DNA relatedness between field isolates of Mycoplasma F38 group, the agent of contagious caprine pleuropneumonia, and strains of Mycoplasma capricolum

A mini-review on diagnosis of contagious caprine pleuropneumonia

Diagnosis of contagious caprine pleuropneumonia is imperative for timely detection and devising interventions that prevent disease spread and loss to farmers. Diagnosis of contagious caprine pleuropneumonia involves clinical signs, gross morphological lesions on postmortem, histopathology, culture and isolation, hematological, biochemical, serological and molecular diagnostic tests. Culture and isolation confirms the disease however it has been costly, cumbersome and difficult owing to the requirements of specific media, slow and difficult growth of causative agent Mycoplasma capricolum subsp. capripneumoniae. With the recent developments, diagnosis has comparatively eased by novel readymade media, advanced serological latex agglutination test (LAT), competitive enzyme linked immunosorbent assay (cELISA) or gene-based amplification of DNA, viz. polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), hybridization and sequencing than the cumbersome and lengthy conventional tests; however they have financial implications and require sophisticated laboratory infrastructure and technical manpower. The latex agglutination test (LAT) is rapid, simple, and better test for field and real-time diagnosis applicable to whole blood or serum and is more sensitive than the compliment fixation test (CFT) and easier than the cELISA. PCR and monoclonal antibody based ELISA being specific aid to confirmation of CCPP. Future thrust is on developing rapid, sensitive, and specific tests that are cheap and convenient for field application.

Contagious caprine pleuropneumonia - a comprehensive review

Contagious caprine pleuropneumonia (CCPP) is a serious disease of goats, occasionally sheep and wild ruminants, caused by Mycoplasma capricolum subspecies capripneumoniae (Mccp). The disease is characterized by severe serofibrinous pleuropneumonia, very high morbidity (∼100%), and mortality (80–100%). CCPP affects goats in more than 40 countries of the world thereby posing a serious threat to goat farming around the globe. The characteristic clinical signs of CCPP are severe respiratory distress associated with sero-mucoid nasal discharge, coughing, dyspnea, pyrexia, pleurodynia, and general malaise. In later stages, severe lobar fibrinous pleuropneumonia, profuse fluid accumulation in pleural cavity, severe congestion of lungs and adhesion formation is observed. Mycoplasmal antigen interactions with host immune system and its role in CCPP pathogenesis are not clearly understood. CCPP is not a zoonotic disease. Diagnosis has overcome cumbersome and lengthy conventional tests involving culture, isolation, and identification by advanced serological (LAT, cELISA) or gene-based amplification of DNA (PCR, RFLP, and hybridization) and sequencing. The latex agglutination test (LAT) is rapid, simple, and better test for field and real-time diagnosis applicable to whole blood or serum and is more sensitive than the CFT and easier than the cELISA. Moreover, the studies on antibiotic sensitivity and exploration of novel antibiotics (fluoroquinolones, macrolides) can help in better therapeutic management besides preventing menace of antibiotic resistance. Re-visiting conventional prophylactic measures focussing on developing novel strain-based or recombinant vaccines using specific antigens (capsular or cellular) should be the most important strategy for controlling the disease worldwide.

Mycoplasma capricolum subsp. capripneumoniae, the cause of contagious caprine pleuropneumonia, comprises two distinct biochemical groups

Mycoplasma capricolum subsp. capripneumoniae, the cause of the World Organisation of Animal Health- listed contagious caprine pleuropneumonia, is a member of the Mycoplasma mycoides cluster which comprises five pathogenic mycoplasmas of ruminants. These mycoplasmas are closely related immunologically and genetically which can lead to difficulties for differential diagnosis. The patterns of substrate metabolism of strains of M. c. capripneumoniae, gathered from diverse geographic regions, were studied by measurement of oxygen uptake rates. The strains fell into two major biochemical groups: one which only oxidised organic acids and glycerol and the other which could additionally metabolise sugars. Furthermore when DNA-DNA hybridisation tests were carried out these two groups of strains could be separated by their degree of DNA homology, the mean hybridisation value between members of the two groups was 86% well above the value of 70% normally used to indicate separate species. DNA-DNA hybridisation was also carried out between M. c. capripneumoniae strains and other members of the M. mycoides cluster. These experiments used labelled DNA from two representative subsp. capripneumoniae strains; these were 7/1a (organic acid-oxidising) and 4/2 LC (glucose-oxidising). The results showed a particularly close relationship of the glucose-oxidising strain to M leachii strains.

