H1N1 virusOne of the mysteries to be solved since the emergence of new H1N1 virus was whether those who had already suffered a flu throughout their lives were immunized against this pathogen.

After much debate, a team of researchers at the La Jolla Institute for Allergy and Immunology (USA) has found the answer. Their research indicates H1N1 has similarities with some of the influenza viruses that have circulated over the past 20 years, so that those who have spent any flu are partly protected.

There are two types of immunity that allow the body to remember past flu and provide protection against other similar: antibodies and T cells (cells of the immune system defenses.) Antibodies can prevent infection because they destroy the virus before that enter the cells and multiply. The T-cells detect the virus once it has infected the cell, then eliminate it, not prevent infection but it makes it more light.

After comparing the molecular structure of the novel H1N1 influenza virus that humans have been among the last decades (since 1988), researchers have found that despite its many features, the head of the influenza A virus has similarities above.

Specifically, found that T cells recognize up to 69% of the markers of H1N1. Therefore, the severity of the pandemic has not been lower than expected at first. The course of the disease is being generally rather mild because these cells know how to fight the pathogen. By contrast, the antibodies do not recognize more that 17% of the molecules of the new virus and hence the transmission is still very high, because those in charge of detecting time they do.

To reach this finding, the La Jolla team compared the molecular markers of influenza A virus with molecular markers of past flu viruses, which are contained in the Immune Epitope Database, one of the largest databases in the world on the immune response to infections.

Until now it was said that only those who lived through the influenza of 1957 (the most similar to the present) could be protected. However, Bjoern Peters states that all those who have passed the flu, whatever, have some immunity. What happens is that those born before 1957 have extra protection and, therefore, were not influenza A is affecting as much as the younger.

The finding explains why the infection is not being as serious as feared. But nevertheless, the recommendation of vaccination is kept because it is the vaccine that will induce an antibody response that can help eliminate infections, which the body’s memory alone can not achieve.