Specific detection and typing of Mycoplasma synoviae strains in poultry with PCR and DNA sequence analysis targeting the hemagglutinin encoding gene vlhA

Rapid and sensitive detection of Mycoplasma synoviae using RPA combined with Pyrococcus furiosus Argonaute

Mycoplasma synoviae (MS) is an important pathogen in laying hens and causes serious economic losses in poultry production. Rapid, accurate and specific detection is important for the prevention and control of MS. Argonaute from Pyrococcus furiosus (PfAgo) is emerging as a nucleic acid detector that works via "dual-step" sequence-specific cleavage. In this study, an MS detection method combining recombinase polymerase amplification (RPA) and PfAgo was established. Through elaborate design and screening of RPA primers and PfAgo gDNA and condition optimization, amplification and detection procedures can be completed within 40 min, whereas the results were superficially interpreted under UV and blue light. The sensitivity for MS detection was 2 copies/µL, and the specificity results showed no cross reaction with other pathogens. For the detection of 31 clinical samples, the results of this method and qPCR were completely consistent. This method provides a reliable and convenient method for the on-site detection of MS that is easy to operate without complex instruments and equipment.

Molecular assay for detecting MS-H vaccine strain and immune response mechanisms in chickens receiving one or two doses of live MS-H vaccine

The MS-H vaccine, containing a live strain of Mycoplasma synoviae, is a feasible option for controlling M. synoviae infection in poultry flocks. A comprehensive understanding of vaccinated chickens, including strain differentiation and immune response mechanisms, is required to optimize vaccination strategy. This study aimed to verify the PCR-RFLP molecular assay as a convenient technique for detecting the MS-H vaccine strain and to characterize the immune response mechanisms in experimental layer-type chickens receiving one of three different vaccination programmes; a single dose at either 9 or 12 weeks of age or two doses at both 9 and 12 weeks of age. The PCR-RFLP assay, using restriction enzyme TasI to digest vlhA gene-targeted PCR amplicons, was performed to evaluate vaccine administration by detecting the MS-H vaccine strain in vaccinated chickens and differentiating it from non-vaccine strains such as WVU1853 reference strain and Thai M. synoviae field strains. Results demonstrated that vaccination in layer-type chickens, whether as one or two doses, stimulated immune response mechanisms with no significant advantages of two administrations over a single administration. Serological responses in vaccinated chickens, examined by RPA test and ELISA, were initially detected at 2 weeks post-vaccination, continuously increased, and then remained at the baseline levels from 6 to 9 weeks post-vaccination. Cellular immune responses against both homologous and heterologous antigens, examined by the MTS tetrazolium assay, were similar in the early period post-vaccination, whereas cellular immune response against the homologous MS-H antigen was improved in the late period post-vaccination.

Molecular characterization and antimicrobial susceptibility profiles of Thai Mycoplasma synoviae isolates

Mycoplasma synoviae (MS) infection is mainly controlled by pathogen-free flocks' maintenance, medication in infected flocks, and vaccination in high-risk flocks. The effective control strategy requires convenient approach for detecting and differentiating MS strains and reliable drug susceptible evidence for deciding on reasonable antimicrobial usage. This study aimed to characterize the partial vlhA gene of nine Thai MS isolates circulated in chickens in 2020, to verify the PCR-RFLP assay for strain differentiation, and to determine the eight antimicrobial susceptibility profiles using microbroth dilution method. Based on sequence analysis of the partial vlhA gene, Thai MS isolates in 2020 were classified as types E and L with 19 and 35 amino acid lengths, respectively. The developed PCR-RFLP assay could detect and differentiate vaccine and Thai field strains. Most Thai MS isolates in this study were susceptible to tylosin, tylvalosin, tiamulin, doxycycline, oxytetracycline, tilmicosin, and lincomycin-spectinomycin at MIC₅₀ values of 0.0391, 0.0098, 0.0781, 0.1563, 0.1563, 0.625 and 0.625 μg/mL, respectively; and resistance to enrofloxacin at MIC₅₀ value of 10 μg/mL. In conclusion, this study revealed diagnostic assays for differentiating MS strains and the antimicrobial susceptibility profiles of Thai MS, which are necessary to design suitable MS control procedures for poultry flocks.

Insights on Mycoplasma gallisepticum and Mycoplasma synoviae infection in poultry: a systematic review

Avian mycoplasmosis mainly caused by Mycoplasma gallisepticum and M. synoviae is an economically important disease of poultry industry. It causes huge economic losses in terms of decrease in weight gain, feed conversion efficiency, egg production, hatchability; increase in embryo mortality, carcass condemnation, prophylaxis and treatment cost in broiler, layer and breeder flocks. The disease is caused by four major pathogenic mycoplasmas viz., M. gallisepticum (MG), M. synoviae (MS), M. meleagradis (MM) and M. iowae (MI). The MG and MS are World Organization for Animal Health listed respiratory pathogens. MG causes chronic respiratory disease in chicken and infectious sinusitis in turkey; however, MS causes synovitis and airsacculitis in birds. The infection is transmitted both horizontally and vertically. Prevention and control measures of avian mycoplasmosis mainly comprises of biosecurity, treatment and vaccination. For vaccination of birds, inactivated bacterins, live attenuated and/or recombinant live poxvirus vaccines are commercially available against MG and MS infection. The present systematic review summarizes the different epidemiological studies carried out on MG and MS infection in poultry in different geographical locations of India and abroad over the last decade (2010-2020), economic impact, diagnosis and prevention and control.