Multi-locus sequence analysis of Mycoplasma capricolum subsp. capripneumoniae for the molecular epidemiology of contagious caprine pleuropneumonia

Mycoplasma capricolum subsp. capripneumoniae (Mccp) is the causative agent of contagious caprine pleuropneumonia (CCPP), a devastating disease of domestic goats. The exact distribution of CCPP is not known but it is present in Africa and the Middle East and represents a significant threat to many disease-free areas including Europe. Furthermore, CCPP has been recently identified in Tajikistan and China. A typing method with an improved resolution based on Multi-Locus Sequence Analysis (MLSA) has been developed to trace new epidemics and to elucidate whether the recently identified cases in continental Asia were due to recent importation of Mccp. The H2 locus, a polymorphic region already in use as a molecular marker for Mccp evolution, was complemented with seven new loci selected according to the analysis of polymorphisms observed among the genome sequences of three Mccp strains. A total of 25 strains, including the two new strains from Asia, were analysed by MLSA resulting in the discrimination of 15 sequence types based on 53 polymorphic positions. A distance tree inferred from the concatenated sequences of the eight selected loci revealed two evolutionary lineages comprising five groups, which showed good correlation with geographic origins. The presence of a distinct Asian cluster strongly indicates that CCPP was not recently imported to continental Asia. It is more likely that the disease has been endemic in the area for a long time, as supported by historical clinical descriptions. In conclusion, this MLSA strategy constitutes a highly discriminative tool for the molecular epidemiology of CCPP.

Mycoplasma leachii sp. nov. as a new species designation for Mycoplasma sp. bovine group 7 of Leach, and reclassification of Mycoplasma mycoides subsp. mycoides LC as a serovar of Mycoplasma mycoides subsp. capri

The Mycoplasma mycoides cluster consists of six pathogenic mycoplasmas causing disease in ruminants, which share many genotypic and phenotypic traits. The M. mycoides cluster comprises five recognized taxa: Mycoplasma mycoides subsp. mycoides Small Colony (MmmSC), M. mycoides subsp. mycoides Large Colony (MmmLC), M. mycoides subsp. capri (Mmc), Mycoplasma capricolum subsp. capricolum (Mcc) and M. capricolum subsp. capripneumoniae (Mccp). The group of strains known as Mycoplasma sp. bovine group 7 of Leach (MBG7) has remained unassigned, due to conflicting data obtained by different classification methods. In the present paper, all available data, including recent phylogenetic analyses, have been reviewed, resulting in a proposal for an emended taxonomy of this cluster: (i) the MBG7 strains, although related phylogenetically to M. capricolum, hold sufficient characteristic traits to be assigned as a separate species, i.e. Mycoplasma leachii sp. nov. (type strain, PG50(T) = N29(T) = NCTC 10133(T) = DSM 21131(T)); (ii) MmmLC and Mmc, which can only be distinguished by serological methods and are related more distantly to MmmSC, should be combined into a single subspecies, i.e. Mycoplasma mycoides subsp. capri, leaving M. mycoides subsp. mycoides (MmmSC) as the exclusive designation for the agent of contagious bovine pleuropneumonia. A taxonomic description of M. leachii sp. nov. and emended descriptions of M. mycoides subsp. mycoides and M. mycoides subsp. capri are presented. As a result of these emendments, the M. mycoides cluster will hereafter be composed of five taxa comprising three subclusters, which correspond to the M. mycoides subspecies, the M. capricolum subspecies and the novel species M. leachii.

