining, motility using dedicated sporozoite motility orienting and organizing tool software (SMOOT), and infectivity of HC-04.j7 liver cells at 14, 17 and 20 days after mosquito feeding have been investigated. In vitro co-culture assays with SPZ stimulated monocyte-derived macrophages (MoMɸ) and CD8+ T-cells, analysed by flow cytometry, were used to investigate immune responses. RESULTS SPZ age did not result in different SPZ numbers or viability. However, a markedly different motility pattern, whereby motility decreased from 89% at day 14 to 80% at day 17 and 71% at day 20 was observed (p ≤ 0.0001). Similarly, infectivity of day 20 SPZ dropped to ~ 50% compared with day 14 SPZ (p = 0.004). MoMɸ were better able to take up day 14 SPZ than day 20 SPZ (from 7.6% to 4.1%, p = 0.03) and displayed an increased expression of pro-inflammatory CD80, IL-6 (p = 0.005), regulatory markers PDL1 (p = 0.02), IL-10 (p = 0.009) and cytokines upon phagocytosis of younger SPZ. Interestingly, co-culture of these cells with CD8+ T-cells revealed a decreased expression of activation marker CD137 and cytokine IFNγ compared to their day 20 counterparts. These findings suggest that older (day 17-20) P. falciparum SPZ are less infectious and have decreased immune regulatory potential. CONCLUSION Overall, this data is a first step in enhancing the understanding of how mosquito residing time affects P. falciparum SPZ and could impact the understanding of the P. falciparum infectious reservoir and the potency of whole SPZ vaccines.
Collapse
Affiliation(s)
- Roos van Schuijlenburg
- Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands
| | - Samaneh Azargoshasb
- Interventional Molecular Imaging Laboratory, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
| | - Clarize M de Korne
- Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands
- Interventional Molecular Imaging Laboratory, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
| | - Jeroen C Sijtsma
- Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands
| | - Sascha Bezemer
- Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands
| | - Alwin J van der Ham
- Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands
| | - Els Baalbergen
- Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands
| | - Fiona Geurten
- Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands
| | - Laura M de Bes-Roeleveld
- Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands
| | - Severine C Chevalley-Maurel
- Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands
| | - Matthias N van Oosterom
- Interventional Molecular Imaging Laboratory, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
| | - Fijs W B van Leeuwen
- Interventional Molecular Imaging Laboratory, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
| | - Blandine Franke-Fayard
- Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands
| | - Meta Roestenberg
- Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands.
| |
Collapse
|
2
|
Galactionova K, Smith TA, Penny MA. Insights from modelling malaria vaccines for policy decisions: the focus on RTS,S. Malar J 2021; 20:439. [PMID: 34794430 PMCID: PMC8600337 DOI: 10.1186/s12936-021-03973-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 11/04/2021] [Indexed: 11/17/2022] Open
Abstract
Mathematical models are increasingly used to inform decisions throughout product development pathways from pre-clinical studies to country implementation of novel health interventions. This review illustrates the utility of simulation approaches by reviewing the literature on malaria vaccine modelling, with a focus on its link to the development of policy guidance for the first licensed product, RTS,S/AS01. The main contributions of modelling studies have been in inferring the mechanism of action and efficacy profile of RTS,S; to predicting the public health impact; and economic modelling mainly comprising cost-effectiveness analysis. The value of both product-specific and generic modelling of vaccines is highlighted.
Collapse
Affiliation(s)
- Katya Galactionova
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland.,University of Basel, 4001, Basel, Switzerland.,European Center of Pharmaceutical Medicine, Brombacherstrasse 5, 4057, Basel, Switzerland
| | - Thomas A Smith
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland. .,University of Basel, 4001, Basel, Switzerland.
