PBS: This chicken vaccine makes its virus more dangerous
Science Jul 27, 2015 3:01 PM EDT
The deadliest strains of viruses often take care of
themselves — they flare up and then die out.
This is because they are so good at destroying cells and
causing illness that they ultimately kill
their host before they have time to spread.
But a chicken virus that represents one of the deadliest
germs in history breaks from this conventional
wisdom, thanks to an inadvertent effect from a vaccine.
Chickens vaccinated against Marek’s disease
rarely get sick. But the vaccine does not prevent them from
spreading Marek’s to unvaccinated birds.
In fact, rather than stop fowl from spreading the virus, the
vaccine allows the disease to spread faster
and longer than it normally would, a new study finds.