Multispectral Portable Fibre-Optic Reflectometer for the Classification of the Origin of Chicken Eggshells in the Case of Mycoplasma synoviae Infections

The proper classification of the origins of food products is a crucial issue all over the world nowadays. In this paper, the authors present a device-a multispectral portable fibre-optic reflectometer and signal processing patch-together with a machine-learning algorithm for the classification of the origins of chicken eggshells in the case of Mycoplasma synoviae infection. The sensor device was developed based on previous studies with a continuous spectrum in transmittance and selected spectral lines in reflectance. In the described case, the sensor is based on the integration of reflected spectral data from short spectral bands from the VIS and NIR region, which are produced by single-colour LEDs and introduced to the sample via a fibre bundle. The measurement is carried out in a sequence, and the reflected signal is pre-processed to be put in the machine learning algorithm. The support vector machine algorithm is used together with three different types of data normalization. The obtained results of the F-score factor for classification of the origins of samples show that the percentages of eggs coming from Mycoplasma synoviae infected hens are up to 87% for white and 96% for brown eggshells.

Epidemiological Investigations and Multi-locus Sequence Typing of Mycoplasma synoviae Isolates from Chicken Farms in China

Mycoplasma synoviae (M. synoviae) is an important pathogen in poultry industry and has led to major economic losses. Understanding the epidemiology is crucial to improve control and eradication program of M. synoviae. In this study, 487 samples suspected with M. synoviae infection were collected from August 2020 to June 2021 in China. Among 487 samples, 324 samples were MS positive, the positive rate was 66.53%, and 104 strains were isolated from 324 positive samples. The multilocus sequence typing (MLST) method based on seven housekeeping genes was used to conduct genotyping 104 M. synoviae strains isolated, and the 104 isolates belonged to 8 sequence types (STs) after MLST genotyping, and ST-34 had the highest proportion. After BURST analysis, all 104 isolates were divided into group 12 with other 56 strains isolated from China. Phylogenetic tree constructed by neighbor-joining method showed that nearly all of Chinese isolates (160 isolates) clustered together and separated from other reference isolates (217 isolates) in the PubMLST database. In conclusion, this study suggested that the M. synoviae strains in China were highly similar and independent of abroad strains.

Rapid and specific detection of Mycoplasma gallisepticum and Mycoplasma synoviae infection in poultry using single and duplex PCR assays

Avian mycoplasmosis, mainly caused by Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS), is an economically important disease of poultry industry. The present study was aimed to develop duplex PCR as a rapid, specific and economical method for accurate detection of MG and MS in poultry and its comparison with single (monoplex) MG/MS PCR. During present investigation, a total of 146 poultry flocks having clinical history of respiratory disease were screened. Pooled tissue samples (trachea, lungs and air sacs) from 4-5 birds of each flock were collected during necropsy at disease investigation laboratories, Hisar, Haryana, India. The single and duplex PCR assays were standardized using primers of intergenic spacer region (IGSR; 16S-23S rRNA) for MG and hemagglutinin vlhA gene for MS, with expected amplicon size of 812 bp and 1200 bp products, respectively. In single PCR, 6.85%, 2.74% and 2.74% tissue samples were found positive for MG, MS and both MG and MS, respectively. However, duplex PCR showed, 7.53%, 2.74% and 1.37% positivity for MG, MS and both MG and MS, respectively. Taking the results of monoplex PCR as a gold standard, sensitivity and specificity of the developed duplex PCR was found to be 94.44% and 100%, respectively. Moreover, Cohen's kappa statistic (k = 0.97) measured a 'perfect' agreement between monoplex and duplex PCR assays. The positive and negative predictive values of duplex PCR was found to be 1.0 and 0.9922, respectively at 95% confidence interval (CI), as compared to monoplex PCR. The simultaneous use of two genes in a duplex PCR was more rapid and economical than two separate single PCR reactions.

Multi-locus sequence typing analysis of Mycoplasma synoviae isolates reveals unique sequence types in China

Mycoplasma synoviae is a common pathogen affecting poultry and has important economic significance. Infectious synovitis is the most common clinical effect. Since 2010, the incidence of M. synoviae infection in China has rapidly risen, causing significant economic losses to the chicken industry; however, the cause of the disease outbreak remains unclear. Phylogenetic and evolutionary analyses of field strains will help unravel the mystery. The multi-locus sequence typing (MLST) method is typically utilized to conduct genotyping and traceability analysis of microorganisms. MLST of M. synoviae has previously been established and shown strong discriminatory power. In this study, 54 Chinese M. synoviae strains isolated from 2016 to 2020 were genotyped by MLST based on seven housekeeping genes. This study aimed to investigate the dominant genotypes of M. synoviae in China and reveal the genetic and evolutionary relationships of these isolates. All 54 isolates were found to have new allelic sequences, which may indicate new sequence types. The results of BURST analysis indicated that all 54 strains belonged to group 11, which is an independent phylogenetic branch, and were separated from any other reference strains (189 isolates) in the PubMLST database. In conclusion, the results of this study suggest that the M. synoviae strains circulating in China are relatively independent in terms of transmission and evolutionary relationships.