Revised minimal standards for description of new species of the class Mollicutes (division Tenericutes)

Minimal standards for novel species of the class Mollicutes (trivial term, mollicutes), last published in 1995, require revision. The International Committee on Systematics of Prokaryotes Subcommittee on the Taxonomy of Mollicutes proposes herein revised standards that reflect recent advances in molecular systematics and the species concept for prokaryotes. The mandatory requirements are: (i) deposition of the type strain into two recognized culture collections, preferably located in different countries; (ii) deposition of the 16S rRNA gene sequence into a public database, and a phylogenetic analysis of the relationships among the 16S rRNA gene sequences of the novel species and its neighbours; (iii) deposition of antiserum against the type strain into a recognized collection; (iv) demonstration, by using the combination of 16S rRNA gene sequence analyses, serological analyses and supplementary phenotypic data, that the type strain differs significantly from all previously named species; and (v) assignment to an order, a family and a genus in the class, with an appropriate specific epithet. The 16S rRNA gene sequence provides the primary basis for assignment to hierarchical rank, and may also constitute evidence of species novelty, but serological and supplementary phenotypic data must be presented to substantiate this. Serological methods have been documented to be congruent with DNA-DNA hybridization data and with 16S rRNA gene placements. The novel species must be tested serologically to the greatest extent that the investigators deem feasible against all neighbouring species whose 16S rRNA gene sequences show >0.94 similarity. The investigator is responsible for justifying which characters are most meaningful for assignment to the part of the mollicute phylogenetic tree in which a novel species is located, and for providing the means by which novel species can be identified by other investigators. The publication of the description should appear in a journal having wide circulation. If the journal is not the International Journal of Systematic and Evolutionary Microbiology, copies of the publication must be submitted to that journal so that the name may be considered for inclusion in a Validation List as required by the International Code of Bacteriological Nomenclature (the Bacteriological Code). Updated informal descriptions of the class Mollicutes and some of its constituent higher taxa are available as supplementary material in IJSEM Online.

Characterisation of Mycoplasma capricolum P60 surface lipoprotein and its evaluation in a recombinant ELISA

This paper reports the identification and characterisation of a 60kDa surface protein antigen (P60) of Mycoplasma capricolum subspecies capricolum (Mcc), and describes its diagnostic application. Genomic localization and presence in P60 of conserved functional domains suggested a structural and functional relationship with the immunodominant antigen P48 of Mycoplasma agalactiae, a basic membrane protein. A rP60-ELISA was developed, and it resulted in a high specificity for Mcc infections after evaluation with 125 goat sera. The comparison with an existent ELISA based on whole Mcc cell lysates showed that the two assays have comparable sensitivities, but the rP60-ELISA has the significant advantage of a greater specificity. Results indicate that P60 is a potential marker of Mcc infection, especially useful in areas where the presence of M. capricolum subspecies capripenumoniae is also reported.

A PCR for the detection of mycoplasmas belonging to the Mycoplasma mycoides cluster: application to the diagnosis of contagious agalactia

Contagious agalactia is a mycoplasmal infection caused by Mycoplasma agalactiae, Mycoplasma mycoides subsp. mycoides LC, M. mycoides subsp. capri, Mycoplasma capricolum subsp. capricolum and Mycoplasma putrefaciens. Identification of the causative organisms is usually performed by isolation and classical biochemical and serological tests, though this is a lengthy and cumbersome process for mycoplasmas. Specific PCR assays have been developed for the identification of Mycoplasma agalactiae and M. putrefaciens. For members of the M. mycoides cluster existing PCR tests are based on the amplification of highly conserved genes coding for ribosomal proteins, hence a possibility of cross-reactions. The gene glk, coding for a glucokinase, that is found in this cluster is very distantly related to any other bacterial glucokinase described so far. It was therefore chosen as target to design a new PCR test. The validation was performed independently in three laboratories in France and India using over 100 mycoplasma strains of various geographical origins. All strains belonging to the M. mycoides cluster were detected by amplification of the expected PCR product (428 bp) while no amplification was obtained from M. agalactiae strains. Our results demonstrate the universality of this PCR in spite of the great heterogeneity found within this cluster. This new tool may be of great help for the implementation of control measures directed towards contagious agalactia.

