www.checkbiotech.org ; www.raupp.info ; www.czu.cz

The Plague, both in its bubonic and pneumonic forms, has played a great part
in human history, May 2006.

Its causative agent is a bacterium called Yersinia pestis, and although it
has largely been eradicated from most of the world, it is still endemic in
certain places in Africa, Asia, the Americas, and the former Soviet Union,
especially where people live in close proximity to rodents. Y. pestis is
most fatal when inhaled, as bacteria can invade the lungs and cause death.

Antibiotics for plague are available but are effective only if the disease
is diagnosed early. Some Y. pestis strains are also resistant to
antibiotics, prompting scientists to search for ways to mass produce more
varieties of the plague vaccine. Luca Santi and Hugh S. Mason, in
particular, explore a ?Protective Plague Vaccine Produced in Tobacco Leaves?
in an article that appears in a recent issue of the newsletter of the
Information Systems for Biotechnology. Transgenic plants present a
convenient alternative vaccine-producing system, as they can express a large
variety of proteins, as well as perform the modifications necessary for
proteins to function. Plant systems are also less likely to harbor microbes
that are pathogenic to animals. They can also be easily scaled up to produce
large amounts of vaccine.

The researchers report a recent study that analyzed the expression in plants
of two proteins from Y. pestis: the F1 antigen, which form part of a
protective capsule that surrounds Y. pestis cells; the V antigen, which is
involved in the bacterium's pathogenic process; and a fusion of both F1 and
V. The genes for these antigens were delivered to tobacco plant cells by
Agrobacterium tumefaciens transformation. The proteins produced were then
analyzed for antigenicity, and subsequently tested as vaccines on guinea
pigs.

Researchers found that: 1) all three antigens were expressed in high levels
in transgenic tobacco leaves; 2) all proteins elicited an immune response in
the guinea pigs; and 3) after animals were challenged with an aerosol dose
of Y. pestis considered 100% lethal to unvaccinated controls, sham-immunized
animals were dead within six days, while all antigen-vaccinated groups
showed significant rates of survival at 21 days post-exposure.

Read the complete article at:
[www.isb.vt.edu]

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