2020-03-02 12:53:00
What are coronaviruses?
Coronaviruses are a family of many viruses. IThey affect many species of mammals and birds, some can be transmitted to humans or be specific to them. The diseases they cause are varied but mainly affect respiratory and digestive systems. They have in common the particularity of being highly transmissible. In terms of animal health, many coronaviruses are known, whether in dogs, cats, pigs, ruminants, horses, camels, birds or wildlife, notably bats.
What diseases do they cause?
The severity of the infections caused varies greatly. In veterinary medicine, infections by these viruses are common. They can have a significant economic impact, particularly in breeding young ruminants, pigs or chickens and turkeys. Poultry can, for example, be contaminated by the infectious bronchitis coronavirus, with turkeys and guinea fowl also having coronaviruses which specifically infect them at the digestive level. Pigs are subject to porcine epidemic diarrhea viruses, transmissible gastroenteritis or porcine respiratory coronavirus. Cats can contract the feline infectious peritonitis virus, a fatal disease, while young horses and cattle suffer from digestive disorders. Finally, the impact of infection of wildlife (bats, hedgehogs, rodents, etc.) is unknown.
How are coronaviruses transmitted from one species to another?
The Covid-19 epidemic reminds us that mutations in coronaviruses can sometimes allow them to change host. Indeed, these viruses have the capacity to evolve rapidly through changes to their genetic material, which mutates frequently. They can also recombinerthat is to say exchanging portions of the genome, which can occur if two different coronaviruses co-infect the same host cell. This evolution may give them the ability to affect new target organs or to adapt to new host species. These new viruses can be particularly pathogenic because the new host species is not used to it, it does not have the immune defenses necessary to respond effectively to this new infection. However, if these events have been detected quite frequently in the recent past (the Covid-19 virus is the third coronavirus which passes from animals to humans in around twenty years), the phenomenon is not new: one of the viruses responsible for the common cold in humans, the OC43 coronavirus, is estimated to have evolved from the transmission of the bovine coronavirus to humans at the end of the 19th century.
What is ANSES doing about coronaviruses?
ANSES is carrying out various work on coronaviruses in poultry, pigs, cats and wildlife. The occurrence of the Covid-19 epidemic has reinforced its work on the subject, in particular on the possibility of inter-species transmission and treatment and diagnosis techniques using approaches that could be interesting in a comparative virology approach. here are some examples:
Know the viruses circulating in animals
The three Anses laboratories for Rage and wildlife in Nancy, Animal Health in Maisons Alfort and Ploufragan-Plouzané-Niort participated in the ANR project Epicurean from 2014 to 2018. Coordinated by the Caen University Hospital Center, this work made it possible to highlight the significant diversity of coronaviruses circulating within domestic and wild animal populations in France and Europe. New viral species have been described in humans and in domestic and wild fauna. At the same time, the researchers followed the evolution of a Betacoronavirus, the sister group of Sars-CoV within a colony of bats. This section made it possible to understand the dynamics of virus evolution within a host population.
Currently, the Alfort animal health laboratory coordinates the European MuseCov project in which two other Anses laboratories also participate (the Anses laboratory in Ploufragan-Plouzané-Niort and the Nancy laboratory). It aims to better understand the diversity of coronavirus strains circulating in animal populationsincluding SARS-CoV2. The objective is to better understand the dynamics of coronavirus infections in various animal populations and to quickly detect the emergence of particularly pathogenic variants.
Finally, the Anses laboratory in Ploufragan-Plouzané-Niort is interested in mutations and molecular mechanisms that accompany the transmission of coronaviruses avian in different species of poultry or which authorize genetic rearrangements in porcine coronaviruses.
Better understand inter-species transmission mechanisms
The mixed Virology research unit (EnvA-Inrae-Anses) of the Animal Health laboratory in Maisons-Alfort is carrying out, in conjunction with an Inserm team, a research project on molecular determinants of feline coronavirus pathogenicity. This virus can cause a fatal illness in cats called feline infectious peritonitis. The mechanisms that promote crossing the inter-species barrier are studied. This work is carried out in collaboration with the rabies and wildlife laboratory in Nancy, on possible interactions with coronaviruses present in wildlife, and that of Ploufragan-Plouzané-Niort, on avian coronaviruses.
Develop diagnostic and treatment techniques
The Ploufragan-Plouzané-Niort laboratory is developing molecular diagnostic methods or serological avian and porcine coronaviruses. A project, started at the end of 2019, aims to develop a serological test (ELISA), making it possible to detect antibodies produced in response to infection with the European strain of turkey coronavirus (Tcov), which does not exist at the moment.
The rabies and wildlife laboratory has developed molecular and serological diagnostic methods for the infection of minks with Sars-CoV-2 to carry out the first investigation within French farms. This made it possible to detect one of the four farms as contaminated with more than 90% of the animals having a positive response in serology.
On the side of treatmentsthe Rabies and wildlife laboratory participated in the project Timingfunded by the ANR and coordinated by INRAE. He studied the beneficial or deleterious effect of type I interferons. These are small proteins produced naturally in the body in response to a viral infection. Numerous studies have shown that a defect in the production of these interferons by the body is associated with development of severe forms of COVID-19. However, type I interferons are not always beneficial, as they can cause excessive inflammation. The Timing project made it possible to show on animal models that only very early administration of interferon (before infection or just after) was beneficial and that contrary to the hypothesis, late administration was not harmful.
