Human infectivity trait in Trypanosoma brucei: stability, heritability and relationship to sra expression

Turner, C.M.R., McLellan, S., Lindergard, L.A.G., Bisoni, L., Tait, A. and MacLeod, A. (2004) Human infectivity trait in Trypanosoma brucei: stability, heritability and relationship to sra expression. Parasitology, 129(4), pp. 445-454. (doi: 10.1017/S0031182004005906)

Abstract

Some Trypanosoma brucei lines infect humans whereas others do not because the parasites are lysed by human serum. We have developed a robust, quantitative in vitro assay based on differential uptake of fluorescent dyes by live and dead trypanosomes to quantify the extent and kinetics of killing by human serum. This method has been used to discriminate between 3 classes of human serum resistance; sensitive, resistant and intermediate. TREU 927/4, the parasite used for the T. brucei genome project, is intermediate. The phenotype is expressed in both bloodstream and metacyclic forms, is stably expressed during chromic infections and on cyclical transmission through tsetse flies. Trypanosomes of intermediate phenotype are distinguished from sensitive populations of cells by the slower rate of lysis and by the potential to become fully resistant to killing by human serum as a result of selection or long-term serial passaging in mice, and to pass on full resistance phenotype to its progeny in a genetic cross. The sra gene has been shown previously to determine human serum resistance in T. brucei but screening for the presence and expression of this gene indicated that it is not responsible for the human serum resistance phenotype in the trypanosome lines that we have examined, indicating that an alternative mechanism for HSR exists in these stocks. Examination of the inheritance of the phenotype in F1 hybrids for both bloodstream and metacyclic stages from 2 genetic crosses demonstrated that the phenotype is co-inherited in both life-cycle stages in a manner consistent with being a Mendelian trait, determined by only one or a few genes.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacLeod, Professor Annette
• Authors: Turner, C.M.R., McLellan, S., Lindergard, L.A.G., Bisoni, L., Tait, A., and MacLeod, A.
• Subjects: Q Science > QL Zoology
• College/School: College of Medical Veterinary and Life Sciences; College of Medical Veterinary and Life Sciences > School of Infection & Immunity
• Journal Name: Parasitology
• Publisher: Cambridge University Press
• ISSN: 0031-1820
• Copyright Holders: Copyright © 2004 Cambridge University Press
• First Published: First published in Parasitology 129(4):445-454
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher