A Research Blog

Dengue fever, caused by the dengue virus, is a tropical disease transmitted by mosquitoes that threatens more than one third of the worldwide population, making it one of the most important arboviruses in the world. They have important economic consequences because of the burden to hospitals, work absenteeism and risk of death for severe symptomatic cases.

Dengue viruses are primarily transmitted from human-to-human by Aedes aegypti mosquitoes. While the mechanisms leading to dengue infection in humans have been defined, there is a lack of knowledge on how dengue viruses influence mosquito transmission and infection, or the genetic factors that affect virus replication in mosquitoes.

With this quest in mind, researchers at Duke-NUS Medical School’s Emerging Infectious Disease Programme led by Assistant Professor Julien Pompon and Professor Mariano A Garcia-Blanco set out to identify the viral determinants of transmission, as well as the mechanism by which dengue viruses harness evolution to cycle between the two hosts.

Esther GanDr Esther Gan, recent Duke-NUS Medical School PhD graduate and speaker for her class shares with Microscope about her journey to Duke-NUS and her plans post-graduation.

How did you first learn about Duke-NUS?

I heard about Duke-NUS from one of my immunology professors during my undergraduate studies at the University of British Columbia.

I have always been interested in infectious diseases research and my experience in an influenza laboratory further piqued my interest in pursuing this avenue. Coincidentally, Dr Ninan Abraham had a collaborator, Dr Veronika von Messling, who had just moved to Duke-NUS to set up a lab and he highly recommended that I did a year of research with her. She was a veterinarian studying the pathogenesis of influenza in animal models. I ended up working for her for a year as a research assistant. It was amazing the amount of techniques that I learnt from her! We worked with mice, ferrets and monkeys all within a span of a year.

We see that you started your Duke-NUS journey as research assistant and not a PhD student. Why didn’t you jump right into the PhD programme and what finally made you decide to take the plunge?

I didn’t know how I would adjust to Singapore culture – the people and the research - after so many years abroad. My idea was to come, work for a year and assess if it would be a suitable place to do my PhD.  It was tough; I missed the nature, the four seasons, the ability to drive two hours and immediately hit a ski slope. But it wasn’t impossible; I did manage to adjust to life here!

mosquito

In 2016, the Zika virus dominated all other public health concerns. It was an epidemic in South America and threatened to become one in Asia. Zika is a flavivirus that is mainly spread by the bite of an infected Aedes mosquito. Symptoms range from mild fever to body aches, while an infection during pregnancy could cause foetal brain defects, such as microcephaly.

This year Zika isn’t the hot topic that it was, but it remains a research priority and health concern.

Recently, Assistant Professor Julien Pompon and his team, from the Emerging Infectious Diseases Programme at Duke-NUS Medical School (Duke-NUS), published research that identified the main carrier for an Asian Zika virus strain and compared different Zika virus strains. This work increases our understanding of the virus transmission.

Asst Prof Pompon compared the susceptibility of Aedes aegypti, Aedes albopictus and Culex quinquefasciatus to an Asian Zika virus strain (H/PF13). The mosquitoes from these species were orally fed infected blood and, at seven days post infection, were examined to determine their infection rate and genome copies of the virus. High infection rates and genome copies indicate that the mosquito is more susceptible to picking up and transmitting a virus.

Arboviruses

Emeritus Professor Duane Gubler is an international expert on vector borne-infectious diseases and a go-to spokesperson for the media for all things infectious disease-related. This year alone he has been interviewed by The New York Times, The Straits Times, and Vox, among other media outlets.

“Arboviruses: Molecular Biology, Evolution and Control on arboviruses”, a well-received book edited by Prof Gubler, looks at viruses that are transmitted by arthropod vectors, such as mosquitoes, flies, sand flies, lice, fleas, ticks and mites. Since Zika was declared a major global emergency last year, and dengue remains a consistent health threat and concern, the text is a much welcome contribution to the literature on these groups of viruses.

Microscope caught up with Prof Gubler for more on his book and his thoughts on global health concerns:

How did you come up with the concept for this book?

I was approached by several publishers to edit and compile a book that looked at arboviruses. In the past 30 years there has been a dramatic increase in emerging epidemic arboviral diseases, which explains the interest and demand for such a book.

What were your considerations when choosing the contributors/topics for each chapter?

My co-editor, Nikos Vasilakis and I, wanted to get the global thought leaders in the field to review current status of various topics including the genomic organisation of arboviruses, host metabolism, arbovirus evolution and more.

Who is this book meant for?

In their second post, Drs Justin Ng and Chionh Yok Teng from the Bat Pack tell us more setting up the first bat colony for research in Singapore.

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