A new study from Tel Aviv University rejects the assertions that the origin of the corona outbreak is in bats. According to the research, in most cases bats do not store viruses in their bodies at all and in any case they have a very effective immune system that allows them to deal relatively easily with viruses that are considered deadly for other mammals.
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The research was conducted under the leadership of Dr. Maya Weinberg from the laboratory of Prof. Yossi Yuval, head of the Segol School of Neuroscience and a faculty member at the Steinhart School of Zoology and Nature Museum at Tel Aviv University. The team of researchers reviewed dozens of leading articles and studies in the field, and their conclusions were published in the ISience journal.
The researchers explain that, as is known both among the general public and among the scientific community, bats are often accused of being reservoirs of viruses, including the corona virus, and of being a threat to public health. In the current study, Dr. Weinberg sought to disprove the wrong theory and show that bats play an important role in insect control, in the reseeding of cut areas and in the pollination of a variety of plants.
Dr. Maya Weinberg, the leader of the study. Photo: Shahar Shahar, spokeswoman for Tel Aviv University
The researchers claim that there is indeed evidence that the origin of the potential ancient Covid virus was in bats. But on the other hand, to this day, two years after the epidemic first broke out, we still do not know for sure what the direct source of the Covid-19 variant is.
Dr. Weinberg: “Bats are often mistakenly seen as reservoirs of viral diseases solely because they are serologically positive, meaning they have antibodies, which means that the bats survived the disease and developed an immune response to it. After that they overcame the virus completely and got rid of it and therefore do not continue to carry it. At the same time, in many cases, a virus similar to the human pathogen may be found in bats, but it is not pathogenic to humans, which is not enough to make bats its reservoir.”
Dr. Weinberg adds: “To examine the general situation, we performed a meta-analysis of the literature and examined the findings for more than 100 viruses for which bats were considered potential reservoirs such as the Ebola virus, SARS, and COVID-19. We found that in a considerable number of cases (48%) this claim was based on the prevalence of antibodies or PCR tests, and not on the actual isolation of the identical viruses.
“Furthermore, many of the reported isolations are not convincing. Isolation of a virus alone is not enough to consider an animal as a reservoir, since a minimum amount of individuals in which the virus is isolated is also required in order to be considered a reservoir animal as well as an established way of transmission. Nor is the mere discovery of a particular virus in bats inevitably guarantees that spillover will occur, and many other biological, ecological, and anthropogenic conditions must exist for such an event to occur.”
According to the researchers, at the same time, in recent years, evidence has been accumulating that bats can deal with various viruses, even deadly ones, in a better way than humans and most other mammals. After more than a century of focusing on the viruses that bats carry, it seems that the immune system of bats is characterized by a restrained response during inflammatory processes. “In our view,” says Weinberg, “the bats have developed an excellent balance between resistance and tolerance: an increased defense response of the host and immune tolerance through a number of different mechanisms. Inflammatory pathways are suppressed, contributing to immune tolerance in bats and a well-balanced response that prevents the virus from developing.”
In conclusion, Dr. Weinberg adds: “The comprehensive research we conducted casts great doubt on the possibility that the origin of the corona outbreak is in bats. The findings show the opposite picture, according to which we must study in depth the anti-viral immunological abilities of bats, and in this way we can obtain new and effective tools in humanity’s fight against viral diseases, aging and cancer.”