Comparative genomic analyses of Mycoplasma synoviae vaccine strain MS-H and its wild-type parent strain 86079/7NS: implications for the identification of virulence factors and applications in diagnosis of M. synoviae

Mycoplasma synoviae is an economically important avian pathogen worldwide, causing respiratory disease, infectious synovitis, airsacculitis and eggshell apex abnormalities in commercial chickens. Despite the widespread use of MS-H as a live attenuated vaccine over the past two decades, the precise molecular basis for loss of virulence in this vaccine is not yet fully understood. To address this, the whole genome sequence of the vaccine parent strain, 86079/7NS, was obtained and compared to that of the MS-H vaccine. Except for the vlhA expressed region, both genomes were nearly identical. Thirty-two single nucleotide polymorphisms (SNPs) were identified in MS-H, including 11 non-synonymous mutations that were predicted, by bioinformatics analysis, to have changed the secondary structure of the deduced proteins. One of these mutations caused truncation of the oppF-1 gene, which encodes the ATP-binding protein of an oligopeptide permease transporter. Overall, the attenuation of MS-H strain may be caused by the cumulative and complex effects of several mutations. The SNPs identified in MS-H were further analyzed by comparing the MS-H and 86079/7NS sequences with the strains WVU-1853 and MS53. In the genomic regions conserved between all strains, 30 SNPs were found to be unique to MS-H lineage. These results have provided a foundation for developing novel biomarkers for the detection of virulence in M. synoviae and also for designing new genotyping assays for discrimination of MS-H from field strains.

Molecular identification of Mycoplasma synoviae from breeder chicken flock showing arthritis in Egypt

Aim:

Arthritis is one of the most economic problems facing poultry industry worldwide. The study was done to detect possible causes of arthritis in breeder chicken flock with emphasis on molecular identification of Mycoplasma synoviae (MS).

Materials and Methods:

This study was carried on chicken from broiler breeder flock of 57 weeks’ age in Dakahlia, Egypt, suffered from arthritis with frequently 5-7% decrease in egg production, reduced fertility, and hatchability. Forty blood samples were randomly collected from individual birds in sterile tubes and used for serum separation. Serum samples were tested using serum plate agglutination (SPA) test against colored antigens for Mycoplasma gallisepticum (MG), MS, and Salmonella gallinarum-pullorum (SGP). On the other hand, 24 joint samples were collected. Of those 24 samples, 12 joint samples were subjected to bacteriological examination, while the other 12 were utilized for molecular diagnosis by polymerase chain reaction (PCR) for MS and avian reovirus (ARV).

Results:

SPA test results revealed the presence of antibodies against MG, MS, and SGP in tested sera in rates of 14/40 (35%), 35/40 (87.5%), and 9/40 (22.5%), respectively. Furthermore, 19 bacterial isolates were recognized from joint samples and identified as five Staphylococcus spp., nine Escherichia coli, three SGP, one Citrobacter, and one Proteus. The identified Staphylococcal isolates were three coagulase-positive staphylococci (two Staphylococcus aureus and one Staphylococcus hyicus) and two coagulase-negative staphylococci (one Staphylococcus epidermidis and one Staphylococcus lentus), while E. coli isolate serotypes were 1 O11, 2 O55, 3 O78, 1 O124, 1 O125, and 1 untyped. PCR proved that 12/12 (100%) samples were positive for MS variable lipoprotein hemagglutinin A (vlhA) gene, while ARV was not diagnosed in any of the examined samples. Four amplified vlhA gene of MS isolates (named MS-2018D1, MS-2018D2, MS-2018D3, and MS-2018D4) was successfully sequenced.

Analysis of phylogenetic tree revealed the presence of 100% identity between each two sequenced isolates(isolates MS-2018D1 and MS-2018D4 and also isolates 2018D2 and MS-2018D3). However, the nucleotide similarity between four isolates was 88.6%. On the other hand, our field isolates MS-2018D1, MS-2018D4, MS-2018D2, and MS-2018D3 showed nucleotide identity with vaccine strain MS-H 98.4%, 98.4%, 88.1%, and 88.1%, respectively. Furthermore, the nucleotide similarities with field strains from Argentina ranged between 87.8% and 98.6%.

Conclusion:

Four field isolates of MS were identified in examined broiler breeder flock. A phylogenetic study of these isolates revealed the variation between isolated MS strains and vaccine strain. Therefore, further studies are required for evaluating the vaccine efficacy against the present field isolates of MS. In addition, application of MS immunization of breeder flocks is necessary for proper control of the disease.

Prevalence and Phylogenetic Analysis of Mycoplasma Synoviae Strains Isolated from Polish Chicken Layer Flocks

Introduction

Mycoplasma synoviae (MS) is a chicken pathogen of major economic importance.

Material and Methods

Between 2010 and 2016, 906 commercial layer chicken flocks in Poland were examined for MS, and the phylogenetic relationship among the strains was established. Regionally dispersed samples were collected and tested with the use of real-time PCR to detect the 16S-23S intergenic spacer region. Positive samples were also tested with LAMP and conventional PCR to detect the vlhA gene.

Results

MS genetic material was detected in 265 (29%) of the tested flocks by real-time PCR, in 227 by the LAMP method and in 202 (22%) by conventional PCR. The by-year percentage of positive samples began at 34% in 2010, rose to 44% in 2012, and declined to 29% in 2016. A phylogenetic analysis of Polish M. synoviae strains using a partial sequence of the vlhA gene showed nine genotypes (A-I), the most frequently occurring being F and C. Pathogenic Polish MS field isolates (n = 27) collected from chickens with clinical signs of infection were grouped for their characteristic symptoms: respiratory for genotypes C, E, F, and I (n = 13), EAA and a drop in laying for genotypes F, E, and C (n = 12), and synovitis for genotype A (n = 2).

Conclusion

These data showed the country's isolate diversity. The high prevalence suggests the need to introduce appropriate control programmes. This is the first report of molecular epidemiological data on M. synoviae infection in layer chickens in Poland.

