Molecular identification and subtyping of Blastocystis sp. in laboratory rats in China

Blastocystis sp. is a ubiquitous protist that has been frequently reported in humans and animals worldwide. A total of 355 fecal samples of experimental rats were collected from four laboratory rearing facilities in China, and Blastocystis sp. was detected by PCR amplification of the partial small subunit ribosomal (SSU) rRNA gene. Twenty-nine (8.2%, 29/355) samples were positive for Blastocystis sp., with the highest infection rate (20.7%, 24/116) in rats of the Zhengzhou1, followed by that in the Zhengzhou2 (5.0%, 2/40), Shenyang (3.0%, 3/100) and Wuhan (0) rearing facilities. Among the three rat strains, Sprague-Dawley (SD) rats had higher infection rates (11.3%, 17/151) compared to Wistar rats (8.7%, 9/104) and spontaneously hypertensive (SH) rats (3.0%, 3/100). Two Blastocystis sp. subtypes (ST4 and ST7) were identified. ST4 was the predominant subtype detected in 26 samples (89.7%). A phylogenetic analysis demonstrated that the sequences of ST4 and ST7 obtained in this study were clustered with their reference subtypes. To our knowledge, this is the first report of Blastocystis sp. in experimental rats in China. Pathogen infections in laboratory animals need to be monitored due to fecal-oral transmission.