Vaccination: an inside view

Dre von MesslingZoomZoom
© Marc Couture

Article written by Julie Potvin-Barakatt, February 16, 2010.

Here we go again! Influenza season is in full swing! As is the case each year, a vaccine is available to immunize people at risk against seasonal influenza. This year, a vaccine against the pandemic influenza was also recommended for everyone. If you received one or the other, or even both of these vaccines, you know that you were injected in the muscle with pieces of viruses. You were informed that it would take at least ten days before your body would be able to defend itself against this intruder. But beyond this synopsis, has anyone ever explained the details and cutting edge ingeniousness of your immune system army?

Very near you, a Laval resident has a great passion: viruses! She studies and unscrupulously handles these small dreaded organisms trying to understand how they interact with us. Her aim? To discover new, more efficient defense mechanisms against viruses. Her name is Veronika von Messling, a professor-researcher in infectious diseases at the INRS-Institut Armand-Frappier, and she has graciously agreed to accompany us on a voyage behind the scenes of our defense system against these microscopic attackers.

"Imagine that your body is a country. Your immune system would be your armed forces," the young researcher explains. Everything is going well in your body when suddenly an attack is detected in the muscle in your left arm. Ouch! A vaccine has just been injected. Policemen and investigators (immune cells, also called "white blood cells") intervene on the scene in the first hours following the invasion. They notice the presence of an enemy unknown to the police: pieces of a new virus! Why pieces? Because in Canada, we deactivate the virus and grind it into a thousand pieces to ensure that the vaccine does not transmit the disease.

This stranger must absolutely reveal his identity so that we can produce efficient weapons against him. Policemen and investigators cannot carry out this work. Therefore, they escort this new opponent to the immune response plants: the spleen and the lymph nodes. Similar to laboratories filled with military psychologists and engineers, these organs are inhabited by immune cells eagerly awaiting the arrival of unknown rivals in order to dissect their personalities and produce antibodies specific to them.

"The influenza virus is a formidable opponent," says Professor von Messling, because, she explains, it requires only twenty-four hours to multiply to the point of making an individual ill. In research this important characteristic allows us to obtain quick results following new vaccine trials and other immune response modulation strategies. However, this is what explains the ten-day delay between the instant of vaccination and the moment when our blood is a well-militarized zone. In effect, we estimate that this delay is necessary for our immune cells to release enough antibodies in our blood to neutralize the real influenza virus as soon as it enters our body and therefore prevent the symptoms of the disease. After immunization, the antibodies circulate continuously in our blood.

The human immune system is a very complex marvel that is sometimes harshly tested by certain microorganisms. Fortunately, several laboratories throughout the world are filled with scientists, who, like Professor von Messling and her team, devote their careers to understanding it better and to developing new types of vaccines, new immune system stimulators, and new antivirals. Their research today will contribute to progress in human health tomorrow.