Say like driving home last night listening to a report about how the vaccine for the new H1N1 (aka swine flu) may be late because the virus grows slowly in egg medium. Now, I added this to my previous knowledge that all human influenza vaccines are grown in chicken eggs (which kills the embryo, but you won't hear about that in the Pro-Life literature). Why? Because it works and it's dirt cheap (Cheep, get it?). Anyway, there's also the previous knowledge about how it's the protein shell of the virus that allows infection, and those protein shells are coded to species that the virus can infect.
With me so far?
Okay, so, this is why you can't (normally) give your dog a cold by sneezing on them. Or, and this is more important here, you can't give it to your cockatoo. Because the protein shell won't be accepted by the other species. And especially by the other species in the different
Now, there are protein shells which are accepted by several species. Flu that pigs can process are notoriously easy for humans to process. This is what swine flu is, after all; a influenza virus that can infect both pigs and humans. This is also why the avian flu (remember avian flu?) is so damn hard to humans to catch. Sure, it can happen. The flu can overwhelm the host, but you need a whole buncha the virus in your system to start it (any virus can enter your system, but if you can't process it, you'll "shed" it out). And then it's very difficult for that infected individual to spread that infection to others of the same species (ie. humans, sapiens-sapiens). The virus just can't break on through to the other side.
Now, this is why when there is a virus that can jump species, it's especially virulent. It's like having a skeleton/pass key, it can get you almost anywhere with great ease. And, if it crosses
Eventually the population will develop resistance (immunological response and natural selection) to the "bug" and it'll no longer be a big deal. Also, the virus will evolve (natural selection) to cause fewer quick deaths. Or the virus will die out by killing its host to quickly (again, natural selection, it's a bitcher, ain't it).
So how do viruses cross species and
Okay, got all that so far.
Now, here's the fun part. Remember when I said that human vaccines are grown in chicken eggs? And remember the part about protein shells? And remember the cross
See the problem? Okay, if you don't let me be a little more blunt. By choosing a method of vaccine reproduction (which is normally deactivated flu) which relies on the virus keying into an avian medium (the egg), and also meant to infect humans (how we gain our immunization response for the vaccine) we are artificially bridging the gap and have created a new reservoir species (the egg medium). And we're doing it because of cost (which, yes, are very high to switch to tissue culture reproduction).
Ladies and gentlemen, your next deadly pandemic. Brought to you by cheap manufacturing and a host of immunologists who will slump back in their chairs after viewing the California stains (DNA/RNA examination technique), scratch their collective heads, and think, "Huhn, how did we not see that coming?"
(to be fair our immunization vaccine flu would have to infect an animal, like a pig, swap out the inactive virus part with an active avian flu, keep the cross
And that's your story bone.