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Title: Cloning and characterisation of genes expressed by the third stage larvae of the parasitic nematode Brugia malayi
Author: Gregory, William Francis
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2000
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Reverse transcription polymerase chain reaction (RT-PCR) of RNA from the infective larval stages of Brugia malayi with the nematode-specific 5' spliced leader sequence and oligo d(T) has been used to identify genes expressed during early larval stages. Products resolved on agarose gels show a number of prominent bands and cloning of these bands has revealed a total of 14 genes. Of these, four genes have been analysed in detail. One highly stage-specific transcript Bm-cpi-1, a cystatin-type cysteine proteinase has been characterised in parallel to a second, constitutively expressed, cystatin, Bm-cpi-2, identified by EST sequencing. The two inhibitors have been functionally expressed in E. coli and have distinct inhibitory specificities. In addition, both CPIs have been localised to the parasite surface and found in parasite secretions. An abundant transcript, Bm-alt-1, is a member of a large family of genes found in nematodes but lacks clear homologues outside the nematode phylum. Analysis of Expressed Sequence Tags (ESTs) deposited in dbEST has identified a total 10 family members in B. malayi. Genomic structures of the two most abundant family members have revealed conservation in the position of introns. However there is considerable sequence divergence within introns, with one gene containing distinct repeat units within its introns. In addition, heterogeneity is seen within this due to variation in the number of repeat units. Two further genes have been characterised. One is a homologue of the human histamine-releasing factor, a constitutively expressed, cytokine-like molecule of interest as a potential modulator of antiparasite responses. A second is a member of a family of proteins of unknown function, rich in glycine and tyrosine residues, which may form part of the nematode cuticle. The discovery of these abundant genes provides candidates for future analysis of immune evasion by filariae and identifies potential targets for vaccination or chemotherapy.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available