mulTiplex Immunoassay qualiTy assuRance Panel (TITRE)

Development of Group B Streptococcus Quality Assurance Panel for the GASTON Multiplex Anti-CPS IgG Immunoassay.

Collection of serum from women not living with HIV, who received the GBS6 vaccine in the "a placebo-controlled clinical trial investigating the safety and immunogenicity of GBS6 in pregnant women with and without human immunodeficiency virus (HIV) infection and their infants" (GBS6) Clinical Trial in Kampala, Uganda, for the Development of Group B Streptococcus quality assurance panel for the GASTON multiplex anti-CPS IgG immunoassay

Study Overview

• Status: Recruiting
• Conditions: Group B Strep Infection
• Intervention / Treatment: Other: Collection of 50mls of blood

Detailed Description

This is a single-visit study designed to collect serum samples from women who previously participated in the GBS6 clinical trial, "A placebo-controlled clinical trial investigating the safety and immunogenicity of GBS6 in pregnant women with and without human immunodeficiency virus (HIV) infection and their infants" (GBS6 trial). The purpose of this follow-up study is to obtain serum samples for the development of Quality Control Sera (QCS) and Assay Bridging (AB) panels to support long-term quality control and performance monitoring of the GASTON immunoassay.

The GBS6 trial enrolled 300 pregnant women between October 2022 and July 2023 at Kawempe National Referral Hospital and Kisenyi Health Centre IV. The last participant completed follow-up on 23 October 2024. Of these, 150 participants (75 living with HIV and 75 not living with HIV) were randomized to receive either the GBS6 vaccine or placebo (normal saline). The GBS6 vaccine is a capsular polysaccharide conjugate vaccine targeting the six most common disease-causing GBS serotypes.

For this follow-up study, only participants who received the GBS6 vaccine and are not living with HIV (n=75) will be contacted via telephone using the contact details provided in the GBS6 trial records. Each consenting participant will attend a single study visit for serum collection. Collected samples will be shipped to the City, St George's laboratory for antibody screening. The GASTON assay will measure IgG concentrations for serotypes Ia, Ib, II, III, IV, and V. Based on these results, samples will be ranked by IgG values, and an appropriate pooling strategy will be developed to generate the QCS and AB panels.

• Study Type: Observational
• Enrollment (Estimated): 50

Contacts and Locations

• Study Contact: Name: Madeleine Cochet; Phone Number: +442087255214; Email: mcochet@sgul.ac.uk
• Study Contact Backup: Name: Mary Kyohere; Phone Number: +447490390327; Email: mkyohere@sgul.ac.uk

Study Locations

• Uganda
  • Kampala, Uganda
    • Recruiting
    • MUJHU Care Ltd, Kampala
    • Contact: Zakaria Mukasa, Dr; Phone Number: +256 782 201308; Email: zmukasa@mujhu.org
    • Principal Investigator: Robert Mboizi

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Women not living with HIV, who received the GBS6 vaccine in the "a placebo-controlled clinical trial investigating the safety and immunogenicity of GBS6 in pregnant women with and without human immunodeficiency virus (HIV) infection and their infants" (GBS6) Clinical Trial in Kampala, Uganda.

Description

Inclusion Criteria:

• HIV-uninfected women who received the GBS6 vaccine during pregnancy and completed the whole period of study participation.
• Reachable by phone
• Willing and able to provide consent.
• Willingness to provide a blood sample.

Exclusion Criteria:

• Receipt of blood/plasma transfusion in the last 3 months
• Participants who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids.
• Women who will test positive for Syphilis or HIV at screening
• Current alcohol abuse or illicit drug use, or with a psychiatric condition
• Major illness of the mother that, in the investigator's judgment, will substantially increase the risk associated with the participant's participation in the study, including but not limited to the following:

I. heart disease II. severe anaemia (Hemoglobin level less than 7.0g/dL)

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Women not living with HIV, who received the GBS6 vaccine GBS6 Clinical Trial in Kampala, Uganda; Women not living with HIV, who received the GBS6 vaccine in the "a placebo-controlled clinical trial investigating the safety and immunogenicity of GBS6 in pregnant women with and without human immunodeficiency virus (HIV) infection and their infants" (GBS6) Clinical Trial in Kampala, Uganda. The GBS6 trial enrolled 300 pregnant women between October 2022 and July 2023. Of these, 150 participants (75 living with HIV and 75 not living with HIV) were randomized to receive either the GBS6 vaccine (a capsular polysaccharide conjugate vaccine targeting the six most common disease-causing GBS serotypes) or placebo (normal saline). For this follow-up study, only participants who received the GBS6 vaccine and are not living with HIV (n=75) will be contacted via telephone using the contact details provided in the GBS6 trial records. Each consenting participant will attend a single study visit for serum collection.

Other: Collection of 50mls of blood; 50mls of blood will be collected from all participants who give consent.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Creation of a quality control and bridging panels for the GBS multiplex immunoassay (GASTON assay)	Approx 50mL of blood will be collected from each study participant and will be used only for the development of QCS and AB panels. Blood samples will be processed and serum stored at -20C in Kampala, Uganda. The serum will be transferred to the City St George's, University of London laboratory, in the United Kingdom (UK), where the serum will be assayed for GBS6 serotype-specific anti-capsular antibodies using the GASTON multiplex anti-CPS IgG immunoassay. Concentrations of anti-capsular IgG for the 6 serotypes (Ia, Ib, II, III, IV, and V) will be determined and a serum pooling strategy developed to produce a QCS panel consisting of three samples that span high, medium and low IgG values for each serotype and a 22- member bridging panel that will span the range of the assay for all serotypes. The QC panels will be distributed to members of the GASTON consortium for the purpose of assay performance monitoring until they are depleted.	1 year

Collaborators and Investigators

• Sponsor: St George's, University of London
• Investigators: Principal Investigator: Kirsty Le Doare, City St George's, University of London

Study record dates

Study Major Dates

• Study Start (Actual): March 27, 2026
• Primary Completion (Estimated): May 1, 2026
• Study Completion (Estimated): January 1, 2027

Study Registration Dates

• First Submitted: April 16, 2026
• First Submitted That Met QC Criteria: April 24, 2026
• First Posted (Actual): May 1, 2026

Study Record Updates

• Last Update Posted (Actual): May 1, 2026
• Last Update Submitted That Met QC Criteria: April 24, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Infections; Gram-Positive Bacterial Infections; Bacterial Infections; Bacterial Infections and Mycoses; Streptococcal Infections
• Other Study ID Numbers: SE0306; INV-087236 (Other Grant/Funding Number: Gates Foundation)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No