[FoRK] avian flu/home grown/PastFutureTense
Thu Oct 13 21:30:21 PDT 2005
As Stephen notes, there is a kind of immunity -- inherent
resistence to certain infections -- that is inherited.
Also, even acquired immunities could be inherited --
gestation and nursing provide many plausible mechanisms
by which a child's immune system could be fortified or
even trained by the experience of the mother's immune
For example, the best tests estimate that *most* people
are technically chimeras -- with cells of multiple
genotypes in their body. Occasionally, this is from a
(perhaps lost in the womb) twin; more often, we carry
around cells from our mothers for our whole lives.
(The exchange is mutual; fetuses also donate cells
to their mothers.)
And, since mom was most likely a chimera with our
grandmother, and so on, we each may have cells from
several matrilineal generations back.
See for example:
Cheating, or an Early Mingling of the Blood?
# Dr. Ann Reed, chairwoman of rheumatology research
# at the Mayo Clinic, who uses sensitive DNA tests to
# look for chimerism, finds that about 50 to 70 percent
# of healthy people are chimeras. The more scientists
# look for chimerism, the more they find it. It seemed
# not to exist in the past, she said, because no one
# was explicitly looking for small amounts of foreign
# cells in people's bodies.
# "Some believe that if you look hard enough you can
# find chimerism in anybody," said Dr. Reed, who
# has not been involved in the Hamilton case. It is so
# common that she thinks there must be a biological
# reason for it. It also may cause problems, she and
# others say.
Passing on acquired immunities would be a pretty
compelling "biological reason for it", so I wouldn't
be surprised if our matrilineal chimerism helps
boost our immune system, when it works, just as it
risks autoimmune diseases, when it doesn't.
And don't even get me started on retroviruses and
latent, weakened viruses from a mother's early life
that could be selectively wakened toprime a baby's
And still, any flus we've caught during our lives --
or been immunized against -- are distant cousins
of the H5N1 bird flu of today, and distant descendants
of the 1918 Spanish Flu. It didn't just sweep across
the world and disappear; it became part of the flu
milieu ever since.
So glib pronouncements that everyone born after 1918
would lack any effective immunity against the original
virus are uninformed on several counts.
It might even be the case that the 1918 virus would
be helpless against *us* -- given the last 87 years
of neverending virus-vs-immune-system warfare, we're
as far beyond its quaint tactics as a 2005 armed
Predator drone is beyond a WW1 biplane.
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