Chicken vaccines combine to produce deadly virus

[saintlyjimjams]

Sorry about the title, but it actually didn't seem to be too daft given the report news.sciencemag.org/sciencenow/2012/07/chicken-vaccines-combine-to-prod.html

Here's the New Scientist report

www.newscientist.com/article/dn22058-vaccines-team-up-to-generate-lethal-new-chicken-virus.html

Now this is an interesting quote from the New Scientist. Something I have been musing on for quite a while (and was arguing about on an annoying thread yesterday).

This work shows that with live vaccines, we need to pay attention to the evolution of the vaccine strains themselves," says Andrew Read at the University of Pittsburgh in University Park, an expert in pathogen evolution who was not involved in the research. In fact, he says, "we should pay a lot more attention to the consequences of vaccination for pathogen evolution in general.

Thanks saintly, I could open the first link but I read the New Scientist. Who'da thunk it. I believe this has been posited before as a possibility (not least I have lurked on threads where posters have suggested similar effects!) and this is interesting.

The new scientist report is probably better anyway. I saw thecheadlines earlier & thought they were going to be an exaggeration but it seems not.

They were vaccinating chickens with three different live viral vaccines against the same virus. How is that relevant to human vaccination?

It's not difficult to see the possible concerns - whether humans are being vaccinated in the same way or not. You must be very very dead set against the idea of there ever being anything wrong with vaccines ever ever ever if you don't want to see that.

I'm sorry I can't see where I said it was directly relevant to human vaccination (well the vaccination schedule right now). Although the new scientist article mentions the possibility of vaccine viruses hybridising with wild type viruses which I would have thought was interesting to those who post in this section who are only interested human vaccination. Although tbh I didn't realise we were only allowed to discuss human vaccination here.

And Andrew Read makes an important point I think. Relates well to the questions I was raising the other day about the selection pressures introduced by mass vaccination - which is relevant fo himan vaccination. I find it interesting.

Aha Andrew Reid looks like my man. His research looks fascinating.

ento.psu.edu/directory/afr3

And interesting as a lot of my questions about selection pressure and the potential effects have come from my particular education in evolutionary biology. And is seems we shared that - only a couple of years apart.

My first thought is -- well he has his work cut out!

His papers are interesting - about resistance in various systems. A very interesting article about aP vaccination and how it affects populations of another whooping cough causing agent.

Public health officials should talk to evolutionary biologists more. The mess we find ourselves with antibiotics was entirely avoidable - and evolutionary biologist warned of he consequences of misuse years ago. The most useful medical finding ever (IMHO) ruined by sheer stupidity.

Vaccination is definitely a powerful intervention (and is described as such in the paper). How much more powerful if mass vaccination programmes considered the broader implications and adjusted policies accordingly. The focus on 'we must destroy pathogen x' in isolation has - IMO - the potential to do damage.

Yes - I'm not as well up on this as you, that is an understatement. However do you remember the introduction of Men C vaccine. We didn't have it and I predicted (in complete ignorance of how this might happen I must say) that while Men C might go down, within a year or two there'd be a comparable increase in Men B or others. This happened. I didn't and don't understand the mechanism tbh but even a layman can see the dangers.

Yes I keep meaning to read up on what actually happened there. If anyone has papers they can link to that would be appreciated.

Viruses do have a tendency to recombine, as does any organism with a rapid rate of reproduction like bacteria etc.

Live vaccines are always risky for this reason, there are many cases of live attenuated vaccines recombining with the wild type and causing disease instead of preventing it. There is a theory that the variant of bluetongue virus circulating in Italy is not actually from midges, but from their use of an African strain live attenuated vaccine which caused disease in the 'wimpier' European breeds.

I'm not sure that public health officials need to talk to evolutionary biologists more, unless these public health officials are vets or scientists. But the researchers developing new vaccines, particularly those working for private firms where profit is the bottom line, do need to keep their eye on the ball and keep recombination in mind when developing new vaccines.

Live attenuated are never the first port of call for vaccines, for precisely this reason. Vaccines using a part of the virus shell, other virus proteins or, the hot topic of the moment, viral DNA, are more popular because it's just a tiny part of the virus and less likely to result in any direct effect on the wild type strain. But nature is a fickle beast, and anything that can happen probably will. Researchers never know what effect adding anything to any biological system will have. That's why very stringent controls are in place before anything is allowed out of the lab and anywhere near the real world

Well the public health officials currently working on treatments for malaria might do well to pay attention to the lab's work on malaria. The pdf's are on the whole available on the lab web page for anyone interested.

Yes, public health officials do need to take their advice from research labs, not just blunder on regardless with what worked 10 years ago. Presumably public health offices employ scientists for just this reason. If they don't, they're being very disingenuous.

And it's not just recombination - it's this sort of thing as well:

www.cidd.psu.edu/research/synopses/acellular-vaccine-enhancement-b.-parapertussis

I saw on another thread someone saying the risky age for hib was 2 and under. But will that still be true with mass vaccination against hib? Will hib continue but just in an older age group? Will that be 'better' or 'worse'? Especially considering immunity appears to wear off faster than expected (and pre-vaccination days most people had developed immunity by 5 iirc - although haven't re-checked that).

Those are the sorts of question I find interesting and I'm not convinced are given enough thought currently when deciding vaccination policies.

Back to chickens

This quote: Recombination can occur naturally when two viruses infect the same cell at the same time. While recombination was recognised as a potential risk associated with live virus vaccines, the likelihood of it happening in the field was thought to be insignificant.

from this source
www.apvma.gov.au/news_media/media_releases/2012/mr2012-04.php

Isn't all that reassuring. Why was the risk thought to be insignificant? Because it wasn't thought two would be given at once (and if so why was that allowed to happen), or was it thought to be a tiny tiny risk anyway? If so does that now need to be reconsidered?

Sorry re: meningitis. I didn't look at papers at that stage, I followed the statistics on what was the the PHLS website. Interestingly within about two years the figures were changed to a form which made it very difficult to find year-year comparisons. They seemed to calculate them by continuing years (number of cases in the previous 12 months?) rather than year by year. However there are still graphs available showing the rise of Men B compared to the drop in Men C, Men B being, of course more dangerous. I doubt I'd be able to find papers but probably would link to some of the graphs I've looked at

Found some figures. It looks as if initially there was a rise and the a drop (in b). Is meningococcal meningitis cyclical? (I know it's seasonal).

There's more out there on hib

Eg

www.ncbi.nlm.nih.gov/pubmed/12508153?dopt=Abstract