A person's blood type may influence their susceptibility to infection with rotavirus, a type of stomach bug, a new study suggests.

The results show that certain strains of rotavirus attach to cells by binding to “A antigen” — a marker on the surface of cells in people with blood types A and AB. The first step of infection is attachment to the cell.

People with these blood types have the “A antigen” not only on their blood cells, but also on the cells that line the gastrointestinal tract, which rotavirus attacks.

This means its possible that people with blood types A and AB are more susceptible to rotavirus infections, but it's too soon to draw firm conclusions, said study researcher B. V. Venkataram Prasad, a professor of biochemistry and molecular biology at Baylor College of Medicine in Houston. For one thing, the virus strains that were found to attach to A antigen are not the most common strains of rotavirus. It's possible the most common strains preferentially infect people with blood type B, for example.

In addition, no one has looked at large populations to see whether those who are infected with rotavirus are more likely to have a certain blood type, Prasad said. Still, the new study could prompt this type of research, now that scientists are aware there might be a link, Prasad said.

Understanding more about how rotavirus interacts with human cells could lead to the development of drugs against the disease, or to improvements in rotavirus vaccines, Prasad said.

Rotavirus causes gastroenteritis, or inflammation of the stomach and intestines, and is the leading cause of severe diarrhea in infants and young children worldwide, according to the Centers for Disease Control and Prevention. Until a vaccine against the virus was introduced in 2006, almost all babies were infected with the virus before they turned five years old, the CDC says.

In the study, the researchers found that cells engineered to express A antigen on their surfaces were easily infected by the rotavirus strain, whereas cells without the antigen were not easily infected. In addition, blocking the A antigen prevented infection with rotavirus in human intestinal cells, the researchers said.

Blood type is already known to determine susceptibility to infection with other pathogens, including norovirus and Helicobacter pylori.

The new study raises the question of whether blood groups arose in people as a way to counteract or evade infections from certain viruses and bacteria, Prasad said.

The study is published today (April 15) in the journal Nature.

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