Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Jan 31;16(2):214.
doi: 10.3390/v16020214.

DENV-1 Titer Impacts Viral Blocking in w Mel Aedes aegypti with Brazilian Genetic Background

Jessica Corrêa-Antônio  1 , Mariana R David  1 , Dinair Couto-Lima  1 , Gabriela Azambuja Garcia  1 , Milan S G Keirsebelik  1 , Rafael Maciel-de-Freitas  1   2 , Márcio Galvão Pavan  1
Affiliations

DENV-1 Titer Impacts Viral Blocking in w Mel Aedes aegypti with Brazilian Genetic Background

Jessica Corrêa-Antônio et al. Viruses. .

Abstract

Several countries have been using Wolbachia deployments to replace highly competent native Aedes aegypti populations with Wolbachia-carrying mosquitoes with lower susceptibility to arboviruses such as dengue, Zika, and chikungunya. In Rio de Janeiro, Wolbachia deployments started in 2015 and still present a moderate introgression with a modest reduction in dengue cases in humans (38%). Here, we evaluated the vector competence of wild-type and wMel-infected Ae. aegypti with a Brazilian genetic background to investigate whether virus leakage could contribute to the observed outcomes in Brazil. We collected the specimens in three areas of Rio de Janeiro with distinct frequencies of mosquitoes with wMel strain and two areas with wild Ae. aegypti. The mosquitoes were orally exposed to two titers of DENV-1 and the saliva of DENV-1-infected Ae. aegypti was microinjected into wMel-free mosquitoes to check their infectivity. When infected with the high DENV-1 titer, the presence of wMel did not avoid viral infection in mosquitoes' bodies and saliva but DENV-1-infected wMel mosquitoes produced lower viral loads than wMel-free mosquitoes. On the other hand, wMel mosquitoes infected with the low DENV-1 titer were less susceptible to virus infection than wMel-free mosquitoes, although once infected, wMel and wMel-free mosquitoes exhibited similar viral loads in the body and the saliva. Our results showed viral leakage in 60% of the saliva of wMel mosquitoes with Brazilian background; thus, sustained surveillance is imperative to monitor the presence of other circulating DENV-1 strains capable of overcoming the Wolbachia blocking phenotype, enabling timely implementation of action plans.

Keywords: Ae. aegypti; DENV-1; Wolbachia; dengue; vector competence; wMel.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figures

Figure 1
Figure 1
Study areas in Rio de Janeiro. A—FI (Tubiacanga); B—PI1 (Bonsucesso); C—PI2 (Fonseca); D—NR1 (Urca); E—NR2 (Vila Valqueire). In green, wMel current released areas, and in orange, wMel-free areas.
Figure 2
Figure 2
Relative density of wMel in Ae. aegypti mosquitoes infected with DENV-1 at low (3 × 104 FFU/mL) and high titers (6 × 108 FFU/mL). The numbers inside parentheses indicate the number of wMel-positive mosquitoes out of the total mosquitoes tested. Different letters (above the graph) indicate statistically significant differences in wMel density (Wilcoxon–Mann–Whitney test; p < 0.05). Horizontal red bars represent the medians. Yellow circles represent samples infected with wMel from PI1, pink circles from PI2, green circles from FI, and gray circles from wMel-positive control (FI).
Figure 3
Figure 3
Number of DENV-1 copies in the whole body of wMel, wMel-free, and wild Ae. aegypti mosquitoes 14 days after the infection with the low titer (3 × 104 FFU/mL) (A) and the high titer (6 × 108 FFU/mL) (B). The numbers inside parentheses indicate the number of DENV-1-positive mosquitoes out of the total mosquitoes tested per area. Different letters (above the graph) indicate statistically significant differences (Wilcoxon–Mann–Whitney test; p < 0.05). Horizontal red bars represent the medians. Blue circles represent wMel-free mosquitoes, red circles represent mosquitoes with wMel, and brown circles represent wild mosquitoes. All negative controls for DENV-1 infection were negative.
Figure 4
Figure 4
DENV-1 load in susceptible wild Ae. aegypti mosquitoes seven days after injecting the saliva of mosquitoes with confirmed infection of DENV-1 in the whole body. Each saliva was intrathoracically injected into 10 susceptible mosquitoes. The injected saliva was obtained from mosquitoes with and without wMel and subjected to DENV-1 oral infections with low (3 × 104 FFU/mL) and high titer (6 × 108 FFU/mL). The number of DENV-1 infective saliva out of the total number of mosquitoes tested is in parenthesis (below the neighborhood name). Horizontal red bars represent the medians. Different letters (above the graph) indicate statistically significant differences (Wilcoxon–Mann–Whitney test; p < 0.05). All mosquitoes that received saliva from DENV-1-negative mosquitoes were negative.
Figure 5
Figure 5
Forest plot showing the odds ratio (OR) and 95% confidence intervals for interactions of wMel in DENV-1-exposed Ae. aegypti mosquitoes. “Infection” results are based on the number of infected and non-infected mosquitoes, and “Viral load” results are the absolute quantity of DENV-1 virus particles. Mosquito bodies were analyzed 14 days post infection (“Body”), and susceptible mosquitoes were analyzed 7 days after receiving an intrathoracic injection of saliva from a mosquito exposed to DENV-1 (“Saliva-microinjected”). Mosquitoes were fed on blood infected with DENV-1 at 3 × 104 FFU/mL (“Low DENV-1 titer”) or 6 × 108 FFU/mL (“High DENV-1 titer”). The asterisks denote statistically significant negative association (i.e., OR < 1.0) between having wMel and body infection or viral loads.
See this image and copyright information in PMC

Similar articles

See all similar articles

References

    1. Brady O.J., Gething P.W., Bhatt S., Messina J.P., Brownstein J.S., Hoen A.G., Moyes C.L., Farlow A.W., Scott T.W., Hay S.I. Refining the Global Spatial Limits of Dengue Virus Transmission by Evidence-Based Consensus. PLoS Negl. Trop. Dis. 2012;6:e1760. doi: 10.1371/journal.pntd.0001760. - DOI - PMC - PubMed
    1. WHO Dengue and Severe Dengue. [(accessed on 7 August 2023)]. Available online: https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengu....
    1. PAHO Epidemiological Update for Dengue, Chikungunya and Zika in 2022. [(accessed on 7 August 2023)]. Available online: https://www3.paho.org/data/index.php/en/mnu-topics/indicadores-dengue-en....
    1. Maciel-de-Freitas R., Marques W.A., Peres R.C., Cunha S.P., Lourenço-de-Oliveira R. Variation in Aedes aegypti (Diptera: Culicidae) Container Productivity in a Slum and a Suburban District of Rio de Janeiro during Dry and Wet Seasons. Mem. Inst. Oswaldo Cruz. 2007;102:489–496. doi: 10.1590/S0074-02762007005000056. - DOI - PubMed
    1. David M.R., Dantas E.S., Maciel-de-Freitas R., Codeço C.T., Prast A.E., Lourenço-de-Oliveira R. Influence of Larval Habitat Environmental Characteristics on Culicidae Immature Abundance and Body Size of Adult Aedes aegypti. Front. Ecol. Evol. 2021;9:626757. doi: 10.3389/fevo.2021.626757. - DOI
-