Characterization of the Variable Antigen Genes Expressed by Trypanosoma brucei rhodesiense during Metacyclic Stage and in the Bloodstream.
Annual rept. 15 Sep 82-1 Sep 83,
UNIV OF IOWA IOWA CITY DEPT OF BIOCHEMISTRY
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Two different cDNA libraries have been constructed using mRNAs extracted from day 5 trypanosomes which have been shown to be expressing predominately metacyclic variable surface glycoproteins metacyclic VSGs. These cDNA libraries have been screened via the - hybridization procedure for those clones which possess metacyclic VSG coding sequences. Five different VSG cDNAs have been identified to date and the complete, or nearly complete, sequence of each has been determined. Two of the five cDNAs are nonoverlapping and appear to code for a specific metacyclic VSG called MVAT 7 which is defined by monoclonal antibodies. We are in the process of performing genomic DNA Southern blots to see if the MVAT 7 VSG gene undergoes rearrangements when it is expressed in trypanosomes as do bloodstream VSG genes. In addition we are constructing vectors suitable for expression of this VSG coding sequence in bacteria so that a sufficient quantity can be obtained for vaccination studies. As a corollary to the metacyclic VSG gene project, we are also characterizing VSG genes expressed during the trypanosome bloodstream stages. We have determined the boundary sequences of an expression-linked extra copy VSG gene and demonstrated that this gene remains in the genome when the trypanosome clone is placed in procyclic culture conditions where the VSG is no longer made. These projects will be continued and expanded in the coming year if the contract is renewed.
- Anatomy and Physiology
- Medicine and Medical Research