EFB Dengue Literature Review

Singh2026 - DENV-Specific Memory B Cell Subsets

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Singh2026 - DENV-Specific Memory B Cell Subsets

Full citation: Singh T, Balakhmet A, Granera JM, Shinkre R, Zambrana JV, Lee NE, Graber AL, Duarte EM, Bos S, Narvaez F, Balmaseda A, Harris E. Dengue virus-specific memory B cell subsets differ as a function of infection history. bioRxiv preprint, doi:10.64898/2026.01.30.702935 (2026).

Raw file: [[raw/Singh2026.pdf]]

Summary

This study provides the first comprehensive immunophenotyping of DENV-specific memory B cell (MBC) subsets in dengue, comparing primary (1°) versus secondary (2°) DENV infections longitudinally from acute infection to 18 months post-symptom onset. The authors developed a modified antigen-based detection approach using Alexa Fluor-labelled whole DENV virions (DENV1, 2, 3 grown on Vero-furin cells) as dual-colour probes (AF488 + AF647) to enumerate DENV-specific B cells by flow cytometry.

The central finding is that 2° DENV immunity represents a qualitative reprogramming of the MBC compartment rather than a quantitative boost: total DENV-specific B cell frequencies did not differ between 1° and 2° groups, but specific MBC subsets — IgG+, IgM+, atypical (CD27⁻CD21⁻), and class-switched IgD⁻ MBCs — were significantly higher in 2° immunity and durable to 18 months. Unexpectedly, several DENV-specific MBC subsets peaked >3 months post-infection in 2° but not 1° responses, and an uptick between 12–18 months was observed in 3/4 secondary cases, suggesting ongoing maturation or tissue-circulation dynamics.

A hypothetical working model built from temporal correlations posits IgD+ naive B cells and IgG+ MBCs as early responders in 1° immunity, while IgM+ MBCs and atypical MBCs are the early responders in 2° immunity — fundamentally different initiating compartments depending on infection history.

Study Design

  • Type: Longitudinal cohort + cross-sectional convenience sample
  • Sample size: 58 PBMC samples from 18 pediatric patients (9 primary, 9 secondary DENV infection)
  • Setting: Hospital Infantil Manuel de Jesús Rivera (HIMJR), Managua, Nicaragua; Pediatric Dengue Hospital Study (PDHS); children aged 6 months–14 years with confirmed DENV infection (DENV1 and DENV3 serotypes)
  • Population: Pediatric dengue cases; 1° vs 2° infection classified by DENV iELISA titer (<2560 = primary, ≥2560 = secondary in convalescent samples)
  • Longitudinal Set: 8 patients (4 per group), 6 timepoints each: acute, early convalescence (EC; 2–4 weeks), 3M, 6M, 12M, 18M post-symptom onset
  • Singlets Set: 10 patients (5 per group), single timepoint at EC or 3M

Key Findings

DENV-specific B cell frequencies

  • DENV-specific cells average ~0.72% of all B cells and ~0.78% of class-switched IgD⁻ MBCs; concordant with prior flow cytometry estimates (0.3–0.9%)
  • No significant difference in total DENV-specific B cell frequency between 1° (median 54/10,000 B cells) and 2° (median 66/10,000) groups across all timepoints
  • DENV-specific class-switched IgD⁻ MBCs (1°=53 vs 2°=105 per 10,000; p<0.001) and IgG+ MBCs (1°=43 vs 2°=84 per 10,000; p<0.001) significantly higher in 2° immunity
  • Resting MBCs (CD27+CD21+) did not differ by infection history

Acute-phase differences

  • DENV-specific IgM+ MBCs significantly higher in 2° than 1° dengue (p<0.05, n=4/group) — the only significantly different MBC subset at the acute timepoint
  • IgM⁻ plasmablasts (likely IgG+) significantly higher in 2° than 1° dengue (p<0.05)
  • Total plasmablasts (CD38+CD27+) did not differ

