Assessing the vertical transmission potential of dengue virus in field-reared Aedes aegypti using patient-derived blood

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Parasites & Vectors Open Access

RESEARCH

Assessing the vertical transmission potential of dengue virus in field‑reared Aedes aegypti using patient‑derived blood meals in Ho Chi Minh City, Vietnam Daniela da Silva Goncalves1, Kien Duong Thi Hue1, Vi Tran Thuy1, Nhu Vu Tuyet1, Giang Nguyen Thi1, Van Huynh Thi Thuy1, Trang Huynh Thi Xuan1, Dui Le Thi1, Long Thi Vo1, Huynh Le Anh Huy1, Nguyen Thi Van Thuy1, Bridget A. Wills1, Phong Nguyen Thanh2, Cameron P. Simmons1,3 and Lauren B. Carrington1*

Abstract  Background:  Dengue viruses (DENV) can be transmitted from an adult female Aedes aegypti mosquito through the germ line to the progeny; however, there is uncertainty if this occurs at a frequency that is epidemiologically significant. We measured vertical transmission of DENV from field-reared Ae. aegypti to their F1 progeny after feeding upon blood from dengue patients. We also examined the transmission potential of F1 females. Methods:  We examined the frequency of vertical transmission in field-reared mosquitoes, who fed upon blood from acutely viremic dengue patients, and the capacity for vertically infected females to subsequently transmit virus horizontally, in two sets of experiments: (i) compared vertical transmission frequency of field-reared Ae. aegypti and Ae. albopictus, in individual progeny; and (ii) in pooled progeny derived from field- and laboratory-reared Ae. aegypti. Results:  Of 41 DENV-infected and isofemaled females who laid eggs, only a single female (2.43%) transmitted virus to one of the F1 progeny, but this F1 female did not have detectable virus in the saliva when 14 days-old. We complemented this initial study by testing for vertical transmission in another 460 field-reared females and > 900 laboratoryreared counterparts but failed to provide any further evidence of vertical virus transmission. Conclusions:  In summary, these results using field-reared mosquitoes and viremic blood from dengue cases suggest that vertical transmission is uncommon. Field-based studies that build on these observations are needed to better define the contribution of vertical DENV transmission to dengue epidemiology. Keywords:  Vertical transmission, Dengue virus (DENV), Mosquitoes, Aedes aegypti, Aedes albopictus Background Dengue is a mosquito-borne viral disease. There are an estimated 390 million infections per year, and 3.9 billion people living in 128 countries at risk of infection [1, 2]. *Correspondence: [email protected] 1 Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, District 5, Ho Chi Minh City, Vietnam Full list of author information is available at the end of the article

Dengue is caused by one of four dengue virus (DENV) serotypes, which are transmitted primarily by Aedes aegypti and Ae. albopictus mosquitoes [3]. In recent years, both species have expanded their geographical distribution and, predictions of various climate change scenarios suggest their distribution will increase further. Such scenarios are likely to trigger emergence and reemergence of ar