Season 3, Episode 8: Sleepers
Forest fires erupt in British Columbia and firefighters become afflicted with strange pox-like blisters and lung conditions that appear deadly but not contagious. NorBAC investigates and discovers an engineered form of a horse disease, glanders, may be the cause. Meanwhile, David receives a mysterious package containing smallpox, which after some analysis turns out to be a strain that somebody must have made from scratch! The race is on to find the renegade molecular biologist.
IS IT POSSIBLE TO NEVER DEVELOP IMMUNITY TO A DISEASE LIKE GLANDERS?
 Image provided courtesy of Shaftesbury Films. |
 |
Bob tells David about glanders, an infectious disease for which no immunity has ever developed. |
What is glanders?
Glanders is an infectious disease caused by the bacteria Burkholderia mallei. B. mallei primarily affects horses, mules and donkeys but can also infect humans, dogs, cats and goats and is, therefore, classified as a zoonotic agent.
The disease is spread by direct contact with infected animals. B. mallei can enter the body through inhalation, contact with mucosal surfaces, cuts in the skin or ingestion of contaminated food or water. It occurs mainly in lesser developed countries in Africa, Asia, the Middle East, and Central and South America.
Symptoms include ulceration of mucous membranes in the respiratory tract, nasal discharge, coughing, and fever. Infection can be short-term or chronic, leading to death within days or months.
Because it takes very few individual B. mallei bacteria in one’s body to kill a person, it is considered a potential biological warfare agent—a weapon. During World War I, German agents were thought to have spread glanders to Russian horses on the Eastern Front. And during World War II the Japanese deliberately used B. mallei to infect Chinese prisoners of war and horses.
How does the immune system develop immunity?
|
|
|
Artist’s rendition of white blood cells – key components of the human immune system. |
The immune system has many layers of defense. The first time the body encounters a foreign substance, cells near the site of infection make and secrete proteins that activate other cells nearby to kill and/or get rid of the invading substance. This immediate response is called the “innate response”.
The immune system also has a longer acting defense called the “adaptive response”. The adaptive response relies on certain immune cells to “remember” foreign substances the body has encountered. If the body encounters these substances again, these special memory cells become activated and multiply to fight off the infection.
Adaptive immunity is the reason why vaccines help to prevent infections. Vaccines are designed to trigger memory cells to remember the signature of infectious agents like chicken pox or measles so if the body ever encounters them again, it is better able to fight off these infections.
Vaccines and adaptive immunity can fail, however, and this can happen in two ways: primary failure is when, upon first encounter of an infectious agent, the immune cells do not react strongly enough to recognize the agent, and cannot make proteins or other chemicals to signal to other cells to recognize or fight the agent. Secondary failure is when the immune cells react strongly after the first encounter but the memory cells are not triggered after future encounters.
So...
Yes, it is possible to experience immune failure against certain infectious agents. Vaccine failures generally occur due to bad timing of vaccination. Given too early in childhood, a vaccine can be neutralized by a mother’s immune proteins from breast milk and fail to trigger a child’s own immune response.
IS IT POSSIBLE TO BUILD A VIRUS?
What is a virus?
A virus is a microscopic particle that usually consists of a protein shell surrounding genetic material, either DNA or RNA. Viruses cannot reproduce on their own; they only can replicate and spread by infecting a host cell.
How does one make viral components?
Since viruses cannot replicate on their own and must rely on host cells to do so, it’s possible to engineer a host cell to make viral components. A cell can be engineered to carry a gene that encodes the protein component of the virus’s outer shell. When the cell turns on that gene, it will make the viral coat protein. That same cell also can be engineered to carry a copy of the viral genome, which is copied by enzymes the host cell routinely uses for replication of its own genome.
Scientists also have devised ways of using purified protein enzymes and chemical building blocks from cells to make viruses in test tubes without using any whole, live cells. These so-called “cell-free” methods have been used to make poliovirus and hepatitis C virus. In the case of poliovirus, which is an RNA-based virus, the scientists bought from a company DNA matching the exact sequence of the poliovirus genome. Using that DNA as a template, they used a cellular enzyme to copy that DNA into RNA then added to the test tube other proteins that enveloped the RNA into infectious virus particles.
So...
Yes, it is possible to build a virus. In fact, many vaccines are made from viruses that have been built from scratch, but engineered to be faulty so they cannot cause full blown infections and disease.
- by Audrey M. Huang, Ph.D.
Want to read and learn more?
To learn more about glanders, visit:
http://www.phac-aspc.gc.ca/msds-ftss/msds25e.html
http://www.cdc.gov/nczved/dfbmd/disease_listing/glanders_gi.html
To learn more about the immune system, visit:
http://en.wikipedia.org/wiki/Immune_system
To learn more about viruses, visit:
http://en.wikipedia.org/wiki/Virus