Early convalescence (EC) differences

  • DENV-specific IgD⁻ class-switched MBCs (p<0.01) and IgG+ MBCs (p<0.05) significantly higher in 2° vs 1°
  • DENV-specific atypical MBCs (CD27⁻CD21⁻; p<0.01) and activated MBCs (CD27+CD21⁻; p<0.05) significantly higher in 2° vs 1°

Durability at 18 months

  • IgG+, IgM+, and atypical MBCs significantly higher in 2° than 1° at 18M (p<0.05)
  • IgD⁻ class-switched and IgD⁻/IgM⁻/IgG⁻ MBCs trending (p=0.06 and p=0.1)
  • These subsets durable and accumulating with exposures → bona fide memory compartment

Naïve-like DENV-specific B cells

  • IgD+/IgM+ naïve-like B cells (CD20+/IgD+/IgM+) contain DENV-specific cells persisting to 18M
  • Constitute ~14% (1°) and ~8% (2°) of all DENV-specific B cells at 18M
  • Appear to diminish with multiple exposures

Temporal dynamics (Two-way RM-ANOVA, n=4/group, 6 timepoints)

  • Significant infection history effect on: class-switched IgD⁻, activated, IgG+, IgD⁻/IgM⁻/IgG⁻, and atypical MBC subsets (p<0.01) — 2° higher than 1°
  • Atypical MBCs (CD27⁻/CD21⁻) but not resting MBCs (CD27+/CD21+) differed by infection history
  • Delayed MBC peaks in 2° immunity: 3 subsets peaked significantly later in 2° than 1° (p<0.05), 2 trending (p<0.06)
  • 12–18M uptick in 2° immunity: DENV-specific IgD⁻, IgG+, IgD⁻/IgM⁻/IgG⁻, and atypical MBCs showed an uptick from 12M to 18M in 3/4 secondary cases; not present in 1° or in total B cell compartments

Fold-change from acute to EC

  • 1° response: IgM+ MBCs show greatest fold-change (7-fold)
  • 2° response: activated, atypical, and IgD⁻/IgM⁻/IgG⁻ MBCs show greatest fold-change (2.3-, 2.3-, 2.1-fold)

Hypothetical working model (temporal correlations)

  • 1° immunity: IgD+ naive B cells → largest network; IgG+ MBCs most influential at acute/EC
  • 2° immunity: IgM+ MBCs → largest network at acute; atypical MBCs correlate with later IgD⁻ class-switched and activated MBCs
  • Long-term (12–18M) correlations from IgD⁻ class-switched subsets in both groups; IgM+ and resting MBCs show self-replenishment

Flow cytometry panel (12-color conventional)

  • Dump: CD3-V500, CD14-V500, CD16-V500
  • Viability: Aqua Live/Dead
  • B cell gate: CD19-APC-Cy7
  • Subset markers: CD20-PerCP-Cy5.5, IgD-V450, IgM-BV605, IgG-BV786, CD21-PE-CF594, CD27-PE-Cy7, CD38-PE
  • Antigen probes: AF488-DENV (1+2+3), AF647-DENV (1+2+3) — 6-antigen cocktail
  • Instrument: BD LSRFortessa
  • Key gating: FMO for CD21 and CD27; no-antigen control for DENV-specific threshold
  • Average events: ~1,000,000 PBMCs, ~100,000 live B cells, 561 DENV-specific cells per sample

B cell subsets defined (9 subsets + PBs)

  1. Naive B cells: CD20+/IgD+
  2. IgD+/IgM+ naive B cells: CD20+/IgD+/IgM+
  3. Class-switched MBC: CD20+/IgD⁻
  4. Activated MBC: CD20+/IgD⁻/CD27+/CD21⁻
  5. Resting MBC: CD20+/IgD⁻/CD27+/CD21+
  6. Atypical MBC: CD20+/IgD⁻/CD27⁻/CD21⁻
  7. IgG+ MBC: CD20+/IgD⁻/IgG+
  8. IgM+ MBC: CD20+/IgD⁻/IgM+
  9. IgD⁻/IgM⁻/IgG⁻ MBC (likely IgA+)
  10. Plasmablasts: CD38+/CD27+ within IgD⁻/CD20⁻

