The Anaplasma ovis genome reveals a high proportion of pseudogenes

Abstract

BackgroundThe genus Anaplasma is made up of organisms characterized by small genomes that are undergoing reductive evolution. Anaplasma ovis, one of the seven recognized species in this genus, is an understudied pathogen of sheep and other ruminants. This tick-borne agent is thought to induce only mild clinical disease; however, small deficits may add to larger economic impacts due to the wide geographic distribution of this pathogen.ResultsIn this report we present the first complete genome sequence for A. ovis and compare the genome features with other closely related species. The 1,214,674 bp A. ovis genome encodes 933 protein coding sequences, the split operon arrangement for ribosomal RNA genes, and more pseudogenes than previously recognized for other Anaplasma species. The metabolic potential is similar to other Anaplasma species. Anaplasma ovis has a small repertoire of surface proteins and transporters. Several novel genes are identified.ConclusionsAnalyses of these important features and significant gene families/genes with potential to be vaccine candidates are presented in a comparative context. The availability of this genome will significantly facilitate research for this pathogen.

First Whole Genome Sequence of Anaplasma platys, an Obligate Intracellular Rickettsial Pathogen of Dogs

“…Except for those involved in biotin metabolism, genes distinctively present or absent in A. platys do not seem to encode proteins associated with metabolic pathways. Consequently, the metabolic capacity of A. platys is likely to be similar to that previously discussed for other Anaplasma species [8,9,12], characterized by incomplete pathways for glycolysis and the synthesis of most amino acids. In fact, metabolic reconstruction of the A. platys strain showed that the pathways that appear to be complete are the central pathways of energy metabolism from pyruvate oxidation to the citric acid cycle and oxidative phosphorylation, the non-oxidative phase of the pentose phosphate pathway, as well as biosynthetic pathways for fatty acids, coenzyme A, glutathione, and nitrogenous bases (Table S6).…”

“…Subunits of these complex are encoded by at least 11 genes (virB1-11), all of which are considered important determinants of virulence in Anaplasmataceae. Expansion of gene families associated with the type IV secretion system is well documented in Anaplasma, with several reported copy number variations across species [12,28,29]. In the A. platys genome, we found duplication or expansion in the genes encoding VirB2, VirB8, VirB9, and VirB10.…”

“…These basic metrics are similar to those from previously published Anaplasma genomes ( Table 1). The GC percent calculated for our A. platys genome draft is relatively lower than that for A. marginale or A. ovis, a finding that has also been reported for A. phagocytophilum [9,12]. The annotated genome was deposited in the GenBank database with accession number CP046391, under BioProject PRJNA578763.…”

“…The sequencing of the A. marginale genome was initially achieved by using the laborious and expensive strategy of creating bacterial artificial chromosome (BAC) libraries of bacterial and host DNA with minimal purification of the pathogen from the host cell, followed by the selection of clones containing bacterial genes [8]. Subsequent genomic studies, involving Anaplasma isolation, used dedicated laboratory procedures such as culturing the bacteria in vitro in host cells [9] or cells from the tick vector [10] or inoculating the original isolates in splenectomized animals in order to obtain relatively high levels of bacteremia [11,12]. Targeted enrichment of genomic DNA has also been used as an alternative to sequence A. marginale, A. phagocytophilum and Wolbachia genomes [13][14][15].…”

A Multiplex PCR Detection Assay for the Identification of Clinically Relevant Anaplasma Species in Field Blood Samples

“…A. ovis is an intraerythrocytic rickettsial pathogen that mainly affects domestic sheep and goats, but has also been reported to be present in some wild ruminants and dogs with mild clinical symptoms (Zaid et al, 2019). However, symptoms may be exacerbated by stressors such as co-infection, elevated temperature, and animal movement disorders throughout Asia, Africa, Europe and the United States (Hornok et al, 2011;Cabezas-Cruz et al, 2019;Enkhtaivan et al, 2019;Liu et al, 2019). This pathogen also poses a potential threat to humans (Wei et al, 2017).…”