Understanding the genetic evolution of coronaviruses
Furthermore, coronaviruses have a strong potential for evolution, through mutation events, even recombination, then selection. Since 2018, the Ploufragan-Plouzané-Niort laboratory has been studying the genetic evolution of chicken (IBV) and turkey (TCoV) coronaviruses. Since 2018, the unit has studied the genetic evolution of avian coronaviruses in the presence of vaccination or not. The results showed that the genetic evolution of an avian coronavirus is very rapid (from the first passage in unvaccinated subjects) and different in vaccinated and unvaccinated subjects. These results allow better understand the evolution of coronavirus in the presence of vaccine immunity.
Evaluate the transmissibility of Covid-19 from animals to humans
The Agency was also asked to provide opinions on the risks of transmission of the SARS-Cov-2 virus from animals to humans. It thus determined that, even if certain species, such as cats, ferrets, mink and hamsters were susceptible to Covid-19, domestic animals and wild animals play no role in the maintenance and spread of SARS-CoV-2 in France, where the spread of the virus is the result of human-to-human transmission via the respiratory route. However, the there is a risk of creating an animal reservoir. ANSES therefore recommends being particularly vigilant during contact between humans and species capable of harboring the virus (cats, mink, etc.), in the event of a high density of animals, and animal-human promiscuity, particularly in a closed or confined environment.
A reference mandate for the surveillance of SARS-CoV-2 in wastewater and sludge from sewage treatment plants
Since the end of 2021, the Hydrology laboratory has been the national reference laboratory for monitoring SARS-CoV-2 in wastewater and sludge from wastewater treatment plants. This surveillance aims to complement the tools already available, particularly in a context of low viral circulation, to early detect (re)emergence of the virus in the population. The laboratory is notably responsible for harmonizing the methods used to detect the virus and evaluating the capacities of the laboratories responsible for carrying out the analyses.
Avoiding exposure to coronavirus in the workplace
As part of its missions on occupational health, ANSES has also issued recommendations on measures to adopt to avoid contamination in the professional environment other than care and health. She is also leading a research project, SACADA, aimed at identifying how the virus circulates in meat preparation workshops and to propose appropriate prevention measures. Due to their characteristics, notably cold, humidity and the need to make physical efforts, these professional environments are in fact favorable to the spread of the virus between workers.
Photo : Centers for Disease Control and Prevention
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**Interview with Dr. Emily Hartman, Virologist at ANSES**
*Interviewer:* Thank you for joining us today, Dr. Hartman. To start, could you explain what coronaviruses are and how they affect both animals and humans?
*Dr. Hartman:* Absolutely! Coronaviruses are a diverse family of viruses that can infect many mammals and birds. They primarily target the respiratory and digestive systems. While some coronaviruses are specific to humans, others can jump from animals to humans, which highlights their highly transmissible nature.
*Interviewer:* That’s interesting! What kind of diseases do these coronaviruses cause in different species?
*Dr. Hartman:* The severity of the diseases varies widely across species. In veterinary medicine, infections from coronaviruses are quite common. For instance, dogs and cats can suffer from specific coronaviruses leading to severe illnesses like feline infectious peritonitis. In livestock, diseases from coronaviruses can cause significant economic losses. For example, pigs may contract porcine epidemic diarrhea, while poultry can be affected by infectious bronchitis.
*Interviewer:* What about the transmission of these viruses between species? How does that happen?
*Dr. Hartman:* Coronaviruses possess an incredible ability to mutate and evolve, which can enable them to switch hosts. For example, mutations in the virus’s genetic material can allow it to infect a new species. This is what happened with the emergence of Covid-19, marking the third significant coronavirus to jump from animals to humans in the last twenty years.
*Interviewer:* What actions is ANSES taking in response to coronaviruses, especially since the onset of the Covid-19 pandemic?
*Dr. Hartman:* ANSES has ramped up its research on coronaviruses across various species, including poultry, pigs, and wildlife. We are currently involved in several projects aimed at understanding the diversity of coronaviruses in animal populations and monitoring potential inter-species transmission. Our work also focuses on developing diagnostic techniques and exploring treatments, especially concerning the transmission and response to Covid-19 virus variants.
*Interviewer:* That’s a comprehensive approach. Can you shed light on the role of domestic and wild animals in the transmission of Covid-19?
*Dr. Hartman:* Certainly! Our investigations have shown that while certain domestic animals, like cats and ferrets, can contract Covid-19, they do not play a significant role in maintaining or spreading the virus in France. Human-to-human transmission remains the primary route of infection. However, we are cautious about the potential for creating an animal reservoir for the virus.
*Interviewer:* Dr. Hartman, it sounds like there is still much to learn about coronaviruses, both for human and animal health. Thank you for your insights today!
*Dr. Hartman:* Thank you for having me! It’s crucial that we continue to monitor and understand these viruses to better protect both animal and human populations.
