Phylogeny of Some Mycoplasmas from Ruminants Based on 16S rRNA Sequences and Definition of a New Cluster within the Hominis Group

Abstract

Almost complete (>96%) 16s rRNA sequences from nine ruminant mycoplasmas have been determined by solid-phase DNA sequencing. Polymorphisms were found in four of the 16s rRNA sequences, which indicated the existence of two different rRNA operons. Seven polymorphisms were found in Mycoplasma agalactiae, three were found in Mycoplasma bovis, one was found in Mycoplasma alkalescens, and one was found in Mycophinu bovirhinis. The sequence data were used for construction of phylogenetic trees. All but one of the ruminant mycoplasmas sequenced in this work clustered in the hominis group. A close relationship was found between M. agalactiae and M. bovis, with a 99% nucleotide similarity between their 16s rRNA sequences. They were also found to be members of the Mycoplasma lipophilum cluster of the hominis group. Furthermore, the 16s rRNA comparisons showed that Mycoplasma alkalescens and Mycoplasma canadense are closely related (>98.5%), and these species were found to cluster in the Mycoplasma hominis cluster of the hominis group. Interestingly, M. bovirhinis grouped in a new phylogenetic cluster of the hominis group. The new cluster, which was supported by bootstrap percentage values, signature nucleotide analysis, and higher-order structural elements, was named the Mycoplasma synoviae cluster. Mycoplasma bovoculi, Mycoplasma conjunctivae, and Mycoplasma ovipneumoniae clustered in the Mycoplasma neurolyticum cluster of the hominis group. Mycoplasma alvi clustered with Mycoplasma pirum in the M. pneumoniae cluster of the pneumoniae group.Mycoplasmas (class Mollicutes) are among the smallest microorganisms capable of self-replication and autonomous life. About 150 species are known today, and they are closely related to gram-positive bacteria with a low G+C content in the genome (17). Many mycoplasmas are pathogenic for animals, and they are therefore of great concern in veterinary medicine (18,20). Most mycoplasmas are host specific, and ruminants harbor a number of interesting species. Two very important and closely related species are Mycoplasma bovis and Mycoplasma agalactiae. The former causes calf pneumonia, mastitis, and arthritis in cattle (3,21), and the latter species is the causal agent of contagious agalactia in goats and sheep (10). The other species used for 16s rRNA sequencing in this study are also of clinical significance, except Mycoplasma alvi. Mycoplasma alkalescens causes arthritis in cattle. M. alvi has no known disease-causing potential, but has been isolated from the respiratory tract of cattle. Mycoplasma bovirhinis is often isolated from cattle with respiratory disease, but is probably not a primary pathogen. Mycoplasma bovoculi is associated with conjunctivitis and keratoconjunctivitis in cattle and is often found in the eyes of calves. Mycoplasma canadense is believed to cause mastitis in cattle. Mycoplasma conjunctivae is the causal agent of keratoconjunctivitis in goats and sheep, but it is not clear whether it is a primary or a secondary pathogen. Mycoplasma ovipneumoniae is by far the mos...

Molecular and Antigenic Characterization of aMycoplasma BovisStrain Causing an Outbreak of Infectious Keratoconjunctivitis

“…A strikingly similar banding pat- tern was observed for the 2 strains, whereas no bands were detected when sera were tested against M. agalactiae MA7, although M. agalactiae and M. bovis are closely related according to biochemical, immunological, 3 and molecular methods. 25,32 Figure 3 shows the reactivity of three representative calf sera against total proteins of M. agalactiae MA7, M. bovis PG45 T , and M. bovis Sar1. As a further tool for establishing identity of all the 39 colonies isolated in this study as M. bovis, ␣-rP48 39,40 was tested by immunoblotting against total and hydrophobic proteins extracted from M. agalactiae MA7, from M. bovis PG45 T , and from the 39 colonies designated as M. bovis Sar1.…”

Re-evaluation of the classical Mycoplasma lipophilum cluster (Weisburg et al. 1989) and description of two new clusters in the hominis group based on 16S rDNA sequences.

“…Primers RIT593 and RIT390B were used in one of the amplifications and RIT388 and RIT620B were used in the other semi-nested reaction. All PCR primers have been published previously (Pettersson et al, 1996). The first set covered the U1 to U5 regions (Gray et al, 1984) of the 16S rRNA gene and the second set defined the segment between the U2 and U8 regions.…”

“…The major group is the socalled hominis group, which was named after the human mollicute Mycoplasma hominis. The hominis B. Pettersson and others group has been subdivided into eight sublineages (clusters and branches containing single species) by Weisburg et al (1989) and Pettersson et al (1996Pettersson et al ( , 2000.…”

Characterization of Mycoplasma Isolated From an Ibex (Capra Ibex) Suffering From Keratoconjunctivitis in Northern Italy

“…This etiologic agent was first reported by Surman (1968) from an Australian sheep suffering from phlogosis of the ocular mucosa and was further identified and classified by Barile et al (1972). Phylogenetically, M. conjunctivae belongs to the Mycoplasma neurolyticum cluster of the hominis group, and is closely related to Mycoplasma bovoculi and Mycoplasma ovipneumoniae (Pettersson et al, 1996). The disease, recently described in Europe (in the Alps and Pyrenees) and in New Zealand, affects domestic small ruminants and various wild ruminants, such as chamois (Rupicapra rupicapra rupicapra), ibex (Capra ibex ibex), and mouflon (Ovis orientalis musimon; Sarrazin et al, 1990;Mayer et al, 1996;Giacometti et al, 1998;Degiorgis et al, 2000).…”