70 0007-4888/13/1561-0070 © 2013 Springer Science+Business Media New York Integral Approach to Evaluation of the Pathogenic Activity of Trypanosoma Cruzi Clones as Exemplified by the Mexican Strain Valery Melnikov 1 , Francisco Espinoza-Gomez 1 , Oscar Newton-Sanchez 1 , Ivan Delgado-Ensiso 1 , Oswal Antonio Montesinos-Lopez 2 , M. V. Dalin 3 , Bertha Espinoza 4 , Ignacio Martinez 4 , L. A. Sheklakova 3 , Oksana Dobrovinskaya 5 , and L. P. Karpenko 3 Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 156, No. 7, pp. 82-84, July, 2013 Original article submitted March 25, 2012 Comparative histopathological study and analysis of parasite load in different muscle groups were carried out in BALB/c mice during the acute phase of Chagas disease. Activities of C104 clone of T. cruzi strain TPAP/MX/2002/Albarrada and the parental strain were compared. Pan- oramic 2D-microscopy imaging of sample surface was used and quantitative analysis of parasit- ism and pathologic damage was performed. The infection rates in various muscle groups were as follows: myocardium=abdominal muscles=lumbar muscles=femoral muscles←diaphragm for the clone and myocardiumabdominal muscles=lumbar muscles=femoral muscles→ dia- phragm for the parental strain. Key Words: Trypanosoma cruzi; muscle tissue tropism; myocardium; diaphragm; myositis 1 Medical Faculty, 2 Faculty of Telematics, University of Colima, Co- lima, Mexico; 3 Medical Faculty, the Russian University of Peoples’ Friendship, Moscow, Russia; 4 Departamento de Immunologia Insti- tuto de Investigaciones Biomédicas, UNAM (U.N.A.M.), Mexico D. F., Mexico; 5 Center of Biomedical Investigations, University of Colima, Colima, Mexico. Address for correspondence: melnik@ucol.mx. V. Melnikov Chagas disease caused by Trypanosoma cruzi ( T. cruzi) flagellar protozoon is a serious public health problem in America. In mammalian host, the disease evolves through three periods: acute, intermediate, and chronic [1]. During the acute phase, the bloodstream forms invade the host tissues and are converted into intracellular proliferating forms (amastigotes). Myo- cyte parasitism, myositis, degeneration, and necrosis of myofibers were observed during the infection [1]. T. cruzi strains are multiclonal populations. The distribution of the parasites in the host tissues is de- termined by specific features of the clones constitut- ing the infective strain. According to the polyclonal theory, uneven distribution of the parasites in tissues is determined by specific features of the clones con- stituting the integral strain [2]. Hence, some clone can be tropic to a certain or several tissue types and in- fect them to the same degree. The host by its reaction modifies the infective characteristics of the parasite and these host-parasite relations presumably explain different virulence of the same clone in different hosts. Similar logics, however, may be applied also for dif- ferent tissues within the same host, so that their dif- ferential infection/damage can be expected even with a single clone. However, parasite distribution in differ- ent groups of muscles and their invasion in the same host have been never evaluated quantitatively. We compared parasitism and histopathological changes in the heart and four groups of skeletal muscles during the acute phase of T. cruzi infection in mice. MATERIALS AND METHODS T. cruzi strain TPAP/MX/2002/Albarrada was isolated from Triatoma pallidipenis (Stål, 1868) recollected in Bulletin of Experimental Biology and Medicine, Vol. 156, No. 1, November, 2013 IMMUNOLOGY AND MICROBIOLOGY