Can a clever microbiology person answer a question about human swine flu please? :D

tallaght01

Just wondering......this virus is H1N1.

I always thought the important thing about influenza was it's haemgluttinin and neuraminidase.

I thought these were the important thing in establishing virulence, and immunological naivety.

So, what makes this virus different than the H1N1 that's just doing the rounds as seasonal flu?

flerb22

only 1 cleavage point on the neuraminadase means that it is less virulent than say that h5n1 birdflu which had multiple cleavage points
the neuraminidase is the surface antigen that allows the virus to leave a human cell, the haemagglutinin is for the entering of the human cell.
generally, to be highly virulent, a flu virus needs to have multiple cleavage points in its neuraminidase

the restructuring of these H and N particles is, as you say, allowing immunological naivety, (caused by genomic shift and drift etc), however, this isnt just a seasonal flu, as it isnt a mutated human pathogen, its a new entity entirely for our immune systems, again the same way bird flu was/is a few years back. this virus has more in common with the spanish influenza than the normal seasonal flu, and theres very few people about now who would have a passive immunity to it.

however, it isnt just the surface antigens - this swine flu seems to be an upper respiratory virus rather than a lower respiratory - its causing a bronchitis rather than an interstitial pneumonia. probs to do with its genomic material, which i dont really know anything about.

MrCreosote

Nice answer thanks

MrCreosote

And mind that apostrophe in "its" Tallagh01

tallaght01

MrCreosote wrote: »

And mind that apostrophe in "its" Tallagh01

Another schoolboy error.....made worse by the fact that I got busted for it in a uni essay this week too.

But if we're talking about say Nigel, for example, and his tractor (to keep things culturally relevant ), we says Nigel's tractor. So when we talk about the possessive of "it", why is there no apostrophe???

Anyway, thanks for the answer.

With regard the issue at hand....I'm sorry flerb22, I'm a bit slow. I still don't understand what exactly id different between the H1 of seasonal and swine flu. I know how heamagluttinin works, but I don't know what the molecular difference is.

ZorbaTehZ

'Its' is a possessive pronoun by itself, whereas 'it's' is the contraction of it is/it has - the test of whether you use 'its' is whether you can replace it in a sentence with his/her.

flerb22

ok i understand the question i think - think of it this way: there is a normal seasonal H1N1 (or whatever), and then there is swine flu H1N1. normal seasonal flu we have had exposure to, whereas swine flu we havent. the Hs and Ns in swine flu perform the same tasks as the Hs and Ns of seasonal flu, but are completely new to the human immune system, as they have come from the pig reservoir and not the normal human to human transmission (at least to begin with). they are completely new rather than rehashed old antigens.

tallaght01

If the H is completely new, then why is it called h1?

sam34

pfft, i'm only a psychiatrist, so none of this fancy high-falutin microbiology talk for me.

come back to me when the swine flu is causing people to hallucinate :pac:

PurplePrincess

flerb22 wrote: »

only 1 cleavage point on the neuraminadase means that it is less virulent than say that h5n1 birdflu which had multiple cleavage points
the neuraminidase is the surface antigen that allows the virus to leave a human cell, the haemagglutinin is for the entering of the human cell.
generally, to be highly virulent, a flu virus needs to have multiple cleavage points in its neuraminidase.

I'm just amazed Tallaght got past the word "cleavage"

Phototoxin

So, what makes this virus different than the H1N1 that's just doing the rounds as seasonal flu?

what about the media. One paper said that nothing short of a nuclear bomb would stop it. I CAN HAZ VAXINE NOWZ?

tallaght01

IN case anyone's interested, I spoke to one of our local virology experts about this.

He couldn't tell me for sure! But he said that, looking at the sequencing, it looks like a reassortment.

So, all the bits of the H1 are relatively well preserved, though not completely so. But there's not enough change to make it into a new haemagglutinin.

However, the structure is altered enough, so that it's not similar enough to seasonal H1 to allow immunological cross-reactivity.

Does that make sense to anyone? It did to me.

It's not 100% set in stone, but that was his take on it.