Dengue and Chikungunya Coinfection – The Emergence of an Underestimated Threat

Both Dengue (DENV) and Chikungunya (CHIKV) viruses can be transmitted by Aedes mosquito species and the diseases that they cause have several clinical symptoms in common. Co-circulation of DENV and CHIKV is increasing around the world and must therefore be considered as an emerging threat with an important public health concern. At present, very little is known about the clinical manifestations and biological consequences of coinfection by both viruses. Thus, numerous questions such as clinical severity and dynamics of viral replication of DENV and CHIKV coinfections, as well as vectorial competence, have yet to be addressed in this important and challenging research area. The ensuring knowledge will enhance the clinical surveillance and the development of diagnostic tools able to differentiate DENV and CHIKV in order to early detect virus invasion and local transmission, as well as to improve patient care and timely control measures. In this review, we highlight the current knowledge on DENV and CHIKV coinfections. We also discuss research perspectives and challenges in order to further understand the ecology and biology of this phenomenon

Induction of a Peptide with Activity against a Broad Spectrum of Pathogens in the Aedes aegypti Salivary Gland, following Infection with Dengue Virus

The ultimate stage of the transmission of Dengue Virus (DENV) to man is strongly dependent on crosstalk between the virus and the immune system of its vector Aedes aegypti (Ae. aegypti). Infection of the mosquito's salivary glands by DENV is the final step prior to viral transmission. Therefore, in the present study, we have determined the modulatory effects of DENV infection on the immune response in this organ by carrying out a functional genomic analysis of uninfected salivary glands and salivary glands of female Ae. aegypti mosquitoes infected with DENV. We have shown that DENV infection of salivary glands strongly up-regulates the expression of genes that encode proteins involved in the vector's innate immune response, including the immune deficiency (IMD) and Toll signalling pathways, and that it induces the expression of the gene encoding a putative anti-bacterial, cecropin-like, peptide (AAEL000598). Both the chemically synthesized non-cleaved, signal peptide-containing gene product of AAEL000598, and the cleaved, mature form, were found to exert, in addition to antibacterial activity, anti-DENV and anti-Chikungunya viral activity. However, in contrast to the mature form, the immature cecropin peptide was far more effective against Chikungunya virus (CHIKV) and, furthermore, had strong anti-parasite activity as shown by its ability to kill Leishmania spp. Results from circular dichroism analysis showed that the immature form more readily adopts a helical conformation which would help it to cause membrane permeabilization, thus permitting its transfer across hydrophobic cell surfaces, which may explain the difference in the anti-pathogenic activity between the two forms. The present study underscores not only the importance of DENV-induced cecropin in the innate immune response of Ae. aegypti, but also emphasizes the broad-spectrum anti-pathogenic activity of the immature, signal peptide-containing form of this peptide

Role of Aedes aegypti saliva in Dengue virus transmission

Lors de la prise d'un repas sanguin par le moustique Aedes (Ae) aegypti, le virus de la dengue (DENV) est transmis à l'homme avec la salive du moustique. Ce mélange complexe est en partie déposé dans le compartiment cutané extravasculaire lors de la piqûre de moustique. Il est donc important de prendre en compte la triade virus-vecteur-hôte vertébré dans les mécanismes de transmission de ce virus à l'hôte vertébré. Des analyses de génomique et protéomique des glandes salivaires d'Ae. Aegypti infectées ou non par le DENV nous ont permis de mettre en évidence dans les glandes salivaires de moustiques infectés, la surexpression d'un gène codant pour un peptide antimicrobien (PAM) cationique. Nous avons démontré, que ce PAM possède une activité antibactérienne et antivirale contre les virus de la dengue et du chikungunya. Nos travaux soulignent l'importance chez les invertébrés, du compartiment « glandes salivaires » dans la réponse immunitaire innée du moustique. Nous avons également démontré que les kératinocytes humains sont des cellules permissives pour le DENV et que l'infection de ces cellules stimule la réponse immunitaire innée antivirale. Nos travaux démontrent que des extraits de glandes salivaires d'Ae. Aegypti augmentent l'infection du virus de la dengue dans les kératinocytes humains. Nous avons par la suite identifié une protéine salivaire d'Ae. Aegypti (34kDa), qui augmente l'infection du DENV en supprimant la production d'interféron. L'ensemble de ces travaux ont permis de contribuer aux connaissances sur la transmission du DENV, mais aussi d'identifier de nouvelles cibles potentielles pour le contrôle de la réplication virale.Dengue virus (DENV) transmission is initiated when a blood-feeding Aedes (Ae) aegypti mosquito injects saliva, together with the virus, into the epidermis of its mammalian host. Studies of DENV should, therefore, take into account the triad virus-vector-vertebrate host. We have used functional genomic and proteomic analyses, of the salivary glands of female Ae. Aegypti, to demonstrate that this compartment harbors a potent immune response against DENV, represented by the production of an antimicrobial peptide (AMP). This AMP was found to exert, in addition to its anti-bacterial activity, an anti-viral activity against DENV and Chikungunya. Our data demonstrate, for the first time, the permissiveness of human epidermal keratinocytes to DENV infection. Remarkably, DENV replication in keratinocytes contributes to the establishment of anti-viral innate immunity that might occur shortly after the mosquito bite. To investigate the role of Ae. aegypti saliva in DENV transmission to man, primary human keratinocytes were infected with DENV in the presence of Ae. aegypti salivary gland extract. We show that Ae. aegypti saliva enhances dengue virus infection of human keratinocytes by suppressing innate immune responses. Furthermore, we have found a 34-kDa protein, in the saliva of Ae.aegypti, that strongly enhances DENV replication by suppressing type-I IFN production. This study provides new insights into the role of Ae. aegypti salivary glands and saliva in DENV transmission. The data presented here provide novel targets for the control of DENV replication in mammalian hosts

