In the new study, Baskin and colleagues examine the host-pathogen responses to a common influenza virus and two ressortant strains of the 1918 H1N1 virus, each containing HA and NAkey surface antigens closely linked to the 1918 strain's potent virulence. The effects of these strains on host tissues and gene expression was compared with those of a 2004 Vietnam isolate of the Highly Pathogenic Avian Influenza (HPAI) H5N1. In a non-human primate model of the disease, the avian virus was found to significantly outpace not only run-of-the-mill influenza but even the highly virulent 1918 ressortants, in terms of its relentless pathogenicity.
Ressortant viruses occur when different influenza subtypes or strains simultaneously infect the same host. A shuffling and exchange of genetic material between two or more such viruses can occur under these conditions, giving rise to new viral forms which share genetic characteristics with each parent strain but may also possess novel attributes, including heightened virulence. (Researchers borrow this ressortant technique from nature in order to create deactivated viral strains for use in yearly influenza vaccines.)
The perfect storm
Unlike typical seasonal flu which poses the greatest threat to juveniles, elderly and those with compromised immunity; the 1918 flu reserved the worst of its wrath for healthy young adults with robust immune systems. In the case of the avian H5N1 virus, statistics of human fatalities reveal a similar trend. In both cases, the highly pathogenic strains replicate rapidly and induce a massive transcription of genes associated with the innate immune response, the body's first line of defense for combating viral challenges.
The group sought to compare the 1918 flu strain with H5N1 through a systems biology approach, pioneered by Dr. Baskin's mentor, Michael G. Katze, Ph.D. at the University of Washin
|Contact: Joe Caspermeyer|
Arizona State University