Chikungunya Virus Transmission Potential by Local Aedes Mosquitoes in the Americas and Europe

Citation: Vega-Rua, A., Lourenco-de-Oliveira, R., Mousson, L., Vazeille, M., Fuchs, S., Yebakima, A., . . . Failloux, A. B. (2015). Chikungunya Virus Transmission Potential by Local Aedes Mosquitoes in the Americas and Europe. Plos Neglected Tropical Diseases, 9(5), 18. doi:10.1371/journal.pntd.0003780Background Chikungunya virus (CHIKV), mainly transmitted in urban areas by the mosquitoes Aedes aegypti and Aedes albopictus, constitutes a major public health problem. In late 2013, CHIKV emerged on Saint-Martin Island in the Caribbean and spread throughout the region reaching more than 40 countries. Thus far, Ae. aegypti mosquitoes have been implicated as the sole vector in the outbreaks, leading to the hypothesis that CHIKV spread could be limited only to regions where this mosquito species is dominant. Methodology/Principal Findings We determined the ability of local populations of Ae. aegypti and Ae. albopictus from the Americas and Europe to transmit the CHIKV strain of the Asian genotype isolated from Saint-Martin Island (CHIKV_SM) during the recent epidemic, and an East-Central-South African (ECSA) genotype CHIKV strain isolated from La Reunion Island (CHIKV_LR) as a well-characterized control virus. We also evaluated the effect of temperature on transmission of CHIKV_SM by European Ae. albopictus. We found that (i) Aedes aegypti from Saint-Martin Island transmit CHIKV_SM and CHIKV_LR with similar efficiency, (ii) Ae. aegypti from the Americas display similar transmission efficiency for CHIKV_SM, (iii) American and European populations of the alternative vector species Ae. albopictus were as competent as Ae. aegypti populations with respect to transmission of CHIKV_SM and (iv) exposure of European Ae. albopictus to low temperatures (20 degrees C) significantly reduced the transmission potential for CHIKV_SM. Conclusions/Significance CHIKV strains belonging to the ECSA genotype could also have initiated local transmission in the new world. Additionally, the ongoing CHIKV outbreak in the Americas could potentially spread throughout Ae. aegypti-and Ae. albopictus-infested regions of the Americas with possible imported cases of CHIKV to Ae. albopictus-infested regions in Europe. Colder temperatures may decrease the local transmission of CHIKV_SM by European Ae. albopictus, potentially explaining the lack of autochthonous transmission of CHIKV_SM in Europe despite the hundreds of imported CHIKV cases returning from the Caribbean.Additional Authors: de Lamballerie, X.;Failloux, A. B

