Summary auto-generated
This study demonstrates that Eperythrozoon ovis, a wall-less bacterium causing hemolytic anemia in sheep and goats worldwide, is actually a mycoplasma rather than a rickettsia as previously thought. Using 16S rRNA gene sequencing and phylogenetic analysis, researchers showed that E. ovis clusters with other haemotrophic mycoplasmas within the pneumoniae group of Mycoplasma. Electron microscopy confirmed the organism is a 0.3–0.4 μm coccoid, wall-less bacterium located on erythrocyte surfaces, with fine fibrils potentially involved in attachment. The bacterium is transmitted by blood-feeding arthropods including ticks and mosquitoes, causes mild to severe anemia in sheep and more severe disease in goats, and is completely resistant to penicillin and other cell-wall-targeting antibiotics. Based on these molecular findings, the authors propose reclassifying E. ovis as Mycoplasma ovis comb. nov., aligning it with other haemotrophic mycoplasmas. This reclassification provides new insights into the pathogenic mechanisms and biology of blood-parasitic mycoplasmas, a novel mode of parasitism previously unrecognized in the Mollicutes class.
Key findings
- Eperythrozoon ovis is phylogenetically a mycoplasma, not a rickettsia, based on 16S rRNA gene sequencing and analysis
- E. ovis is most closely related to Mycoplasma wenyonii among known haemotrophic mycoplasmas (95% sequence similarity)
- Electron microscopy revealed wall-less coccoid bacteria (0.3–0.4 μm diameter) on erythrocyte surfaces with fine attachment fibrils
- The organism causes hemolytic anemia in sheep and goats, is transmitted by blood-feeding arthropods, and is resistant to penicillin and other cell-wall-targeting antibiotics
- The proposed reclassification as Mycoplasma ovis comb. nov. represents a novel mode of parasitism in the Mollicutes class
This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.
Abstract
Eperythrozoon ovis, an erythrocytic agent that causes haemolytic anaemia in sheep and goats, occurs worldwide and is currently thought to be a rickettsia. To determine the relationship between this agent and other haemotrophic bacterial parasites, the 16S rRNA gene of this organism was sequenced. Phylogenetic analysis revealed that this wall-less bacterium is not a rickettsia, but a mycoplasma. This mycoplasma is related closely to several other uncultivated, epierythrocytic mycoplasmas that comprise a recently identified group, the haemotrophic mycoplasmas (haemoplasmas). The haemoplasma group is composed of former Eperythrozoon and Haemobartonella species, as well as newly identified epierythrocytic mycoplasmas. Haemoplasmas parasitize the surface of erythrocytes of a wide variety of vertebrate animal hosts and are transmitted mainly by blood-feeding arthropod vectors. Recognition that E. ovis is a mycoplasma provides a new approach to dealing with this bacterium. It is proposed that E. ovis should be reclassified as Mycoplasma ovis comb. nov.