and Men
the virus has in store By Laura Sanders
none seem to be particularly menacing. Another study in animals finds that
the virus didn’t jump at the chance to
mingle its genetic material with other
strains of influenzas, even when the
viruses infected the same cells at the
same time.
While the virus’s genome is missing
some of the worst danger signs of past
pandemics, it has picked up a few new
tricks that might be cause for concern.
And just because the virus hasn’t yet
morphed in a dangerous way doesn’t
mean it won’t. Now that the virus has
a huge new playground in the human
population, the possibility of its recombining with other influenzas can’t be
dismissed.
“Once we think we have this virus figured out, the virus shows us otherwise,”
says influenza expert Daniel Perez of the
University of Maryland in College Park.
Predicting exactly what will happen
is impossible. The virus may grow up
to replace the seasonal flu viruses, or it
may grow up to become an additional
burden to contend with each winter. It
may morph into a dangerous killer. Or
it may not change much at all, existing
only as a memory of the swine flu scare
of ’09 and ’ 10.
Around the globe
One of the reasons public health offi-
cials are keeping such a close eye on
this H1N1 strain is that some important
parts of its makeup are unrecognizable
to most people’s immune systems — pre-
sumably setting the stage for it to go rip-
ping and snorting through the global
population. But data from animal mod-
els and patient reports suggest that
this influenza’s movements, propelled
by sneezes, coughs and germy door-
knobs (see “The skinny on the bacon,”
Page 26), look more like those of sea-
sonal influenzas than disastrous pan-
demics of the past.
H1N1 Eurasian swine H1N1 avian virus
Tracing the virus shuffle
H1N1
classical
swine
PB2
PB1
PA
H
NP
N
M
NS
Each
virus’s
eight
genomic
segments
are shown
as parallel
lines.
Pandemic
H1N1 human
outbreak,
2009
H1,H3,N1,N2
triple-reassortant
swine
H3N2
seasonal
human
April 2009 1992
1997
19981979
The current pandemic H1N1 virus is a mix of genomic segments from the H1N1 Eurasian swine
;u and a swine ;u made up of segments from avian virus, swine virus and seasonal human ;u.
The chart above shows how each ;u virus’s eight genomic segments mixed and mingled to get
the virus causing the current pandemic.
