Lithuanian scientists: Tissues are not destroyed due to mutations in the SARS-CoV-2 virus found in them

Martens (ferrets, minks, squirrels, etc.) are known to be infected with human respiratory viruses due to the similarity of their airways to those of the human respiratory tract, e.g. Eg ferrets are widely used in influenza research. For this reason, human-to-tissue transmission of the virus is not surprising, and this was first reported in the spring of this year on tissue farms in the Netherlands, media reported.

“All organisms make mistakes when they copy their genetic material, which are known as mutations. RNA viruses like SARS-CoV-2 experience these mutations about a million times more frequently than larger organisms like us. If each person has an average of 60 new mutations that did not exist in their parents, following the SARS-CoV-2 genealogical line, a new mutation will be detected approximately every 2.3 weeks. The frequency, meaning, and effects of mutations in organisms in biology are radically different from their representations in the media. There are no non-mutant viruses, so it makes no sense to talk about each mutation as if it were extremely significant and important, ”explains Gytis Dudas, an evolutionary biologist at the Evidence-Based Medical Group.

The case of Lithuania

As for the infections and their mutations in the Jonava farm, the ongoing sequencing of the SARS-CoV-2 genetic material (viral genome scan) will be able to confirm or rule them out. Infection has been observed in animals since the beginning of their mortality, so the prevalence of the virus in the farm must be evaluated with greater precision. According to the media, 22 samples were taken from the cages, all of which were positive and all tissues in them (~ 40 animals) were destroyed, so we can conclude that the prevalence among farm tissues may be significantly higher.

“The sequence is likely to show that SARS-CoV-2 in the Jonava tissue farm is more similar to the virus circulating in humans in Lithuania than to viruses in other tissue farms in Europe, viruses that have been found in many sometimes in tissues of infected caregivers, “says Gytis Dudas. – We cannot be sure, but it would not be surprising if a Y453F mutation was detected in Jonava’s tissues, which is related to the adaptation of the virus to infect tissues. SARS-CoV-2 with this mutation has already been detected circulating among people in North Jutland, with no apparent changes in the properties of the virus. “

Animal husbandry is not the only way out

The uncontrolled spread of SARS-CoV-2 between densely packed tissues poses a threat both to the possibility of human infection with tissues and to the long-term risk that viral variants with altered properties in tissues may be selected. One solution to this problem is the destruction of animals, the other is to closely monitor infected farms, make the best use of the best personal protective equipment for agricultural workers, carry out preventive examinations and, ideally, separate workers. agriculture from the general public. It will be resolved if all the tissues and workers are sick or vaccinated.

In April this year, during a newsletter and press conference, the Statens Serum Institut (SSI, one of the Danish public research institutes) announced that it had detected SARS-CoV-2 in tissues. According to an SSI report, a scan of the virus’s genetic material found in both tissues and people who came into contact with them revealed that the tissues were infected with the virus from humans and that 12 people were most likely infected. with tissues.

In the media, the sensation was caused by one (of 5) groups of SARS-CoV-2 viruses mentioned by SSI, which are very widespread in tissues and have 4 mutations. The non-SSI groups reporting their analyzed data were likely defined as five different SARS-CoV-2 exposures to tissue populations from diseased individuals.

“Two of these mutations are common in human sprouts, so humans are likely to enter tissues. Of the remaining two mutations, Y453F was also seen in a tissue sprout in the Netherlands, so it is likely that it is an adaptation of SARS-CoV-2 to spread to tissues, says Gytis Dudas – Y453F is known to alter the binding of SARS-CoV-2 to the ACE2 receptor of the viral host, which differs between humans and tissues. The last mutation (I692V) is distant from functionally important parts of the SARS-CoV-2 S protein (vaccine target), so it is questionable whether it will affect the efficacy of the vaccine or the transmission of the virus. Therefore, although The argument put forward by Danish scientists to justify the killing of tissues is unfounded, the killing of densely packed tissues may be rational for other reasons. “

Decommissioning decisions have also been applied in the Netherlands, where a loom ban was adopted in 2013, and such farms must be closed by 2023. One of the justifiable reasons is a reluctance to impose an additional burden on the healthcare system. COVID-19 outbreaks in humans are currently not being controlled in many parts of Europe, and allowing the virus to spread in animals from which it can return to humans and monitoring changes in its genome is a major burden on the system. of health.

There is also a more hypothetical argument for tissue destruction. Tissues on farms are kept very densely, which facilitates the spread of SARS-CoV-2. From the outbreaks of avian influenza in poultry farms, we know that densely raised animals select for higher mortality from influenza viruses. We cannot say that SARS-CoV-2 follows the same path, all the more so since coronaviruses and influenza viruses are not related but do not respond to active spread within animal farms would be irresponsible. In summary, while we do not know if viruses adapted to spread between densely housed tissues may become more dangerous to humans, we do know that the SARS-CoV-2 virus can be transmitted in both directions between humans and tissues. Therefore, it is appropriate to respond to these situations at an early stage and monitor the spread of SARS-CoV-2 in pig farms and the surrounding people.