| | - Melissa A Penny
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland.,University of Basel, 4001, Basel, Switzerland
| |
Collapse
|
3
|
A peptide-based Plasmodium falciparum circumsporozoite assay to test for serum antibody responses to pre-erythrocyte malaria vaccines. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 18:776-82. [PMID: 21411600 DOI: 10.1128/cvi.00547-10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Various pre-erythrocyte malaria vaccines are currently in clinical development, and among these is the adenovirus serotype 35-based circumsporozoite (CS) vaccine produced on PER.C6 cells. Although the immunological correlate of protection against malaria remains to be established, the CS antibody titer is a good marker for evaluation of candidate vaccines. Here we describe the validation of an anti-Plasmodium falciparum circumsporozoite antibody enzyme-linked immunosorbent assay (ELISA) based on the binding of antibodies to a peptide antigen mimicking the CS repeat region. The interassay variability was determined to be below a coefficient of variation (CV) of 15%, and sensitivity was sufficient to detect low antibody titers in subjects from endemic regions. Antibody titers were in agreement with total antibody responses to the whole CS protein. Due to its simplicity and high performance, the ELISA is an easy and rapid method for assessment of pre-erythrocyte malaria vaccines based on CS.
Collapse
|
4
|
Diap G, Amuasi J, Boakye I, Sevcsik AM, Pecoul B. Anti-malarial market and policy surveys in sub-Saharan Africa. Malar J 2010; 9 Suppl 1:S1. [PMID: 20423536 DOI: 10.1186/1475-2875-9-s1-s1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
At a recent meeting (Sept 18, 2009) in which reasons for the limited access to artemisinin-based combination therapy (ACT) in sub-Saharan Africa were discussed, policy and market surveys on anti-malarial drug availability and accessibility in Burundi and Sierra Leone were presented in a highly interactive brainstorming session among key stakeholders across private, public, and not-for-profit sectors. The surveys, the conduct of which directly involved the national malaria control programme managers of the two countries, provides the groundwork for evidence-based policy implementation. The results of the surveys could be extrapolated to other countries with similar socio-demographic and malaria profiles. The meeting resulted in recommendations on key actions to be taken at the global, national, and community level for better ACT accessibility. At the global level, both public and private sectors have actions to take to strengthen policies that lead to the replacement of loose blister packs with fixed-dose ACT products, develop strategies to ban inappropriate anti-malarials and regulate those bans, and facilitate technology and knowledge transfer to scale up production of fixed-dose ACT products, which should be readily available and affordable to those patients who are in the greatest need of these medicines. At the national level, policies that regulate the anti-malarial medicines market should be enacted and enforced. The public sector, including funding donors, should participate in ensuring that the private sector is engaged in the ACT implementation process. Research similar to the surveys discussed is important for other countries to develop and evaluate the right incentives at a local level. At the community level, community outreach and education about appropriate preventive and treatment measures must continue and be strengthened, with service delivery systems developed within both public and private sectors, among other measures, to decrease access to ineffective and inappropriate anti-malarial medicines. What was clear during the meeting is that continuing commitment, strengthened interaction and transparency among various stakeholders, with focus on communities, national governments, and evidence-based policy and action are the only way to sustainably address the control of malaria, a disease which continues to have a significant health and socio-economic impact worldwide, particularly in sub-Saharan Africa. Details on the methodology employed in carrying out the studies discussed at this meeting, as well as more detailed results, data analysis and discussion of the studies are soon to be published.
Collapse
Affiliation(s)
- Graciela Diap
- Drugs for Neglected Diseases initiative (DNDi), Geneva 1202, Switzerland.
