To date, none of them has been able to determine how this virus has managed to pass into the human population. One of the first scenarios put forward, that of the Wuhan market which would have led to a rapid dispersion of the virus, seems less credible given the data currently available. Despite a year of intensive research, the virus has not been identified in any animal.
However, animal-to-human transmission remains one of the most solid hypotheses that would explain the appearance of this new coronavirus. Thus, it is proposed that a member of the coronavirus family may have been transmitted from bats to humans via an intermediate host. Such a situation is not unique and we can refer to the origin of the MERS-CoV coronavirus (Middle East respiratory syndrome): camels would have served as intermediate host. In the case of the Covid-19 virus, that host could be the pangolin, illegally sold in the Wuhan market, although this hypothesis requires more convincing evidence.
Professor in the Department of Biological Sciences at the University of Quebec in Montreal, I am an expert in virology, more particularly in human retroviruses and more recently in human coronaviruses.
“Function gains”
Fairly quickly after the start of the pandemic, the idea of a virus leak from the containment level 4 (NC4) laboratory located in the Wuhan Institute of Virology (WIH) began to circulate. Although most likely accidental, such an event has not been ruled out.
In fact, in recent weeks this possibility has resurfaced and thus placed Dr Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases (NIAID), in an embarrassing situation. Thus, the United States would have funded this research laboratory, and the funded projects would have focused on gain-of-function studies. Some American newspapers, such as the Wall Street Journal, argue that Dr. Fauci would have supported these ongoing gain-of-office experiments at WIV.
However, despite the advantages attributed to it, this approach is not without risk.
But what is the search for gain of function? Although it is sometimes referred to in the broad sense of certain studies dealing with the analysis of protein functions, at the medical level, it has a particular connotation around research on viruses. Thus, the objective of gain-of-function studies is to create a virus having acquired new properties which makes it more pathogenic and / or more transmissible in humans.
Traditionally, this type of change has focused on using animal / human cells in which the virus was grown. In recent years, animal models and molecular biology techniques targeting precise modifications of certain viral genes have led to important advances. This process can thus lead to the rapid generation (compared to the natural evolution of viruses which take place over several years) of new viruses better adapted to the human species with possible changes in their virulence and their capacity to be transmitted between humans.
The rationale for this type of research is that the isolation of such new viruses could identify the specific changes in their genome that led to these new characteristics. Thus, such knowledge could help scientists to better predict the imminent arrival of new pandemics and also lead to the development of vaccines and treatments adapted to these possible infectious agents.
–
