Paratransgenesis

Paratransgenesis is a technique that attempts to eliminate a pathogen from vector populations through transgenesis of a symbiont of the vector. The goal of this technique is to control vector-borne diseases. The first step is to identify proteins that prevent the vector species from transmitting the pathogen. The genes coding for these proteins are then introduced into the symbiont, so that they can be expressed in the vector. The final step in the strategy is to introduce these transgenic symbionts into vector populations in the wild.

The first example of this technique used "Rhodnius prolixus" which is associated with the symbiont "Rhodococcus rhodnii". "Rhodnius prolixus" is an important insect vector of Chagas's disease that is caused by "Trypanosoma cruzi". The strategy was to engineer "R. rhodnii" to express proteins such as Cecropin A that are toxic to "Trypanosoma cruzi" or that block the transmission of "Trypanosoma cruzi". [Durvasula, R.V., Gumbs, A., Panackal, A., Kruglov, O., Aksoy, S., Merrifield, R.B., Richards, F.F., and Beard, C.B. (1997). Prevention of insect-borne disease: an approach using transgenic symbiotic bacteria. Proc. Natl. Acad. Sci. U. S. A. "94", 3274-3278.]

In order to perform paratransgenesis, there are several requirements:

*The Symbiotic bacteria can be grown "in vitro" easily.
*They can be genetically modified, such as through transformation with a plasmid containing the desired gene.
*The engineered symbiont is stable and safe.
*The association between vector and symbiont cannot be attenuated.
*Field delivery is easily handled.

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