Date of Award

January 2016

Document Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Doug Brackney

Abstract

Introduction

Dengue virus is the leading cause of morbidity and mortality among mosquito-borne viruses globally. There are four Dengue serotypes; immunity to one serotype provides protective immunity to that serotype but increases the risk of severe disease upon infection with a second serotype. Dengue virus, like all Flaviviruses, utilizes class II fusion proteins to gain entry into the host cytoplasm. The fusion loop, which is responsible for viral-host fusion, lies within the envelope (E) glycoprotein and has nearly 100% amino acid identity among all Flaviviruses. Two anti-Dengue virus human monoclonal antibodies (hMAbs), 1.6D and D11C, were isolated from Dengue infected patients, and determined to target the fusion loop (1). These antibodies not only neutralize all four Dengue serotypes, but also have broadly anti-Flavivirus cross-neutralizing capabilities in mammalian cells. While these antibodies could contribute to antibody enhancement of infection in humans, their neutralizing capabilities could be employed within a transgenic mosquito line serving as a novel control strategy to block arbovirus transmission.

Methods

The neutralization capacity of purified hMAbs 1.6D and D11C were tested against Dengue virus 2, 3, and 4, and Zika virus in C6/36 Aedes albopictus mosquito cells using a Fluorescent Focal Unit Assay. Additionally, the inhibitory capacity of 1.6D was evaluated in Aedes aegypti mosquitoes. Mosquitoes were intrathoracically inoculated with Dengue virus 2 and either 1.6D or C11, a hMAb anti-Gp41 HIV1, used as an antibody control. Viral RNA was extracted from mosquitoes two and four days post infection and viral loads were quantified by qRT-PCR.

Results

Antibodies 1.6D and D11C reduced viral infections in C6/36 cells for all Dengue serotypes tested, in a dose-dependent manner. Both antibodies inhibited 50% of each Dengue virus at less than 2μg/ml, comparable to what was reported in mammalian cells, although inhibition was not observed for Zika virus. Dengue 2 viral loads were significantly decreased in Aedes aegypti mosquitoes treated with 1.6D compared to the control antibody.

Conclusion

This study demonstrates the efficacy of broadly neutralizing human antibodies to reduce Flavivirus infections in mosquitoes. Additional research should assess the efficacy of this approach in a biologically relevant context and determine the impact of this strategy to reduce mosquito vector competence for Flaviviruses.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 06/07/2018

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