The role of polyamines and related metabolites in the growth and morphology of two piscine trypanosomes

In comparison with the vast amount of literature available on the trypanosomes of mammals, relatively little is understood of those of lower vertebrates, including those present in the blood of fishes. Previous studies on fish trypanosomes have been concerned mainly with their life cycles and morphology, but this project presents data on their ultrastructure, polyamine and thiol metabolism and their responses to polyamine biosynthesis inhibitors. ‘Trypanosoma granulosum’ from the European eel and ‘Trypanosoma danilewskyi’ from the crucian carp were isolated from the blood of their respective hosts and successfully cultured ‘in vitro’ in an undefined diphasic medium. Several semi-defined and fully-defined media were then tested for their suitability to sustain growth of the parasites. A modified version of SDM-79 successfully provided the growth and, conditions necessary for morphological, ultrastructural and biochemical studies of both parasites. The ultrastructure of bloodstream ‘T. granulosum’ highlighted similarities with some stercorarian trypanosomes. In diphasic medium and modified SDM-79 the bloodstream parasites transformed into forms similar to those reportedly found in their leech vector. Mainly trypomastigote forms were present in modified SDM-79, although epimastigotes, not found in any blood smears were also present. Ultrastructurally, cultured ‘T. granulosum’ was similar to other members' of the genus ‘Trypanosoma’. Biochemical analyses of the parasites using high performance liquid chromatography, enzyme assays and radiolabelling studies revealed that their polyamine and thiol metabolisms were unusual amongst trypanosomatids for example the African trypanosomes and ‘Leishmania’ spp. Low levels of intracellular free polyamines, a rapid high affinity saturable uptake system for putrescine, the presence of glutathione as the major intracellular thiol, and the presence of the newly discovered thiol homotrypanothione, suggested that both ‘T. granulosum’ and ‘T. danilewskyi’ were similar to ‘Trypanosoma cruzi’ in their polyamine and thiol metabolism. Known inhibitors of polyamine metabolism Dl-[alpha]-difluoromethylornithine (DFMO), methylglyoxal-bis-(guanylhydrazone) (MGBG) and diminazene aceturate (Berenil) were all shown to inhibit growth and to cause drastic alterations to the morphology and ultrastructure of ‘T. granulosum’ (and ‘T. danilewskyi’). These anti-parasitic actions did not appear to result from polyamine depletion

New genetic predictors for abacavir tolerance in HLA-B*57:01 positive individuals.

Abacavir hypersensitivity syndrome (ABC HSS) is strongly associated with carriage of human leukocyte antigen (HLA)-B*57:01, which has a 100% negative predictive value for the development of ABC HSS. However, 45% of individuals who carry HLA-B*57:01 can tolerate ABC. We investigated immune and non-immune related genes in ABC HSS (n = 95) and ABC tolerant (n = 43) HLA-B*57:01 + patients to determine other factors required for the development of ABC HSS. Assignment of phenotype showed that ABC HSS subjects were significantly less likely than tolerants to carry only ERAP1 hypoactive trimming allotypes (p = 0.02). An altered self-peptide repertoire model by which abacavir activates T cells is in keeping with observation that endoplasmic reticulum aminopeptidase 1 (ERAP1) allotypes that favour efficient peptide trimming are more common in ABC HSS patients compared to patients who tolerate ABC. Independently, non-specific immune activation via soluble cluster of differentiation antigen 14 (sCD14) may also influence susceptibility to ABC HSS