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Journal of Parasitology Research
Volume 2011, Article ID 316067, 10 pages
Research Article

Trypanosoma congolense Infections: Induced Nitric Oxide Inhibits Parasite Growth In Vivo

1College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
2Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK, Canada S7N 5B4

Received 20 September 2010; Accepted 7 February 2011

Academic Editor: Ana Maria Jansen

Copyright © 2011 Wenfa Lu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Wild-type (WT) C57BL/6 mice infected intraperitoneally with Trypanosoma congolense survive for more than 30 days. C57BL/6 mice deficient in inducible nitric oxide synthase (iNOS−/−) and infected with 103 or parasites do not control the parasitemia and survive for only or days, respectively. Bloodstream trypanosomes of iNOS−/− mice infected with   T. congolense had a significantly higher ratio of organisms in the S+G2+M phases of the cell cycle than trypanosomes in WT mice. We have reported that IgM anti-VSG-mediated phagocytosis of T. congolense by macrophages inhibits nitric oxide (NO) synthesis via CR3 (CD11b/CD18). Here, we show that during the first parasitemia, but not at later stages of infection, T. congolense-infected CD11b−/− mice produce more NO and have a significantly lower parasitemia than infected WT mice. We conclude that induced NO contributes to the control of parasitemia by inhibiting the growth of the trypanosomes.