Influenza: what’s in a name?

H1N1, H3N2, H1N7; we hear their names daily, but have you ever wondered what they mean? Why do we refer to the different strains of influenza by a ‘H’ and ‘N’ followed by a series of seemingly random numbers?

In order to replicate (reproduction is the ultimate ‘aim’ of all organisms!), viruses must first enter a host’s cell. In order to achieve this the virus must first interact with molecules on the host’s surface. These molecules must fit together like a lock and a key. If either one is the wrong shape, the virus won’t be able to enter the cell. As I described in ‘MERS CoV – will the Time-Bomb Explode?‘, this is especially important when looking at viruses which evolve to infect new species.

The letter ‘H’ stands for haemagglutinin, the ‘key’ on the virus. It binds to the ‘lock’ on the host cell, a molecule called sialic acid, and then enters. Interestingly, sialic acid is only found on animal lung cells, which is why we must inhale the virus to become infected!

The letter ‘N’ stands for neuraminidase. This is the ‘key’ which lets the virus back out of the cell. The virus needs to exit again so that it can go on to infect the next cell!

The haemagglutinin and neuraminidase proteins can vary, and each strain of virus will have one type of each. The number of each has been allocated purely based on the order in which it was discovered, so H1N1 has the first haemagglutinin and first neuraminidase proteins to be discovered.

That’s all very well, but why name a virus after these two proteins? The reason is that these proteins are the proteins that can most easily be ‘seen’ by the host’s immune system. Antibodies are made against these proteins, and this is what allows for the creation of immunity. That’s why being infected with H2N7 won’t protect you against H3N2 infection, and why scientists have to make informed guesses as to which strains should be vaccinated against in any one year.

Is the Ebola epidemic really coming to an end?

A thought-provoking post on Ebola from what seems to me an interesting virology blog. Check out the comments section too where we’ve begun to discuss the future evolution of the virus. Please feel free to join in!

viirulentscience

The initial announcement of the latest outbreak of Ebola was on 25 March, in Guinea – part of West Africa, where the virus has never been known in the population, meaning that they would have been totally unprepared for such an epidemic to occur. As of 14 April, a total of 202 clinical cases of Ebola virus disease (EVD) – which includes confirmed and suspected cases – have been reported in Guinea, Liberia, Mali and Sierra Leone, including 128 deaths. Researchers have also determined that it is genetically similar to Ebola Zaire, but it is a brand new strain. This is significant because it shows that this Ebola epidemic has arisen separately from the previous epidemics in Central Africa. The Ministry of Health of Guinea has announced that with the decrease in the number of new cases, this latest epidemic of EBV is coming to an end; however, the…

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Catching the bug

Infectious diseases are by no means glamorous subjects of conversation; most people avoid the topic like the plague (I’m sorry, I can be partial to the odd pun), and yet infectious disease is quite possibly the most fascinating area of all life sciences. The aim of this blog is to convince anyone who will listen that this is indeed the case.

This is where I hit my first hurdle – ‘anyone’ is a rather large potential audience, and it’s clearly impossible to write a post to suit everyone’s level of understanding at once. However, I’ll do my best to write a variety of posts so that everyone from the biologically uninitiated (my dad will be a good proof-reader for these!) to the most intense of professors will be able to find something that they enjoy.

I also intend to cover a range of subjects, from focussing on an individual pathogen of interest to discussing current disease outbreaks. If you have any topics that you’d like covered, let me know. Equally, if you have any questions along the way, get in touch – I can’t guarantee to be able to answer them all, but being a PhD student at one of the best univeristies in the world, it’s safe to say that I can find someone who can!

 

Spreading interest in infectious disease.