Science News - February 27, 2010

seasonal influenzas and the H1N1 strain and found no signs of new viruses, the team reported online August 25, 2009, in the non–peer-reviewed journal PLoS Currents: Influenza.

The results don’t mean that those viruses aren’t exchanging genes, Perez says, as low levels of reassortment could go undetected. Perez and his colleagues are currently testing more and different versions of the virus for their propensity to mix. Scientists don’t yet understand why only some viruses reassort and under what conditions they do so.

So far, sequences of virus from
infected people don’t show signs of reas-
sortment, either, Perez says. “Epide-
miological data suggests that there are
not reassortments happening, at least
not this season,” he says. “That doesn’t
mean that next season, things might not
change a little bit. It’s a question that’s
always an open question. We don’t have
an answer for that.”
Researchers have, however, already
pinpointed genetic changes, mutations
acquired during the virus’s replication,
that enhance its ability to make copies
of itself in human cells.

The skinny on the bacon

The current pandemic, known to many around the world as swine ;u,
suffered an image problem in its early days. Misinformation led to mass
slaughters of pigs in misguided attempts to halt the virus’s spread. The
H1N1 virus can’t be transmitted by eating pork: The virus infects the respi-
ratory tract of pigs, not the edible muscle or fat, and cooking deactivates the
virus anyway. So the risk from eating infected pork is nil, unless pig throat
sushi is on the menu, says Peter Palese, an in;uenza expert at Mount Sinai
Medical Center in New York City.

Instead, the current H1N1 in;uenza travels in the same way as most seasonal ;us—through the air and on virus-laden surfaces. Flu viruses hitch rides on droplets expelled from sneezes and coughs, ;oat through the air and then infect a person when inhaled. Dry wintry conditions lead to smaller droplets, which can persist in the air for hours, Palese says.

Flu viruses can also move from person to person through contact, such as handshaking or doorknob turning. The good news is that most in;uenzas, including this one, are relatively fragile outside of a host. H1N1 doesn’t survive long on surfaces outside of the body and can be easily destroyed with disinfectants.

Precautions such as frequent hand washing can slow the virus’s spread, but Palese says avoiding every tiny particle of in;uenza is often impossible.

“The best way to prevent in;uenza, whatever way it’s being transmitted, is
vaccines,” Palese says. “That’s the bottom line.”
To ;nd an H1N1 vaccine, go to www.; u.gov. — Laura Sanders

H1N1 virus can’t be transmitted by eating pork: The virus infects the respi-
ratory tract of pigs, not the edible muscle or fat, and cooking deactivates the

l -
i

Although researchers’ best guesses are improving as detailed molecular and genetic data and doctors’ reports pour in, divining the virus’s future is impossible.

Molecular epidemiologist Martha Nelson of the National Institutes of Health in Bethesda, Md., and her colleagues compared the genetic sequences of H1N1 from around the world to see if the virus had taken on other genetic changes as it copied itself. The team’s analysis, published online November 5 in PLoS Currents: Influenza, finds that the virus shows slight regional differences. On the basis of these differences, Nelson and colleagues divided it into seven distinct clades. None of the differences among clades seem to be ominous, though, Nelson says. “In the grand scheme of things, these clades are still very closely related,” she says. Likewise, scientists at the World Health Organization report that all of the sequenced H1N1 clades are very similar to the original strain, rendering the H1N1 vaccine — designed to combat the original sequence of the virus—accurate and effective.

As the pandemic virus spreads to more
people around the world, the diversity
among clades may disappear as they
mingle with each other, Nelson adds.
“We’ll have to wait for the next round of
data to see if it’s more mixed.”
Although researchers’ best guesses
are improving as detailed molecular and
genetic data and doctors’ reports pour in,
divining the virus’s future is impossible.

“This is a new virus,” Palese says, but it is still subject to the same rules and regulations as other influenzas. “Never predict anything,” he says, “but I would argue that it will change like the other seasonal influenzas have in the past.” s