The Chikungunya virus : evolutionnary mechanisms and reverse genetic methods

L’émergence de certains arbovirus pathogènes pose un problème majeur en termes de santé public. Le virus Chikungunya (CHIKV) est un exemple de virus émergent car il s’est récemment adapté à un nouveau vecteur et cause des épidémies explosives. Cette émergence est en partie la conséquence de phénomènes liés à la grande plasticité génomique du CHIKV. Mieux comprendre les mécanismes d’adaptation des arbovirus pourrait permettre de mieux contrôler ces pathogènes viraux. La première partie de cette thèse porte sur l’étude des mutations associées à l’évolution à long terme du CHIKV sur différentes lignées de mammifères et de moustiques. Les résultats montrent des profils d’évolution distincts sur cellules de mammifères ou de moustiques, illustrant les difficultés liées à l’alternance d’hôte au cours du cycle naturel du CHIKV. La deuxième partie porte sur l’étude chez le CHIKV de la recombinaison génétique, un mécanisme fondamental pour l’évolution des virus à ARN. Les résultats montrent une absence de recombinaison homologue entre virus non défectifs, mais ces expériences ont permis de mettre en évidence la présence de virus délétés qui semblent aider par trans-complémentation la réplication d’un virus atténué. La dernière partie de cette thèse porte sur l’étude de méthodes de génétique inverse qui permettent de générer des virus et d’étudier les mutations associées à l’émergence de certains arbovirus. En utilisant le CHIKV comme modèle, nous avons étudié l’impact qu’ont certaines méthodes sur le génotype et le phénotype du virus in-cellulo et in-vivo chez le moustique. Les résultats montrent une stabilité du phénotype alors que le génotype viral dépend de la méthode utilisée.Emergence of some pathogenic arboviruses is a major public health concern. The Chikungunya virus (CHIKV) is a typical example of re-emerging pathogen since it recently caused large outbreaks in human population, adapted to a new vector and spread to new areas. This emergence is the consequence of phenomena related to the high genomic plasticity of CHIKV. Understanding the mechanisms of adaptation of arboviruses could help to better control these viral pathogens. The first part of this thesis presents a study of the mutations associated with long-term replication of CHIKV in mammalian and mosquito cells. Our results revealed different evolutionary patterns in mammalian and mosquito cells highlighting the difficulties encountered by arboviruses related to host alternation during their natural cycle. The second part of this thesis deals with the homologous recombination, an important process that play a role in the evolution of RNA viruses. Working with the CHIKV, we did not detect any recombination events between attenuated infectious viruses. However, we detected viruses harboring large genomic deletion that could help an attenuated virus by trans-complementation. The last part of this thesis focused on reverse genetic methods that give the possibility to rescue viruses and can be used to study mutations associated with emergence phenomena. Using the CHIKV as a model, we compared the genotype and the phenotype of viruses generated using different reverse genetic methods in cellulo and in vivo using Aedes mosquitos. Our results showed that the choice of the method influenced the genetic diversity of viral populations but whatever the method used, the phenotype was similar

Longitudinal Study of Viral Diversity Associated with Mosquito Species Circulating in Cambodia

Arthropod-borne viruses (arboviruses) pose a significant global health threat and are primarily transmitted by mosquitoes. In Cambodia, there are currently 290 recorded mosquito species, with at least 17 of them considered potential vectors of arboviruses to humans. Effective surveillance of virome profiles in mosquitoes from Cambodia is vital, as it could help prevent and control arbovirus diseases in a country where epidemics occur frequently. The objective of this study was to identify and characterize the viral diversity in mosquitoes collected during a one-year longitudinal study conducted in various habitats across Cambodia. For this purpose, we used a metatranscriptomics approach and detected the presence of chikungunya virus in the collected mosquitoes. Additionally, we identified viruses categorized into 26 taxa, including those known to harbor arboviruses such as Flaviviridae and Orthomyxoviridae, along with a group of viruses not yet taxonomically identified and provisionally named “unclassified viruses”. Interestingly, the taxa detected varied in abundance and composition depending on the mosquito genus, with no significant influence of the collection season. Furthermore, most of the identified viruses were either closely related to viruses found exclusively in insects or represented new viruses belonging to the Rhabdoviridae and Birnaviridae families. The transmission capabilities of these novel viruses to vertebrates remain unknown

Comparison of chikungunya viruses generated using infectious clone or the Infectious Subgenomic Amplicons (ISA) method in Aedes mosquitoes

International audienceReverse genetics systems provide the opportunity to manipulate viral genomes and have been widely used to study RNA viruses and to develop new antiviral compounds and vaccine strategies. The recently described method called ISA (Infectious Subgenomic Amplicons) gives the possibility to rescue RNA viruses in days. We demonstrated in cell culture that the use of the ISA method led to a higher genetic diversity of viral populations than that observed using infectious clone technology. However, no replicative fitness difference was observed. In the present study, we used the chikungunya virus as a model to compare in Aedes aegypti and Aedes albopictus mosquitoes the genotypic and phenotypic characteristics of viruses produced either from an infectious clone or using the ISA method. We confirmed the results found in cellulo corroborating that the use of the ISA method was associated with higher genetic diversity of viral populations in mosquitoes but did not affect the vector competence validating its use for in vivo experiments

Subtstitutions generated using the ISA method and detected in <i>Aedes</i> mosquitoes infected by the ISA_virus.

