OPTIMALVAC Initiative on Optimising Malaria Vaccine Laboratory Assays Evaluation

OPTIMALVAC Initiative on Optimising Malaria

Vaccine Laboratory Assays Evaluation

About the project

• EC FP7 Coordination and Support Action• EC Budget €1 mil.• Complementary contributions from the

PATH Malaria Vaccine Initiative and the Centers for Disease Control and Prevention (€0.5 mil ).

• 13 Partners; Coordinator : EVI; Global Coordinator: WHO

• Start Date: 01 April 2009, three years

Objectives

The goal is to identify and harmonise key immunoassays to facilitate comparison of results and improve decision-making in malaria vaccine development.

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Immunoassays in Malaria Vaccine Development

Assess immunogenic potential of candidate vaccines

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Keyword: Correlates of protection

• Correlates of immunity/protection to a virus or other infectious pathogen are measurable signs that a person (or other potential host) is immune, in the sense of being protected against becoming infected and/or developing disease.

• Without knowing the correlates of immunity, scientists cannot know exactly what sort of immune response a vaccine would need to stimulate

Naturally aquired Immunity or immune potection demonstrated in clinical trials or challenge studies

Y

Vaccine Candidate A

Vaccine Candiate B

Down selection of vaccine candidates

• Malaria vaccines: correlates of protection not fully characterised

• 2/3 of malaria vaccines use IgG assays, 1/3 T cell based assays as readout

• Immunoassays used to determine intake of vaccines

• Robust assays requried to compare different approaches

Malaria Vaccine Assay Harmonisation

Identify Key Assays and Labs

1st Comparison with Existing SOPs/

Reagents

Harmonisation of SOPs/Reagents

Iterative Comparisons with Harmonised

SOPs

Agreed Community Harmonised SOPs & Reagent Repository

Establishment of Reference Centre Assay Validation


Reagents


Assay Validation

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Key immunoassays identified for harmonisation in OPTIMALVAC

Cell mediated immunity

• ICS• ELISPOT

Humoral Assays• Blood Stage IFA

Functional Assays• Antibody-

dependent cellular inhibition assay

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T cell mediated immunity• Assess number of cytokine producing T cells in peripheral blood

mononuclear cells after stimulation• Cell-mediated immunity (CMI) does not involve antibodies but rather

the activation of macrophages and NK-cells, the production of antigen-specific cytotoxic T-lymphocytes , and the release of various cytokines in response to an antigen .

T cell

YLabelled CD4 AB

Y

Labelled anti-cytokine AB

Intracellular Cytokine staining (ICS)Enyzme linked Immunospot (ELISpot)

Work package leader: Dr Patrice Dubois, Immunovacc Consulting

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ICS – Intracellular cytokine staining

• Whole blood is cultured and stimulated

• Brefeldin A added shortly before measurement to trap cytokines in the cell

• T cell subtypes are marked with fluorescent labelled antibodies

• Cells are fixed and permeabilised

• Staining with fluorescent-labelled AB against cytokine

• Analysis by Fluorescence activated Cell Sorting (FACS)

T cell

YLabelled CD4 AB

Y

Labelled anti-cytokine AB

ELISpot - Enzyme Linked Immuno-Spot

• PBMCs cultured and stimulated in 96well plates with antibody coated membrane

• Secreted IFN binds to antibody on membrane

• Detection with secondary antibody coupled to enzyme

• Add substrate and develop

• Analysis in ELISpot plate reader

T cell mediated immunity

• Barcelona Centre for International Health Research (CRESIB), Spain

• Biomedical Primate Research Centre, BPRC, The Netherlands (Only ICS)

• Infectious Disease Research Institute (IDRI), USA (Only ELISpot)

• Institut Pasteur, France • Kenya Medical Research Institute (KEMRI), Kenya • National Institutes of Health (NIH), USA • Radboud University Medical Center, The Netherlands (Only ICS)• Seattle Biomedical Research Institute, USA (Only ELISpot)• University of Oxford, UK • Walter Reed Army Institute for Research (WRAIR), USA Five african laboratories will be added at a later stage


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T cell mediated immunity

• Harmonised ICS and ELISpot SOP from the HIV community will be adapted

• Stimulation (activation of T cells in ELISpot and ICS): – Tetanus Toxoid (Donation from Serum

Institute India Ltd.)– CEF peptides (a pool of MHC class 1

binding peptides derived from the CMV, EBV and Flu viruses (JPT Peptide Technologies GmbH).