Proteomic analysis of an Aedes albopictus cell line infected with Dengue serotypes 1 and 3 viruses

Background: Proteomic analysis was performed to identify proteins regulated during infection by Dengue serotypes 1 and 3 in an Aedes albopictus cell line. The potential of these viruses to cause severe disease at primary infection is of interest although few studies have been performed with these two Dengue serotypes. Results: The most relevant observation of our study is the significant overexpression of proteins involved in the cellular stress response and the glycolysis pathway after 48 hours of infection. Viral infection activates the translation of some host genes, which may result in stress due to responses involving unfolded proteins. Conclusions: Therefore, the oxidation reduction and glycolytic mechanisms could participate in the antiviral response against Dengue virus. The results of our study should help to improve our knowledge of the virus-mosquito interaction at a cellular level with the aim of designing efficient strategies for the control of Dengue virus

Proteomic analysis of an <it>Aedes albopictus </it>cell line infected with Dengue serotypes 1 and 3 viruses

<p>Abstract</p> <p>Background</p> <p>Proteomic analysis was performed to identify proteins regulated during infection by Dengue serotypes 1 and 3 in an <it>Aedes albopictus </it>cell line. The potential of these viruses to cause severe disease at primary infection is of interest although few studies have been performed with these two Dengue serotypes.</p> <p>Results</p> <p>The most relevant observation of our study is the significant overexpression of proteins involved in the cellular stress response and the glycolysis pathway after 48 hours of infection. Viral infection activates the <it>translation </it>of some <it>host </it>genes, which may result in stress due to responses involving unfolded proteins.</p> <p>Conclusions</p> <p>Therefore, the oxidation reduction and glycolytic mechanisms could participate in the antiviral response against Dengue virus. The results of our study should help to improve our knowledge of the virus-mosquito interaction at a cellular level with the aim of designing efficient strategies for the control of Dengue virus.</p

Dengue virus replication in infected human keratinocytes leads to activation of antiviral innate immune responses

Dengue virus (DENV) infection is the most prevalent mosquito-borne viral diseases in the world. Vector-mediated transmission of DENV is initiated when a blood-feeding female Aedes mosquito injects saliva, together with the virus, into the skin of its mammalian host. Understanding the role of skin immune cells in the activation of innate immunity to DENV at the early times of infection is a critical issue that remains to be investigated. The purpose of our study was to assess the contribution of human keratinocytes as potential host cells to DENV in the activation of immune responses at the anatomical site of mosquito bite. We show that primary keratinocytes support DENV replication with the production of negative-stranded viral RNAs inside the infected cells. In the course of DENV life cycle, we observed the activation of host genes involved in the antiviral immune responses such as intracellular RNA virus sensors Toll-Like Receptor-3, Retinoic Acid Inducible Gene-I, Melanoma Differentiation Associated gene-5 and the RNA-dependent protein kinase R. DENV infection of primary keratinocytes also resulted in up-regulation of the expression of the antiviral Ribonuclease L gene, which subsequently led to enhanced production of IFN-beta and IFN-gamma. Depending on stages of viral replication, we observed the activation of host genes encoding the antimicrobial proteins beta-defensin and RNase 7 in infected keratinocytes. Our data demonstrate for the first time the permissiveness of human epidermal keratinocytes to DENV infection. Remarkably, DENV replication in keratinocytes contributes to the establishment of antiviral innate immunity that might occur in the early times after the bite of mosquito

Inflammasome signaling pathways exert antiviral effect against Chikungunya virus in human dermal fibroblasts.

International audienceArboviruses represent an emerging threat to human. They are transmitted to vertebrates by the bite of infected arthropods. Early transmission to vertebrates is initiated by skin puncture and deposition of virus in this organ. However, events at the bite site remain largely unknown. Here, we report that Chikungunya virus (CHIKV) and West Nile virus (WNV), despite belonging to distinct viral families, elicit a common antiviral signature in primary human dermal fibroblasts, attesting for the up regulation of interferon signaling pathways and leading to an increased expression of IFN-β, interleukins and chemokines. Remarkably, CHIKV and WNV enhance IL-1β expression and induce maturation of caspase-1, indicating the capacity of these pathogens to elicit activation of the inflammasome program in resident skin cells. CHIKV and WNV also induce the expression of the inflammasome sensor AIM2 in dermal fibroblasts, whereas inhibition of caspase-1 and AIM2 with siRNA interferes with both CHIKV- and WNV-induced IL-1β production by these cells. Finally, inhibition of the inflammasome via caspase-1 silencing was found to enhance CHIKV replication in dermal fibroblasts. Together, these results indicate that the skin contributes to the pro-inflammatory and anti-viral microenvironment via the activation of the inflammasome in the early stages following infection with arboviruses