<p>Subtstitutions generated using the ISA method and detected in <i>Aedes</i> mosquitoes infected by the ISA_virus.</p

Vector competence in <i>Aedes</i> mosquitoes.

<p>Dissemination efficiency (DE; proportion of mosquito with infectious virus in the head) was determined by testing mosquito heads with a TCID₅₀ assay (Panel <b>A</b>). The intensity of viral dissemination was assessed by comparing amounts of infectious particles in collected heads (Panel <b>B</b>; only positive heads were taken into account). Transmission efficiency (TE; proportion of mosquitoes with infectious virus in the saliva) was determined by testing mosquito saliva with a TCID₅₀ assay (Panel <b>C</b>). The intensity of viral transmission was assessed by comparing amounts of infectious particles in collected saliva (Panel <b>D</b>; only positive saliva were taken into account). In panels <b>B</b> and <b>D</b>, the average values are shown and error bars represent standard deviation. IC and ISA mean group of mosquitoes infected by IC_virus and ISA_virus respectively. “dpi” means days post-infection.</p

Comparison of chikungunya viruses generated using infectious clone or the Infectious Subgenomic Amplicons (ISA) method in <i>Aedes</i> mosquitoes

<div><p>Reverse genetics systems provide the opportunity to manipulate viral genomes and have been widely used to study RNA viruses and to develop new antiviral compounds and vaccine strategies. The recently described method called ISA (Infectious Subgenomic Amplicons) gives the possibility to rescue RNA viruses in days. We demonstrated in cell culture that the use of the ISA method led to a higher genetic diversity of viral populations than that observed using infectious clone technology. However, no replicative fitness difference was observed. In the present study, we used the chikungunya virus as a model to compare in <i>Aedes aegypti</i> and <i>Aedes albopictus</i> mosquitoes the genotypic and phenotypic characteristics of viruses produced either from an infectious clone or using the ISA method. We confirmed the results found <i>in cellulo</i> corroborating that the use of the ISA method was associated with higher genetic diversity of viral populations in mosquitoes but did not affect the vector competence validating its use for <i>in vivo</i> experiments.</p></div

High SARS-CoV-2 Prevalence among Healthcare Workers in Cochabamba, Bolivia

Healthcare workers (HCWs) are at increased risk of SARS-CoV-2 infection. The aim of the study was to estimate the SARS-CoV-2 seroprevalence among HCWs in Cochabamba, Bolivia and to determine the potential risk factors. In January 2021, a cross-sectional SARS-CoV-2 seroprevalence study was conducted in 783 volunteer clinical and non-clinical HCWs in tertiary care facilities. It was based on IgG detection using ELISA, chemiluminiscence, and seroneutralisation tests from dried blood spots. Analysis revealed a high seroprevalence (43.4%) of SARS-CoV-2 IgG antibodies. The combination of anosmia and ageusia (OR: 68.11; 95%-CI 24.83&ndash;186.80) was predictive of seropositivity. Belonging to the cleaning staff (OR: 1.94; 95%-CI 1.09&ndash;3.45), having more than two children in the same house (OR: 1.74; 95%-CI 1.12&ndash;2.71), and having been in contact with a close relative with COVID-19 (OR: 3.53; 95%-CI 2.24&ndash;5.58) were identified as risk factors for seropositivity in a multivariate analysis. A total of 47.5% of participants had received medication for COVID-19 treatment or prevention, and only ~50% of symptomatic subjects accessed PCR or antigenic testing. This study confirms a massive SARS-CoV-2 attack rate among HCWs in Cochabamba by the end of January 2021. The main risk factors identified are having a low-skilled job, living with children, and having been in contact with an infected relative in the household

Mosquito populations used.

<p>AE: <i>Ae</i>. <i>aegypti;</i> AL: <i>Ae</i>. <i>albopictus</i>.</p><p>Populations are listed according to their collection locality.</p><p>Mosquito populations used.</p