This slice of lung from a patient who died of influenza pneumonia was heavier and redder than normal and uniformly firm throughout. Large airways were patent. Researchers have revealed that a protein in influenza virus called M2, which helps it multiply, also damages lung epithelial cells, causing fluid build-up in the lungs. They say that the accumulation of fluid in the lungs makes it difficult for the patient to breathe and prevents oxygen from reaching the blood stream. They have found that M2 damages a protein responsible for clearing fluid from the lungs by increasing the amount of oxidants within the cells. Oxidants are necessary for proper cell function, but can become toxic if uncontrolled.

Andhranews 2009, how flu virus attacks the lungs, Andhra Pradesh, viewed 28 October 2009, <>
Image source:

Bishoy Aiad