Mutation of oppF gene in the Mycoplasma synoviae MS-H vaccine strain and its implication for differential serological responses to vaccination versus field challenge

Mycoplasma synoviae (MS) is a major pathogen of poultry globally, causing chronic respiratory disease and arthritis. Vaccination is an effective means for the control of the disease. The MS-H vaccine is an attenuated strain developed through chemical mutagenesis of an Australian field strain, 86079/7NS. Analysis of whole genome of MS-H and its comparison with that of 86079/7NS has revealed a frameshift mutation early in a gene (oppF) that codes for an oligopeptide transporter permease, OppF. Monospecific antibodies raised against peptides upstream and downstream of the mutation in OppF revealed that only N-terminus of the OppF was expressed in MS-H while the full version was expressed in 86079/7NS. Also, examination of the recombinant N- (OppF-N) and C termini (OppF-C) of OppF, upstream and downstream of the mutation site respectively, as well as the full length OppF in Western immunoblotting experiments showed that serum from MS-H vaccinated chicken strongly bound OppF-N while serum from 86079/7NS challenged chicken detected OppF, OppF-N and OppF-C. The potential of the recombinant OppF, OppF-N and OppF-C to discriminate antibody responses to MS-H reisolates with wild or vaccine type OppF was assessed against 88 chicken sera in indirect ELISA and ratios were calculated between optical densities (OD) over those obtained in MS major membrane protein MSPB ELISA. Comparison of the OD ratios revealed that the MSPB/OppF and MSPB/OppF-C OD ratios of the sera against isolates with vaccine type OppF were significantly higher than those against isolates with wild type OppF. These results are in accordance with oppF gene mutation in MS-H and confirms that MS-H does not express OppF beyond the frame shift mutation found in its oppF gene. Also, the indirect ELISA based on OppF-C in combination with the MSPB has the potential to differentiate between MS-H and field strain antibody responses.

Genotyping Mycoplasma synoviae: Development of a multi-locus variable number of tandem-repeats analysis and comparison with current molecular typing methods

Control of one of the most important avian mycoplasmas, Mycoplasma synoviae, and tracing the spread of the infection can be challenging as the pathogen is transmissible by both horizontal and vertical routes, and it can be disseminated through long distances via the hatching eggs, day-old chicks or pullets during intensive international trade. Genetic information provided by molecular typing methods support control programmes and epizootiologic studies. The aims of the present study were to develop a multi-locus variable number of tandem-repeats analysis (MLVA) method for the typing of M. synoviae isolates and to evaluate the currently used molecular typing methods which are applicable directly on clinical samples. Tandem repeat (TR) regions were selected from the whole genome sequence of the M. synoviae type strain (WVU1853) to characterise the genetic diversity of 86 M. synoviae strains originating from 15 countries. The strains were also submitted to multi-locus sequence typing (MLST) assays, vlhA gene sequence analysis and to assays designed to differentiate live vaccine strains from field strains. The developed MLVA involves the examination of seven TR regions and provides similar genetic resolution as the tested MLST assays by identifying 35 genotypes among the tested strains. Differentiation of the live vaccine strains from field strains was also successful with the developed assay. The provided MLVA method proved to be a highly discriminative, rapid and cost-effective alternative typing technique for the genetic characterisation of M. synoviae and it is also suitable for the complementation of live vaccine strain differentiating assays in ambiguous cases.

Identification of a new genetic marker in Mycoplasma synoviae vaccine strain MS-H and development of a strategy using polymerase chain reaction and high-resolution melting curve analysis for differentiating MS-H from field strains

Mycoplasma synoviae (MS) is an economically important avian pathogen worldwide, causing subclinical respiratory tract infection and infectious synovitis in chickens and turkeys. A temperature-sensitive (ts⁺) live attenuated vaccine MS-H, derived from the Australian field strain 86079/7NS, is now widely used in many countries to control the disease induced by MS. Differentiation of MS-H vaccine from field strains is crucial for monitoring vaccination programs in commercial poultry. Comparison of genomic sequences of MS-H and its parent strain revealed an adenine deletion at nucleotide position 468 of the MS-H oppF-1 gene. This mutation was shown to be unique to MS-H in further comparative analyses of oppF-1 genes of MS-H re-isolates and field strains from Australia and other countries. Based on this single nucleotide, a combination of nested PCR and high-resolution melting (HRM) curve analysis was used to evaluate its potential for use in differentiation of MS-H from field strains. The mean genotype confidence percentages of 99.27 and 48.20 for MS-H and field strains, respectively, demonstrated the high discriminative power of the newly developed assay (oppF PCR-HRM). A set of 13 tracheal swab samples collected from MS-H vaccinated specific pathogen free birds and commercial chicken flocks infected with MS were tested using the oppF PCR-HRM test and results were totally consistent with those obtained using vlhA genotyping. The nested-PCR HRM method established in this study proved to be a rapid, simple and cost effective tool for discriminating the MS-H vaccine strain from Australian and international strains in pure cultures and on tracheal swabs.

Characterization of Thai Mycoplasma synoviae Isolates by Sequence Analysis of Partial vlhA Gene

