Sending a virus in an envelope

Some viruses are enclosed inside a lipid bilayer annexed from the infected cell. Protruding from these envelopes are glycoprotein "spikes" which are important in anchoring and fusing the virus particle to the target cell. In my lab we are very interested in these ENVELOPED viruses including HIV, Flu and Ebola.

If you are unfortunate to have a virus such as HIV, you will have gazillions of these virus particles floating around your body. Have a look at the little bugger. This one was drawn by my MEng student Penny Miles (who is now working at Ely Lilly).

                The HIV virion

At first sight you can see a beautiful symmetry, in fact you could say this is almost a perfect self-assembled structure. I use the term self-assembled lightly as obviously the particle is assembled with the help of the host cell machinery. The spikes attach the virus particle, or virion, to the immune cell surface. This then fuses and infects the target cell with its cargo, the viral RNA. Now here is the clever bit. The virus particle also contains an enzyme that turns the RNA into DNA, so that this DNA can then be incorporated into the host genome, hijacking the cellular machinery to produce tonnes more virus particles.

It turns out that this conversion from RNA to DNA is highly prone to error, which means the virus particle often mutates, rendering some treatments useless. In my lab we are interested in how the virus attaches, fuses and infects at the molecular level. If we understand this perhaps more generic drugs could be developed targeting these processes and being less susceptible to viral mutation.

Viral mutation is a real pain. Take the new flu jab. It is only 3% effective largely because of mutated viral strains. This demonstrates how fast viruses can mutate. Our next system will be Ebola. One hypothesis regarding why Ebola is so deadly is that the glycoprotein spikes "shed" when the cell is churning them out. These spikes then cause an immune response severe enough to cause organ shutdown and probable death.

HIV, Ebola...deadly but fascinating!