Detection of NS1 protein from dengue virus in excreta and homogenates of wild-caught Aedes aegypti mosquitoes using monoclonal antibodies

Development of an Enzyme-Linked Immunosorbent Assay (ELISA) as a tool to detect NS1 of dengue virus serotype 2 in female Aedes aegypti eggs for the surveillance of dengue fever transmission

Dengue is a significant disease transmitted by Aedes mosquitoes in the tropics and subtropics worldwide. The disease is caused by four virus (DENV) serotypes and is transmitted to humans by female Aedes aegypti mosquito bites infected with the virus and vertically to their progeny. Current strategies to control dengue transmission focus on the vector. In this study, we describe an indirect Enzyme-Linked Immunosorbent Assay (ELISA), using a monoclonal antibody against the non-structural dengue virus protein 1 (NS1), to detect DENV2 in Ae. aegypti eggs. The assay detects NS1 in eggs homogenates with 87.5% sensitivity and 75.0% specificity and it is proposed as a tool for the routine entomovirological surveillance of DENV 2 in field mosquito populations.

Excretion Dynamics of Arboviruses in Mosquitoes and the Potential Use in Vector Competence Studies and Arbovirus Surveillance

The increasing threat of arboviruses such as West Nile virus (WNV) and Usutu virus (USUV) requires the fast and efficient surveillance of these viruses. The examination of mosquitoes takes up an important part; however, these investigations are usually very time-consuming. An alternative sample type for arbovirus surveillance might be mosquito excreta. In order to determine the excretion dynamics under laboratory conditions, laboratory colonies of Aedes vexans and Culex pipiens biotype molestus were infected with WNV, USUV or tick-borne encephalitis virus (TBEV). After infection, the excreta were sampled and investigated for viral RNA. Excretion of viral RNA together with infectious blood meal could be detected up to five days after infection. Further excretion seemed to correlate with a disseminated infection in mosquitoes, at least after USUV infection. In addition, it could be determined that the amount of viral RNA in the excretions correlated positively with the viral load in the mosquito bodies. Overall, this study shows that the usage of mosquito excreta as a sample type for surveillance enables the detection of endemic viruses (WNV, USUV) as well as non-mosquito-borne viruses (TBEV). In addition, examination of viral shedding during vector competence studies can provide insights into the course of infection without sacrificing animals.

Detection of Dengue Virus 2 with Single Infected Mosquito Resolution Using Yeast Affinity Bionanofragments and Plasmonic SERS Nanoboxes

Dengue disease is an emerging global threat triggered by dengue virus (DENV) transmission, primarily by the mosquito Aedes aegypti. The accurate surveillance and sensitive detection of DENV in mosquito populations are critical for the protection of human populations worldwide that are in the habitat of these mosquito species. There are four DENV serotypes with DENV2 reported to cause the most severe complications. There are limited ultrasensitive methods to early detect DENV2 mosquito infection and prevent human infection. Herein, we report an innovative nanobased immunoassay platform for early, specific, and ultrasensitive detection of DENV2-secreted nonstructural 1 (NS1) protein biomarker in single infected mosquitoes with the limit of detection of 500 fg of recombinant DENV2 NS1. The high sensitivity and DENV2 serotype specificity of the platform are the result of using nanomixing, plasmonic SERS nanoboxes, and yeast affinity bionanofragments displaying single-chain variable fragments (nanoyeast scFvs). Nanoyeast scFvs used for high affinity capture of DENV2 NS1 provided an innovative and cost-efficient alternative to monoclonal antibodies and differentiated DENV2 NS1 from other DENV serotypes and Zika virus NS1. The platform used electrohydrodynamically driven nanomixing to enhance NS1 capture by the nanoyeast scFvs while reducing nonspecific interactions. High sensitivity detection of captured DENV2 NS1 was achieved using NS1-specific surface-enhanced Raman scattering (SERS) nanotags. These nanotechnologies provide a significant innovation for early DENV2 detection in single infected mosquitoes, improving the accurate surveillance of mosquito habitats and preventing infection and severe disease arising from DENV2 transmission.