Mycoplasma synoviae (MS), a remarkable pathogen in poultry, causes subclinical infection of the upper respiratory tract and an infectious synovitis, especially in the tendon sheaths and synovial membranes of joints. Because the specific detection of MS 16S rRNA gene-based PCR was unsuitable for strain differentiation, vlhA gene-based PCR was designed to differentiate the MS strains. The vlhA gene of MS encodes for hemagglutinin and other immunodominant membrane proteins involved in colonization, antigenic variations, and virulence. Sequence analysis of the vlhA gene based on the nucleotide insertion/deletion of the proline-rich repeat (PRR) region and the nucleotide polymorphisms of the RIII region in vlhA gene fragments was useful for typing and subtyping of MS strains. This study aimed to characterize the Thai MS field isolates and to differentiate the field and vaccine strains in Thailand by using sequence analysis of the partial vlhA gene. In total, 20 MS field isolates submitted from registered chicken farms in Thailand during 2015 were identified as Type C1 (n = 1), C2 (n = 4), E1 (n = 9), E2 (n = 1), and L (n = 5). The results revealed that six of the nine isolates resulting in respiratory signs were Type E1. In addition, four isolates from lame chickens showing joint swelling were identified as Type L, with a length of 105 nucleotides. This study provides the first molecular data of Thai MS isolates and the first evidence of Type L for being an arthropathic strain that differs from a previous study demonstrating that only MS Type B, with a longer PRR of 135 nucleotides, could be highly invasive strains and associated with infectious synovitis in chickens. Furthermore, one farm showed coinfection of MS Types E and L, but most of the farms were affected by only one type of MS. The results indicated that sequence analysis of the partial vlhA gene can be used as a tool for tracing MS characterization.

Development and evaluation of a multi-locus sequence typing scheme for Mycoplasma synoviae

Reproducible molecular Mycoplasma synoviae typing techniques with sufficient discriminatory power may help to expand knowledge on its epidemiology and contribute to the improvement of control and eradication programmes of this mycoplasma species. The present study describes the development and validation of a novel multi-locus sequence typing (MLST) scheme for M. synoviae. Thirteen M. synoviae isolates originating from different poultry categories, farms and lesions, were subjected to whole genome sequencing. Their sequences were compared to that of M. synoviae reference strain MS53. A high number of single nucleotide polymorphisms (SNPs) indicating considerable genetic diversity were identified. SNPs were present in over 40 putative target genes for MLST of which five target genes were selected (nanA, uvrA, lepA, ruvB and ugpA) for the MLST scheme. This scheme was evaluated analysing 209 M. synoviae samples from different countries, categories of poultry, farms and lesions. Eleven clonal clusters and 76 different sequence types (STs) were obtained. Clustering occurred following geographical origin, supporting the hypothesis of regional population evolution. M. synoviae samples obtained from epidemiologically linked outbreaks often harboured the same ST. In contrast, multiple M. synoviae lineages were found in samples originating from swollen joints or oviducts from hens that produce eggs with eggshell apex abnormalities indicating that further research is needed to identify the genetic factors of M. synoviae that may explain its variations in tissue tropism and disease inducing potential. Furthermore, MLST proved to have a higher discriminatory power compared to variable lipoprotein and haemagglutinin A typing, which generated 50 different genotypes on the same database.

Molecular identification of Mycoplasma synoviae from seroprevalent commercial breeder farms at Chittagong district, Bangladesh

Aim:

Worldwide, Mycoplasma synoviae (MS) is an important pathogen of poultry, especially for chicken and turkey. It causes respiratory tract infection and infectious sinusitis. The study was conducted to determine the seroprevalence of MS infection with associated risk factors and identification of MS organism in unvaccinated flocks of commercial breeder farms of the Chittagong district, Bangladesh.

Materials and Methods:

A total of 365 serum samples were collected and tested for MS using serum plate agglutination (SPA) test for determination of MS seroprevalence. On the other hand, tracheal swabs were collected from each seropositive flocks for polymerase chain reaction (PCR) to determine the presence of MS organism.

Results:

Among the farms, the highest prevalence was found to be 69% and the lowest prevalence was 28% with the average 60%. The seroprevalence of MS infection in breeder farms was highest 70% with the flock size >10,000 birds, whereas it was lowest 57% in the flocks ranging from 4000 to 7000. According to age group, the prevalence was found highest 70% in >60 weeks age group of birds and lowest 42% in 10-19 weeks group. The seroprevalence of MS in winter season was found as highest as 64%, whereas it was found lowest 60% in the summer season. There was a statistically significant difference (p<0.01) among the seroprevalence of MS in different breeder farms, flock size, and age groups, but there was no significant (p>0.05) difference in the winter, summer, and rainy season. To confirm the presence of MS in the samples, PCR test was applied using specific primers to amplify a 214 bp region of the 16S rRNA gene of the organism. In PCR, all seropositive flocks showed a positive result for MS.

Conclusion:

As the plate agglutination test result showed 100% similar with PCR result, it can be suggested that agglutination test is better than molecular and culture techniques for MS detection and it is also cheaper and less time-consuming method.

Rapid and sensitive detection of Mycoplasma synoviae by an insulated isothermal polymerase chain reaction-based assay on a field-deployable device

Mycoplasma synoviae (MS), causing respiratory diseases, arthritis, and eggshell apex abnormalities in avian species, is an important pathogen in the poultry industry. Implementation of a biosecurity plan is important in MS infection management. Working on a field-deployable POCKIT™ device, an insulated isothermal polymerase chain reaction (iiPCR) assay has a potential for timely MS detection on the farm. The MS iiPCR assay had limit of detection 95% of about 9 genome equivalents by testing serial dilutions of a standard DNA. The detection endpoint of the assay for detection of MS genomic DNA was comparable to a reference real-time PCR. The assay did not crossreact with other important avian pathogens, including avian reovirus, Mycoplasma gallisepticum, Staphylococcus aureus, Escherichia coli, Pasteurella multocida, and Salmonella Pullorum. When 92 synovial fluid and respiratory tract swab samples collected from chickens, turkeys, and geese suspected of MS infection were tested, the clinical performance of the MS iiPCR had 97.8% agreement (Cohen's kappa value, 0.95) with that of the reference real-time PCR. In conclusion, the MS iiPCR/POCKIT™ system, working with field-deployable manual or automatic nucleic acid extraction methods, has potential to serve as a rapid and sensitive on-site tool to facilitate timely detection of MS.

