Dengue Literature Review

Vo2020 - Autoantibody Profiling in Dengue

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Vo2020 - Autoantibody Profiling in Dengue

Full citation: Vo HTM, Duong V, Ly S, Li QZ, Dussart P, Cantaert T. Autoantibody Profiling in Plasma of Dengue Virus–Infected Individuals. Pathogens. 2020;9(12):1060. doi:10.3390/pathogens9121060

Raw file: [[raw/Vo2020.pdf]]

Summary

This exploratory study used a protein microarray containing 123 putative autoantigens to screen IgM and IgG autoantibody reactivity in plasma from 40 Cambodian children: 8 healthy donors (HD), 11 asymptomatic DENV-infected (ASD), and 21 hospitalized dengue patients (13 DF, 8 DHF) at 6–10 days post-virologically confirmed DENV infection. The cohort was predominantly secondary infections (26/32 DENV-positive individuals) and predominantly DENV-1.

The study found that 80 IgM and 6 IgG autoantibodies were elevated in DENV-infected patients vs. HD, consistent with polyclonal B cell activation. Counterintuitively, primary DENV infection was associated with significantly higher IgG autoantibody levels than secondary infection — the opposite of what severity-based expectations would predict. No significant differences in total autoantibody load were found between asymptomatic and hospitalized dengue patients. In DHF specifically, 19 IgG autoantibodies — directed against complement (Factor P, C4), coagulation (prothrombin), and nuclear antigens (KU/P70/P80, Smith, Sm/RNP, histone H3/H4, nucleosome antigen) — positively correlated with platelet counts, suggesting these antibodies are consumed via immune complex formation as disease worsens.

The authors interpret the IgM autoantibody elevation as bystander B cell activation, the primary-infection IgG excess as a tolerance checkpoint failure unique to first DENV exposure, and the positive autoantibody-platelet correlation in DHF as reflecting consumption of these antibodies through immune complex formation (rather than direct pathogenicity).

Study Design

  • Type: Cross-sectional observational study (exploratory)
  • Sample size: n=40 total; 32 DENV-positive (11 ASD, 13 DF, 8 DHF); 8 HD
  • Setting: Kampong Cham province, Cambodia (three hospitals); sampling June–October 2012 and 2013; Institut Pasteur du Cambodge for laboratory analysis
  • Population: Cambodian children; mean age ~9–11 years across groups; predominantly secondary DENV infection (81.25%); asymptomatic individuals identified via household cluster investigation around confirmed cases

Key Findings

  • 80 IgM and 6 IgG autoantibodies elevated in DENV-infected patients vs. HD (p < 0.01 for total IgM NFI by Mann–Whitney); consistent with bystander polyclonal B cell activation
  • IgM autoantibodies elevated against: β2-glycoprotein-I (β2GPI), complement components C5, C8, C9, Factor B, Factor H, Factor P
  • Primary infection showed significantly higher IgG autoantibodies than secondary infection (p < 0.01): 70 IgG autoantibodies had higher NFI in primary vs. secondary; IgM did not differ significantly. Primary group included only 6 individuals (all male, all DENV-1) — an acknowledged limitation
  • No significant difference in total autoantibody load between ASD and DF/DHF patients; individual autoantibody analysis identified 4 IgM and 14 IgG autoantibodies decreased in DF/DHF vs. ASD (targeting heparan sulfate, proteoglycan, mitochondrial antigens)
  • 19 IgG autoantibodies positively correlated with platelet counts in DHF (Spearman r = 0.74–0.83, all p < 0.05):
    • Complement: Factor P (r=0.7563), complement C4 (r=0.7857)
    • Coagulation: Prothrombin (r=0.7807)
    • Nuclear: KU (P70/P80) (r=0.8333), SmD (r=0.8333), SRP54 (r=0.8333), Sm/RNP (r=0.7619), SmD1 (r=0.7619), Histone H3 (r=0.8264), Histone H4 (r=0.7857), Nucleosome antigen (r=0.7381)
    • Other: Vitronectin (r=0.8095), M2 (r=0.8095), PR3 (r=0.791), MPO (r=0.7619), Alpha Fodrin (r=0.7425), CRP antigen (r=0.7381), Mi-2 (r=0.7381), U1-snRNP-C (r=0.7381)
  • Low anti-Factor P IgG and low anti-complement C4 IgG associated with low platelet counts in DHF — proposed interpretation: these autoantibodies are consumed through immune complex formation, contributing to complement cascade dysregulation
  • Viral load significantly higher in DHF vs. ASD (6.21×10⁴ vs. 1.17×10³ copies/mL, p=0.02)
  • DENV-1 dominant across all groups (72.7–87.5%); all 8 DHF patients were secondary infection

Methods Used

  • Autoantigen Microarray (University of Texas Southwestern platform; 123 autoantigens; cy3-IgG/cy5-IgM detection; Genepix scanner)
  • RT-PCR (RT-qPCR for DENV RNA confirmation and serotyping)
  • NS1 Antigen Detection (SD Bioline Dengue Duo rapid test for some hospitalised patients)
  • IgM-IgG Serology ELISA (IgM seroconversion used for diagnosis of some hospitalised patients)

Entities Mentioned

  • DENV-1 (dominant serotype, 72.7–87.5%)
  • DENV-2 (18.18% of ASD, 12.5% of DHF)
  • DENV-4 (9.09% of ASD, 15.4% of DF)
  • NS1 Protein (anti-NS1 cross-reactivity with platelets cited; B cell receptor context)

Concepts Addressed

Relevance & Notes

This is the first paper in this wiki to use a high-throughput autoantigen microarray in dengue, providing a systematic rather than targeted view of autoantibody reactivity. The finding that IgG autoantibodies are higher in primary than secondary infection directly challenges the expectation that secondary infection — with its higher disease burden and ADE — would show more immunological dysregulation. The authors attribute this to “leakiness in tolerance mechanisms” in primary infection, where naïve B cells may escape checkpoints more readily in the absence of memory-dominated competition.

The nuclear antigen correlations in DHF (KU, Smith, histone, nucleosome, Sm/RNP — all canonical ANA targets) are highly relevant to the ANA thread. Their positive correlation with platelet counts (low Ab = low platelets) implicates consumption rather than pathogenesis, contrasting with the Lin group’s finding that anti-platelet IgM causes thrombocytopenia. These two pictures are not contradictory — they target different antibody populations — but they complicate the narrative of autoantibody-mediated platelet destruction.

Limitations acknowledged: very small sample (n=40, primary group n=6); cross-sectional (no follow-up); insufficient plasma for cross-validation; primary group confounded by sex (all male) and serotype (all DENV-1); no adjustment for multiple comparisons in the 19 DHF autoantibody correlations.

Questions Raised

  • Does the primary-infection IgG autoantibody excess persist longitudinally, or resolve by convalescence? If it decays faster than expected (via tolerance re-establishment), it would reconcile with Wan2012’s months-of-persistence model.
  • What is the temporal relationship between the depletion of the 19 DHF-correlated autoantibodies and the onset of plasma leakage? If depletion precedes leakage, it could be a prognostic biomarker.
  • Are the nuclear antigen IgGs (KU, Smith, histone, Sm/RNP) that correlate with platelet counts in DHF the same antibodies measured as ANA by IIFA in Garcia2009/Chatterjee2024? If so, this provides a mechanistic explanation for why ANA levels might paradoxically decline in the most severe dengue patients.
  • Do asymptomatic secondary infected individuals have the same reduced-IgG-autoantibody profile as symptomatic secondary patients, or is the reduction specific to those who develop clinical disease?

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