Ignorance is truly bliss under many circumstances, but when it comes to a person’s health and well-being, knowledge is definitely power.
A case in point is the recent public health scare occurring in response to the swine flu. With the barrage of media attention, it’s easy to get lost among the flurry of information, creating confusion and, ultimately, panic within the population. To lessen fears, it can be useful to understand exactly what makes the influenza virus, something that already affects many people each year, tick.
An Influenza virus invades the cells of a person’s respiratory system in order to accomplish one goal: to multiply, or make more copies of itself. After gaining entry to a cell, the virus hijacks the machinery contained therein, forcing it to make the components necessary for new viruses. When the task is complete, the newly created virus particles burst out of the cell and search for other healthy cells to invade. Its “life” cycle then begins again.
An influenza virus has two components that are needed to enter and then exit a cell. These proteins are called hemagglutinin and neuraminidase, respectively. The scientific terminology for the swine flu virus, H1N1, actually corresponds to the names of these two proteins, and the numbers correspond to particular variants of these proteins. Hence, H1 is hemagglutinin variant 1 and N1 is neuraminidase variant 1 .
There are 16 varieties of hemagglutinin and 9 varieties of neuraminidase, and the combinations of these two constitute different strains of the virus. Some may remember when the world turned its attention to H5N1, or the “bird flu,” only a few short years ago. The virus’s neuraminidase protein has become an effective target for anti-viral drugs such as Tamiflu. Because a virus needs its neuraminidase to leave the cell it invaded, blocking its ability to function keeps the initial virus and all its new copies bound inside the cell instead of being able to leave and prey upon other cells.
Each year, scientists keep a close watch on influenza outbreaks that occur across the country; based upon the information, a prediction is made about which influenza strains are likely to affect the human population during the upcoming flu season that typically occurs from December to March. Vaccines are then tailored to these predicted strains so that the immune system will be armed with protective molecules to recognize and kill a virus in the event of infection.
Flu vaccines are not effective from year to year, however, because the virus mutates continually in an effort to avoid being noticed by the immune system. Influenza type A viruses, which includes 2009 H1N1, have a high rate of mutation and can affect people of all ages, pigs, and birds. In some cultures, it is common for people to live closely among these species, breathing the same air and creating an opportune environment for the influenza subtype A viruses to be passed between each other. These conditions, combined with the propensity of the virus to mutate, facilitate the evolution of a strain such as H1N1 that is problematic because it spreads easily from person to person, people do not have immunity to it, and there is not yet a vaccine.