Immunity: The Human Body’s Army

History books across the globe never fail to mention immunization’s most successful feat; the eradication of smallpox. A deadly disease that struck fear through everyone in the 20th century, it had killed 300-500 million people and left life-long scars in its wake. What started as a theory by Edward Jenner ended with the development of the first vaccine.

But how did Edward Jenner know that material from the cowpox virus could potentially inoculate a person against smallpox? To understand how vaccines work we need to understand how our body’s immune system functions. When a foreign pathogen enters our body the immune system triggers a series of responses to identify and remove them from our bodies. Symptoms such as fever, coughing and inflammation are indications of these responses taking place.

But that’s just our first line of defense. Our second line of defense, or adaptive immunity is the star of the show. Not only do they (B cells and T cells) attack these potentially harmful pathogens, but they also record information about them in case of a re-infection. The only downside to adaptive immunity is the race for time. The body takes time to build up these defenses and therefore puts those with weaker or immature immune systems (e.g. elders and infants) in danger of severe re-infection.

This is where vaccines use the same principles as our body’s immune system to defend us. Vaccines trigger our adaptive immune system without exposing us to the full strength of the disease. Today we have several different types of vaccines that work in different ways. Live attenuated vaccines and inactive vaccines are examples but they have a downside in that they are difficult to make and again, put those with weaker immune systems at risk. Subunit vaccines are far better because they only contain part of the pathogen that triggers the immune response. Scientists are now developing DNA vaccines where they can isolate the genes that make the specific antigens the body needs to respond to a particular type of infection. Once injected, these genes instruct the body cells to make the antigen to trigger the response and protect the body from any future infections.

The longest running, most deadly and incurable diseases out there are HIV AIDS and cancer. Immunization has contributed to the following successes in the last 2 years;

In 2015, a new AIDS vaccine was given the green light to proceed for human trials. The scientist who was also the first to claim that HIV triggered the disease said the vaccine took 15 years to develop and thorough testing on monkeys was required before they could collect the funds and develop the vaccine for humans. They, quote ‘wanted more and more answers before going into people.’ Called the “full-length single chain vaccine,” it contains the HIV surface protein gp120 that has been engineered to attach to parts of the CD4 receptor on our immune cells and trigger antibodies against this protein.

In June 2016, a new universal cancer vaccine was developed and scientists conducted the first trials on humans and mice. Using the principle of immunotherapy (using patients’ own immune system to attack cancer), this vaccine can be given to patients who already have cancer and it works by shooting ‘darts’ of RNA extracted from the patient’s cancer cells at the body’s immune cells to trigger a massive attack on any and all tumors. The RNA in the ‘darts’ can be extracted from patients with different cancers and the vaccine can be made quickly and inexpensively for each type of cancer rendering it ‘universal.’

Immunization has come a long way with many great successes. As the world anticipates another breakthrough like the eradication of smallpox, Edward Jenner would have been proud to know that his theory has been exaggerated to great extents and is saving the lives of millions of people.

Written by: Sadiya Badurdeen