Development of a species-specific DNA probe for Mycoplasma capricolum

Mycoplasma agalactiae, an Etiological Agent of Contagious Agalactia in Small Ruminants: A Review

Mycoplasma agalactiae is one of the causal agents of classical contagious agalactia (CA), a serious, economically important but neglected enzootic disease of small ruminants. It occurs in many parts of the world and most notably in the Mediterranean Basin. Following the infection common complications are septicaemia, mastitis, arthritis, pleurisy, pneumonia, and keratoconjunctivitis. Primary or tentative diagnosis of the organism is based upon clinical signs. Various serological tests, namely, growth precipitation, immunofluorescence, complement fixation test, haemagglutination inhibition, agglutination, immunodiffusion, enzyme immunoassays, immunoelectrophoresis, blotting techniques, and others, are available. Molecular tools seem to be much more sensitive, specific, and faster and help to differentiate various strains. The real-time PCR, multiplex PCR, quantitative PCR, PCR-RFLP, MLST, and gene probes, complementary to segments of chromosomal DNA or 16S ribosomal RNA (rRNA), have strengthened the diagnosis of M. agalactiae. Both live attenuated and adjuvant (alum precipitated or saponified) inactivated vaccines are available with greater use of inactivated ones due to lack of side effects. The present review discusses the etiology, epidemiology, pathogenesis, and clinical signs of contagious agalactia in small ruminants along with trends and advances in its diagnosis, treatment, vaccination, prevention, and control strategies that will help in countering this disease.

Cloning of Mycoplasma synoviae genes encoding specific antigens and their use as species-specific DNA probes

A genomic library of Mycoplasma synoviae (MS) was generated by using bacteriophage lambda gt11 as a cloning and expression vector. Identification of recombinant clones highly specific to MS was achieved by screening the library for expression of MS proteins with polyclonal antiserum that had been preadsorbed with 6 heterologous avian mycoplasma species antigens. Expression of the recombinant clones in Escherichia coli followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the total cell lysates and immunoblot yielded a predominant reactive fusion protein of 165 kD. Two clones (MS2/28 and MS2/12) that yielded inserts of different size were selected. The 2 MS DNA inserts were subcloned in a plasmid vector, labeled with digoxigenin, and used as probes for the specific recognition of several MS strains. A high degree of conservation was demonstrated for the MS2/12 and MS2/28 genes in tested MS strains. In addition, neither DNA fragment recognized any other avian mycoplasma species (M. gallisepticum, M. meleagridis, M. gallinarum, M. iners, M. anatis, and M. iowae), thus indicating their high specificity to MS. The sensitivity of the slot blot hybridization method using digoxigenin-labeled MS2/12 and MS2/28 probes for direct detection of MS from broth cultures of field isolates was 10(5) colony-forming units/ml. These results demonstrate the effectiveness of adsorbed antisera for the isolation of species-specific mycoplasma DNA and the potential for its use as probes for the specific and direct detection of MS from broth cultures of field isolates.

Polymerase chain reaction and restriction endonuclease digestion for selected members of the "Mycoplasma mycoides cluster" and Mycoplasma putrefaciens

A specific diagnostic method using the polymerase chain reaction, together with restriction endonuclease digestion patterns, was developed for members of the "Mycoplasma mycoides cluster" that normally occur in the United States (i.e., Mycoplasma mycoides subsp. mycoides Large Colony and Mycoplasma capricolum subsp. capricolum in addition to "cluster" mycoplasma, bovine serogroup 7, and Mycoplasma putrefaciens. The digestion of "cluster" polymerase chain reaction DNA (1,225 bp) amplification products with restriction enzymes AseI and SspI gave mycoplasma species-specific patterns for all strains of M. mycoides subsp. mycoides Large Colony, M. capricolum subsp. capricolum, and bovine group 7 tested. Moreover, we found a nonspecific amplification product for M. putrefaciens that occurred with the oligonucleotide primers used for the "M. mycoides cluster" reaction. However, the restriction endonuclease digestion patterns observed with the restriction enzymes AluI, AseI, and SspI for M. putrefaciens were different than the digestion patterns obtained for the other "cluster" mycoplasmas. This report confirms the usefulness of polymerase chain reaction DNA amplification allied with restriction enzyme digestion profile analysis for the rapid and specific identification of mycoplasmas belonging to the "M. mycoides cluster" and M. putrefaciens.

Detection of Mycoplasma agalactiae in sheep milk samples by polymerase chain reaction

We developed a simple and rapid method for DNA extraction from sheep milk to use for polymerase chain reaction (PCR) diagnosis of Mycoplasma agalactiae. We tested 357 samples from 21 newly infected flocks (group 1) and 87 samples from 8 flocks infected in the past (group 2). PCR results were compared with those of conventional culture. By PCR we detected 175 positives in group 1, while by culture we detected only 153. Milk samples from group 2 were negative, both by PCR assay and by culture. Our PCR is much faster than culture and reduces the time required for diagnosis from several days to 5 h. The method could be used for the routine diagnosis of contagious agalactia caused by Mycoplasma agalactiae.

