Generation and characterization of a monoclonal antibody that cross-reacts with the envelope protein from the four dengue virus serotypes

Cross-Reaction, Enhancement, and Neutralization Activity of Dengue Virus Antibodies against Zika Virus: A Study in the Mexican Population

Zika virus (ZIKV), an emerging mosquito-borne flavivirus, has quickly spread in many regions around the world where dengue virus (DENV) is endemic. This represents a major health concern, given the high homology between these two viruses, which can result in cross-reactivity. The aim of this study was to determine the cross-reacting antibody response of the IgM and IgG classes against the recombinant envelope protein of ZIKV (rE-ZIKV) in sera from patients with acute-phase infection of different clinical forms of dengue, i.e., dengue fever (DF) and dengue hemorrhagic fever (DHF) (before the arrival of ZIKV in Mexico 2010), as well as acute-phase sera of ZIKV patients, together with the implications in neutralization and antibody-dependent enhancement. Differences in IgM responses were observed in a number of DF and DHF patients whose sera cross-reacted with the rE-ZIK antigen, with 42% recognition between acute-phase DHF and ZIKV but 27% recognition between DF and ZIKV. Regarding IgG antibodies, 71.5% from the DF group showed cross-reactivity to rE-ZIKV in contrast with 50% and only 25% of DHF and ZIKV serum samples, respectively, which specifically recognized the homologous antigen. The DHF group showed more enhancement of ZIKV infection of FCRγ-expressing cells compared to the DF group. Furthermore, the DHF group also showed a higher cross-neutralizing ability than that of DF. This is the first report where DF and DHF serum samples were evaluated for cross-reactivity against Zika protein and ZIKV. Furthermore, DENV serum samples cross-protect against ZIKV through neutralizing antibodies but at the same time mediate antibody-dependent enhancement in the sequential ZIKV infection.

Human keratinocyte cultures (HaCaT) can be infected by DENV, triggering innate immune responses that include IFNλ and LL37

The skin is the first anatomical region that dengue virus (DENV) encounters during the natural infection. Although the role of some skin resident cells like dendritic cells and fibroblasts has been demonstrated to be crucial to elucidate the role of resident cells and molecules participating during the early events of the innate immune response, the participation of keratinocytes during DENV infection has not been fully elucidated. In this paper we aimed to evaluate the use of the HaCaT cell line as a model to study the immune responses of skin keratinocytes to DENV infection. We demonstrated productive DENV-2 infection of HaCaT cells and their capability to establish an antiviral response through production of type I and type III interferons (IFN-β and IFN-λ). The production of these cytokines by HaCaT cells correlated with upregulation of IFN-inducible transmembrane protein-3 (IFITM3) and viperin in bystander, uninfected cells. We also observed an increase in secretion of IL-6 and IL-8. Skin keratinocytes are known to secrete antimicrobial peptides (AMPs) during viral infections. In our model, DENV-2 infected HaCaT cells upregulate the production of cytoplasmic LL-37. We evaluated the dual role of LL-37, HBD2, and HBD3 antiviral activity and immunoregulation during DENV-2 infection of HaCaT cells and found that LL-37 significantly reduced DENV-2 replication. This indicates that the HaCaT cell line can be used as a model for studying the innate response of keratinocytes to DENV infection. Our results also suggest that skin keratinocytes play an important role in the skin microenvironment after DENV infection by secreting molecules like type I and type III IFNs, pro-inflammatory molecules, and LL-37, which may contribute to the protection against arboviral infections.

Construct and expression of recombinant domains I/II of dengue virus- 2 and its efficacy to evaluate immune response in endemic area: Possible use in prognosis

The envelope (E) protein from DENV, contain three functional and structural domains (DI, DII and DIII). Some studies suggest that neutralizing antibodies during natural DENV infection are predominantly against DI and DII, in contrast, low proportion of the antibodies were against DIII. Thus it is necessary to establish the proportion of human antibodies against DENV E protein that bind to DI and DII during the normal course of infection; as an indicator of the quality of the antibody response and to further design new vaccine candidates for DENV. The aim of this study was to express recombinant proteins harboring a 240-aminoacid fragment of the E protein from DI and DII of DENV serotypes 2 and 3 in a eukaryotic S2 system. Further, we evaluate the antibodies against these antigens in samples from patients in acute phase of DF or DHF and compare it with the response of samples from healthy individuals from the same endemic areas and samples from healthy individuals from a non-endemic area (EA and NEA, respectively). These results suggest that the presence of antibodies against rEDI/DII might be used to identify patients at risk for severe disease.

New opportunities for control of dengue virus

PURPOSE OF REVIEW

Dengue is a rapidly spreading vector-borne disease estimated to infect 400 million people worldwide. To date, there are no licensed treatments or vaccines. The last few years have seen significant developments in dengue control strategies. In this review, we will address four key areas: vaccines, vector control, antivirals and immunotherapeutics.

RECENT FINDINGS

The first generation of dengue vaccines is able to induce good serological responses in test individuals. However, the recent Sanofi-Pasteur trial in Thailand found that a good serological response did not correlate with clinical protection. This trial did not demonstrate an increase in cases of severe disease following immunization, suggesting that concerns over vaccine-related immune enhancement may have been overcome. The bacterium Wolbachia appears to control dengue proliferation in Aedes mosquitoes, and field studies are underway. A large number of antivirals are in early-stage development and may prove useful in epidemics. Monoclonal antibodies have been postulated to have a clinical role. Whether their clinical application is feasible has yet to be seen.

SUMMARY

Marked improvements in our knowledge of dengue have been made over the recent years. Sadly, clinical application remains some years away.