USA prepares defences against smallpox attack

[Guest guest]

From Lancet's infectious disease journal ?date

Newsdesk

USA prepares defences against smallpox attack

A 20-year contract recently awarded to OraVax

(now Acambis Inc, Cambridge, MA, USA) for

large-scale production of smallpox vaccine for

the US Centers for Disease Control and

Prevention (CDC), highlights growing concern in

the USA about the threat of biological warfare

and terrorism. Smallpox, along with anthrax,

plague, and botulism, is in the US Army's

high-priority (A) category of organisms that can

be easily disseminated and require special

action for public-health preparedness. The new

smallpox vaccine will be used to create a

national stockpile to counter the threat of

bioterrorism.

Research on variola vaccine has been at a virtual

standstill since 1980, when natural smallpox

was eradicated, and only two research

institutions--CDC in the USA and the State Research

Centre of Virology and Biotechnology in

Novosibirsk, Russia--officially retain the virus. " A

troubling concern is that no vaccine is now being

manufactured " , says LeDuc (CDC,

Atlanta, GA), " so our objective has been to

establish sustained production " . The USA still has

15·4 million doses of smallpox vaccine left over

from the pre-eradication era, and according to

LeDuc and Jahrling (Army Medical Research

Institute of Infectious Diseases, Fort Detrick,

MD, USA), most lots of the vaccine are still

potent (Emerg Infect Dis 2001; 7: 155-57), but that is

unlikely to be enough for a national emergency.

(s Hopkins School of

Public Health, Baltimore, MD) suggests that " a

large stockpile of vaccine is very high priority,

because smallpox has a 30% fatality rate and a

capacity to spread, there is no vaccine

production capacity anywhere in the world, and we

now have a very susceptible population. The

release of smallpox could result in a catastrophe

of unprecedented proportions " .

Acambis is contracted to manufacture 40 million

doses of vaccine by mid-2005 and to maintain

stocks of vaccine at that level until 2020. The

Acambis vaccine, like the old smallpox vaccine,

will contain live vaccinia virus. " Modern

production methods will be used, including virus culture

in MRC-5, a human diploid lung cell line approved

for the manufacture of other live attenuated

vaccines " , says Tom Monath, medical director of

Acambis' US arm.

The construction of a variola genomic signature

database is part of a new, intensive research

effort at the CDC, where research into

nucleic-acid-based diagnostics and the development of

antiviral drugs is also in progress. " We need to

build up as much information as we can before

all remaining variola virus stocks are destroyed

at the end of 2002 " , explains LeDuc. " Another

major goal " , he adds, " is to define an animal

model that faithfully replicates human smallpox

virus " .

Meanwhile in Australia, scientists developing

immunocontra-ception for rodents discovered that

genetic modifications of the harmless mousepox

virus made it deadly, thus raising concerns

about possible genetic manipulation of smallpox

virus (J Virol 2001; 75: 1205-10).

Researchers at the Co-operative Research Centre

for the Biological Control of Pest Animals,

Canberra, used mousepox virus as a vector to

insert the interleukin 4 (IL4) gene, so that

animals mounted an immune response to their own

reproductive cells. But IL4 also

suppressed the animals' defence against viral

infection and partly blocked the effect of vaccines

that normally protect against mousepox. belle

Duncan (CSIRO, Canberra) says that

" research will sometimes throw up unexpected

results, some of which have the potential to be

misused " . Fortunately, " making a biological

weapon is much harder than many people

imagine " .

Dorothy Bonn

[Guest guest]

i wondered when USAMRIID and CDC would begin to produce the vacine again. i

wonder if the vaccine is effective against mutations?