1. Subversion of early innate antiviral responses during antibody-dependent enhancement of Dengue virus infection induces severe disease in immunocompetent mice
Julia T. de Castro

2. UNIVERSIDADE FEDERAL DE MINAS GERAIS IMMUNOFARMACOLOGY GROUP
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UNIVERSIDADE FEDERAL DE MINAS GERAIS
IMMUNOFARMACOLOGY GROUP
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4. Summary Introduction to Dengue Antibody-Dependent Enhancement (ADE)
Methods
Results
Conclusion
Paper discussion

5. Dengue Fever Tropical and subtropical disease
Transmitted by the bite of the female mosquito Aedes aegypti
Female mosquitoes generally lay their eggs above the water inside containers as tires, buckets, birdbaths, water storage jars, and flower pots.
dengue.org.br
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6. Dengue Map
Absent
Improbable
Probable
Present

7. Dengue virus DENV is a RNA virus
Four well-known serotypes (DENV1, DENV2, DENV3 and DENV4)
A fifth type was discovered in 2013

8. Immune Response Infection of Langerhans cells Innate immunity
Secretion of IFN
Infected cells go to lymph nodes
Adaptive immunity
Abs, complement, Cytotoxic T lymphocytes

9. Dengue fever

10. Severe Dengue
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11. How severe disease is developed?
Few hypotheses
Antibody-Dependent Enhancement (ADE)

12. Antibody-Dependent Enhancement (ADE)
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Antibodies from the first infection are cross-reactive with other DENV serotypes
But Abs are subneutralizing
FcγR recognizes Abs and internalizes immunocomplex
Evidences suggest that the mechanism is associated with both increase in the number of infected cells, a phenomenon called “Extrinsic ADE,” and a subversion of the intracellular innate immune host responses through suppression of a the type I IFN and proinflammatory cytokines production—an event denominated as “Intrinsic ADE”

13. Let’s go to the paper… Methods ELISA PCR Immunohistochemistry
Plaque Assay
Plaque reduction neutralization test in Vero Cells (PRNT)
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14. Results
B cells are necessary for host resistance to primary Dengue infection
*B-cell-deficient mice (μMT−/−)
Fig. 1

15. Conclusions
B cells are protective to primary infection

16. Fig. 2 Preexisting immunity can exacerbate disease?
*Mice injected with anti-DENV3 serum and infected with DENV-2
Fig. 2

17. Conclusions B cells are protective to primary infection
B-cell activation and antibody production can exert a dual role

18. To test whether the levels of Ab would directly impact on severe disease
*Commercial anti-DENV clone 4G2 (15 μg and 400 μg) at day −1, day +1 and day +3
Fig. 3

19. Conclusions B cells are protective to primary infection
B-cell activation and antibody production can exert a dual role
Presence of non-neutralizing or subneutralizing levels of Ab can worsen disease (ADE)

20. ADE-mediated severe disease resembles primary disease with high inoculum
*4G2 treated mice, sub lethal inoculum (100 PFU) and lethal (1000 PFU)
Fig. 4

21. Parameters of disease in day 7 (peak)
Fig. 5

22. Conclusions B cells are protective to primary infection
B-cell activation and antibody production can exert a dual role
Presence of non-neutralizing or subneutralizing levels of Ab can worsen disease (ADE)
subneutralizing levels of anti-DENV antibodies enhance viral replication to similar extents found in mice primarily infected with a higher DENV inoculum

23. Fig. 6 Involvement of FcγRs
*Mice treated with an FcγR-blocking Ab in the presence or not of 4G2
Fig. 6

24. Conclusions B cells are protective to primary infection
B-cell activation and antibody production can exert a dual role
Presence of non-neutralizing or subneutralizing levels of Ab can worsen disease (ADE)
subneutralizing levels of anti-DENV antibodies enhance viral replication to similar extents found in mice primarily infected with a higher DENV inoculum
FcγRs play an essential role in disease

25. Intrinsic ADE
Mice A129 -/- have more severe disease (supplementary figures)
Fig. 7

26. Conclusions B cells are protective to primary infection
B-cell activation and antibody production can exert a dual role
Presence of non-neutralizing or subneutralizing levels of Ab can worsen disease (ADE)
subneutralizing levels of anti-DENV antibodies enhance viral replication to similar extents found in mice primarily infected with a higher DENV inoculum
FcγRs play an essential role in disease
Type I IFN play an essential role during primary and secondary infections

27. Passive intravenous immunoglobulin therapy (IVIG) containing subneutralizing titers of Ab
Fig. 8

28. Conclusions B cells are protective to primary infection
B-cell activation and antibody production can exert a dual role
Presence of non-neutralizing or subneutralizing levels of Ab can worsen disease (ADE)
subneutralizing levels of anti-DENV antibodies enhance viral replication to similar extents found in mice primarily infected with a higher DENV inoculum
FcγRs play an essential role in disease
Type I IFN play an essential role during primary and secondary infections

29. Conclusions
Vaccines
Treatments