• Positive control: – Human PBMCs selected for reactivity to

TT and CEF peptides (Dr Gepi Pantaleo, CHUV in Lausanne)

• Three separate rounds of testing planned starting from Q1 2011



Reagents



Reagents



SOPs

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Blood stage Immunofluorescence Assay (IFA)

• Assess capacity of purified murine and human antibodies to recognise malaria parasites in infected red blood cells.

• As quantification of the IFA, anti-parasite IgG endpoint titers are determinedYY

Infected RBC

Primary AB

Labelled Secondary AB

Parasite

Work package leader: Dr David Cavanagh, University of Edinburgh

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• Participating laboratories– Biomedical Primate Research Centre, BPRC,

Netherlands– Radboud University Nijmegen, RUNMC,

Netherlands– University of Edinburgh, UK


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• Identification of standard reagents:– Positive controls

• 4G2 (rat anti-AMA1 mAb) – BPRC,• polyclonal anti-AMA-1 rabbit IgG (lyophilized) - BPRC• mAb 12.8 (mouse anti-MSP1-19) – UEDIN• pooled anti-MSP-1-19 rabbit sera

– Negative control: naïve rabbit IgG - UEDIN– Single, synchronised batch of mature P.falciparum schizont

rich IFA slides (Wellcome isolate)• Test reagents diluted, coded and shipped by National Institute for

Biological standards and Control (NIBSC)• First round of testing currently finalised and data analysed by

NIBSC



Reagents


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Antibody Dependent Cell Inhibition (ADCI) Assay

• ADCI is based on the capacity of purified human or murine antibodies to inhibit malaria parasite growth in cooperation with effector cells (monocytes)

• Mechanism shown to correlate with protection after passive transfer of antibodies1

• Low IgG concentrations required for activity

1 Bouharoun-Tayoun et al., JEM, 1990

Work package leader: Dr Patrice Dubois, Immunovacc Consulting

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ADCI (Antibody Dependent Cell Inhibition) Assay - Protocol

• Serum IgG preparation using ion exchange chromatography

• Monocyte isolation from a healthy blood donor

• Preparation of P. falciparum parasites including synchronisation and schizont enrichment

• Parasite culture, for 96h, in the presence of antibodies and monocytes

• Inhibition effect assessed by microscopic observation and parasite counting

Y

Y


• Biomedical Primate Research Centre, BPRC, Netherlands

• Centers for Disease Prevention and Control, CDC, USA

• Institut Pasteur, IP, France• International Centre for Genetic Engineering and

Biotechnology, ICGEB, India • Radboud University Nijmegen, RUNMC,

Netherlands• University of Edinburgh, UK


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Identification of standard reagents:• Positive standard:

– Pools of human sera collected in malaria endemic regions with shown ADCI reactivity – ethical clearance from NIBSC ethical review board

– Monoclonal RAM-1 Ab (Human IgG1 specific for P.falciparum MSP-3) with shown ADCI activity – quality control under way

Existing protocols will be compared using standardised positive controls and from this a consensus SOP determined.



Reagents


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Reference Reagent Repository

www.malariaresearch.eu



Reagents



SOPs


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Outlook

• Harmonised SOP and control reagents available in reference reagent repository by the end of the project

• Sharing of harmonisation activities in- and outside of the malaria vaccine community→ Contacts established:Sylvia Janetzki, Cancer Vaccine Consortium (T cell

harmonisation/Cancer)Tom H.M. Ottenhoff, Leiden University Medical Center (T

cell harmonisation/TB)

Thomas N.Denny, Barton F.Haynes, Duke University Human Vaccine Institute (T cell harmonisation/HIV)

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Questions?

Project website: www.optimalvac.eu

Coordinator Dr Odile Leroy

Project Manager Dr Agnes Kisser

European Vaccine Initiative

UniversitätsKlinikum Heidelberg

Im Neuenheimer Feld 326 - 3. OG

69120 HeidelbergGermanywww.euvaccine.eu

Global Coordinator Dr Vasee Moorthy

WHO Initiative for Vaccine Research

Geneva

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Documents

OPTIMALVAC Initiative on Optimising Malaria Vaccine Laboratory Assays Evaluation