A new study has reported that healthy adults may have a level of protective immune memory to the swine flu virus. This, it claims, can blunt the severity of infection caused by the 2009 H1N1 influenza.
In the study, researchers showed that molecular similarities exist between the 2009 H1N1 influenza virus and other strains of seasonal H1N1 virus that have been circulating in the population since 1988.
The results suggest that healthy adults may have a level of protective immune memory that can blunt the severity of infection caused by the 2009 H1N1 influenza virus.
Led by Dr. Bjoern Peters and Dr. Alessandro Sette of La Jolla Institute for Allergy and Immunology, Calif., the researchers examined molecular structures known to be recognized by the immune system-called epitopes-on 2009 H1N1 influenza and seasonal H1N1 viruses.
Viral epitopes are recognized by immune cells called B and T cells- B cells make antibodies that can bind to viruses, blocking infection, and T cells help to eliminate virus-infected cells.
The data gathered and reviewed from the scientific literature was deposited into the Immune Epitope Database and Analysis Resource supported by the National Institute of Allergy and Infectious Diseases (NIAID).
The researchers used the information to find that some viral epitopes are identical in both the 2009 and seasonal H1N1 viral strains.
Those epitopes that could be recognized by two subsets of T cells, called CD4 and CD8 T cells, are 41 percent and 69 percent identical, respectively.
Subsequent experiments using blood samples taken from healthy adults demonstrated that this level of T-cell epitope conservation might provide some protection and lessen flu severity in healthy adults infected with the 2009 H1N1 influenza virus.
Analysis of the database also found that among six viral surface epitopes that can bind antibody, thereby preventing infection, only one is conserved between 2009 and seasonal H1N1 viral strains.
The results suggest that healthy individuals may have immune memory that recognizes the 2009 H1N1 strain and therefore can mount some measure of an immune attack.
The findings may also help explain why the 2009 H1N1 influenza pandemic affects young children more severely than it does healthy older adults and also why two H1N1 vaccinations are needed to protect children ages nine years and under.