Updated on September 7, 2020, 12:53 p.m.
Anyone who has already had a cold will probably survive the flu wave better. Researchers have found that an immune system that has been stimulated by other pathogens is better able to ward off similar attacks. Could the phenomenon also play a role in Corona?
With the end of summer the flu season is also approaching – it could immune system have a surprising ally. Doctors at Yale University in the USA report that rhinovirus infection is the most common cause of Colds could provide protection against flu viruses, at least for a short time, as the body’s defenses are mobilized.
Whether this mechanism might also provide better defense against the Coronavirus SARS-CoV-2 could mean, but it cannot be said yet, explain the researchers in the journal “The Lancet Microbe”.
The reason for the investigation by the scientists led by Ellen Foxman from the Yale School of Medicine was a riddle about the swine flu virus (H1N1), which first spread in North America in 2009 and led to numerous deaths: although it was expected that the number of cases would be in the fall – that is At a time when colds were also dealt with – would also increase noticeably in Europe, this increase did not occur.
Infection with cold virus protects against influenza in the laboratory
Foxman and her team examined the data of more than 13,000 patients who presented at Yale New Haven Hospital with symptoms of a respiratory infection during the winter months of 2016-2019.
The analysis showed that the flu virus was usually undetectable when the cold virus was present – although the samples came from a time when both types of virus were active and a common occurrence seemed likely. “When we looked at the data, it became clear that very few people had both viruses at the same time,” said Foxman.
To test the virus interference, i.e. the interaction between the two pathogens, the doctors first exposed human respiratory tissue to rhino and then flu viruses. They made the tissue in the laboratory from stem cells from which epithelial cells develop, which line the airways of the lungs and are a main target of respiratory viruses.
The result: an infection with rhinoviruses protected against the influenza viruses. “The antiviral defense was activated even before the flu virus hit,” says immunologist Foxman. Rhinoviruses are one of the most common causes of colds. Their very presence triggered the production of the body’s own antiviral interferons. Those proteins are part of the immune system’s early response to the invasion of pathogens, explained Foxman. “This effect lasted at least five days.”
Previous infections affect disease
Your laboratory has now started to investigate whether a similar protective mechanism could also work for the SARS-CoV-2 coronavirus. With a view to the upcoming cold season, that is still unclear. “It is impossible to predict how two viruses will interact without doing the research,” said the medical professional. However, recent studies suggest that earlier infection with harmless coronaviruses could at least lead to a faster immune response.
A team led by immunologist Jose Mateus from the US La Jolla Institute for Immunology reported in the journal “Science” recently that T cells, i.e. white blood cells that are part of the immune system, reacted to SARS-CoV-2 in some people, even though they had not previously been exposed to the virus. Instead, they had contact with certain cold viruses, which also belonged to the group of coronaviruses. According to the scientists, this cross-reactivity could influence the severity of an infection with SARS-CoV-2 and, under certain circumstances, lead to milder courses of the disease.
Effects of T cells on coronavirus still unknown
A research team led by the immunologist Andreas Thiel from the Charité Berlin and from the Max Planck Institute for Molecular Genetics also had an article that has not yet been independently checked and published of the journal “Nature” described that about a third of the people in their study who had never had contact with the novel coronavirus had memory T cells that responded to SARS-CoV-2.
They also suspected an infection with conventional cold coronaviruses as the cause. The exact effects of these activated T cells on the new coronavirus cannot yet be said, the scientists warned. (dpa / kad)
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