Abstract
Most researchers who study unicellular eukaryotes work with an extremely limited number of laboratory-adapted isolates that were obtained from the field decades ago, but the effects of passage in laboratory rodents, and adaptation to in vitro culture, have been little studied. For example, the vast majority of studies of Trypanosoma brucei biology have concentrated on just two strains, Lister 427 and EATRO1125, which were taken from the field over half a century ago and have since have undergone innumerable passages in rodents and culture. We here describe two new Trypanosoma brucei brucei strains. MAK65 and MAK98, which have undergone only 3 rodent passages since isolation from Ugandan cattle. Adaptation of these strains to culture was accompanied by changes in gene copy numbers, some of which were also evident when other lab-adapted strains, field isolates of T. rhodesiense, and the genome strain TREU927 were compared. Reproducible increases were seen for genes encoding histones, enzymes of mRNA processing and degradation, the cytosolic chaperone HSP70, and two proteins required for the DNA damage response. These results indicate that similar work with other eukaryotic pathogens would be worthwhile. Meanwhile, the two new T. brucei strains should be useful to researchers interested in trypanosome differentiation and pathogenicity. They have differing pathogenicities in mice and may also differ in their propensity for stumpy-form differentiation, as judged by morphology and mRNA expression. MAK65 grows better than MAK98 in bloodstream-form culture, and is uniformly diploid, whereas MAK98 is triploid for chromosome 5. Genome sequence exceeding 100-fold coverage is available for both strains.
Competing Interest Statement
The authors have declared no competing interest.