Morphologic and molecular characterization of Isospora belli oocysts from patients in Thailand.
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.
Jongwutiwes
Somchai
S
Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. fmedsjw@md2.md.chula.ac.th
Putaporntip
Chaturong
C
Charoenkorn
Malee
M
Iwasaki
Takuya
T
Endo
Takuro
T
D000328:Adult; D000818:Animals; D001483:Base Sequence; D003048:Coccidiosis / Q000453:epidemiology* / Q000209:etiology / Q000469:parasitology*; D017931:DNA Primers; D005243:Feces / Q000469:parasitology; D005260:Female; D015658:HIV Infections; D006801:Humans; D016867:Immunocompromised Host; D007549:Isospora / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012335:RNA, Ribosomal / Q000032:analysis; D013785:Thailand / Q000453:epidemiology
D017931:DNA Primers; D012335:RNA, Ribosomal