A specific PCR for the identification of Mycoplasma capricolum subsp. capripneumoniae, the causative agent of contagious caprine pleuropneumonia (CCPP)

Contagious caprine pleuropneumonia is a severe infectious disease of goats in Africa and the Middle East. It is caused by a fastidious mycoplasma, Mycoplasma capricolum subsp. capripneumoniae, a member of the "M. mycoides cluster". Members of this cluster share genomic and antigenic features, which result in common biochemical and serological properties, complicating species identification. Two species of this cluster, M. mycoides subsp. capri and M. mycoides subsp. mycoides large colony biotype, are very often isolated from clinical cases resembling contagious caprine pleuropneumonia. Furthermore, in the laboratory, M. capricolum subsp. capripneumoniae can be easily confused with the closely related capricolum subspecies. Considering these constraints and the scarcity of available methods for identification, a specific polymerase chain reaction was developed. A DNA fragment of 7109 bp containing genes coding for the arginine deiminase pathway (ADI) was chosen as target sequence for the selection of a specific primer pair. The full ADI operon from M. capricolum subsp. capripneumoniae strain GL100 was sequenced. Polymorphism within this locus was analyzed by comparison with the sequence from the closely related IPX strain (M. capricolum subsp. capricolum). It varied from 0.6% to 3.5%. The highest divergence was found in a region coding for arcD. Therefore, this gene was chosen as target for the specific amplification of a 316 bp-long DNA fragment. The specificity of this PCR was validated on 14 M. capricolum subsp. capripneumoniae strains and 27 heterologous strains belonging to the "M. mycoides cluster" and M. putrefaciens. This new PCR will be a valuable tool for the surveillance of contagious caprine pleuropneumonia.

Genetic diversity among Mycoplasma species bovine group 7: clonal isolates from an outbreak of polyarthritis, mastitis, and abortion in dairy cattle

A comprehensive genetic analysis of 60 Mycoplasma sp. bovine group 7 isolates from different geographic origins and epidemiological settings is presented. Twenty-four isolates were recovered from the joints of calves during sporadic episodes of polyarthritis in geographically distinct regions of Queensland and New South Wales, Australia, including two clones of the type strain PG5O. A further three Australian isolates were also recovered from the tympanic bulla, retropharyngeal lymph node and the lung and another three isolates had unconfirmed histories. Six isolates originated from Germany, Portugal, Nigeria, and France. Twenty-four epidemiologically related isolates of Mycoplasma sp. bovine group 7 were recovered from multiple tissue sites and body fluids of infected calves with polyarthritis, mastitic milk, and from the stomach contents, lung and liver from aborted foetuses in three large, centrally managed dairy herds in New South Wales, Australia. Restriction endonuclease analysis (REA) of genomic DNA differentiated 29 Cfol profiles among these 60 isolates and grouped all 24 epidemiologically related isolates in a defined pattern showing a clonal origin. Three isolates of this clonal cluster were recovered from mastitic milk and the synovial exudate of clinically-affected calves and appeared sporadically for periods up to 18 months after the initial outbreak of polyarthritis indicating a persistent, close association of the organism with cattle in these herds. The Cfol profile representative of the clonal cluster was distinguishable from profiles of isolates recovered from multiple, unrelated cases of polyarthritis in Queensland and New South Wales and from other countries. All 24 isolates from the clonal cluster possessed a plasmid (pBG7AU) with a molecular size of 1022 bp. DNA sequence analysis of pBG7AU identified two open reading frames sharing 81 and 99% DNA sequence similarity with hypothetical replication control proteins A and B respectively, previously described in plasmid pADB201 isolated from M. mycoides subspecies mycoides. Other isolates of bovine group 7, epidemiologically unrelated to the clonal cluster, including two clones of the type strain PG5O, possessed a similar-sized plasmid. These data confirm that Mycoplasma sp. bovine group 7 is capable of migrating to, and multiplying within, different tissue sites within a single animal and among different animals within a herd.