Rapid and specific detection of Mycoplasma agalactiae by polymerase chain reaction

A polymerase chain reaction (PCR)-based test was developed for the detection of Mycoplasma agalactiae in sheep milk samples. Two oligonucleotide primers were designed to amplify a 375 bp fragment of M. agalactiae chromosomal DNA. Amplified products were analyzed by agarose gel electrophoresis and Southern blot hybridization using a fluorescein labeled 528 bp probe. The primers allowed the amplification of fragment of M. agalactiae DNA and did not amplify any specific fragment of other mycoplasmal DNAs (M. capricolum, M. mycoides subsp. mycoides, M. mycoides subsp. capri, M. putrefaciens, M. arginini and M. bovis) or other bacterial DNAs (S. aureus, S. epidermidis, P. haemalytica, E. coli, S. agalactiae, S. dysgalactiae, S. uberis, B. cereus, P. aeruginosa, S. durans, L. lactis, L. lactis var. diacetilactis, L. mesenteroides, S. thermophilus, L. bulgaricus and L. casei). The limit of detection of PCR assay was between 2.5 and 25 fg of purified DNA and 10(2) CCU ml-1 on mycoplasma cultures. These results indicate that the PCR technique can be used as a rapid and specific diagnostic method for detection of M. agalactiae.

Development of two PCR assays for the identification of mycoplasmas causing contagious agalactia

A new detection test for the mycoplasmas causing contagious agalactia, Mycoplasma agalactiae, M. capricolum subsp. capricolum and M. mycoides subsp. mycoides L. C., was developed. It was based on two polymerase chain reaction assays: the Ma-PCR for the detection of M. agalactiae and the MYC-PCR for the 'mycoides cluster' thus including M. capricolum subsp. capricolum and M. mycoides subsp. mycoides L. C. An M. agalactiae strain was identified by a 933-bp Ma-PCR product and no amplification with the MYC-PCR. In contrast, a 460-bp MYC-PCR product and a negative or a 350-bp Ma-PCR product characterized a 'mycoides cluster' strain. M. capricolum subsp. capricolum and M. mycoides subsp. mycoides L. C. were identified by their species-specific AseI pattern of the 460-bp MYC-PCR product.

A PCR-based test for the specific identification of Mycoplasma mycoides subspecies mycoides SC

The polymerase chain reaction (PCR) was used to develop a test for the detection of Mycoplasma mycoides subspecies mycoides SC in the tissues of animals infected with contagious bovine pleuropneumonia (CBPP). Two sets of primers were designed; one set (MC323/MC358) to amplify a approximately 1.5-kbp DNA fragment from all the members of the M. mycoides 'Cluster' and the other set (MM450/MM451) specifically amplified a 574-bp DNA fragment from M. mycoides subspecies. The PCR products could be differentiated further by digestion with the restriction enzyme AsnI. Enzyme digestion of amplification products from M. m. mycoides SC produced 2 fragments, whereas the other 2 M. mycoides subspecies, M. m. mycoides LC and M. m. capri, produced 3 fragments. This test was shown to be very sensitive, being able to detect between 10 and 100 organisms. Cattle were experimentally infected with the Gladysdale strain of M. m. mycoides SC, and samples of serum and mucus were taken periodically, as were postmortem samples of lung, lymph node, pleural fluid, synovial fluid, and tracheal swabs. Complement fixation test on serum samples, culture of postmortem tissues, and histopathologic examination confirmed disease. DNA was extracted from postmortem samples and amplified by PCR using primers MM450 and MM451. Digestion of products using AsnI allowed the specific identification of M. m. mycoides SC. This test could confirm CBPP in 48 hours and was thus capable of giving a more rapid result than the traditional methods of culture, isolation, and identification using biochemical and serological techniques.

A species-specific DNA probe for the detection of Mycoplasma agalactiae

A 4.5 kb M. agalactiae DNA fragment present in strains from different areas of Sardinia was cloned and used to detect M. agalactiae DNA in sheep milk samples by dot blot hybridization. The probe recognized only M. agalactiae strains and did not cross-hybridize with other mycoplasmas (M. capricolum, M. mycoides subsp. capri, M. mycoides subsp. mycoides, M. putrefaciens and M. arginini) or bacteria (E. coli, P. hemolytica, S. aureus, S. epidermis, L. casei, S. durans, S. lactis and S. thermophilus) which may also be found in sheep milk.