Rapid detection of Mycoplasma synoviae by loop-mediated isothermal amplification

Mycoplasma synoviae (MS) remains a serious concern in production of poultry and affects world production of chickens and turkeys. Loop-mediated isothermal amplification (LAMP) of DNA has been recently used for the identification of different economically important avian pathogens. The aim of this study was to develop LAMP for simple and inexpensive detection of MS strains in poultry using specifically designed primers targeting hemagglutin A (vlh) gene. The assay was conducted in a water bath for 1 h at 63 °C. The results were visualized after addition of SYBR Green(®) fluorescent dye. LAMP was specific exclusively for MS without cross-reactivity with other Mycoplasma species. The sensitivity of LAMP was determined as 10(-1) CFU/ml and was 1,000 times higher than MS-specific polymerase chain reaction. LAMP assay was conducted on 18 MS field strains to ensure its reliability and usefulness. This is the first report on LAMP development and application for the rapid detection of MS isolated from chickens. This simple method may be applied by diagnostic laboratories without access to expensive equipment.

Isolation and Identification of Mycoplasma synoviae From Suspected Ostriches by Polymerase Chain Reaction, in Kerman Province, Iran

Background:

Mycoplasma synoviae is an important avian pathogen which can cause both respiratory disease and synovial joint inflammation (synovitis) in poultry. Mycoplasmas spp. may cause the respiratory system infection in ostriches with symptoms such as inflammation of the nose, trachea and also damages of lungs.

Objectives:

The current study aimed to use the M. synoviae specific Polymerase Chain Reaction (PCR) and microbiological methods in order to isolate and identify M. synoviae from suspected ostriches in Kerman Province, Iran, and compare the two methods (microbiological and PCR) employed to confirm Mycoplasmal contamination of ostrich lungs.

Materials and Methods:

Fifty three samples of different parts of lung and trachea were immediately collected after slaughtering the ostriches in Kerman Province six months. Samples were cultured in the same conditions in pleuropneumonia-like organism (PPLO) broth and to isolate and identify M. synoviae, PCR and microbiological methods were conducted. The identified isolates were confirmed by specific amplification of 16S rRNA gene (163 and 207 base pair).

Results:

In the current study, 25 and 17 out of 53 ostrich samples were identified as Mycoplasma-positive in the PCR and microbiological methods, respectively; and 13 out of 25 the mentioned Mycoplasma-positive samples were also confirmed by PCR method.

Conclusions:

The current study showed that PCR method is time consuming, effective, and efficient method to detect M. synoviae infection in ostriches. PCR method could be recommended as an alternative for culturing; M. synoviae was isolated from ostriches for first time in Kerman Province, Iran.

High-resolution melting-curve analysis of obg gene to differentiate the temperature-sensitive Mycoplasma synoviae vaccine strain MS-H from non-temperature-sensitive strains

Temperature-sensitive (ts⁺) vaccine strain MS-H is the only live attenuated M. synoviae vaccine commercially available for use in poultry. With increasing use of this vaccine to control M. synoviae infections, differentiation of MS-H from field M. synoviae strains and from rarely occurring non-temperature-sensitive (ts^–) MS-H revertants has become important, especially in countries where local strains are indistinguishable from MS-H by sequence analysis of variable lipoprotein haemagglutinin (vlhA) gene. Single nucleotide polymorphisms (SNPs) in the obg of MS-H have been found to associate with ts phenotype. In this study, four PCRs followed by high-resolution melting (HRM)-curve analysis of the regions encompassing these SNPs were developed and evaluated for their potential to differentiate MS-H from 36 M. synoviae strains/isolates. The nested-obg PCR-HRM differentiated ts⁺ MS-H vaccine not only from field M. synoviae strains/isolates but also from ts^– MS-H revertants. The mean genotype confidence percentages, 96.9±3.4 and 8.8±11.2 for ts⁺ and ts^– strains, respectively, demonstrated high differentiating power of the nested-obg PCR-HRM. Using a combination of nested-obg and obg-F3R3 PCR-HRM, 97% of the isolates/strains were typed according to their ts phenotype with all MS-H isolates typed as MS-H. A set of respiratory swabs from MS-H vaccinated specific pathogen free chickens and M. synoviae infected commercial chicken flocks were tested using obg PCR-HRM system and results were consistent with those of vlhA genotyping. The PCR-HRM system developed in this study, proved to be a rapid and reliable tool using pure M. synoviae cultures as well as direct clinical specimens.

Validation of a previously developed quantitative polymerase chain reaction for the detection and quantification of Mycoplasma synoviae in chicken joint specimens

A quantitative polymerase chain reaction (qPCR) was validated for the detection of Mycoplasma synoviae (PCR equivalents of colony-forming units [CFU eq.]) in chicken joint specimens with time and compared with direct mycoplasma culture. Joint specimens were obtained from 70 layer pullets inoculated intravenously with M. synoviae at 6 weeks of age. Ten control birds were injected intra-articularly with Freund's complete adjuvant. Macroscopic joint lesions were observed in 54 infected birds, of which 11 showed positive M. synoviae culture. The specificity of direct mycoplasma culture was high (100%, 95% confidence interval [CI] = 74 to 100), but its sensitivity low (16%, 95% CI = 8 to 26). Most positive results were obtained during the first 2 weeks after onset of joint swelling using synovial fluid. The qPCR was positive in 26 of 28 synovial fluid samples and in 51 of 70 joint swabs. The sterile joint samples obtained from Freund's complete adjuvant-injected birds were negative in the mycoplasma culture. The specificity and sensitivity of the qPCR for synovial fluid samples were 100% (95% CI = 65 to 100) and 93% (95% CI = 77 to 99); for joint swabs they were 100% (95% CI = 74 to 100) and 73% (95% CI = 61 to 83), respectively. Positive qPCR results (10(0.3) (to) (4.6) CFU eq./ml) were found until the end of the experiment (12 weeks post inoculation). At the end of the study, eight out of 16 joint swabs from birds without macroscopic joints lesions were positive in the qPCR (10(2.0) (to) (2.8) CFU eq./ml). Under the conditions of this study, the sensitivity of the qPCR was higher than that of direct mycoplasma culture (P< 0.0001) during the acute, subacute and chronic stages of arthritis.

