Identification of Sarcocystis spp. in synanthropic (Muridae) and wild (Cricetidae) rodents from Argentina

Abstract

The occurrence of Sarcocystis species was investigated in synanthropic (Muridae) and wild (Cricetidae) rodents from Argentina. Nine species were captured (n = 356). Sarcocysts were detected in muscles of 8.7% (31/356) and 3.7% (4/106) of the rodents by histopathology and direct microscopy, respectively. PCRs-sequencing targeting the 18S rRNA, cox1 and ITS1 regions were performed on samples with positive histopathology. Four different 18S rRNA sequences or sequence groups with high intra-group identities (99.6-100%) were detected in Mus musculus, Oxymycterus rufus, Akodon azarae and Necromys lasiurus. Eight sequences showed 99.5-99.7% identity with S. dispersa. Thirteen sequences showed low identity (95.3-96.4%) with other Sarcocystis spp. The obtained coxI sequences (n = 9) were almost identical among them and showed a high similarity with S. strixi (99.2-99.5%) and S. lutrae (99.1%), despite the 18S rRNA sequences from the same samples suggested the occurrence of at least two species. This suggests that coxI may not show high variability in Sarcocystis spp. that use rodents as intermediate hosts. Six ITS1 sequences were obtained, showing high identity but low coverage with several Sarcocystis spp. Multilocus sequence typing and BLAST analysis did not allow accurate species identi cation. Possible reasons are the detection of new species or the lack of molecular information from previously described ones. Phylogeny suggests that the detected Sarcocystis spp. may use raptor birds or snakes as de nitive hosts. This study represents the rst molecular identi cation of Sarcocystis spp. in naturally infected rodents of the Cricetidae and Muridae families in South America.

Detection of Three Sarcocystis Species (Apicomplexa) in Blood Samples of the Bank Vole and Yellow-Necked Mouse from Lithuania

“…In China, a study found that 25% of large oriental voles ( Eothenomys miletus ) were infected with Sarcocystis species [ 14 ]. Similarly, in Argentina, wild Cricetidae species exhibited a prevalence of 16.08% [ 12 ], while in Japan, 16.85% of Bedford’s red-backed voles ( Clethrionomys rufocanus bedfordiae ) were infected [ 52 ]. Moreover, research conducted in the Netherlands on M. arvalis reported seasonal variations in Sarcocystis spp.…”

“…Currently, only sequences of the 18S rRNA and 28S rRNA genes have been obtained [ 9 , 10 ]. Apart from cox1 , which was used in numerous studies [ 12 , 16 , 21 , 47 , 70 , 71 ], additional genetic markers, such as ITS1 , mitochondrial cytochrome b ( cytb ), complete ITS1 – 5.8S rRNA– ITS2 region, two apicoplast genes—RNA polymerase beta subunit ( rpoB ) and caseinolytic protease C ( clpC ) demonstrate promising prospects for improved discrimination of Sarcocystis spp. in small mammals [ 47 , 66 , 72 , 73 ].…”

“…However, due to the low level of research on different rodent species, it is suggested that the true number of Sarcocystis spp. in these hosts is higher [ 12 , 13 ]. In recent years, several new Sarcocystis species have been described in rodents [ 14 , 15 , 16 ].…”

“…Therefore, the list of known Sarcocystis species is revised and new species are described by using combined morphological and molecular methods [ 21 ]. Currently, ribosomal RNA genes ( 28S rRNA or 18S rRNA), internal spacer region 1 ( ITS1 ), and mitochondrial cytochrome oxidase 1 ( cox1 ) are mostly used for Sarcocystis species identification [ 12 ]. The selection of the genetic regions for the identification of the parasites depends on its host taxonomic group as it has been shown that Sarcocystis species co-evolved with their hosts [ 22 ].…”

First Observations of Buzzards (Buteo) as Definitive Hosts of Sarcocystis Parasites Forming Cysts in the Brain Tissues of Rodents in Lithuania

“…Although this genetic region has not been commonly applied for the characterization of Sarcocystis spp. from rodents, it has shown more variability compared to cox1 [9,13,59]. In contrast, cox1 is relatively conservative considering Sarcocystis spp.…”