Establishing a New SpeciesEncephalitozoon pogonaefor the Microsporidian Parasite of Inland Bearded DragonPogona vitticepsAhl 1927 (Reptilia, Squamata, Agamidae)

Abstract

The microsporidium parasitizing Inland Bearded Dragons Pogona vitticeps, and developing primarily in macrophages within foci of granulomatous inflammation of different organs, is described as a new species Encephalitozoon pogonae. Establishing the new species was based on sequencing the ITS-SSUrDNA region of the ribosomal gene and consequent SSUrDNA-inferred phylogenetic analyses, as well as on comparison of pathogenesis, host specificity, and ultrastructure among Encephalitozoon species and isolates. The new species is closely related to E. lacertae and E. cuniculi. Analysis of the literature suggests that this microsporidium has been reported previously as an unidentified microsporidian species or isolate of E. cuniculi and may represent a common infection in bearded dragons. All stages of E. pogonae develop in parasitophorous vacuoles. Uninucleate spores on methanol-fixed smears measured 2.1 × 1.1 μm, range 1.7-2.6 × 0.9-1.7 μm; on ultrathin sections spores measured 0.8-1.1 × 1.8-2.2 μm. Ultrastructural study revealed 3-6 polar filament coils, a mushroom-shaped polar disk, and a polar sac embracing half of the volume occupied by the lamellar polaroplast. In activated spores, polar filament everted eccentrically. The overall morphology and intracellular development of E. pogonae were similar to other Encepahalitozoon spp. We also review the existing data on microsporidia infecting reptiles.

3-Dimensional Organization and Dynamics of the Microsporidian Polar Tube Invasion Machinery

“…1b,c, Supplementary Video 1). First, the anchoring disc forms an umbrella-shaped structure at the anterior tip of the spore underlying the thinnest region of the endospore, as previously described 28,44 (Fig. 1b,c).…”

First report of fatal disseminated microsporidiosis in two inland bearded dragons Pogona vitticeps in Japan

“…Sokolova et al . [ 7 ] described E. pogonae as a novel species from a study of isolates from inland bearded dragons with disseminated granulomatous diseases in the USA, and the species found in bearded dragons in Austria was later classified as E. pogoinae as well. In this study, intracellular microorganisms were found in two inland bearded dragons with similar pathological lesions.…”

“…The spores found in the present study present similar shape and size to those of other species of the genus Encephalitozoon parasitizing reptiles, for example, E. cuniculi , E. hellem and E. intestinalis . These can be distinguished morphologically from another reptilian microsporidium, E. lacerate, by their smaller size and less elongated shape [ 7 ]. Analysis based of the ITS region sequence of the detected microorganisms revealed the divergence of E. pogonae from other reptilian pathogens.…”

“…Phylogenetic analysis using ribosomal DNA sequences revealed a close relationship between E. pogonae isolated from inland bearded dragons and E. cuniculi isolated from human, fox, mouse, rabbit and dog [ 7 ]. Furthermore, the sequence diversity of the non-coding regions of genomic DNA, such as the ITS region of the ribosomal RNA gene, has already been demonstrated to include polymorphisms that allow differentiation among individual strains of the genus Encephalitozoon.…”

“…These sequences were 100 % identical and deposited in the DDBJ database under the accession number LC214885. Analysis using the nucleotide basic local alignment search tool ( www.ncbi.nlm.nih.gov/Blast.cgi ) demonstrated that the obtained ITS sequence had 100 % identity (query cover 100 %) with E. pogonae (KR998311) isolated from the small intestine of an inland bearded dragon from the USA [ 7 ] and an uncultured clone of the genus Encephalitozoon (JQ682643) isolated from small intestinal tissue of an inland bearded dragon from the USA [ 5 ].…”