Molecular analysis of field strains of Mycoplasma capricolum subspecies capripneumoniae and Mycoplasma mycoides subspecies mycoides, small colony type isolated from goats in Tanzania

A molecular analysis of strains of Mycoplasma capricolum subsp. capripneumoniae (M. capripneumoniae) and Mycoplasma mycoides subsp. mycoides, small colony type (M. mycoides SC) isolated from goats was performed using the amplified fragment length polymorphism (AFLP) and pulsed-field gel electrophoresis (PFGE) fingerprinting techniques. Among the 11 field strains of M. capripneumoniae from Tanzanian goats, two AFLP patterns were demonstrated, with 10 of the strains showing indistinguishable patterns. Five Kenyan strains of M. capripneumoniae produced three AFLP patterns, with two of them being indistinguishable from the 10 identical Tanzanian and one Ugandan strain (M74/93) isolated from sheep. The AFLP pattern of the type strain (F38(T)) was identical to two Kenyan strains (Baringo and G183/82). On PFGE analysis, all the examined M. capripneumoniae strains exhibited identical PFGE profiles.Five field strains of M. mycoides SC isolated from goats displayed identical AFLP patterns except for one strain which differed from others at only one position. The AFLP pattern of the type strain of M. mycoides SC (PG1(T)) was different from the field strains. The five field strains of M. mycoides SC produced identical PFGE profiles, which were, however, different from the type strain. The AFLP and PFGE profiles of M. mycoides SC strains from goats were identical to those of six strains isolated from cattle affected with contagious bovine pleuropneumonia (CBPP) in the same areas. The results of this study suggest a close epidemiological linkage between strains of M. capripneumoniae and between M. mycoides SC type, respectively, isolated from goats in Tanzania.

Phylogeny of the Mycoplasma mycoides cluster as shown by sequencing of a putative membrane protein gene

The Mycoplasma mycoides cluster is made of six species that are closely related both genetically and phenotypically. Two are of particular importance, M. mycoides subsp. mycoides SC causing contagious bovine pleuropneumonia and M. capricolum subsp. capripneumoniae causing contagious caprine pleuropneumonia. The sequences of a putative membrane protein gene and partial flanking open reading frames have been obtained from various strains in this cluster, including all reference strains. Sequence analysis showed this locus is present and fully conserved in all strains of M. mycoides subsp. mycoides SC isolated from geographically most distant places worldwide. In M. capricolum subsp. capripneumoniae polymorphism in this locus has been found at seven positions and revealed that they can be used as epidemiological markers. Conserved regions were used to define a primer pair that enables the amplification by PCR of two fragments 302 and 1298bp long, respectively. The 302bp long fragment contains an intergenic sequence that can be used for phylogenetic studies or for identification purposes. Parsimony analysis on an alignment of 49 DNA sequences show a subdivision of the M. mycoides cluster into two subgroups that is in accordance with results obtained by phenotypic methods. Two lineages exist within the capricolum subgroup, one of them clustering strains identified as M. capricolum subsp. capricolum, M. capricolum subsp. capricolum and M. sp Bovine Group 7. However M. capricolum subsp. capripneumoniae strains can readily be identified by three specific nucleotide positions or by sequencing the 1298bp long fragment. There is no clear subdivision within the mycoides subgroup, supporting the idea that M. mycoides subsp. mycoides LC and M. mycoides subsp. capri should not be separated into two subspecies. Mycoplasma mycoides subsp. mycoides SC strains can easily be distinguished as they bear an insertion sequence 15bp downstream from the stop codon of the membrane protein gene.

Genomic variations of Mycoplasma capricolum subsp. capripneumoniae detected by amplified fragment length polymorphism (AFLP) analysis

The genetic diversity of Mycoplasma capricolum subsp. capripneumoniae strains based on determination of amplified fragment length polymorphisms (AFLP) is described. AFLP fingerprints of 38 strains derived from different countries in Africa and the Middle East consisted of over 100 bands in the size range of 40-500 bp. The similarity between individual AFLP profiles, calculated by Jaccard's coefficient, ranged from 0.92 to 1.0. On the basis of the polymorphisms detected, the analysed strains can explicitly be grouped into two major clusters, equivalent to two evolutionary lines of the organism found by 16S rDNA analysis. The present data support previous observations regarding genetic homogeneity of M. capricolum subsp. capripneumoniae, and confirm the two evolutionary lines of descent found by analysis of 16S rRNA genes.

