In Grenada, West Indies, What Is the Degree of Bat-human Interaction in Households and Is It Associated to Arboviral Disease?

Background: Bats are reservoirs for several zoonotic pathogens, making human-bat interactions particularly concerning. Recent studies documented that Grenadian bats can be infected with Zika, dengue and Chikungunya viruses and Leptospira bacteria among other pathogens. The objective of this study was to estimate the number of homes in Grenada that have a bat infestation, and to determine whether there is a correlation between the number of bat infested homes with the type of roofing or the presence of arbovirus infections of human inhabitants. Methods: An institutional review board (IRB) approved questionnaire delivered through a semi-structured interview was administered at the central bus stop in St. George, Grenada to recruit participants from all six parishes and the island of Carriacou. Results determined the percentage of individuals that had bat roosts in their households, whether this was of concern to them, whether they had taken any steps to keep bats out of their residence, and whether they had confirmed or suspected cases of dengue, Zika or Chikungunya virus infections. Information on the type of roofing and presence of window screens were also documented. Bat type (fruit vs insect eating bats) was attempted by guano description. Results: Results from 210 individual responses provided data showing all six parishes were represented although not equally. Having bats at the household was not associated with parish of residence, roof type or presence or absence of window screens. The results showed 60% of homes in Grenada are bat-infested and 51% of people self-reported recent arbovirus infection; but no correlation between the two. Also, no correlation to a specific type of roof or type of bat was found.Conclusions: A statistically significant number of inhabitants had attempted to remove bats from their homes, indicating that bats are perceived as pest to homes in Grenada, and justifying further research into relocating bats through the use of construction changes, awareness, and the creation of bat houses.

Arboviruses: How Saliva Impacts the Journey from Vector to Host

Arthropod-borne viruses, referred to collectively as arboviruses, infect millions of people worldwide each year and have the potential to cause severe disease. They are predominately transmitted to humans through blood-feeding behavior of three main groups of biting arthropods: ticks, mosquitoes, and sandflies. The pathogens harbored by these blood-feeding arthropods (BFA) are transferred to animal hosts through deposition of virus-rich saliva into the skin. Sometimes these infections become systemic and can lead to neuro-invasion and life-threatening viral encephalitis. Factors intrinsic to the arboviral vectors can greatly influence the pathogenicity and virulence of infections, with mounting evidence that BFA saliva and salivary proteins can shift the trajectory of viral infection in the host. This review provides an overview of arbovirus infection and ways in which vectors influence viral pathogenesis. In particular, we focus on how saliva and salivary gland extracts from the three dominant arbovirus vectors impact the trajectory of the cellular immune response to arbovirus infection in the skin.

Uncovering the Worldwide Diversity and Evolution of the Virome of the Mosquitoes Aedes aegypti and Aedes albopictus

Aedes aegypti, the yellow fever mosquito, and Aedes albopictus, the Asian tiger mosquito, are the most significant vectors of dengue, Zika, and Chikungunya viruses globally. Studies examining host factors that control arbovirus transmission demonstrate that insect-specific viruses (ISVs) can modulate mosquitoes’ susceptibility to arbovirus infection in both in vivo and in vitro co-infection models. While research is ongoing to implicate individual ISVs as proviral or antiviral factors, we have a limited understanding of the composition and diversity of the Aedes virome. To address this gap, we used a meta-analysis approach to uncover virome diversity by analysing ~3000 available RNA sequencing libraries representing a worldwide geographic range for both mosquitoes. We identified ten novel viruses and previously characterised viruses, including mononegaviruses, orthomyxoviruses, negeviruses, and a novel bi-segmented negev-like group. Phylogenetic analysis suggests close relatedness to mosquito viruses implying likely insect host range except for one arbovirus, the multi-segmented Jingmen tick virus (Flaviviridae) in an Italian colony of Ae. albopictus. Individual mosquito transcriptomes revealed remarkable inter-host variation of ISVs within individuals from the same colony and heterogeneity between different laboratory strains. Additionally, we identified striking virus diversity in Wolbachia infected Aedes cell lines. This study expands our understanding of the virome of these important vectors. It provides a resource for further assessing the ecology, evolution, and interaction of ISVs with their mosquito hosts and the arboviruses they transmit.