Combination of differential growth at two different temperatures with a quantitative real-time polymerase chain reaction to determine temperature-sensitive phenotype of Mycoplasma synoviae

Mycoplasma synoviae infections result in significant economic losses in the chicken and turkey industries. A commercially available live temperature-sensitive (ts (+)) vaccine strain MS-H has been found to be effective in controlling M. synoviae infections in commercial layer and broiler breeder farms in various countries, including Australia. Detection and differentiation of MS-H from field strains (ts (-)) and from ts (-) MS-H reisolates in vaccinated flocks is vital in routine flock status monitoring. At present microtitration is the only available technique to determine the ts phenotype of M. synoviae. This technique is time consuming and not amenable to automation. In the present study, a quantitative real-time polymerase chain reaction (Q-PCR) was combined with simultaneous culturing of M. synoviae at two different temperatures (33°C and 39.5°C) to determine the ts phenotype of 22 Australian M. synoviae strains/isolates. The M. synoviae type strain WVU-1853 was also included for comparison. A ratio of the copy numbers of the variable lipoprotein haemagglutinin (vlhA) gene at the two temperatures was calculated and a cut-off value was determined and used to delineate the ts phenotype. In all M. synoviae strains/isolates tested in this study, the ts phenotype determined using Q-PCR was in agreement with that determined using conventional microtitration. Combination of Q-PCR with differential growth at two different temperatures is a rapid, reliable and accurate technique that could be used as an effective tool in laboratories actively involved in ts phenotyping of M. synoviae strains/isolates.

Genotyping of Japanese field isolates of Mycoplasma synoviae and rapid molecular differentiation from the MS-H vaccine strain

Mycoplasma synoviae is an important causative agent of avian mycoplasmosis. In the present study the conserved domain of the variable lipoprotein and hemagglutinin (vlhA) gene of M. synoviae was sequenced and analyzed for 19 field strains of M. synoviae isolated from chickens across Japan. This analysis revealed that there were at least nine genotypes of M. synoviae present in Japan. Furthermore, we found a single nucleotide polymorphism (SNP) within this region in all the Japanese isolates, and based on this finding, we established a PCR method with cycling probe technology to differentiate between these field isolates and the live M. synoviae vaccine strain Mycoplasma synoviae-H (MS-H).

Analysis of the 16S to 23S rRNA intergenic spacer region of Mycoplasma synoviae field strains

Mycoplasma synoviae has been associated with economic loss in the chicken and turkey industries. The molecular characterization of M. synoviae at strain level allows the analysis of relationships between strains that may be valuable in epidemiological investigations. In the present study, the intergenic spacer region (ISR) between the 16S and 23S rRNA genes was examined to see whether useful information about strains could be derived. M. synoviae has two copies of this region, which may not be exactly the same (intercistronic heterogeneity). Sequencing of the ISRs of 21 M. synoviae isolates and the type strain revealed that 19 of them had such heterogeneity so DNA cloning was performed where necessary. All sequences were analysed and aligned; the percentage similarity of the DNA was calculated and a dendrogram was constructed. The length of the ISRs varied between 305 and 309 base pairs. Apart from having extra A/Ts in poly-A or poly-T regions and the presence of a few polymorphisms, the sequences of the M. synoviae strains were similar. Based on phylogenetic analysis, the strains were assigned to 10 groups-taking into account that within each group the DNA similarity was 100%, while the lowest similarity between groups was 95.8%. The results were compared with those obtained with the vlhA gene, resulting in very similar M. synoviae groups. Although the ISR could be a good target for strain typing, as has been shown by others for Mycoplasma gallisepticum, the method may be too cumbersome for routine use with M. synoviae because of complications with intercistronic heterogeneity. However, if the ISR sequence information was to be combined with other mutation detection techniques it could increase the discriminatory power.

Comparative Study of Serological Tests for Mycoplasma synoviae Diagnosis in Commercial Poultry Breeders

Avian mycoplasmosis causes great economic losses to the poultry industry, and one of the major agents involved is Mycoplasma synovie (MS). Serum from commercial poultry breeders (n = 2781) was tested for MS by serum plate agglutination (SPA), hemagglutination inhibition (HI), and enzyme-linked immunosorbent assay (ELISA). From 2,781 samples tested, 736 (26.46%) were positive in SPA. From 712 SPA-positive sera, 30 samples (4.21%) were positive in HI, and 150 samples (21.06%) were positive in ELISA. Copositivity between ELISA and HI was 90%, and conegativity was 82.0%. Agreement between HI and ELISA was rejected by McNemar's test (P ≤ .001), and Kappa coefficient showed a weak correlation between the two techniques (k = 0.25; 0.21 ≤ k < 0.40). Weak statistical correlation was observed between all serological tests (SPA, HI, and ELISA), and they should only be used for initial screening for MS.

