Explain the spread of flu in 1918

MIT researchers have discovered two mutations in the H1N1 virus causing bird flu, the main cause of the 1918 pandemic spreading throughout Europe and killing 50 million people. This could help scientists promptly detect & prevent future outbreaks of bird flu from birds to humans.

The research team showed that the 1918 influenza pandemic developed into a pandemic because two mutations in the molecule lie on the surface structure of the influenza virus, which has occurred two mutations in the hemagglutinin (HA) structure - one The glycoprotein antigen is located on the surface of the virus and works to help the virus cling to the host cell. This allows them to be able to connect closely with the human respiratory apparatus.

The new discovery helps researchers track changes in HA molecules in the H5N1 influenza virus, which is spreading in migratory birds and poultry in a variety of Asian countries. Epidemiologists worry that mutations in the HA molecule could allow bird flu viruses to aggressively attack humans with tremendous spread - a potentially greater loss of life than flu 1918.

Image of the 1918 flu virus taken under an electron microscope.The virus was recreated in 2005 by the US Center for Flu Control & Prevention.(Photo: Web.mit.edu)

In the report of Natural Biotechnology published last January, Professor Ram Sasisekharan & colleagues found that the virus could only hide in cells and tissues of the human respiratory apparatus if they adapt to the form of sugar receptors (or polysaccharides) found in human cells.

The agency perceives pilosacarit in the human respiratory apparatus known as the 2-6 alpha receptor, they have two types of enmity - an open umbrella-shaped form and a cone-like form. In order to cause illness in humans, the influenza virus must acquire the ability to bind to the alpha 2-6 receptor in the form of an umbrella.

In the current study, the team discovered two mutations in the HA molecule that allow flu viruses to closely connect or have a high affinity for parietal polysaccharide receptors . "The affinity between HA influenza virus and polysaccharide receptors reveals a key determinant of viral transmission," Sasisekharan said.

The researchers used the 1918 influenza virus strain as a sample system to study the biochemical binding between HA and polysaccharides, which led to the spread of the virus. The virus that caused influenza 1918 (ie SC18) was compared to two other virus strains: NY18 differed only from the SC18 virus strain by only one amino acid & AV18 virus strain, only different from SC18 virus strain by 2 amino acids.

The experiment was conducted on ferret ferret (which is very sensitive to human flu strains), researchers soon received results, while SC18 effectively spread flu among ferrets. together, NY18 only causes very small infections and AV18 is not spread.

This finding corresponds to the ability of the virus to bind to the alpha 2-6 polysaccharide receptors in the form of an umbrella.

NY18, the only strain that spreads mildly, is able to bind to alpha 2-6-shaped receptors, but not as strongly as SC18, the virus spreads strongly. The virus does not cause human infection - AV18 does not have any affinity for alpha receptor 2-6 images and is only able to connect to alpha receptors 2-3. Another strain, TX18, is able to connect to alphe 2-6 and alpha 2-3 because of its affinity for alpha-receptor 2-6, though it is more infectious than NY18.

For this study, scientists have for the first time explained exactly the biochemical causes of the spread of influenza virus in humans and the basis for other studies.

Nam Hy Hoang Phong (Translated by Anne Trafton, MIT's News Office)