For longer than our fear of cancer, we have been plagued by the common cold. Actually caused by a collection of different viruses, the common cold includes of all the classic symptoms: fever, runny nose, sore throat, and a cough. Like any viral disease, it’s difficult to treat and most of the time physicians suggest rest and hydration, so the cold can run its course.
This may all be about to change, according to the recent work of Dr. Leo James at the Cambridge Immunology Department. Announced by the Medical Research Council (London) on Monday, we may now have a better idea of how invaded cells can defend themselves against viruses.
Our cells have within them a system for identifying unwanted items and reducing them to their component parts. Sometimes this system is used to break down old cell parts. Other times, the machinery is used to break down an invading protein and present the pieces to the immune system.
Dr. James and his team have been able to observe human cells in the lab interacting with viruses in an unexpected way. One of the proteins in our cells is called TRIM21. It is hypothesized to recognize bound antibodies and signal for their destruction (and the destruction of anything they are attached to). James used a common model virus, adenovirus. Adenovirus is an unenveloped virus, like the rhinovirus. Both are causes of upper-respiratory infections, like the common cold.
In an interview James explained, “[An] antibody is attached to the virus and when the virus gets sucked inside the cell, the antibody stays attached, there is nothing in that process to make the antibody to fall off. The great thing about it is that there shouldn’t be anything attached to antibodies in the cell, so that anything that is attached to the antibody is recognized [by TRIM21] as foreign and destroyed.”
At this point in James’ paper, I was really amazed. The process requires synergy between an “adaptive” immune component (the antibodies) and an “innate” immune component (the TRIM21). If you’ll recall my previous discussion of immunology, these two systems frequently talk to one another, but rarely is the interaction this close.
James continues, “[This is a] key concept that is different from how we think about immunity. At the moment we think of professional immune cells such as T-cells [white blood cells] that patrol the body. [If] they find anything, they kill it. This system is more like an ambush because the virus has to go into the cell at some point and every time they do this, this immune mechanism has a chance of taking it out.”
The discovery and study of TRIM21 is a big deal. We knew in the past that antibodies could neutralize the effects of a virus, but it was generally thought that the antibodies were simply blocking up the viral surface and inhibiting binding. Now, the effects of TRIM21-mediated degradation will have to be investigated to see if there is an additional link. People who design vaccines can take this new knowledge and ensure they are building drugs with TRIM21 in mind. It has already been suggested that a nasal spray with TRIM21 be developed.
Again from Dr. James: “This is a way of boosting all the antibodies you’d be naturally making against the virus. The advantage is that you can use that one drug against potentially lots of viral infections. We can think of administering these drugs as nasal sprays and inhalers rather than taking pills… It could lead to an effective treatment for the common cold.
“The beauty of this system is that you give the virus no chance to make its own proteins to fight back. It is a way for the cell to get rid of the virus and stay alive itself.”
Very cool stuff – this is one excited microbiology grad student! Let me know what you think in the comments below or on Twitter!
Other installments in the “Science is Sexy” series:
- Science is Sexy: The Cure for Cancer
- Science is Sexy: Will Nanobots Save Us From Cancer?
- Science is Sexy: What is Swine Flu?
- Science is Sexy: How Do Vaccines Work and Are They Dangerous?
- Science is Sexy: Will the Large Hadron Collider Blow Us Up?
- Science is Sexy: How Does the Body Defend Against Diseases?
- Science is Sexy: Why Do We Get Sick More in the Wintertime?
- Science is Sexy: What is DNA and how does its replication mechanism work?
- Science is Sexy: What Exactly Is HIV?
- Science is Sexy: What’s The Big Deal About Synthetic Life?
- Science is Sexy: What is Evolution?