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

Researchers from the USA discussed the crucial importance and problems of
plant-derived mucosal vaccines to prevent transmission of sexually
transmitted diseases as HIV, Hepatitis B, Herpes Simplex and others,
November 2005 b Silke Luetzelschab, Checkbiotech.

In a recent publication in the journal Vaccine, a team of researchers
wrote, "With the annual incidence of sexually transmitted infections (STIs)
at epidemic levels worldwide, there is clear need for more effective methods
of preventing transmission of prevalent pathogens". Translated into numbers,
sexually transmitted and reproductive diseases account for about one-third
of diseases among women of reproductive age and about one-fifth among the
entire population.

Due to these staggering statistics, there is a lot of ongoing research to
develop vaccines against STIs. Most vaccines work by controlling or
eliminating the infection, whereas mucosal vaccines prevent the transmission
of the disease at the mucosal surface. Gel-like mucosal vaccines against HIV
are already being applied in clinical trials in several African countries.
So far all vaccines on the market are derived by the conventional method.
But the idea of vaccine production in transgenic plants is gaining more and
more interest. The advantages compared to conventional methods are increased
efficiency, lower price and a more environmentally conscious method of
production.

That is why the work of Dr. Kevin J. Whaley and his team from Mapp
Biopharmaceutical Inc. in San Diego, USA is so important. Mapp
Biopharmaceuticals Inc. is collaborating with the Biodesign Institute at
Arizona State University, USA and the University of Maryland at Baltimore
Vaccine Center on the development of plant-derived microbicides and mucosal
vaccines to four crucial STIs: HIV, Hepatitis B Virus, Herpes Simplex Virus
and Human Papilloma Virus.

Looking at the high prices of vaccines in sexual and reproductive health,
Dr. Whaley and his team have a justifiable concern about their availability
to the general public, especially in developing countries. The researchers
envision lower costs for plant derived vaccines, although Dr. Whaley told
Checkbiotech that this cannot be confirmed until a plant-derived product is
on the market.

Mucosal delivery of a vaccine means that there is no need for disposal of
syringes and needles, which is often a burden in the delivery of vaccines,
especially in developing countries. Dr. Whaley sees as suitable dosing forms
tampons, tablets or combined application with microbicides.

Dr. Whaley and his team described in their report that it has been difficult
to achieve high concentration of antibodies upon internal application of a
plant-derived vaccine. "So this still remains a challenge," he told
Checkbiotech. If this impediment could be overcome, vaccines derived by
molecular farming would also offer the additional advantage of multi-agent
products, preventing transmission of several STIs at once.

In Dr. Whaley's opinion, another important point is the significantly higher
specificity of biopharmaceuticals, compared to conventional vaccines or
microbicides. "This may enhance safety and efficacy," he concludes.

"In contrast to concerns of the general public, manufacturing of
plant-derived microbicides and mucosal vaccines can take place in enclosed
facilities," Dr. Whaley further explained. But to reach the point of
manufacturing a lot remains to be worked out: manufacturing procedures
according to cGMP (Good Manufacturing Practice) need to be elaborated,
clinical trials have to be planned and carried out according to GCP (Good
Clinical Practice) and finally the regulatory authorities have to give their
stamp of approval.

There is still a long way to go until plant-derived mucosal vaccines or
microbicides may be available. Mapp Biopharmaceutical Inc. has been
contributing, with past and present collaborators, and is hoping to do so in
future as well.

www.checkbiotech.org

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