Comparative analysis of the lppA locus in Mycoplasma capricolum subsp. capricolum and Mycoplasma capricolum subsp. capripneumoniae

The lppA gene, encoding the lipoprotein named LppA[Mcaca] was characterised in Mycoplasma capricolum subsp. capricolum. It encodes a lipoprotein with an apparent molecular mass of 57 kDa as determined by SDS-PAGE. Using antibodies directed against recombinant LppA[Mcaca], we showed the expression of this lipoprotein in all M. capricolum subsp. capricolum by immunoblot analysis. The serum did not cross-react with other members of the Mycoplasma mycoides cluster, hence showing that LppA[Mcaca] was antigenically specific to M. capricolum subsp. capricolum. The lppA gene was conserved within the subspecies and was used for the development of a specific PCR assay for the identification of M. capricolum subsp. capricolum. The taxonomically related Mycoplasma capricolum subsp. capripneumoniae (F38) was found to contain an lppA-pseudo-gene. It showed high similarity to functional lppA genes of other mycoplasmas in the M. mycoides cluster. However, it contained interrupted open reading frames. Moreover, the nucleotide sequence of the lppA pseudo-genes in different strains of M. capricolum subsp. capripneumoniae were quite variable. Interestingly, the lppA pseudo-gene had a size similar to that of the functional lppA genes of other mycoplasmas of the M. mycoides cluster and occupied the same genomic location as the latter ones in the vicinity of the mtlD genes. This study showed that all members of the M. mycoides cluster contain each a species-, subspecies- respectively type- specific lppA gene analogue which encodes a lipoprotein that has structural and functional relationship to the surface lipoprotein LppA [MmymySC], previously named P72, of M. mycoides subsp mycoides SC, with the exception of M. capricolum subsp. capripneumoniae which seems not to express an LppA analogue.

Molecular evolution of Mycoplasma capricolum subsp. capripneumoniae strains, based on polymorphisms in the 16S rRNA genes

Mycoplasma capricolum subsp. capripneumoniae belongs to the so-called Mycoplasma mycoides cluster and is the causal agent of contagious caprine pleuropneumonia (CCPP). All members of the M. mycoides cluster have two rRNA operons. The sequences of the 16S rRNA genes of both rRNA operons from 20 strains of M. capricolum subsp. capripneumoniae of different geographical origins in Africa and Asia were determined. Nucleotide differences which were present in only one of the two operons (polymorphisms) were detected in 24 positions. The polymorphisms were not randomly distributed in the 16S rRNA genes, and some of them were found in regions of low evolutionary variability. Interestingly, 11 polymorphisms were found in all the M. capricolum subsp. capripneumoniae strains, thus defining a putative ancestor. A sequence length difference between the 16S rRNA genes in a poly(A) region and 12 additional polymorphisms were found in only one or some of the strains. A phylogenetic tree was constructed by comparative analysis of the polymorphisms, and this tree revealed two distinct lines of descent. The nucleotide substitution rate of strains within line II was up to 50% higher than within line I. A tree was also constructed from individual operonal 16S rRNA sequences, and the sequences of the two operons were found to form two distinct clades. The topologies of both clades were strikingly similar, which supports the use of 16S rRNA sequence data from homologous operons for phylogenetic studies. The strain-specific polymorphism patterns of the 16S rRNA genes of M. capricolum subsp. capripneumoniae may be used as epidemiological markers for CCPP.

Late lesions of experimental contagious caprine pleuropneumonia caused by Mycoplasma capricolum ssp. capripneumoniae

A clinical, bacteriological, serological and patho-anatomical study was carried out on 12 goats surviving the acute stage of contagious caprine pleuropneumonia (CCPP), experimentally produced with Mycoplasma capricolum ssp. capripneumoniae (M. capripneumoniae), with the major aims of investigating the chronic stage of the disease and elucidating the possibility of a carrier state beyond the acute fulminant phase. The goats were killed 9, 16, 82 or 126 days after the onset of acute clinical signs. On day 9, clinical signs included low grade fever and persistent coughing. Thereafter, only intermittent coughing was recorded. Serum titres of complement-fixing antibodies to M. capripneumoniae were high at the period of fever but dropped thereafter. Post-mortem examination showed acute fibrinous pleuropneumonia on days 9 and 16, and chronic pleuropneumonia on days 82 and 126, including sequester formations in goats killed on day 126. Mycoplasma capripneumoniae was isolated on days 9 and 16 but not on later occasions. The study showed that goats recovered from acute CCPP may have lesions for a long time thereafter but provide no evidence of a carrier state among long-term survivors.

