Monday, April 2, 2012

OBJECT #6: T2 virus

    If you’ve never read about bacteriophages, I doubt you would ever be able to guess what this thing is.  This is a paper model of a virus.  When you think of viruses, usually what comes to mind is sneezing and coughing.  It’s easy to forget that viruses don’t just affect humans.  There are many types viruses, each one specialized to attack one particular part of one particular type of living cell.  The first virus ever discovered was in plants.  There are also viruses that attack bacteria.  These types of viruses are called bacteriophages (“phage” means “eat” in Greek).  This type of bacteriophages is known as the T2.  There are also T4s and T6s.  The T2 is my favorite “phage” and is the one most common one drawn by artists who are illustrating articles on these things.  The reason for this is pretty obvious-- they look bizarre.  Usually people say they look like a lunar landing module.

    This model is just made from paper (heavy card stock paper) and a few chenille stems.  (It’s one of my free downloads, so you can make one, too!)  I sprayed the top lightly with silver spray paint to try to make it look less like paper.   In a real T2, the top part is made of protein and has a piece of DNA inside it.  The legs are not called legs, but rather “tail fibers.”  The ends of these fibers are what grabs onto the outside of the bacteria cell.  After it latches on, the neck sort of retracts, pulling the head down and propelling the DNA into the cell.  Once in the cell, the DNA takes over the cell machinery and turns the poor bacteria into a T2-producing factory.  When the bacteria gets full of T2s, it bursts open and all those new T2s go out looking for more bacteria cells to infect.

    Sounds gruesome (and even more so when you think that the same process happens to our cells when we catch a virus) but we could use these phages to our advantage to fight unwanted bacteria in our bodies.  The phage cannot possibly attack your cells.  The tail fibers will only stick to certain bacteria.  They won’t stick to your cells.  So... why are we not using these things to fight infections?  Some countries are-- such as Georgia (the country in Asia, not the US state).  They’ve got quite a research program going on these things.  They’ve found that these viruses are able to keep up with the survival mutations of the bacteria.  Antibiotic resistance is a big problem when dealing with bacteria.  But the T2 can manage to counter these mutations with mutations of their own, constantly keeping their mode of attack up to date.  Whenever the research hospital in Georgia finds an antibiotic resistant bacteria, all they need to do is take a microbial culture from the hospital’s sewer pipes and they’ll find phages that have already learned how to attack this new resistant strain.  So why aren’t other countries pursuing this research?  My guesses are that most people would say “No” to any treatment that involved a virus, and, more importantly, I don’t think you can get a patent on them, which rules them out as a cash cow for pharmaceutical companies.  But it’s nice to know that there is a Plan B out there, when all the drugs stop working.

    A number of years ago, I made a very large T2 for a science fair I did with my homeschool group.  I don’t know why I do things like this.  One day I just got it into my head that I needed a huge T2 virus.  I can’t brag that the construction was anything to “write home” about.  The top was just cardboard covered with sequined fabric.  The legs (oops--tail fibers) were hard to assemble because of the angles in involved.  I used metal angles that I adjust to less than 90 degrees.  The legs could be unscrewed for storage, and poor T2 spent many months in storage, only coming out for special events now and then.  The last time I got it out I discovered that it had become very wobbly, and making the determination that rebuilding was easier that repair, I decided to retire the T2 from my collection of junk in the garage.  (But I have not made a replacement yet.  Space is getting tight in the garage.)  I decided a better replacement was a hands-on activity about phages, where kids could assemble and disassemble T2s.  I made dozens of little cardboard heads, plastic DNAs, wooden necks and chenille stem legs.  When the kids finish assembling the T2s, they go around to the other side and take them apart.  Kids think taking them apart is just as fun as putting them together, because there are little slots to stick all the parts into.  Kids love sticking things into holes and slots.  This exhibit is part of my traveling summer science museum.

No comments:

Post a Comment