The University of Georgia College of Veterinary Medicine

eorgia Veterinary Scholars Program

GVSP Summer 2007 Scholars

Georgia Veterinary Scholar	Faculty Mentor

Katherine MacMillan University of Georgia Class of 2010	Dr. Michael Yabsley

Infection dynamics of Trypanosoma cruzi strains from North and South America in degus (Octodon degus) and short-tailed opossums (Monodelphis domestica)

*Katherine McMillan1, Dawn M. Roellig1, 2, and Michael J. Yabsley1,3
1Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens Georgia 30602,
2Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30602
3D.B. Warnell School of Forestry and Natural Resources. University of Georgia, Athens Georgia 30602, USA

Abstract

Trypanosoma cruzi, causative agent of Chagas disease, is a diverse species with two primary genotypes, type I and type II, with type II being further subdivided into five subtypes. Regardless of genotype, isolates are highly variable and can differ in numerous biological characteristics including host range and pathogenicity. This project evaluated the infection dynamics of four genetically diverse T. cruzi strains from a wide geographic range in two South American reservoirs, Octodon degus and Monodelphis domestica. Isolates in this study included two type I strains (Y strain from Brazil and OPO3 from Florida, USA) and two type II strains (Tulahuen strain from Chile and RAC9 from Florida, USA). Animals were randomly assigned to one of six groups; four groups were intraperitoneally inoculated with 1x106 trypomastigotes of a single strain, one group was coinoculated with 2 USA strains (types I and II), and a control group was inoculated with uninfected media. Blood samples were collected weekly and used for determining parasitemias and seroconversion. Animals were monitored daily for clinical signs. After 40 days post-infection (DPI), animals will be euthanized and major organs will be examined for T. cruzi by PCR and histopathologic lesions. On DPI7, the O. degus, parasitemias for the Y and FLOPO3 strains were high (1.8x105 parasites/mL and 1.2x104 parasites/mL, respectively), and on DPI 14, the Y strain parasitemia decreased (2.34x104 parasites/mL) while the FLOPO3 increased (5.97x104 parasites/mL). On DPI7, the FLOPO3 parasitemias in M. domestica were higher than the Y strain (2x103 parasites/mL vs. 6.7x102 parasites/mL, respectively), but both were lower than in O. degus. These results indicate that both South American reservoirs support infections with parasites of genotype I from North and South America. Remaining results will provide data on infection dynamics, histopathologic lesions, and susceptibility of these hosts to both genotypes of the parasite.