| | | | | | | | | |
Collapse
|
5
|
Diap G, Amuasi J, Boakye I, Sevcsik AM, Pecoul B. Anti-malarial market and policy surveys in sub-Saharan Africa. Malar J 2010; 9 Suppl 3:S1. [PMID: 20423536 PMCID: PMC3002145 DOI: 10.1186/1475-2875-9-s3-s1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
At a recent meeting (Sept 18, 2009) in which reasons for the limited access to artemisinin-based combination therapy (ACT) in sub-Saharan Africa were discussed, policy and market surveys on anti-malarial drug availability and accessibility in Burundi and Sierra Leone were presented in a highly interactive brainstorming session among key stakeholders across private, public, and not-for-profit sectors. The surveys, the conduct of which directly involved the national malaria control programme managers of the two countries, provides the groundwork for evidence-based policy implementation. The results of the surveys could be extrapolated to other countries with similar socio-demographic and malaria profiles. The meeting resulted in recommendations on key actions to be taken at the global, national, and community level for better ACT accessibility. At the global level, both public and private sectors have actions to take to strengthen policies that lead to the replacement of loose blister packs with fixed-dose ACT products, develop strategies to ban inappropriate anti-malarials and regulate those bans, and facilitate technology and knowledge transfer to scale up production of fixed-dose ACT products, which should be readily available and affordable to those patients who are in the greatest need of these medicines. At the national level, policies that regulate the anti-malarial medicines market should be enacted and enforced. The public sector, including funding donors, should participate in ensuring that the private sector is engaged in the ACT implementation process. Research similar to the surveys discussed is important for other countries to develop and evaluate the right incentives at a local level. At the community level, community outreach and education about appropriate preventive and treatment measures must continue and be strengthened, with service delivery systems developed within both public and private sectors, among other measures, to decrease access to ineffective and inappropriate anti-malarial medicines. What was clear during the meeting is that continuing commitment, strengthened interaction and transparency among various stakeholders, with focus on communities, national governments, and evidence-based policy and action are the only way to sustainably address the control of malaria, a disease which continues to have a significant health and socio-economic impact worldwide, particularly in sub-Saharan Africa. Details on the methodology employed in carrying out the studies discussed at this meeting, as well as more detailed results, data analysis and discussion of the studies are soon to be published.
Collapse
Affiliation(s)
- Graciela Diap
- Drugs for Neglected Diseases initiative (DNDi), Geneva 1202, Switzerland.
| | | | | | | | | |
Collapse
|
6
|
Targett GA, Greenwood BM. Malaria vaccines and their potential role in the elimination of malaria. Malar J 2008; 7 Suppl 1:S10. [PMID: 19091034 PMCID: PMC2604874 DOI: 10.1186/1475-2875-7-s1-s10] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Research on malaria vaccines is currently directed primarily towards the development of vaccines that prevent clinical malaria. Malaria elimination, now being considered seriously in some epidemiological situations, requires a different vaccine strategy, since success will depend on killing all parasites in the community in order to stop transmission completely. The feature of the life-cycles of human malarias that presents the greatest challenge to an elimination programme is the persistence of parasites as asymptomatic infections. These are an important source from which transmission to mosquitoes can occur. Consequently, an elimination strategy requires a community-based approach covering all individuals and not just those who are susceptible to clinical malaria. The progress that has been made in development of candidate malaria vaccines is reviewed. It is unlikely that many of these will have the efficacy required for complete elimination of parasites, though they may have an important role to play as part of future integrated control programmes. Vaccines for elimination must have a high level of efficacy in order to stop transmission to mosquitoes. This might be achieved with some pre-erythrocytic stage candidate vaccines or by targeting the sexual stages directly with transmission-blocking vaccines. An expanded malaria vaccine programme with such objectives is now a priority.
Collapse
Affiliation(s)
- Geoffrey A Targett
- Department of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK.
| | | |
Collapse
|
7
|
Greenwood BM, Fidock DA, Kyle DE, Kappe SHI, Alonso PL, Collins FH, Duffy PE. Malaria: progress, perils, and prospects for eradication. J Clin Invest 2008; 118:1266-76. [PMID: 18382739 DOI: 10.1172/jci33996] [Citation(s) in RCA: 409] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
There are still approximately 500 million cases of malaria and 1 million deaths from malaria each year. Yet recently, malaria incidence has been dramatically reduced in some parts of Africa by increasing deployment of anti-mosquito measures and new artemisinin-containing treatments, prompting renewed calls for global eradication. However, treatment and mosquito control currently depend on too few compounds and thus are vulnerable to the emergence of compound-resistant parasites and mosquitoes. As discussed in this Review, new drugs, vaccines, and insecticides, as well as improved surveillance methods, are research priorities. Insights into parasite biology, human immunity, and vector behavior will guide efforts to translate parasite and mosquito genome sequences into novel interventions.
Collapse
Affiliation(s)
- Brian M Greenwood
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | | | | | | | | |
Collapse
|
8
|
Walther B, Walther M. What does it take to control malaria? ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2008; 101:657-72. [PMID: 18028727 DOI: 10.1179/136485907x229013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
More than 125 years after the discovery of the causative parasites, human malaria remains a major global-health problem. Despite many important discoveries in the epidemiology and pathogenesis of the disease, and the availability of effective treatment and control measures, there was no decline in global malarial mortality from 1954 to 1997. The economic prospects of the countries in which malaria is endemic are closely related to the burden of the disease, a situation that calls for an enhanced, concerted effort from the global community in the fight against the disease. This review explains the effects and limitations of the available control tools, summarises the extent to which they are currently employed, describes how their use could be improved, and discusses the particular importance of a vaccine in controlling the disease.
