2 May 2009 | NewScientist | 9

THERE are three approaches to an

infectious disease: you can survive it

(or not), kill off the bug responsible,

or best of all prevent it. If swine flu

goes pandemic, what should we do?

First, there’s treating it. The

Mexican swine flu resists older

antiviral drugs like rimantadine. It is

still susceptible to the Tamiflu and

Relenza in national stockpiles – such

as they are – but virologists were

shocked this past flu season when

ordinary human H1N1 spontaneously

developed near-total resistance to

Tamiflu . Swine H1N1 could well do

the same, particularly if it starts

swapping genes with the human virus.

Our best hope might lie in

monoclonal antibodies, which could

both prevent infection and help fight

it. These immune proteins can be

engineered to recognise a specific

virus, and then churned out in

production plants. Several research

groups have made monoclonal

antibodies to H5N1 bird flu from the

antibodies of survivors, and these

have protected mice against H5N1.

The same trick should work for swine

flu – and once developed, large

amounts could be produced in a

matter of weeks. Several companies

are already mass-producing flu

monoclonals for ordinary H5N1, and

could be switched to swine flu.

Then there are treatments that

help you survive flu symptoms rather

than attacking the virus directly. Flu

kills mainly by triggering a cytokine

storm – runaway inflammation in the

immune system. The steroids

normally used to reduce inflammation

don’t work, because they also

suppress the immune responses you

need to fight the virus. Last year,

researchers in Hong Kong reported

that combining Relenza with two

readily available non-steroidal anti-

inflammatory drugs called COX-2

inhibitors helped save mice from

H5N1. This year, US researchers had

similar success with an experimental

anti-inflammatory drug.

Ultimately though, no one wants

to catch a potentially lethal virus and

it’s pretty hard to hide from pandemic

flu. That leaves vaccines. Right now

these are made from killed or

weakened flu viruses. But growing

them takes time: New Scientist has

seen part of a confidential report for

the International Federation of

Pharmaceutical Manufacturers and

Associations which says that in the

next four months we can make a

billion doses of pandemic vaccine at

best, but more probably 340 million

doses. This is not nearly enough for

the world’s people. Very few

countries have vaccine production

plants, and people in those that don’t

could get little vaccine or none (see

editorial comment, page 3).

Other kinds of vaccine could be

cooked up much faster in more

countries. DNA vaccines are loops of

DNA coding for the surface genes of

the flu virus. Once injected into the

skin, these are taken up by immune

cells and turned into proteins. In the

process, the immune cells learn how

to recognise and fight the viruses

that usually express those proteins –

and even slightly different ones that

might emerge as a pandemic evolves.

Peter Dunnill of University College

London calculated in 2006 that the

entire world could be vaccinated with

a mere 150 kilograms of DNA vaccine ,

and called for a global task force to

scale up production. It didn’t happen.

Meanwhile, several groups are

looking for a universal vaccine

that will work against all flu, once

and for all. Several proteins common

to all flu viruses show promise in

animal and early human trials, and

more were recently found that

might prompt strong immune

responses. Protein vaccines could be

made in existing factories in the

quantities needed. Under normal

circumstances that wouldn’t happen

without years of testing – but

circumstances may no longer be

normal. Debora MacKenzie ■

“Several proteins common to all flu viruses show promise in animal and early human vaccine trials”

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How you can survive a potential killer

–One way to fight flu–

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