Norovirus resistance

Norovirus resistanceGenetic testing and norovirus resistance

Noroviruses, also called Norwalk-like viruses (NLV), are one of the main causes of non-bacterial epidemics of gastroenteritis or “stomach flu” which means inflammation of the stomach and small intestine. Virus usually appears in closed communities like family, school, ships, military and many others. Norovirus is the main cause of inflammation of intestinal and stomach mucosa. Because it is simply transmitted from person to person, it spreads fast and tends to infect a large number of people.

Nevertheless, despite this mode of transmission and fast infection, there exist some people who do not become infected and do not develop symptoms despite their exposure to the virus. A simple genetic change that prevents formation of special protein is responsible for this.

More details about norovirus resistance

The symptoms of gastroenteritis include nausea, vomiting, diarrhea, abdominal cramping, fever and weakness. They are usually short-lasting and disappear within 48 hours; the patients do not require professional medical attention. Children, in whom this virus is the main cause of gastroenteritis, elderly people and patients with chronic diseases, however, need to be followed, mainly because of the danger of dehydration from loss of fluids.

Genetic resistance

Norovirus is highly contagious; nevertheless, some people do not become infected upon exposure. 20% of Europeans are thought to be resistant to it. This indicates a special trait which turns out to be genetic. The FUT2 gene plays a decisive role; it is responsible for the formation of proteins called carbohydrates H type 1 that are found in the intestinal mucosa and in mucous gland discharge. One fifth of Europeans do not possess these proteins due to a mutation in both FUT2 genes and the entry of the virus into the body, and infection, are thus prevented.

Resistance to infection with noroviruses, or the presence of a certain mutation and development of a non-expressing individual type, has certain advantages as well as disadvantages. The obvious advantage is the resistance to noroviruses as well as a supposedly lower chance of acquiring the HIV infection. The disadvantage is a higher chance of infection with certain bacteria, such as E.coli. A problem can also appear in the case of breast-feeding mothers who are resistant to infection. If the baby does not have genetic resistance like the mother does, it needs antibodies for protection against infection. Babies receive antibodies in the mother's milk. However, since resistant mothers have never been infected with noroviruses, they have not developed immunity. Thus, there are no antibodies against noroviruses in their milk and their babies may become infected.