Assessment of Immune Memory - Humoral and Cellular - in mPOX-infected Patients : an Ancillary Study of the ANRS0258s MOSAIC Cohort (POXAIM)

May 14, 2026 updated by: ANRS, Emerging Infectious Diseases

Primary objective The overall objective is to assess the long-term amplitude and durability of the immune responses after mpox virus (MPXV) infection.

Primary endpoint The main outcomes are: the presence of neutralizing antibodies in the serum and the presence of detectable mpox virus-specific memory B cells. Neutralizing antibodies titers will be measured with a semi-automated cell-based assay using live mpox virus. Memory B cells will be measured by flow cytometry and other techniques.

Secondary objectives

  1. Assess the amplitude and the stability of the MPXV antigen-specific B-cell memory response after infection, against the immunodominant antigens A27, A33, B5, L1, D8, and H3.
  2. Assess the breadth of the B-cell repertoire and its neutralizing capacity in a subset of patients
  3. Assess the humoral immunity using different serological techniques, for the detection and quantification of anti-MPXV antibodies, and assess the seroneutralization capacities of each antibody.

Secondary endpoints

  1. The presence of MPXV antigen-specific B-cell memory. Memory B cells will be measured by flow cytometry and other techniques.
  2. The breadth and neutralizing capacity of the B-cell repertoire in a subset of patients.
  3. The humoral immunity using serological techniques.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Single inclusion visit with data collection and blood sample. No further follow-up of participants.

A total of 60 participants previously enrolled in the main cohort ANRS 0758s MOSAIC are planned to be included, distributed among France (n = 35), Italy (n = 20), and Switzerland (n = 5).

Study Type

Interventional

Enrollment (Estimated)

60

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Written informed consent, signed by the participant and the investigator prior to any study-related procedure
  • Person previously enrolled in the ANR0258s-MOSAIC cohort (see Appendix 19.2 for MOSAIC inclusion criteria) between July 2022 and July 2023
  • Person with a blood sample taken within 8 months following mpox infection
  • ≥ 18 years old

Exclusion Criteria:

  • Individuals who, in the investigator's opinion, are unlikely to comply with study procedures or whose medical condition is incompatible with study participation
  • For France only: person not affiliated to or not benefiting from a social security scheme in accordance with article L1121-11 of the French Public Health Code (Aide Médicale d'Etat [AME] does not constitute a social security scheme)
  • Pregnant or breastfeeding women
  • Individuals under guardianship or curatorship, or deprived of liberty by judicial or administrative decision

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Health Services Research
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: study population
Procedure: Patients included in the ANRS0758s MOSAIC cohort will be recalled >3 years after their infection to come to hospital to have a review of medical history since mpox infection, a clinical examination in case of symptoms suggestive of a mpox infection and samples taken for the study.
Procedure: blood sampling
Procedure: Patients included in the ANRS0758s MOSAIC cohort will be recalled >3 years after their infection to come to hospital to have a review of medical history since mpox infection, a clinical examination in case of symptoms suggestive of a mpox infection and samples taken for the study.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
The main outcomes are: the presence of neutralizing antibodies in the serum and the presence of detectable mpox virus-specific memory B cells.
Time Frame: Baseline (Day 1)
Neutralizing antibodies titers will be measured with a semi-automated cell-based assay using live mpox virus. Memory B cells will be measured by flow cytometry and other techniques.
Baseline (Day 1)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

ANRS, Emerging Infectious Diseases

Collaborators

Assistance Publique - Hôpitaux de Paris

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

July 1, 2026

Primary Completion (Estimated)

July 1, 2027

Study Completion (Estimated)

July 1, 2028

Study Registration Dates

First Submitted

May 10, 2026

First Submitted That Met QC Criteria

May 14, 2026

First Posted (Actual)

May 18, 2026

Study Record Updates

Last Update Posted (Actual)

May 18, 2026

Last Update Submitted That Met QC Criteria

May 14, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ANRS0791s POXAIM

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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