BES overview.

In this paper, we propose a new simple and logical VSG nomenclature. The hyphenated name indicates the T. brucei strain, followed by a number that identifies each unique VSG. For very closely related (probably antigenically indistinguishable) members of a VSG family, the number may be followed by a lower-case letter (for example Lister 427-3). When no misunderstanding can occur between strains under discussion in a particular context, the strain information may be omitted and the VSG referred to only by its number (for example, VSG 3). ND: not determined; N/A: not applicable; IC: intermediate chromosome; MBC: Megabase chromosome. (a) BES1, 2 and 17 had been previously cloned in BACs and identified as 221 ES, VO2 ES and Bn-2 ES, respectively [27]. (b) TAR65 and TAR51 were re-classified as belonging to BES group 7 and 17, respectively, based on global alignments showing sequence identity along the length of the sequence. The only differences were found in the promoter region, the target site for recombination during construction of the library. (c) Restriction mapping of the NEO tagged BES suggests the existence of two promoters, whereas the TAR clone has a single promoter. (d) TAR clone 128 is likely to be a recombinant between expression sites belonging to BES groups 1 and 15 (see text).