By Cyrill Götz, Checkbiotech
HIV is a growing problem globally which continues to cause a
significant amount of deaths. This has motivated thousands of researchers to
battle against this virus. Now, one armed with a tomato has begun to turn
some heads.
Developing an effective HIV drug or vaccine is not the only challenge
that researchers face. Once a drug or vaccine exists other barriers often
stand in the way of delivering the needed medication to developing
countries, such as: insufficient infrastructures, logistical problems and
the lack of adequate medical care.

Dr. Ramirez of the Department of Plant Genetic Engineering
(Departamento de Ingenieria Genetica de Plantas) in Irapuato, Mexico, and
his team may have found a way to vaccinate people and solve at the same time
the problems that developing countries face. They created a vaccine which
can be easily taken orally by eating a genetically modified tomato.

Dr. Ramirez and his team enhanced the genome of a tomato in a way that
allows the fruit to act as a vaccine. The tomato is able to function as a
vaccine, because it was given the ability to synthesize an HIV protein
called Tat.

Tests showed that after giving the tomatoes the Tat gene, they
produced on average about 1 microgram of Tat in 1 milligram fruit extract -
a concentration high enough to stimulate the immune system. This stimulation
would be high enough to protect an organism if it came into contact with the
virus at a later point - this is the principle of vaccination.

One possibility to create an effective vaccine is to attack sensitive
components of HIV replication. The Tat protein is such a target. It is
responsible for processes which are important for viral reproduction and
also help HIV spread into neighboring uninfected cells. Thus, neutralizing
the Tat protein is an important step in getting HIV disease under control.

Tomato Test

An important fact about HIV is that the mucosal structures in the
human body are one of the first tissues which are infected. Therefore it is
important to generate immunity in areas such as the reproductive and the
digestive system.

So the next step was to test the tomato in mice. After feeding mice
the enhanced tomato, Dr. Ramirez and his team noticed that it worked. The
mice produced a remarkable number of antibodies, which is an important part
of an immune response in preventing the virus from entering a cell.

More importantly, however, Dr. Ramirez`s group discovered that the
immunization led to enhanced protection in mucosal linings as well as
overall general immunity after mice were fed extracts from the genetically
modified tomato. Dr. Ramirez`s group determined that the oral immunization
was nearly as good as the immunization observed when mice were injected with
tomato extracts.

The results of this approach to find a new vaccine against HIV show
that plant are steadily playing a more important role in producing
inexpensive and effective vaccines.

Cyrill Götz is a Science Writer for Checkbiotech in Basel,
Switzerland, and is currently studying biology at the University of Basel.


www.checkbiotech.org