At home in the lungs
Latest research on the bird flu virus, H5N1 will give an important leg-up to global efforts to check the spread of the disease. Two independent groups of researchers from the Erasmus University in Rotterdam, and the Universities of Tokyo and Wisconsin at Madison, US, have reportedly discovered why the H5N1 causes lethal pneumonia in people, but stays — as yet — out of the human-to-human loop. The H5N1 currently poses a limited threat to humans as it cannot spread easily from person to person. But once it acquires this ability, it would spread rapidly.
The latest findings apparently indicate that the H5N1 prefers the surface of human pulmonary (lung) cells — where it binds to sugars — to cells lining the nose and throat. This validates what scientists have found in autopsies performed on H5N1 victims that show damage to the alveoli — delicate sacs deep in the lungs, where oxygen enters the blood. Since people usually ‘catch’ the flu through sneezing and inhalation from the nose and throat, it stands to reason that poor binding of the H5N1 in the respiratory tract probably keeps it from spreading easily among people.
The next step for researchers will be to work out possible mutations of the H5N1 that may allow it to bind in the upper respiratory tract. This will help identify new strains of the virus and predict how they could affect human tissues other than the gut and the brain as is happening now. Also, it will complement the focus of scientists on ascertaining virus components that help the H5N1 adapt to humans, as they make a list of molecules to look for in emerging bird flu strains that threaten people and develop new therapies to target those molecules.