Serological and molecular epidemiology of the Dengue, Zika and Chikungunya viruses in a risk area in Brazil

Background The co-circulation of types of arbovirus in areas where they are endemic increased the risk of outbreaks and limited the diagnostic methods available. Here, we analyze the epidemiological profile of DENV, CHIKV and ZIKV at the serological and molecular level in patients with suspected infection with these arboviruses in the city of Juazeiro do Norte, Ceará, Brazil. Methods In 2016, the Central Public Health Laboratory (LACEN) of Juazeiro do Norte received 182 plasma samples from patients who visited health facilities with symptoms compatible with arbovirus infection. The LACEN performed serological tests for detection of IgM/IgG to DENV and CHIKV. They then sent these samples to the Retrovirology Laboratory of the Federal University of São Paulo and Faculty of Medical of the ABC where molecular analyses to confirm the infection by DENV, ZIKV and CHIKV were performed. The prevalence of IgM/IgG antibodies and of infections confirmed by RT-qPCR were presented with 95% confidence interval. Results In serologic analysis, 125 samples were positive for antibodies against CHIKV and all were positive for antibodies against DENV. A higher prevalence of IgG against CHIKV (63.20% with 95% CI: 45.76–70.56) than against DENV (95.05% with 95% CI: 78.09–98.12) was observed. When the samples were submitted to analysis by RT-qPCR, we observed the following prevalence: mono-infection by ZIKV of 19.23% (95% CI: 14.29–34.82) patients, mono-infection by CHIKV of 3.84% (95% CI: 2.01–5.44) and co-infection with ZIKV and CHIKV of 1.09% (95% CI: 0.89–4.56). Conclusion The serologic and molecular tests performed in this study were effective in analyzing the epidemiological profile of DENV, CHIKV and ZIKV in patients with suspected infection by these arboviruses in the city of Juazeiro do Norte, Ceará/Brazil.

TBE in Ukraine

The available data indicate that infection with tick-borne encephalitis virus (TBEV) is the most common arbovirus infection in Ukraine. Natural TBE foci are mainly located in the Polissya territories (Volyn, Rivne, Zhytomyr, Kyiv, and the Chernigiv region), as well as the Pre-Carpathian and Trans–Carpathian regions; a highly intensive distribution of TBEV was also observed in the entire mountain forest zone of Crimea and in Volinskij.

Diagnostic Performance of a Magnetic Field-Enhanced Agglutination Readout in Detecting Either Viral Genomes or Host Antibodies in Arbovirus Infection

Arbovirus diagnostics on blood from donors and travelers returning from endemic areas is increasingly important for better patient management and epidemiological surveillance. We developed a flexible approach based on a magnetic field-enhanced agglutination (MFEA) readout to detect either genomes or host-derived antibodies. Dengue viruses (DENVs) were selected as models. For genome detection, a pan-flavivirus amplification was performed before capture of biotinylated amplicons between magnetic nanoparticles (MNPs) grafted with DENV probes and anti-biotin antibodies. Magnetization cycles accelerated this chaining process to within 5 min while simple turbidimetry measured the signal. This molecular MFEA readout was evaluated on 43 DENV RNA(+) and 32 DENV RNA(−) samples previously screened by real-time RT-PCR. The sensitivity and the specificity were 88.37% (95% CI, 78.76%–97.95%) and 96.87% (95% CI, 90.84%–100%), respectively. For anti-DENV antibody detection, 103 plasma samples from donors were first screened using ELISA assays. An immunological MFEA readout was then performed by adding MNPs grafted with viral antigens to the samples. Anti-DENV antibodies were detected with a sensitivity and specificity of 90.62% (95% CI, 83.50%–97.76%) and 97.44% (95% CI, 92.48%–100%), respectively. This adaptable approach offers flexibility to platforms dedicated to the screening of emerging infections.

Mosquito saliva sialokinin-dependent enhancement of arbovirus infection through endothelial barrier leakage

SummaryViruses transmitted by Aedes mosquitoes constitute an increasingly important global health burden. Defining common determinants of host susceptibility to this large group of heterogenous pathogens are key for informing the rational design of new pan-viral medicines. Infection of the vertebrate host with these viruses is enhanced by the presence of mosquito saliva, a complex mixture of salivary gland-derived factors and microbiota. We show that enhancement of infection by saliva was dependent on vascular function and was independent of most anti-saliva immune responses, including to salivary microbiota. Instead, the Aedes gene product sialokinin mediated enhancement of virus infection through a rapid reduction in endothelial barrier integrity. Sialokinin is unique within the insect world as having vertebrate-like tachykinin sequence and is absent from non-vector competent Anopheles mosquitoes, whose saliva was not pro-viral and did not induce similar vascular permeability. Therapeutic strategies targeting sialokinin have potential to limit disease severity following infection with Aedes mosquito-borne viruses.