Acta Tropica 82 (2002) 25–29 Identification of antigenically distinct populations of Leishmania (Viannia ) guyanensis from Manaus, Brazil, using monoclonal antibodies Gustavo Adolfo Sierra Romero a, *, Edna Ishikawa b , Elisa Cupolillo c , Cristiane Bentin Toaldo c , Marcus Vinitius de Farias Guerra d , Marcilene Gomes Paes d , Vanize de Oliveira Mace ˆdo a , Jeffrey J. Shaw e a Nu ´cleo de Medicina Tropical, Uniersidade de Brası ´lia, Campus Uniersita ´rio, Asa Norte. Caixa Postal 04517, Brasilia, DF, 70919 -970, Brazil b Programa de Leishmaniose, Instituto Eandro Chagas, Aenida Almirante Barroso 492, Belem, PA, Brazil c Departamento de Imunologia – FIOCRUZ, Aenida Brasil 4365, Manguinhos, Rio de Janeiro, RJ, 21045 -900, Brazil d Fundac ¸a ˜o de Medicina Tropical – Instituto de Medicina Tropical do Amazonas, Aenida Pedro Teixeira No. 25, Manaus, Amazonas, 69040 -000, Brazil e Departamento de Parasitologia – ICB – Uniersidade de Sa ˜o Paulo, A. Prof. Lineu Prestes 1374, Sao Paulo, SP, 05508 -900, Brazil Received 10 August 2001; received in revised form 8 October 2001; accepted 23 October 2001 Abstract Eighty Leishmania isolates from patients who contracted cutaneous leishmaniasis in the Manaus region, Amazonas State, Brazil, were identified as Leishmania (Viannia ) guyanensis by the electrophoretic profiles of six enzymes. None reacted with the species-specific monoclonal antibody B19. Two L.(V.) guyanensis subpopulations were detected with the monoclonals B2 and B12. The lack of B19 expression by the L.(V.) guyanensis strains in the present study contrasts with that of the vast majority of the strains of the same parasite from eastern Amazonia and French Guyana that express the epitope. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Leishmania (Viannia ) guyanensis ; Monoclonal antibodies; Antigenic variation; Serodemes; Brazilian Amazon www.parasitology-online.com 1. Introduction Monoclonal antibodies (MAbs) and enzyme electrophoresis have been extensively used for identification and classification of the New World Leishmania parasites (Cupolillo et al., 1994; Grimaldi and McMahon-Pratt, 1996). Enzyme electrophoresis has been the gold standard for identification at the species level but MAbs have a better discriminant capacity for identifying popu- lations of parasites that belong to the same species (Cupolillo et al., 1993). Antigenic variation within * Corresponding author. Tel.: +55-61-273-5008; fax: +55- 61-273-2811. E-mail address: gromero@unb.br (G.A.S. Romero). 0001-706X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0001-706X(02)00002-5