Cryptosporidium rubeyi n. sp. (Apicomplexa: Cryptosporidiidae) in multiple Spermophilus ground squirrel species.

Xunde Li,Royce Larsen,Ralph Phillips,Karl Striby,Edward R Atwill,Maria Das Graças Cabral Pereira,Chengling Xiao,Brenda Mccowan

doi:10.1016/j.ijppaw.2015.08.005

Abstract

Previously we reported the unique Cryptosporidium sp. “c” genotype (e.g., Sbey03c, Sbey05c, Sbld05c, Sltl05c) from three species of Spermophilus ground squirrel (Spermophilus beecheyi, Spermophilus beldingi, Spermophilus lateralis) located throughout California, USA. This follow-up work characterizes the morphology and animal infectivity of this novel genotype as the final step in proposing it as a new species of Cryptosporidium. Analysis of sequences of 18S rRNA, actin, and HSP70 genes of additional Cryptosporidium isolates from recently sampled California ground squirrels (S. beecheyi) confirms the presence of the unique Sbey-c genotype in S. beecheyi. Phylogenetic and BLAST analysis indicates that the c-genotype in Spermophilus ground squirrels is distinct from Cryptosporidium species/genotypes from other host species currently available in GenBank. We propose to name this c-genotype found in Spermophilus ground squirrels as Cryptosporidium rubeyi n. sp. The mean size of C. rubeyi n. sp. oocysts is 4.67 (4.4–5.0) μm × 4.34 (4.0–5.0) μm, with a length/width index of 1.08 (n = 220). Oocysts of C. rubeyi n. sp. are not infectious to neonatal BALB/c mice and Holstein calves. GenBank accession numbers for C. rubeyi n. sp. are DQ295012, AY462233, and KM010224 for the 18S rRNA gene, KM010227 for the actin gene, and KM010229 for the HSP70 gene.

Highlights

Cryptosporidium spp. are a group of protozoan parasites that infect a wide range of vertebrate hosts including companion animals, livestock, wildlife, and humans
We have shown that inoculation up to 104 Sbey03c oocysts failed to infect neonatal BALB/c mice (Atwill et al, 2004) and the current results confirm this, indicating that Cryptosporidium sp. c-genotype oocysts from Spermophilus ground squirrels are not infectious to neonatal BALB/c mice-and exhibit some degree of host specificity
We previously reported DNA fingerprinting of Cryptosporidium isolates from Spermophilus ground squirrels collected throughout California, USA (Pereira et al, 2010)

Summary

Introduction

Cryptosporidium spp. are a group of protozoan parasites that infect a wide range of vertebrate hosts including companion animals, livestock, wildlife, and humans. 30 species of Cryptosporidium have been described in vertebrate hosts that include fish, amphibians, reptiles, birds and mammals (Slapeta, 2013). Host specificity, when documented, is highly variable between Cryptosporidium species, with some species or genotypes, for example Cryptosporidium parvum, capable of infecting multiple vertebrate hosts, while other species, for example, Cryptosporidium andersoni, appear restricted to a much smaller number of hosts. Systematic challenge studies for many recently described species of Cryptosporidium in taxonomically-related or unrelated vertebrate hosts are often lacking. Li et al / International Journal for Parasitology: Parasites and Wildlife 4 (2015) 343e350

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