Subversion of early innate antiviral responses during antibody-dependent enhancement of Dengue virus infection induces severe disease in immunocompetent.

Subversion of early innate antiviral responsesduring antibody-dependent enhancement of

Dengue virusinfection induces severe disease in

immunocompetent mice

Julia T. de Castro

MOST OF

THEM

UNIVERSIDADE FEDERAL DE MINAS GERAISIMMUNOFARMACOLOGY GROUP

Where is… I STUDY AND WORK!

Summary

• Introduction to Dengue• Antibody-Dependent Enhancement (ADE)• Methods• Results• Conclusion

Paper discussion

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 nature.com

saude.hsw.uol.com.br

Dengue Map

Absent Improbable Probable Present

Dengue virus• DENV is a RNA virus• Four well-known serotypes (DENV1, DENV2,

DENV3 and DENV4)• A fifth type was discovered in 2013

Immune Response

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

Dengue fever

Severe Dengue

healthxchange.com.sg

How severe disease is developed?

Few hypotheses

Antibody-Dependent Enhancement (ADE)

Antibody-Dependent Enhancement (ADE)

nature.com

• 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”

Let’s go to the paper…Methods

• ELISA• PCR• Immunohistochemistry• Plaque Assay• Plaque reduction neutralization test in Vero

Cells (PRNT)

virology.ws

Results

Fig. 1

B cells are necessary for host resistance to primary Dengue infection

*B-cell-deficient mice (μMT−/−)

Conclusions

• B cells are protective to primary infection

Fig. 2

Preexisting immunity can exacerbate disease?

*Mice injected with anti-DENV3 serum and infected with DENV-2

Conclusions

• B cells are protective to primary infection• B-cell activation and antibody production can

exert a dual role

Fig. 3

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

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)

Fig. 4

ADE-mediated severe disease resembles primary disease with high inoculum

*4G2 treated mice, sub lethal inoculum (100 PFU) and lethal (1000 PFU)

Fig. 5

Parameters of disease in day 7 (peak)

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

Fig. 6

Involvement of FcγRs

*Mice treated with an FcγR-blocking Ab in the presence or not of 4G2

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

Fig. 7

Intrinsic ADE

Mice A129 -/- have more severe disease (supplementary figures)

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

Fig. 8

Passive intravenous immunoglobulin therapy (IVIG) containing subneutralizing titers of Ab

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

Conclusions

• Vaccines• Treatments