Methods Used

Entities Mentioned

Concepts Addressed

  • Memory B Cell — qualitative reprogramming of MBC compartment with repeat exposure
  • Extrafollicular Response — atypical MBCs and IgM+ MBCs as potential EF-derived memory; delayed peaks suggest ongoing maturation
  • Germinal Center — delayed MBC peaks in 2° immunity may indicate prolonged GC reactions
  • Class Switch Recombination — IgG+, IgM+, and IgD+/IgM+ subsets tracked; CSR accumulates with exposures
  • Somatic Hypermutation — paper discusses limited further affinity maturation in flavivirus immunity (citing Wong et al. 2020)

Relevance & Notes

This is the first paper in the wiki directly studying dengue, and the first to comprehensively phenotype DENV-specific MBC subsets. All prior sources were SLE, COVID-19, or cross-disease reviews used as comparative benchmarks.

Critical link to existing wiki content:

  • The “atypical MBCs” defined here as CD27⁻/CD21⁻ within IgD⁻CD20+ correspond to the DN B cell compartment in wiki nomenclature. However, Singh2026 does not include CXCR5 or CD11c in the panel, so DN1/DN2/DN3 subdivision is not possible. Per the Sanz2025 Watch Item, this panel cannot distinguish whether the expanded “atypical” DENV-specific cells are DN2 (EF effectors), DN1 (memory), or a mix. The IgD inclusion is notable — this study passes the Sanz2025 IgD audit criterion.
  • The finding that IgM+ MBCs are recalled in 2° dengue connects to the wiki’s existing coverage of IgM+ memory as a GC-independent memory layer (Tipton2015) and IgM+ memory B cell debate (cited: Hale2022, Wec2020 on SARS-CoV-2 and YFV).
  • The delayed MBC peaks (>3 months in 2° immunity) are consistent with prolonged GC reactions described for SARS-CoV-2 vaccination (Turner et al. 2021, cited in paper).
  • The 12–18M uptick in 2° cases raises the question of subclinical boosting in endemic settings — directly relevant to the EF/GC dynamics question.

Limitations:

  • Very small longitudinal sample size (n=4 per group) — limits statistical power
  • Convenience sampling design
  • Only DENV1 and DENV3 serotypes evaluated
  • No functional assays (stimulation, neutralization, repertoire)
  • No CXCR5 or CD11c — cannot resolve DN1/DN2/DN3 within the “atypical” gate
  • No T-bet staining — cannot determine if atypical MBCs are T-bet+
  • Preprint — not yet peer-reviewed

Questions Raised

  • Do the DENV-specific atypical MBCs (CD27⁻/CD21⁻) that accumulate in 2° dengue express T-bet and CD11c — i.e., are they DN2 (EF-derived effectors) or DN1 (GC-derived memory)?
  • Is the IgM+ MBC recall in 2° dengue mediated by class-switched IgM+ memory cells (IgD⁻IgM+) or by unswitched marginal zone-like cells — and what is their BCR repertoire?
  • What drives the delayed (>3 month) MBC peaks in 2° dengue — prolonged GC reactions, tissue redistribution, or subclinical re-exposure in endemic settings?
  • Can the 12–18M uptick in 2° cases be distinguished from subclinical boosting by a different DENV serotype?
  • Do the persisting DENV-specific IgD+/IgM+ “naïve-like” B cells represent true antigen-experienced cells with SHM, or germline-encoded polyreactive B cells?
  • Does the qualitative reprogramming of MBC subsets correlate with neutralizing antibody breadth or ADE-relevant cross-reactivity?

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