A novel candidate species of Anaplasma that infects avian erythrocytes

Ralph Eric Thijl Vanstreels,Liandrie Swanepoel,Pierre A Pistorius,Michael J Yabsley,Nola J Parsons

doi:10.1186/s13071-018-3089-9

Ralph Eric Thijl Vanstreels, Liandrie Swanepoel + Show 3 more

Open Access

https://doi.org/10.1186/s13071-018-3089-9

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Abstract

BackgroundAnaplasma spp. are Gram-negative obligate intracellular bacteria transmitted by ticks. Even though numerous studies have detected DNA from Anaplasma spp. in the blood of birds, thus far mammals were the only vertebrates demonstrated to serve as competent hosts to these organisms. We report a novel candidate species of Anasplasma that was associated with cytoplasmic inclusions in the erythrocytes of an African penguin (Spheniscus demersus) in South Africa.MethodsCytoplasmic inclusions were morphologically characterized from freshly-produced blood smears, and phylogenetic analysis of 16S rRNA and groEL genes were used to evaluate the evolutionary relationships of the organism to other Anaplasmataceae.ResultsDark-purple round or oval inclusions consistent with Anaplasmataceae morulae were observed in the cytoplasm of erythrocytes. Phylogenetic trees produced using different methods agreed that the organism detected in this study belongs to the genus Anaplasma, and suggested that it is most closely related to the cluster comprising A. centrale, A. capra, A. marginale and A. ovis. We propose provisionally naming the strain detected in this study as “Candidatus Anaplasma sphenisci”.ConclusionsThis is the first species of Anaplasma shown to produce cytoplasmic inclusions in avian cells, opening the possibility that cytoplasmic inclusions in avian erythrocytes that had previously been attributed to Aegyptianella sp. might in fact correspond to Anaplasma. Further studies on the molecular biology of avian-infecting Anaplasmataceae will be valuable to provide insight into the evolution and epidemiology of these organisms.

Highlights

Anaplasma spp. are Gram-negative obligate intracellular bacteria transmitted by ticks
We describe a novel candidate species of Anaplasma that is associated with cytoplasmic inclusions in the erythrocytes of the African penguin (Spheniscus demersus), and discuss the phylogenetic relationships of this organism to other Anaplasmataceae
In addition to the erythrocytic inclusions, one lymphocyte contained dark-purple cytoplasmic inclusions (Additional file 3: Figure S1); despite extensive searching (> 1000 leukocytes examined), no other leukocytes or thrombocytes were seen with similar cytoplasmic inclusions and it was not possible to determine the identity of these structures

Summary

Introduction

Anaplasma spp. are Gram-negative obligate intracellular bacteria transmitted by ticks. Even though numerous studies have detected DNA from Anaplasma spp. in the blood of birds, far mammals were the only vertebrates demonstrated to serve as competent hosts to these organisms. Anaplasmataceae (Alphaproteobacteria: Rickettsiales) are Gram-negative obligate intracellular bacteria found exclusively within membrane-bound inclusions or vacuoles in the cytoplasm of vertebrate and invertebrate host cells [1]. This family comprises five recognized genera (Aegyptianella, Anaplasma, Ehrlichia, Neorickettsia and Wolbachia) [1], and four candidate genera (“Candidatus Cryptoplasma”, “Candidatus Neoehrlichia”, “Candidatus Xenohaliotis”, and “Candidatus Xenolissoclinum”) [2,3,4,5]. No studies demonstrated the presence of Anaplasma spp. cytoplasmic inclusions within blood cells of birds, and it was considered unclear whether these organisms are able to Vanstreels et al Parasites & Vectors (2018) 11:525

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