A year of pandemic | On the path to the next pandemic

How can the next pandemic be detected more quickly? Should we take a closer look at the bat populations in Asia from which the SARS and COVID-19 viruses appeared? Or tracking antibodies in donations and blood samples from the population? Researchers are exploring a range of avenues.

Matteo Perrault
Journalism

Asian bats

Ebola, SARS, Middle East respiratory virus (MERS), Nipah fever, Marburg virus disease, and rabies. And of course, COVID-19. The list of diseases with their origin in bats is long. “We have recently realized that bats play a major role in many human infections,” said Lin Fa Wang, a biologist from the National University of Singapore who has worked on these animals for 25 years. Last month, Mr. Wang published two important studies on the topic, one in Temperate nature, Where he hypothesizes that the next pandemic could be much less deadly if bats are known and better monitored, another in Nature connections, It showed that the cousins ​​of SARS-CoV-2, the coronavirus responsible for COVID-19, are found in bats in northern Thailand, not just in China. “However, we do not have a good laboratory model for mice to study bats, and we have only sequenced the genomes of 20 out of 1,300 species of bats. If we had a bat monitoring mechanism in southern China, northern Thailand, Laos and Vietnam, we could definitely identify new mutations in viruses that are capable of infecting.” “Early humans will accelerate the development of vaccines and treatments against new infections.”

Immune floaters

Another surveillance system, the Global Immunology Observatory, was proposed last summer by researchers in Princeton and Harvard, in the journal. eLife. The idea is to systematically collect a small portion of donated blood samples and unused vials to monitor the presence of several hundreds of human and animal viruses, as well as any abnormal activity of human antibodies present in a large number of patients. A similar project at Princeton University in 2018 made it possible to reveal the beginnings of an outbreak of measles in Madagascar, and could have made it possible to detect the Zika virus before its first tangible effects: a large number of children with hydrocephalus. Researchers who proposed this “observatory” compare it to weather buoys that detect storms and hurricanes brewing in the oceans. Such a project would cost $ 100 million to build in the United States, according to the project published in eLife.

No cancer, no infection

Bats are unique among mammals in many ways. Wang said, “Usually, the smaller the animal, the shorter its life expectancy and the more likely it is to develop cancerous tumors.” However, bats live very long lives and have very few cancers. […] It is likely that their great ability to harbor pathogens that do not make them sick is related to the characteristics that set them apart from other mammals. For example, flying is an activity that requires a high heart rate, which explains the high body temperature of bats: pathogens have been said to be contained by the bat’s immune system thanks to this high temperature. ”

Bat-inspired drug

Dr. Wang patented a bat immune system molecule that might help calm an overreactive immune system to the pathogen. “It is one of the main causes of serious illness with COVID-19. There are also many anti-inflammatories that have been tested as anti-COVID-19 drugs. I will start clinical trials in animals to see if this bat molecule can give a drug against infection. It can also be used.” Against cancer, autoimmune diseases and against the effects of aging. ”Mr. Wang is not in his first steps with treatments derived from his research on bats: he designed an equine vaccine to prevent Hendra fever in horses, a disease caused by the bat virus.

Russian immunologist

The importance of bats in the development of infectious diseases was highlighted by Ili Michnikov, an immunologist of Russian origin who discovered the role of white blood cells in the immune response against bacteria. Michnikov, a 1908 Nobel Prize Winner in Medicine, discovered in 1909 that bats played a vital role in rabies transmission, according to his study Temperate nature January.

White Nose Secret

In recent years, a mysterious disease has wiped out bat colonies in the United States. Fungi are responsible for this “white nose disease”. Why is the bat powerless against this pathogen? “It’s not the fungus that kills the bat,” said Wang. It disrupts its hibernation, causing the bat to wake up early, at a time when it cannot find food in the wild. So she is starving. The bat appears weak only during hibernation. Perhaps this means that this is a very important time in his ability to control the immune system in order not to overreact to the infection. “

Pangolins

The SARS-CoV-2 cousins ​​identified in Thailand by Dr. Wang were unable to infect humans because they lack the ability to bind to human cells through a cellular receptor called ACE2. The same was the case with similar coronaviruses found in bats in China earlier in the epidemic. “This may mean that there was another evolution, in another animal, before SARS-CoV-2 took its present form, capable of infecting humans,” Wang said. We talked about the pangolin, which is sold in the Chinese market, but it is not yet known which animal it is. It is highly probable, but it must be proven. ”

weather changes

Why do SARS and COVID-19 seem so close? Because of mutations in bat viruses? “There is definitely a link to urbanization in China,” said Wang. 30 years ago, Shenzhen was a fishing village, and now millions of people live there. This is where SARS-CoV-1 comes in [responsable du SRAS en 2003] Back. Wuhan, where SARS-CoV-2 first struck, went on the same path. But there also appears to be an impact of climate change. Perhaps the most notable example of this is the Australian bat, whose habitat stretched for 200 years to 1,000 kilometers south, from Brisbane to Sydney. “