Diagnostic antigens for visceral leishmaniasis: clarification of nomenclatures

BACKGROUND: Stimulated by the increasing recent use of ‘K’ or ‘rK’ nomenclature for antigens reported for visceral leishmaniasis (VL) diagnostic serology, we wished to give a chronological synopsis of their reporting and the potentially confusing terminology. METHODS: The literature was examined for ‘K' or ‘rK’ terminology for VL diagnostic antigens, with emphasis on the original publications in which terms were first used. RESULTS: A chronological account of the first use of these 'K' and 'rK' nomenclatures was compiled. Since the original use of this terminology in 1993 in the name rK39 for a Leishmania antigen fragment, we found nine subsequent instances where ‘K' or ‘rK’ have been used to maintain consistency with this nomenclature. We also found instances where there were ambiguities regarding reported strain name, origin and GenBank accession numbers. CONCLUSIONS: We have documented here the uses in the literature of the ‘K’ or ‘rK’ prefix for VL diagnostic antigen nomenclature. We suggest that, to avoid confusion, the use of such nomenclature for future antigens should either provide the logical derivation of the term or indicate that the designation is entirely empirical.