Of Swine
Scientists study H1N1’s past to predict what
As viruses go, H1N1 is a genetic pip-squeak. Like its influenza brethren, it possesses only eight genes. Yetthosefewgenes are telling researchers
a complex story about where this newly
infamous virus came from, and, more
importantly, where it might go.
That story began about a decade ago,
when an infectious virus was busily packing pieces of its genetic material together,
preparing to burst out of a throat cell and
infect other cells in its host pig. This virus
was already the result of a genetic shuffle
involving a human influenza, an avian
influenza and a swine influenza, genetic
sleuthing reveals. At the same time, a different virus — itself a mixture of a swine
influenza and an avian influenza — was
packaging its genetic material in the same
cell in the pig’s throat.
In an exodus-induced kerfuffle, a wayward piece of viral genome was mistakenly put into the wrong package, creating
a virus never before seen. Sometime in
the past decade, researchers estimate,
the pig harboring this new mix-and-match virus passed it to a human, who
launched its spread to thousands of people around the globe.
“The confusion at the beginning
was that some of the virus’s segments
were coming from birds, some were
coming from pigs, some were human,”
says molecular epidemiologist Hossein
Khiabanian of Columbia University.
“What is this? This is a monster.”
This dizzying tale of genetic min-
gling ultimately resulted in the H1N1
influenza strain currently
circling the planet. This
virus takes its name from
its particular versions of
two proteins, hemagglutinin and neuraminidase.
Although this combination
of H and N has appeared
before in seasonal influenzas and most memorably in
the pandemic flu of 1918,
the virus circulating now
has qualities that make it
distinct enough to demand attention.
Such a history might suggest that
today’s H1N1 — declared by the World
Health Organization on June 11, 2009,
to have caused a pandemic — is ready to
go hog wild, morphing into new forms
that can easily thwart human immune
systems and foil drugs. But new evi-
dence, furiously collected during the
virus’s year or so on the world stage,
hints at a different picture. Instead of a
deranged homicidal killer on the ram-
page, this virus appears to be a more
restrained villain.
Instead of
a deranged
homicidal
killer on the
rampage, this
virus appears
to be a more
restrained
villain.
