In Vitro and In Vivo Effects of Espirito Santo Virus on Dengue Virus Replication

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)
Avian White (Creator)
East Carolina University (ECU )
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Abstract: Arboviruses have been one of the leading causes of morbidity and mortality worldwide for centuries (Morens et al. , 2004). Dengue virus (DENV) , Zika (ZIKV) , Chikungunya (CHIKV) and West Nile virus (WNV) are some of the medically important arboviruses transmitted by mosquitoes. Dengue is one of the most common arthropod diseases with over 400 million people infected yearly. Dengue is now endemic in the WHO regions of Africa , the Americas , the Eastern Mediterranean , South-East Asia and the Western Pacific. Current data estimates 3.9 billion people in 128 countries are now at risk of DENV infection. Dengue , known as break-bone fever , may be caused by one of four serotypes: DENV:1-4. Dengue is primarily transmitted by Aedes aegypti with Aedes albopictus as a secondary vector. Infection with DENV may cause a high fever , swollen glands , muscle and joint pain and nausea. Subsequent infection of DENV with a second serotype may lead to the more serious dengue hemorrhagic fever , which may result in plasma leakage , severe bleeding , fluid accumulation , and/or organ failure. Espirito Santo virus , ESV , is an insect-infecting virus recently discovered in a patient sample in Espirito Santo , Brazil. The virus replicates in mosquito cells but is not known to replicate in vertebrate cells (tested in Vero cells , thus far). Here , we sought to study the effects of ESV on DENV-2. We hypothesized that ESV interferes with replication of DENV-2 in vitro and in vivo. Our findings show that ESV can replicate in absence of DENV-2 and no cytopathic effects were visually observed here in mammalian (Vero) cells 6-days post infection. Immunofluorescence assay results show that during co-infection of C6/36 cells with ESV and DENV-2 , ESV did not prevent DENV-2 from entering cells or expressing proteins (we did not see a difference in staining). However , plaque assays showed a decrease in infectious DENV-2 particles in co-infected cells evidenced by fewer plaques observed in DENV wells also containing ESV. In vivo experiments were performed with three different populations of Aedes aegypti mosquitoes for an incubation period of seven days. While infection rates were not statistically different in a wild-type mosquito population (Costa Rica) , ESV superinfected mosquitoes had significantly lower DENV-2 body titers (p<0.01) and leg titers (p<0.01) than mosquitoes exposed to only DENV (measured via qRTPCR). In the high dissemination colony of mosquitoes , there was no significant difference in body and leg DENV-2 titers between non-ESV infected and ESV infected mosquitoes. In the low dissemination colony , DENV-2 infected mosquitoes had significantly higher body and leg titers than mosquitoes infected with DENV and ESV (p<0.01). These results support our initial hypothesis that mosquitoes previously infected with ESV show lower levels of DENV-2 and we expect that these findings will spur additional research to elucidate the mechanisms involved.

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Language: English
Date: 2018
Espirito Santo virus, Vector competence

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