WNV, Zika, dengue fever and yellow fever are in the sights of a Montreal researcher

Jean-Benoit Legault, The Canadian Press

MONTREAL — Global warming could expose humans to the bites of mosquitoes capable of transmitting to them viruses of which nothing is yet known, warns a Montreal researcher who has just won funding to study the question.

Professor Laurent Chatel-Chaix, of the National Institute for Scientific Research (INRS), has obtained a $700,000 grant from the Canadian Institutes of Health Research to unravel the mystery of flaviviruses, which are transmitted by mosquitoes responsible diseases such as dengue fever, yellow fever or Zika.

West Nile virus, which was first identified in Quebec in 2002, is also a flavivirus.

There is currently no effective treatment or vaccine against West Nile, dengue or Zika viruses. In addition, variations in the demography of insects, and caused among other things by climate change, could lead to the circulation of flaviviruses whose existence is not even known, said Mr. Chatel-Chaix.

“There are probably plenty of flaviviruses circulating that are still unknown and that potentially one day could emerge and affect human and animal health as well,” he explained.

The aim of his work, he said, is “to understand how this virus parasitizes inside the infected cell”, in order to then be able to develop therapies to combat it.

West Nile virus is endemic in Canada and can cause severe and life-threatening encephalitis. In 2018, Quebec experienced a record number of cases of infections with this virus, with 201 cases and 15 deaths listed by the Ministry of Health and Social Services.

Dengue virus causes the most common insect-borne viral disease in the world. Zika virus infection can cause severe neurodevelopmental abnormalities in newborns, including congenital microcephaly. A Zika epidemic that originated in Brazil affected several countries in America in 2015-2016, creating such panic that some women chose to postpone their pregnancies.

Mr. Chatel-Chaix, a specialist in molecular virology, is interested in what happens inside the infected cell and tries to understand how the flavivirus parasitizes the organelles of the cell to its advantage.

“You have to know how it takes control of the cell’s resources and then find mechanisms that are common to all these viruses,” he explained. It would allow us to find therapeutic targets for drugs that could work against all these viruses.”

Interior design

When the flavivirus enters a cell, Professor Chatel-Chaix said, “it completely disrupts the internal organization of the cell”.

“It’s like interior design, if you will,” he said. The virus reprograms the functions of many compartments, and I am interested in a compartment in the cell that is involved in the production of energy.

The virus also manages to silence the alarm systems that would normally alert the cell to the presence of an intruder and trigger an immune response. Instead, the virus manages to replicate quietly inside the cell for a time, before its presence is finally detected.

Professor Chatel-Chaix’s team is currently working on the NS4B protein, which is present in flaviviruses and which plays a critical role in the replication of the virus genome in the cell.

In the field of virology, he warns, climate change represents “a real problem”.

Not only is global warming making some insects better suited to cities, he said, but “we already know that some mosquitoes that transmit diseases like Zika virus, chikungunya virus, yellow fever, well these mosquitoes are in the process of colonizing the northern territories”.

“In fact, we have even already detected some in southern Canada,” said Professor Chatel-Chaix. Potentially, if these mosquitoes colonize southern Quebec, they could bring disease.”

Thawing permafrost that is recirculating pathogens frozen for thousands of years is also worrisome, he said.

When SARS-CoV-2 emerged, the knowledge acquired with the study of the original SARS or the Middle East respiratory syndrome proved to be very useful, recalled the researcher. So if a new flavivirus strikes in 10 or 20 years, the knowledge stored today could be valuable.

“It’s a bit the same philosophy, if you will, he concluded. It is to prepare upstream so that if ever there are new viruses that emerge, then we already have knowledge based on the fact that viruses of the same class use common mechanisms to replicate in the cell and cause disease.”

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