Parasitology
Adaptation of Caenorhabditis elegans technology to
identification and expression of parasite target genes
Knox, D
In developing parasite vaccines, there are two underlying requirements.
The first is the ability to identify target proteins in the parasite
which are essential for survival in the host animal. The second is
the ability to produce the target protein in bulk in a biologically
active form.
The first objective can be addressed by using RNA interference (RNAi).
Every protein in an organism is the product of a specific gene with
the information carried on the gene converted into a messenger RNA
(mRNA) that, in turn, is used to make the specific protein by a series
of biochemical reactions. Removing the mRNA, the underlying basis
of RNAi, thus blocks synthesis of the protein. RNAi has potential
as a powerful tool for identifying proteins which are essential for
parasite survival and are therefore, in turn, potential targets for
vaccines or drugs. RNAi is an effective tool for studying gene function
in Caenorhabditis elegans, a free living nematode which is
closed related at the gene sequence level to the major nematodes infecting
livestock. This project aims to apply RNAi technology for the identification
of genes critical for the survival of strongyle nematodes in sheep
and cattle, this work being underpinned by similar studies in C.
elegans.
In order to produce the target protein in bulk in a biologically active
form (in vitro), the gene encoding the protein of interest
is identified and then transferred into bacteria or yeast which can
be manipulated to express the protein in bulk cultures, a prerequisite
for vaccine production. However, these organisms do not always make
the protein in the same way as a nematode (in vivo) –
it may differ in terms of its shape and in the surface coat, factors
that are often critical for effective vaccination. Here, Moredun scientists
will try and express parasitic nematode genes in C. elegans
and compare the functional properties of the protein product with
the native protein purified from the parasite.