Monoclonal antibody E8-18 identifies an integral membrane surface protein unique to Mycoplasma capricolum subsp. capripneumoniae

Monoclonal antibody (MAb) E8-18 reacted with four isolates of Mycoplasma capricolum subsp. capripneumoniae in Western blots identifying an epitope on a 24 kDa antigen (p24). MAb E8-18 did not react with 11 isolates belonging to four other Mycoplasma species or subspecies closely related to M. capricolum subsp. capripneumoniae. A combination of trypsin treatment of intact organisms and detergent-phase partitioning revealed p24 to be an integral M. capricolum subsp. capripneumoniae surface membrane protein.

Phylogeny of the Mycoplasma mycoides cluster as determined by sequence analysis of the 16S rRNA genes from the two rRNA operons

The so-called Mycoplasma mycoides cluster consists of six species or subspecies of mycoplasmas (Mollicutes). These species are pathogenic for ruminants and some of them are of great concern in veterinary medicine. The members of the M. mycoides cluster have two rRNA operons (rrnA and rrnB). The nucleotide sequences of the 16S rRNA genes of 10 strains, representing all of the known species and subspecies of the M. mycoides cluster, were determined by direct automated solid-phase DNA sequencing. The sequences of both rRNA operons were determined by a novel strategy involving in vitro amplification by PCR with one operon-specific primer pair and one general primer pair. Interestingly, sequence differences (polymorphisms) between the two operons were observed for all strains. Two strains of M. capricolum subsp. capripneumoniae were sequenced, and 15 polymorphisms were found in the type strain (F38) and 17 polymorphisms were found in the other strain (4/2LC). Eight polymorphisms were found in the 16S rRNA genes of the M. mycoides subsp. mycoides small-colony type, and sequence length variations in a poly(A) region were observed in the 16S rRNA genes of the two operons of this species. Secondary-structure analysis showed that polymorphisms were present in both stem and loop regions. The nucleotide substitutions in the polymorphic sites of the stem regions often resulted in a change from a canonical to a noncanonical base pairing or vice versa. A compensatory mutation was never observed in the other nucleotide of the base pair. Phylogenetic analysis based on the 16S rRNA sequences indicated that Mycoplasma sp. strain PG50 should be included in the M. capricolum species group. Furthermore, the 16S rRNA sequences of M. mycoides subsp. capri and the M. mycoides subsp. mycoides large-colony type were 99.9% identical. We therefore suggest that these species be reclassified in a common species group (for instance, "Mycoplasma capri") distinct from the M. mycoides subsp. mycoides small-colony type, which formed an intermediate branch between the M. capricolum species group and the M. capri species group.

Diagnosis of contagious caprine pleuropneumonia by detection and identification of Mycoplasma capricolum subsp. capripneumoniae by PCR and restriction enzyme analysis

Contagious caprine pleuropneumonia (CCPP), one of the most serious and dramatic diseases of goats, is caused by Mycoplasma capricolum subsp. capripneumoniae (M. capripneumoniae). This organism is very difficult to isolate and to correctly identify. In a previous report we described a method for the rapid detection and identification of M. capripneumoniae. This method is based on a PCR system by which a segment of the 16S rRNA gene from all mycoplasmas of the M. mycoides cluster can be amplified. The PCR product is then analyzed by restriction enzyme cleavage for the identification of M. capripneumoniae DNA. This system has now been further evaluated with respect to specificity and diagnostic efficacy for the identification and direct detection of the organism in clinical material. Identification by restriction enzyme analysis of amplified DNA from mycoplasmas of the M. mycoides cluster was verified for 55 strains, among which were 15 strains of M. capripneumoniae. The PCR was applied to clinical samples from the nose, ear, pharynx, pleural fluid, and lung tissue containing M. capripneumoniae or other mycoplasmas. As expected, mycoplasmas belonging to the M. mycoides cluster could be detected by the PCR. Restriction enzyme analysis of the PCR products could then be applied for the identification of M. capripneumoniae. Clinical samples and cultures containing M. capripneumoniae were dried on filter paper, to try an easier sample transport method, and were tested by PCR. M. capripneumoniae DNA could be detected in the dried specimens, but the sensitivity of the PCR test was reduced.

