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NCT Number: NCT07592429

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

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.

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Key information

Conditions

Mpox (Monkeypox) Animal Diseases DNA Virus Infections Infections Mpox, Monkeypox Poxviridae Infections Primate Diseases Rodent Diseases Virus Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

About this study

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).

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

blood sampling

Procedure

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.

Primary outcomes

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.

Study contacts

Contact information is provided by the study sponsor or research team.

Aida TAIEB

CONTACT

[email protected]

+33 (0)1 82 53 35 66

Sponsors and collaborators

Lead sponsor

ANRS, Emerging Infectious Diseases

Other Gov

Collaborators

Assistance Publique - Hôpitaux de Paris

Registry information

Acronym: POXAIM

Important dates

Study start: 2026
Primary completion: 2027
Study completion: 2028
First posted: May 18, 2026
Registry last updated: May 18, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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