Infection biologist Dr. Markus Hoffmann (left) and Prof. Dr. Stefan Pöhlmann, Head of the Infection Biology Unit at the German Primate Center (DPZ) – Leibniz Institute for Primate Research. PHOTO/Karin Tilch.
By PATRICK MAYOYO
Since May 2023, the EG.5 lineage of SARS-CoV-2, known as Eris, has been spreading globally and was classified as a “Variant of Interest” by the World Health Organization (WHO) in early August. However, the cause of the increasing spread of Eris has been unclear.
When vaccinated or infected, our immune system creates antibodies that target the spike protein of SARS-CoV-2, blocking the virus from entering and multiplying inside cells. In turn, the virus evolves mutations that reduce the ability of these antibodies to bind to its spike protein effectively.
Scientists from the German Primate Center – Leibniz Institute for Primate Research in Göttingen have now examined the characteristics of the Eris sublineage EG.5.1 and come up with refreshing findings.
According to a press release from the German Primate Center, the researchers found that EG.5.1 is not more infectious than its predecessors, meaning it cannot infect host cells more effectively.
However, EG.5.1 can escape neutralizing antibodies better than other currently circulating SARS-CoV-2 lineages, giving it an advantage in infecting individuals whose immune systems have produced neutralizing antibodies after vaccination or infection.
The researchers, however say, after exhausting years of the pandemic with multiple waves of infections caused by ever-changing virus variants and corresponding hospitalization rates, the situation has significantly improved by now.
“Large waves of infections outside the cold and wet seasons are not occurring. This success is largely attributed to the rapid development of vaccines,” the scientists note.
Research indicates that the newly emerged Eris lineage (including EG.5 and EG.5.1) of SARS-CoV-2, characterized by moderate antibody escape capabilities, is responsible for its increasing spread; however, the forthcoming vaccines based on the XBB.1.5 lineage are anticipated to be effective against it. The severity of illnesses caused by these variants remains unchanged. PHOTO/GERMAN PRIMATE CENTER
They add that many people have been immunized against SARS-CoV-2. Booster vaccinations with adapted vaccines, known as booster shots, as well as infections in vaccinated individuals with currently circulating virus variants, have further trained our immune system so that it can also counter newly emerging virus variants.
Virus variants: Spike protein mutations can ‘shake off’ neutralizing antibodies and increase infectivity
They add that a part of our immune protection relies on neutralizing antibodies that are produced by the cells of our immune system after vaccination or infection.
“Neutralizing antibodies attach to the spike protein of SARS-CoV-2, preventing the virus from entering into our cells. This mechanism is also referred to as neutralization,” they said.
They however, noted that even with neutralizing antibodies, a 100 percent protection against a SARS-CoV-2 infection is not guaranteed because SARS-CoV-2 can still change adding this leads to the emergence of mutated virus variants that can gain the ability to partially evade neutralizing antibodies.
This process is also known as antibody escape and is based on mutations in the spike protein that make it less optimal for neutralizing antibodies to bind.
“Furthermore, mutations can enhance the transmissibility of SARS-CoV-2 variants by, for example, improving the binding of the spike protein to the cellular receptor ACE2,” says Markus Hoffmann, the leading scientist behind the study.
Mutations in the spike protein of the Eris sublineage EG.5.1 increase the ability to evade neutralizing antibodies
Since May 2023, the SARS-CoV-2 lineage EG.5, including its descendant EG.5.1, has been on the rise in many countries. The lineage, classified as a “Variant of Interest” by the World Health Organization (WHO), is also referred to as Eris, named after the Greek goddess of chaos and discord.
Lu Zhang, PhD student at the German Primate Center – Leibniz Institute for Primate Research. PHOTO/Karin Tilch.
The researchers say while this name may sound dangerous, there is currently no evidence to suggest that infections with EG.5 and EG.5.1 are leading to more severe illnesses
However, they add it is still unclear what is causing the increasing spread of EG.5 and EG.5.1. A team of scientists from the German Primate Center – Leibniz Institute for Primate Research in Göttingen, the Hannover Medical School, and Friedrich-Alexander University Erlangen-Nuremberg has investigated the Eris sublineage EG.5.1.
“We have found evidence that an increased ability to escape from antibodies is the likely cause for the enhanced spread of Eris,” says Markus Hoffmann.
Hoffmann adds they tested how effectively the Eris sublineage EG.5.1 can enter host cells and how efficiently it is neutralized by antibodies in the blood of vaccinated individuals without a SARS-CoV-2 infection and those with a SARS-CoV-2 infection.
The scientist notes that during this process, they found that, in comparison to other currently circulating SARS-CoV-2 lineages, EG.5.1 does not possess an advantage in infecting host cells.
“In summary, our results suggest that the spread of EG.5 and its sublineages primarily relies on antibody escape rather than an enhanced ability to infect host cells. However, the increase in the ability to escape antibodies is rather moderate and by no means sufficient to completely undermine our immunity that has been established through vaccination or prior infection,” comments Markus Hoffmann on the outcome of the study.
Adapted vaccines based on the SARS-CoV-2 XBB.1.5 lineage should also be effective against EG.5 and its sublineages
In the autumn of this year, newly adapted SARS-CoV-2/COVID-19 vaccines based on the widespread XBB.1.5 lineage of SARS-CoV-2 will be deployed. Now the question arises: will these vaccines also be effective against EG.5 and its sublineages?
“Since Eris is a descendant of the closely related XBB.1.9 lineage, and the various XBB sublineages exhibit only minor differences among themselves, it can be assumed that the newly adapted vaccines will also be effective against EG.5 and its sublineages. Primary and booster vaccination, especially for high-risk groups and their close contacts, are therefore advisable,” concludes Stefan Pöhlmann, Head of the Infection Biology Unit at the German Primate Center – Leibniz Institute for Primate Research.