Application of an arbitrarily-primed polymerase chain reaction to mycoplasma identification and typing within the Mycoplasma mycoides cluster

An arbitrarily-primed polymerase chain reaction (AP-PCR) was developed using a primer pair, Mlip1 and Mlip4, for members of the Mycoplasma mycoides cluster, a group containing important pathogens of small and large ruminants. Parameters that influence the reproducibility of this assay were optimized: magnesium, primer and template concentrations, and pH. AP-PCR fingerprinting, carried out on a number of strains of each of the six species or subspecies belonging to the mycoides cluster, allowed the typing of strains within each group. The AP-PCR assay showed that the cluster can be divided into two groups: (i) high and (ii) no genomic polymorphism variation. In addition, specific polymorphic bands for members of species or subspecies included in this cluster were amplified by this AP-PCR method, thus allowing their identification.

The use of monoclonal antibodies in the diagnosis of contagious caprine pleuropneumonia (CCPP)

Contagious caprine pleuropneumonia is a severe disease affecting goats in Eastern Africa and the Middle East, caused by Mycoplasma sp. type F38. Its exact geographical distribution is however not exactly known due to the lack of specificity of the available serological tests and the difficulty in cultivating M. sp. F38. A panel of monoclonal antibodies (mAbs) was produced, using crude or membrane proteins antigens from type F38 strains to immunize mice. The reactivity of the mAbs was tested by an immunobinding assay with crude mycoplasma antigens spotted on nitrocellulose filters. One hundred and twelve antigens, standardized at 0.5 mg protein/ml, were used. Mycoplasma strains were chosen among closely related species of the "mycoides cluster", M. capricolum, Group 7 of Leach, M. mycoides mycoides LC, M. mycoides mycoides SC, M. mycoides capri, as well as among species that are isolated from goat lungs, M. arginini, M. ovipneumoniae, M. putrefaciens, M. agalactiae. Out of 60 mAbs, 4 were chosen to build an identification test for mycoplasmas of the "mycoides cluster". Controls showed that accurate identification could be hampered by antigenic heterogeneity within the M. capricolum species. One mAb was used for the direct detection of M. sp. F38 antigen in pleural fluid from goats suspected of CCPP. The sensitivity of the test can be estimated at 0.5 micrograms protein/ml. Comparison with isolation results show a 74% agreement between the two methods. The same mAb was used to build a blocking ELISA. This serological test was strictly specific for CCPP. It detects antibodies in sera of naturally infected or artificially immunized animals while it remained negative with hyperimmune sera to related strains such as PG 50. Direct antigen detection and blocking ELISA are tools that may enable a better assessment of CCPP distribution.

Characterization of the 16S rRNA genes from Mycoplasma sp. strain F38 and development of an identification system based on PCR

Mycoplasma sp. (strain F38) is the causative agent of contagious caprine pleuropneumonia, which is a goat disease of great global concern. Strain F38 belongs to the so-called "Mycoplasma mycoides cluster," and the members of this cluster have many biochemical and serological properties in common, which makes it difficult to differentiate between them by conventional methods. Their phylogenetic interrelationship are thus uncertain. The 16S rRNA gene of the rrnB operon from strain F38 was cloned and sequenced. The sequence was compared with the 16S rRNA sequences of related mycoplasmas, and phylogenetic trees were constructed by parsimony analysis. A three-way ambiguity among strain F38, Mycoplasma capricolum, and Mycoplasma sp. strain PG50 was observed in the trees. This observation is in agreement with a recent proposal to reclassify strain F38 and M. capricolum. A primer set was designed for in vitro amplification by PCR of a fragment of the 16S rRNA genes from the M. mycoides cluster. The amplimers of strain F38 could be distinguished easily from the corresponding amplimers from other members of the M. mycoides cluster by restriction enzyme analysis with PstI. This observation was utilized to design an identification system for strain F38. Part of the 16S rRNA gene of the rrnA operon from strain F38 was also cloned, and several sequence differences between the two rRNA operons were discovered, revealing microheterogeneity between the two 16S rRNA genes of this organism.