In article <cupton.1132587280H at ra.uvic.ca> cupton at sol.uvic.ca ( Chris Upton) writes:
>From: cupton at sol.uvic.ca ( Chris Upton)
>Subject: Polio vaccination
>Date: Sat, 15 Oct 94 05:40:40 GMT
>I just read in our local newsaper "health column" that polio booster shots
>were not being recommended since of the low prevalence of the disease in the
>Western Hemisphere!!!
> Comments please!
>What kind of protection exists 10 or 20 years after vaccination?
>If there's a reduced resistance in the population..... is there going to be
>a call for work with polio to be done under level 3/4 containment?
>Or maybe all stocks to be destroyed (as per smallpox)?????
>Hmm....
There are many difference between smallpox and
polio. The main point is that polio is a gut-tropic enterovirus, and hence is
passed out in faecal matter. The vaccine strains are live and infectious,
where the smallpox vaccine was not (infectious, that is. Nor was it smallpox
for that matter). It is thus very widespread and constantly circulating
throughout the community, especially in developing countries. The WHO
proposal to erradicate the disease is aimed not at ablating the virus from the
world, but ensuring that the only poliovirus circulating is derived from
vaccine, ie no wt virus is still present.
In addition, the poliovaccine strains are safe examples of a simple RNA virus,
as opposed to the incredible complexity and inherent danger of smallpox. Many
labs around the world are investigating poliovirus to learn the nature of
viral replication, transmission etc, because the poliovirus is so well studied
and understood. The use of vaccine strains in these studies means higher
levels of containment are not required. Note that even at present, any
recombinant work with polio that may involving changing the virus
neurovirulence is done at high containment levels. An example being the
chimaeric virus work being done at Reading, UK under prof JW Almond (where I
used to work).
Poliovirus isn't going to be irradicated, simply it is hoped that the
widespread vaccinations will remove the wt virus from the system. Note that
the health column was talking about booster shots, not the original
vaccination.
Hope these ramblings help.
Mike
------------------------------------------------------------------------------
Dr Mike Poidinger
Microbiology, UWA ==> Animal Welfare NOT Animal Rights
Australia ==> 668, the neighbour of the beast
mikep at uniwa.uwa.edu.au ==>Time flies like an arrow, fruit flies like a banana
-----------------------------------------------------------------------------
