caa a22 4500 38639900X CHVBK 20180307112151.0 cr unu---uuuuu 161130e198908 xx s 000 0 eng 10.1017/S0031182000072103 doi S0031182000072103 pii (NATIONALLICENCE)cambridge-10.1017/S0031182000072103 High frequency of antigenic variation in Trypanosoma brucei rhodesiense infections [Elektronische Daten] Rates at which Trypanosoma brucei rhodesiense trypanosomes switch from expression of one variable antigen type (VAT) to that of another have been determined in cloned populations that have been recently tsetse-fly transmitted. Switching rates have been determined between several, specific pairs of VATs in each population. High rates of switching were observed in 2 cloned trypanosome lines, each derived from a separate cyclical transmission of the same parental stock and each expressing a different major VAT. Five estimates of the switching rate between one particular pair of VATs were consistently high (approximately 1 × 103 switches/cell/generation). These high switching rates were similar both in bloodstream populations of mice and in populations confined to subcutaneously implanted growth chambers in mice, thus indicating that the interaction of the bloodstream population with other trypanosome populations in the lymphatics or extravascular sites in systemic infections did not influence the estimates of the rate of switching. Fourteen estimates were made of VAT-specific switching rates in bloodstream infections involving 8 combinations from among 6 VATs. Switching rate estimates were VAT-specific and showed considerable variation between different combinations of VATs — from 1.9 × 10−6 to 6.9 × 10−3 switches/cel/generation. The rates of switching to different metacyclic-VATs were, however, very similar. Summation of between 3 and 5 VAT-specific switching rate values in each of 4 experiments conducted in bloodstream infections has provided minimum estimates of the overall rate of antigenic variation: 2.0−9.3 × 10−3 switches/cell/generation. These values are between 20 and 66000-fold higher than previously published estimates. It is likely that at least 1 in every 100 trypanosomes switches its VAT expression every generation. Copyright © Cambridge University Press 1989 Trypanosoma brucei rhodesiense nationallicence antigenic variation nationallicence trypanosome transmission nationallicence variable antigen types nationallicence cloned populations nationallicence Turner C. M. R. Department of Zoology, University of Glasgow, Glasgow G12 8QQ Barry J. D. Institute of Genetics, University of Glasgow, Glasgow Gil 5JS Parasitology Cambridge University Press 99/S1(1989-08), 67-75 0031-1820 99:S1<67 1989 99 PAR https://doi.org/10.1017/S0031182000072103 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0031182000072103 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Turner C. M. R. Department of Zoology, University of Glasgow, Glasgow G12 8QQ NATIONALLICENCE 700 1- Barry J. D. Institute of Genetics, University of Glasgow, Glasgow Gil 5JS NATIONALLICENCE 773 0- Parasitology Cambridge University Press 99/S1(1989-08), 67-75 0031-1820 99:S1<67 1989 99 PAR CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence SWISSBIB 38639900X BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge