Mycoplasma ovis comb. nov. (formerly Eperythrozoon ovis), an epierythrocytic agent of haemolytic anaemia in sheep and goats

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.Eperythrozoon ovis is an uncultivated, wall-less bacterium that parasitizes the surface of sheep erythrocytes. This organism is transmitted by blood-feeding arthropods and parasitizes animals in sheep-rearing regions throughout the world. Signs of infection include mild to severe haemolytic anaemia, as well as icterus; animals may exhibit poor weight gain and depression, but death is rare in adults. Infections are frequently unapparent and chronic. E. ovis also infects goats, in which it results in more severe disease (Splitter et al., 1956;Kreier & Ristic, 1963;Daddow, 1979;Mason et al., 1989;Mason & Statham, 1991).As E. ovis has not been cultivated, diagnosis is made by detection of organisms on erythrocytes in Romanowskytype or acridine orange-stained blood smears and by serological methods. Parasitism of erythrocytes often occurs at a low level and is transient; detection requires examination of repeated blood smears. However, erythrocyte parasitaemia can be as high as 100 % in our experience; a high level of parasitaemia can occur even in subclinical infection and can persist for months (Overas, 1969;Brun-Hansen et al., 1997). E. ovis is completely resistant to penicillin and other antimicrobial agents that target the cell wall. Also, tetracycline treatment does not eliminate this agent from chronically infected animals. This organism has been thought to be a rickettsia because of its obligate parasitism, erythrocyte localization, small size, staining properties and transmission by arthropod vectors. E. ovis and a number of similar haemotrophic bacteria have been classified in the order Rickettsiales, family Anaplasmataceae, in the genera Haemobartonella and Eperythrozoon (Kreier & Ristic, 1984;Kreier et al., 1992). Recently, phylogenetic analysis of 16S rRNA gene sequences from four of these bacteria, Haemobartonella felis, Haemobartonella muris, Eperythrozoon suis and Eperythrozoon wenyonii, has demonstrated that these wallless bacteria are not rickettsiae, but tha...

Human Coinfection with Bartonella henselae and Two Hemotropic Mycoplasma Variants Resembling Mycoplasma ovis

“…Previously known as "Eperythrozoon ovis," the organism was reclassified as M. ovis based upon 16S rRNA gene sequence analysis (17). The organism attaches to erythrocytes and causes "ill thrift," hemolytic anemia, and occasionally icterus, hemoglobinuria, and mortality in lambs (20,24).…”

Prevalence and Molecular Characterization of Mycoplasma ovis in Selected Free-Ranging Brazilian Deer Populations

“…A PCR protocol for kappa-casein, gene-specific for ruminants, was performed in all samples to verify the presence of amplifiable DNA (Otaviano et al, 2008; Table 1). The PCR assay for M. ovis detection was performed as described (Neimark et al, 2004). A positive control for M. ovis from a naturally infected white-tailed deer (Odocoileus virginianus) was used in all reactions; water was used as negative control.…”

Phylogenetic analysis and description of Eperythrozoon coccoides, proposal to transfer to the genus Mycoplasma as Mycoplasma coccoides comb. nov. and Request for an Opinion

“…Recently, phylogenetic analysis of 16S rRNA gene sequences from several of these bacteria has demonstrated that these uncultivated wall-less bacteria are not rickettsia, but instead are mycoplasmas (Rikihisa et al, 1997;Neimark & Kocan, 1997;Neimark et al, 2001Neimark et al, , 2002b. In addition, several new haemotrophic Mycoplasma species have been identified in wild and domesticated animals (Messick et al, 2002;Neimark et al, 2002bNeimark et al, , 2004). Here we show that E. coccoides…”