Flu dynasty: 1918 and today

Global diaphragmatic influenza virus in 1918-1919 had a competitive dynasty that existed to this day, according to scientists at the National Institute of Infection and Allergy Diseases (NIAID), affiliated with National Academy of Health.

In an article published online in the June 29 New England Journal of Medicine, authors Dr. Anthony S. Fauci, Dr. Dr. Jeffery K. Taubenberger and Dr. David M. Morens, argued. that we have been living in the flu era since 1918, and they describe how the new H1N1 virus, which is currently on a global scale, is another product of this virus family.

NIAID Director Dr. Fauci said: 'The flu epidemic of 1918-1919 was a significant event in the history of public health. The inherited viruses of the disease have continued to exist in many ways, including the fact that the descendants of the 1918 virus continue to infect for nine decades. '

The influenza virus has eight genes, two of which encode surface proteins - hemagglutinin (H) and neuraminidase (N) - that allow viruses to enter host cells and spread from one cell to another. There are 16 H subtypes and 9 N subtypes, and therefore there are 144 combinations of HN. However, only 3 types (H1N1, H2N2, and H3N2) are found in influenza viruses that are fully adapted to infect humans. Other combinations, such as H5N1 bird flu, sometimes infect humans, but they are bird viruses.

The red arrows point to the human influenza virus strain, the black arrows indicate the flu strain of pigs, and the gray arrows indicate the transfer of one or several genes from the avian influenza virus. The horizontal lines inside the virus express each gene in 8 viral genes, abbreviated PB2, PB1, PA, HA, NP, NA, M and NS. ( Photo: NIAID)

Dr. Moren, an advisor to the NIAID director, said: ' Eight flu virus genes can be considered players in one team: Combining certain players is formed through' opportunity 'and brings re-virus for new capabilities, such as the possibility of infection in another type of host. ' This is most likely the source of the 1918 flu epidemic. Scientists say the virus was originally like the avian flu virus. The virus has a group of 8 new genes and - through an unknown mechanism - is easily infectious in humans.

Not only did the 1918 irut cause an outbreak of disease, which caused 10 million deaths, during the disease process, the virus was transmitted from person to pig and continued to evolve to this day. NIAID authors wrote: 'Since 1918, this powerful virus has used many evolutionary tips to survive in one form or another . and create new strains of descendant viruses in the host body, with new gene clusters, by receiving or transmitting viral genes periodically '.

'All flu viruses adapt to people today - both seasonal changes or viruses that cause widespread diseases - are descendants, direct or indirect, of the original virus', Dr. Taubenberger , researcher from the NIAID's Infectious Diseases Laboratory, emphasized. 'So humans lived in an era of epidemics beginning in 1918'.

How exactly do new flu gene groups jump from birds to a new host body, such as humans or other mammals? These factors determine whether infection in the new host's body is contagious once or more? There has been a lot of research on such topics, but there is no clear answer yet.

The human immune system creates a defensive wall for influenza H and N proteins, mainly in the form of antibiotics. However, when immunity to any new flu appears, the virus reacts by changing in many ways, making it difficult to recognize them for antibiotics. For almost a century, the human immune system has been involved in a non-stop battle with the 1918 flu virus and its descendants.

Although the dynasty set up by the 1918 flu virus seems impossible to overthrow, NIAID authors say there are still some positive signals. When viewed through a microscope for decades, it seems that episodes of disease caused by later generations of the 1918 influenza virus are somewhat less dangerous and intense. This is in part due to advances in pharmaceuticals and community health care methods. However, it also reflects that the path of the virus's evolution goes in the direction of increasing its ability to infect from host to host, combined with a reduction in the tendency to destroy those hosts.

The authors conclude: 'In addition to being prepared to deal with the possibility of a new influenza pandemic newly created by a completely new virus, we must look deeper, and continue to explore the factor. form the era of disease that we live in. '

Refer:

1. DM Morens et al.The persistent legacy of the 1918 influenza virus.New England Journal of Medicine, DOI: 10.1056 / NEJMp0904819 (2009)