Fighting Cancer with Viruses

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A glioma, or brain tumor (Photo credit: aktyuvinsk34)

While I’ve written in the past about viruses that can cause cancer, today I want to introduce the concept of using viruses to selectively kill cancer cells. These types of viruses are called oncolytic viruses, meaning that they kill (-lytic) cancer cells (onco-) but not normal healthy cells.

This makes them potentially very powerful tools in treating cancers that don’t respond well to established approaches of chemotherapy, radiation, or surgery. This approach is still in its infancy, but the potential of viral oncology remains promising.

Keep reading to find out more about how scientists are learning to use these viruses to treat certain kinds of cancers. Continue reading Fighting Cancer with Viruses

The Concept of Viral Quasispecies

Many of us are familiar with the concept of a species at the macro (visible) scale. Dogs are dogs; pigs are pigs, and so on. Each is a distinct species based on the fact that they can only reproduce and generate fertile offspring with other members of the same species. Over the course of many generations mutations may arise in these populations which lead to different genotypes in the species. Left long enough, these two sub-populations may keep mutating to the point where they can no longer interbreed and become their own genetically distinct species. However, when you get down to the viral scale species becomes a much more difficult concept. Viruses don’t have sex in the traditional sense, so how do we determine what makes up a viral species?

Continue reading The Concept of Viral Quasispecies

Viral fossils in our genome: Endogenous retroviruses

The last twenty years have been marked by a veritable explosion in sequencing technology. The Human Genome Project and it’s completion in 2003 was the crowning jewel of this burgeoning genomics revolution . The amount of information to come from this relatively new branch of science is literally mind-boggling and only grows with each passing day.

Interesting observations have come out of this massive amount of genomic data relating to the  non-coding DNA in our genome. Less than 2% of the over 3 billion nucleotides in our genome are responsible for coding all of the protein that makes up a human being. This leaves a large question as to what exactly that other 98% of our genome is up to. Large parts (roughly 50%) are known as “junk DNA” with no accepted role, although new research is beginning to shed light on the functions of this DNA. The remainder of our genome is composed of long and short repeated sequences, transposons, retrotransposons and the topic of today’s article: endogenous retroviruses.

These elements are not human, they are fully viral in origin. This means that our genome is not just ours alone, we carry the DNA of many viruses that infected our ancestors in every cell in our own bodies.

Continue reading Viral fossils in our genome: Endogenous retroviruses

Mind-controlling fungus turns insects into zombies

Deep in forests around the world a strange fungus is lurking. It doesn’t grow on trees, or from the ground like so many other fungi that we are familiar with. Instead, this fungus infects an unfortunate insect, turning it into a mindless zombie and control of its body until the fungus matures, erupting from the dying insect.

Think this sounds like a plot line from the X-Files? It’s not.

For some unfortunate insects this actually happens; enter the Cordyceps fungus.

How can a microbe turn these normal insects into fungus-erupting zombies? Read on to find out more. Continue reading Mind-controlling fungus turns insects into zombies

How do viruses move outside the cell?

In line with the recent article “Are viruses alive?” I would like to further explore the general nature of viruses. One question that I was recently asked was “how does a virus move?”

Being that viruses are not technically alive in the sense that we know it they also cannot move in a self-directed manner. This is in stark comparison to some other microbes such as Schistosoma cercariae, a parasitic worm, which is capable of burrowing through intact human skin and gaining access to the vascular system within 5 minutes (1).

Thankfully viruses cannot do this, much to our benefit. Because of how they are constructed, viruses cannot mechanically move in a self-directed manner and are subject to movement solely based upon environmental interactions. Essentially, they are not only hijackers who take over cellular processes for their own good, but environmental hitchhikers as well. Continue reading How do viruses move outside the cell?

The Problem with Polio

Child receiving polio vaccine.Polio is a disease that has seemed to fade away in the United States since the introduction of the polio vaccine in 1955. However, this disease is alive and well outside of the US despite a strong push by international agencies such as the WHO to eradicate polio in the last few decades. In fact, in 1988 the WHO pledged to eradicate polio by 2000, but this dream has yet to reach reality.

Why is the eradication of polio less successful than the effort to eradicate Smallpox, a goal achieved in the 1970’s?

These difficulties come from the nature of polio itself and the special challenges that this virus poses to those who would halt its transmission. Continue reading The Problem with Polio