American researchers at the University of Chicago have discovered that antibodies to viruses grown in the laboratory can lodge in chicken eggs, by binding to glycan. This phenomenon, which produces an antibody response against this component of the egg unrelated to the virus initially targeted, would not however represent a danger to health.
The scientists who carried out this work studied the responses of antibodies to influenza for several years. They made an astonishing discovery: the antibodies seemed to bind not only to the influenza virus, but also to any viruses that the laboratory could present to them.
Since antibodies react very specifically to different pathogens, this pattern was therefore rather unusual. But on closer inspection, the scientists realized after the fact that the antibodies were not reacting to viruses, but rather to chicken eggs used in the lab and in which the viruses had been grown, specifically in a part called the ‘allantoid.
The antibodies target a sugar molecule, known as glycan, but with a modified version found in eggs, but not known to be expressed in humans. “For this reason, humans can produce antibodies against this sulfur-modified glycan.“, specify the authors of this research published in June in mBio review.
What effects on health?
“Growing vaccines in eggs is the old way because it is cheap and can grow a lot of viruses.“said Jenna Guthmiller, PhD at the University of Chicago and principal investigator of the study.
“We are now seeing that these antibodies bind to this glycan which means that people who are vaccinated produce an antibody response against this component of the egg which is not linked to the virus at all “, she adds.
The effects of these antibodies on human health, however, remain unknown, although so far there is no evidence that their presence has any negative impact. “So many people get the flu shot every year and side effects are extremely rare, so there is no reason to suspect that it could cause any problems.“, reassures Jenna Guthmiller.
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