Abstract
BackgroundThere has been considerable confusion concerning the number and classification of Sarcocystis spp. in chickens. Scarce nucleotide data of Sarcocystis spp. from chickens are provided in GenBank. The study aimed to investigate the morphological and molecular characteristics of Sarcocystis spp. found in chickens in China.MethodsTissues from 33 chickens were collected in 2019. Sarcocysts were observed using light (LM) and transmission electron microscopy (TEM). Individual sarcocysts from different chickens were selected for DNA extraction, and five loci, 18S rDNA, 28S rDNA, ITS1 region, the mitochondrial cox1 gene and the apicoplastic rpoB gene, were amplified from each sarcocyst, sequenced and analyzed.ResultsOnly S. wenzeli was found in 14 of 33 (42.4%) chickens. Under LM, the sarcocysts were microscopic and exhibited palisade-like villar protrusions measuring 1.5–2.8 μm. Ultrastructurally, the sarcocyst wall contained numerous stubby hill-like villar protrusions. The protrusions included scattered microtubules, which extended from the tips of the protrusions into the ground substance. The five loci were successfully sequenced and the sequences deposited in GenBank. At 18S rDNA, ITS1 and cox1, the most similar sequences in GenBank were those of Sarcocystis sp. obtained from the brains of chickens, i.e. 99.9–100%, 98.1–98.5% and 99.3% identity, respectively. The five loci (18S rDNA, 28S rDNA, ITS1, cox1 and rpoB) showed different levels of interspecific sequence similarity with other closely related species of Sarcocystis (e.g. 99.8%, 99.0–99.2%, 89.3–89.7%, 98.5%, and 97.5%, respectively, with S. anasi). Phylogenetic analysis based on four of the loci (18S rDNA, cox1, rpoB and ITS1) revealed that S. wenzeli formed an independent clade with Sarcocystis spp. that utilize geese or ducks as intermediate hosts and canines as the known or presumed definitive host.ConclusionsTo our knowledge, the sequences of 28S rDNA and rpoB reported here constitute the first records of genetic markers of Sarcocystis spp. in chickens. Based on molecular analysis, S. wenzeli might be responsible for the neurological disease in chickens, and ITS1 and rpoB are more suitable for discriminating it from closely related Sarcocystis spp. Phylogenetic analysis revealed that S. wenzeli presents a close relationship with Sarcocystis spp. in geese or ducks.
Highlights
There has been considerable confusion concerning the number and classification of Sarcocystis spp. in chickens
All these nucleotide sequences were obtained from Sarcocystis in chickens associated with neurological lesions in Brazil, and the parasite was closely related to S. anasi and S. albifronsi [8]
light microscopy (LM) and transmission electron microscopy (TEM) examination of S. wenzeli sarcocysts Only sarcocysts resembling those of S. wenzeli were found in 14 of 33 (42.4%) chickens
Summary
There has been considerable confusion concerning the number and classification of Sarcocystis spp. in chickens. Scarce nucleotide data of Sarcocystis spp. from chickens are provided in GenBank. There has been considerable confusion concerning the number and classification of species of Sarcocystis in chickens owing to the imperfection of the original description [5]. The ultrastructure of sarcocysts is traditionally a reliable characteristic for identifying different Sarcocystis species in a given host. PCR assays and sequencing procedures are considered much more practical, accurate, and reliable methods for the delineation and identification of Sarcocystis species than traditional methods based on morphological characteristics [6, 7]. All these nucleotide sequences were obtained from Sarcocystis in chickens associated with neurological lesions in Brazil, and the parasite was closely related to S. anasi and S. albifronsi [8]. Sarcocystis sp, found by these authors was not identified to the species level
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
