Hijacked!

First, a big "thank you" to all of you who have joined in reading my blog! I appreciate all of your support and I sincerely hope you enjoy exploring science with me! With the recent outbreaks of Ebola in West Africa and the isolated cases in the United States and the rest of the western world dominating headlines, your fears over the emergence of this and other viruses have probably increased quite dramatically in the past few weeks! But how can a virus, considered nonliving in the world of biology, become so dangerous? As you may have guessed based on the title of this post, it all lies in the ability of the virus to hijack your cells. Deception, cunning, betrayal. A viral infection has all of the makings of a great spy movie!

As I was sipping my coffee this morning and scanning the headlines, I spotted a very interesting paper published in Science that described how Influenza A virus (IAV, which kills between 250,000 and a few million people very year) uses your own cells against you. To illustrate how this all works, here's a schematic created by the team at Science about how the virus gets into your cells:

Figure 1: Influenza A getting to work! Sneaky sneaky!

Let's start at the very beginning! The virus, shown in yellow, is engulfed by your cells via a process known as endocytosis. Once the virus is enveloped in an endosome (the bubble like structure that results from an object being ingested), the virus begins to increase the acidity within that environment. This increase in acidity results in a fusion of the virus with the endosome, which marks the beginning of Influenza's grand escape.

The goal that the virus is pursuing is to inject its payload into your cell's nucleus. This payload includes things such as viral enzymes and RNA, which the host cell (you) will use to produce viral DNA and viral proteins. This is very clever, as your cell will just assume that genetic material in the nucleus needs to be converted into proteins. At this point, the virus has won! But as you can see from the image above, the virus is enveloped in its own shell that must be broken in order to deliver these things into the nucleus.

To make that happen, Influenza A waves around a little protein called ubiquitin, which is actually a signal your cells used to determine what things need to be degraded. Once your cell sees this signal, it sends proteins to go after the virus in an attempt to degrade it, which was the focus of the paper mentioned at the beginning of this post.

Now here's when things start to get a little mysterious! In the same vein as your favorite murder mystery, there is a span of time in this process that we just can't seem to account for. Experimentally, the authors have shown that something happens in between the recruitment of degradation proteins and the breaking of the viral shell, but we aren't sure exactly what that is. But whatever mechanism that the virus is taking advantage of to break itself free, it will likely become a very promising drug target.

No breakage = no payload delivery = no infection. Virologists, start your engines! The search is on!

*Author's note* Ebola is also an encapsulated virus; thus, it must also break free of its shell to deliver its payload. To what extent it uses the above mechanism performed by its brethren remains to be seen!