Morphologic and Molecular Characterization of Isospora belli Oocysts from Patients in Thailand
- 1 July 2007
- journal article
- Published by American Society of Tropical Medicine and Hygiene in The American Journal of Tropical Medicine and Hygiene
- Vol. 77 (1) , 107-112
- https://doi.org/10.4269/ajtmh.2007.77.107
Abstract
To investigate the extent of genetic heterogeneity in the genus Isospora infecting patients in Thailand, a total of 38 fecal samples containing Isospora oocysts from human immunodeficiency virus/acquired immunodeficiency syndrome patients (n = 30), corticosteroid-treated patients (n = 3) and immunocompetent individuals (n = 5) were recruited for analysis. Remarkable variation in the maximum width and length of oocysts both within and between isolates was observed. However, the average length-width ratio of oocysts was within the range for I. belli (> 1.2). Ex vivo sporogonic development of freshly passed oocysts in feces from three of these isolates was observed longitudinally, showing that 27% of these oocysts underwent complete sporulation. Interestingly, 95% of sporulated oocysts contained two sporocysts in an oocyst with four sporozoites in each sporocyst, and Caryospora-like oocysts, characterized by eight sporozoites enclosed by a single sporocyst, were also detected (5%). The small subunit ribosomal RNA (rRNA), 5.8S rRNA, internal transcribed spacer 1 (ITS-1), and ITS-2 were highly conserved, indicating that there were no cryptic species or extensive strain variation.Keywords
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