Revised Mycoplasma synoviae vlhA PCRs

Mycoplasma synoviae (MS) is an important pathogen of chickens and turkeys. In recent years sequence analysis of the partial MS variable lipoprotein and hemagglutinin A (vlhA) gene PCR product has been utilized routinely for MS strain genotyping. Several PCR assays have been proposed for the amplification of the conserved upstream region of the MS vlhA gene; however, in several clinical instances the published assays failed to generate vlhA PCR products from confirmed MS-positive cases. These occurrences hindered our capability to genotype those cases. In silico analysis of the published MS vlhA PCRs raised concerns, which were addressed by the design of revised MS vlhA PCRs. The published and revised assays were tested for their relative sensitivity and specificity with laboratory and clinical MS-positive samples. One of the revised MS vlhA PCRs (revised Hong) was demonstrated to be more sensitive and specific, and amplified all clinical samples analyzed in this study.

Development and evaluation of an improved diagnostic PCR for Mycoplasma synoviae using primers located in the haemagglutinin encoding gene vlhA and its value for strain typing

Using published primers, detection of Mycoplasma synoviae and strain identification using the vlhA gene sequence was attempted. However, of 21 M. synoviae strains examined, three could not be amplified, so a new reverse primer was designed with a target in the conserved region of the vlhA gene. This allowed all 21 M. synoviae strains, a further nine strains and also material from 11 swab samples from M. synoviae-positive birds, to produce a PCR product, suggesting that the method could also be suitable for clinical specimens. The protocol was then tested on the type strains of M. synoviae and the other 22 recognised avian Mycoplasma species, with amplification of M. synoviae only. Further testing demonstrated that this PCR was equally or more sensitive than other PCR tests used to detect M. synoviae. Subsequent DNA sequence analysis of the PCR product based on percent similarity and evolutionary relationship appeared to be a useful tool for strain differentiation.

Genetic variation in sialidase and linkage to N-acetylneuraminate catabolism in Mycoplasma synoviae

We explored the genetic basis for intraspecific variation in mycoplasmal sialidase activity that correlates with virulence, and its potentially advantageous linkage to nutrient catabolism. Polymorphism in N-acetylneuraminate scavenging and degradation genes (sialidase, N-acetylneuraminate lyase, N-acetylmannosamine kinase, N-acetylmannosamine-6-phosphate epimerase, N-acetylglucosamine-6-phosphate deacetylase, and glucosamine-6-phosphate deaminase) was evident among eight strains of the avian pathogen Mycoplasma synoviae. Most differences were single nucleotide polymorphisms, ranging from 0.34+/-0.04 substitutions per 100 bp for N-acetylmannosamine kinase to 0.65+/-0.03 for the single-copy sialidase gene nanI. Missense mutations were twice as common as silent mutations in nanI; 26% resulted in amino acids dissimilar to consensus; and there was a 12-base deletion near the nanI promoter in strain WVU1853(T), supporting a complex genetic basis for differences in sialidase activity. Two strains had identical frameshifts in the N-acetylneuraminate lyase gene nanA, resulting in nonsense mutations, and both had downstream deletions in nanA. Such genetic lesions uncouple extracellular liberation of sialic acid from generation of fructose-6-phosphate and pyruvate via intracellular N-acetylneuraminate degradation. Retention of nanI by such strains, but not others in the M. synoviae phylogenetic cluster, is evidence that sialidase has an important non-nutritional role in the ecology of M. synoviae and certain other mycoplasmas.

Classification of Mycoplasma synoviae strains using single-strand conformation polymorphism and high-resolution melting-curve analysis of the vlhA gene single-copy region

Mycoplasma synoviae is an economically important pathogen of poultry worldwide, causing respiratory infection and synovitis in chickens and turkeys. Identification of M. synoviae isolates is of critical importance, particularly in countries in which poultry flocks are vaccinated with the live attenuated M. synoviae strain MS-H. Using oligonucleotide primers complementary to the single-copy conserved 5' end of the variable lipoprotein and haemagglutinin gene (vlhA), amplicons of approximately 400 bp were generated from 35 different M. synoviae strains/isolates from chickens and subjected to mutation scanning analysis. Analysis of the amplicons by single-strand conformation polymorphism (SSCP) revealed 10 distinct profiles (A-J). Sequencing of the amplicons representing these profiles revealed that each profile related to a unique sequence, some differing from each other by only one base-pair substitution. Comparative high-resolution melting (HRM) curve analysis of the amplicons using SYTO 9 green fluorescent dye also displayed profiles which were concordant with the same 10 SSCP profiles (A-J) and their sequences. For both mutation detection methods, the Australian M. synoviae strains represented one of the A, B, C or D profiles, while the USA strains represented one of the E, F, G, H, I or J profiles. The results presented in this study show that the PCR-based SSCP or HRM curve analyses of vlhA provide high-resolution mutation detection tools for the detection and identification of M. synoviae strains. In particular, the HRM curve analysis is a rapid and effective technique which can be performed in a single test tube in less than 2 h.

Development and evaluation of a diagnostic PCR for Mycoplasma synoviae using primers located in the intergenic spacer region and the 23S rRNA gene

Mycoplasma synoviae (Ms) is an important pathogen of poultry, causing economic losses to this industry. Early and reliable diagnosis is a key to controlling the spread of this organism. In this study, a polymerase chain reaction with one primer based on the intergenic spacer region (ISR) was validated for detection of Ms. The ISR primer was paired with a general primer from within the 23S rRNA gene. The PCR primers were tested with the 22 other recognised avian Mycoplasma species to check the specificity and with 21 field isolates of Ms from various hosts and countries, and with several swab samples. The PCR appeared to be specific and sensitive. Four different sample preparation methods were compared for use in this PCR, and the amplification protocol was compared with three others, confirming the comparative sensitivity of the new PCR.