Collapse
Affiliation(s)
- B Walther
- Medical Research Council Laboratories, Fajara, P.O. Box 273, Banjul, The Gambia
| | | |
Collapse
|
9
|
Abstract
PURPOSE OF REVIEW This review examines the potential of current preerythrocytic stage malaria vaccine approaches to reduce the global burden of malaria. RECENT FINDINGS Radiation-attenuated parasite vaccines induce lasting sterile protection in all models tested. Inherent safety concerns in conjunction with challenges to produce and deliver a radiation-attenuated parasite vaccine have prevented its mass production and application. Recent advances in genetic engineering and initiatives in production process development of live attenuated malaria vaccines, however, will overcome roadblocks that currently prevent their large-scale application. Development of preerythrocytic subunit vaccines has focused on the circumsporozoite protein and the thrombospondin related anonymous protein, yet the most advanced circumsporozoite protein-based vaccine confers limited protection against infection in malaria endemic areas. Work in rodent malaria models demonstrated that circumsporozoite protein-based immunity is not required for to achieve sterile protection. SUMMARY We conclude that preerythrocytic malaria vaccine efforts should focus on two major areas: development of a safe live attenuated sporozoite vaccine with its accelerated testing in malaria endemic areas and identification of as yet unknown antigens that reproduce sterilizing immune responses induced by vaccination with whole parasites. The sporozoite challenge model provides a unique opportunity to rapidly test preerythrocytic vaccine candidates.
Collapse
|
10
|
Richie T. High road, low road? Choices and challenges on the pathway to a malaria vaccine. Parasitology 2007; 133 Suppl:S113-44. [PMID: 17274843 DOI: 10.1017/s0031182006001843] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Malaria causes much physical and economic hardship in endemic countries with billions of people at risk. A vaccine would clearly benefit these countries, reducing the requirement for hospital care and the economic impact of infection. Successful immunization with irradiated sporozoites and the fact that repeated exposure to malaria induces partial immunity to infection and high levels of protection against the clinical manifestations, suggest that a vaccine is feasible. Numerous candidate antigens have been identified but the vaccine, which has been promised to be 'just round the corner' for many years, remains elusive. The factors contributing to this frustratingly slow progress are discussed including gaps in the knowledge of host/parasite biology, methods to induce potent cell-mediated immune responses, the difficulties associated with defining immune correlates of protection and antigen production and delivery. Finally, the use of attenuated organism vaccines is discussed.
Collapse
Affiliation(s)
- T Richie
- Malaria Program, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, Maryland 20910-7500, USA.
| |
Collapse
|
11
|
Girard MP, Reed ZH, Friede M, Kieny MP. A review of human vaccine research and development: malaria. Vaccine 2006; 25:1567-80. [PMID: 17045367 DOI: 10.1016/j.vaccine.2006.09.074] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2006] [Accepted: 09/25/2006] [Indexed: 11/18/2022]
Abstract
The last several years have seen significant progress in the development of vaccines against malaria. Most recently, proof-of-concept of vaccine-induced protection from malaria infection and disease was demonstrated in African children. Pursued by various groups and on many fronts, several other candidate vaccines are in early clinical trials. Yet, despite the optimism and promise, an effective malaria vaccine is not yet available, in part because of the lack of understanding of the types of immune responses needed for protection, added to the difficulty of identifying, selecting and producing the appropriate protective antigens from a parasite with a genome of well over five thousand genes and to the frequent need to enhance the immunogenicity of purified antigens through the use of novel adjuvants or delivery systems. Insufficient clinical trial capacity and normative research functions such as local ethical committee reviews also contribute to slow down the development process. This article attempts to summarize the state of the art of malaria vaccine development.
Collapse
Affiliation(s)
- Marc P Girard
- University Paris 7, 39 rue Seignemartin, FR-69008 Lyon, France.
| | | | | | | |
Collapse
|