IsMycoplasma synoviaeoutrunningMycoplasma gallisepticum? A viewpoint from the Netherlands

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.

Mycoplasma gallisepticum and Mycoplasma synoviae in Turkeys in Poland

The pathogenic mycoplasmas are among the bacteria causing significant losses in the poultry industry worldwide. Mycoplasma gallisepticum (MG) and M. synoviae (MS) are economically important pathogens causing chronic respiratory disease, decreased growth, egg production and hatchability rates, and significant downgrading of carcasses. Effective diagnosis of infection with these species in poultry is highly requisite considering their two routes of spreading-horizontal and vertical. Their prevalence and molecular epidemiology were investigated in 184 turkey flocks in Poland. Tracheal samples were selected from 144 broiler flocks and 40 turkey breeder flocks collected in 2015-2023. The prevalence of MG was determined by real-time PCR targeting the 16S rRNA gene and PCR targeting the mgc2 gene, and MS was determined by a 16-23S rRNA real-time PCR and a vlhA gene PCR. Further identification and molecular characterization were carried out using PCR and sequencing. M. gallisepticum and M. synoviae were found in 8.33% and 9.72% of turkey broiler flocks respectively. The phylogenetic analysis of MG isolates in most cases showed high similarity to the ts-11-like strains. MS isolates showed high similarity to strains isolated from flocks of laying hens causing EAA. Additional tests detected Ornithobacterium rhinotracheale, Gallibacterium anatis, Enterococcus faecalis and Enterococcus faecium, Staphylococcus aureus and Riemerella anatipestifer. These secondary pathogens could have significantly heightened the pathogenicity of the mycoplasma infections studied.

Mycoplasma synoviae LP78 is a fibronectin/plasminogen binding protein, putative adhesion, and potential diagnostic antigen

Mycoplasma synoviae (M. synoviae) is one of the major poultry pathogens causing infectious synovitis, airsacculitis, a high incidence of shell breakage, and egg production loss. However, the pathogenesis of M. synoviae remains unclear. Adhesion of mycoplasmas to host cells is a crucial step in infection and colonization. The purpose of this study was to determine the adhesive function of a putative P80 family lipoprotein (LP78) and evaluate its application in the detection of antibodies against M. synoviae. Recombinant LP78 (rLP78) was expressed in the supernatant component of Escherichia coli and mouse anti-rLP78 serum was prepared. Bioinformatic analysis and western blotting results revealed that LP78 was conservative among M. synoviae strains. It was distributed not only in the cytoplasm but also on the membrane of M. synoviae through western blotting and indirect immunofluorescence (IFA). The adherence of M. synoviae to DF-1 cells was significantly inhibited by mouse anti-rLP78 serum (p < 0.01). IFA revealed that rLP78 adhered to DF-1 cells, and this adherence was prevented by mouse anti-rLP78 serum. Furthermore, rLP78 was found to bind to the DF-1 cells membrane proteins in a dose-dependent manner by enzyme-linked immunosorbent assay (ELISA). Screening of DF-1 cells membrane proteins by western blotting showed that proteins with molecular weight of 35-40 kDa and 55-70 kDa bound to rLP78. Moreover, rLP78 was identified to be a fibronectin/plasminogen binding protein. The sensitivity and specificity of rLP78-based iELISA were 85.7 and 94.1%, respectively. The maximum dilution of positive serum (HI titer, 1:128) detected via rLP78-based iELISA was 1:6,400, whereas that detected using a commercial ELISA kit was 1:12,800-1:25,600. Both rLP78-based iELISA and the commercial ELISA kit detected seroconversion after 7 days of challenge and immunization. No cross-reactivity with positive sera against other avian pathogens was observed in rLP78-based iELISA. Collectively, these results indicate that LP78 is a fibronectin/plasminogen-binding adhesion protein of M. synoviae and a potential diagnostic antigen. The present study will facilitate a better understanding of the pathogenesis of M. synoviae and the development of new diagnostic.

Evaluation of the protective efficacy of six major immunogenic proteins of Mycoplasma Synoviae

Mycoplasma synoviae (MS) is a primary avian pathogen prevalent worldwide that causes airsacculitis and synovitis in birds. Vaccination is recommended as the most cost-effective strategy in the control of MS infection. Novel alternative vaccines are needed for eradicating and controlling MS infection in flocks. DnaK, enolase, elongation factor Tu (EF-Tu), MSPB, NADH oxidase and LP78 are the major immunogenic antigens of MS and are promising targets for subunit vaccine candidates. In the present study, genes encoding DnaK, enolase, EF-Tu, MSPB, LP78, and NADH oxidase were cloned and expressed in Escherichia coli. Enzyme-linked immunosorbent assay showed that the six recombinant proteins were recognized by convalescent sera, indicating that they were expressed during infection. Two injections of the six subunit vaccines induced a robust antibody response and increased the concentrations of IFN-γ and IL-4, especially rEnolase and rEF-Tu. The proliferation of peripheral blood lymphocytes was enhanced in all of the immunized groups. Chickens immunized with rEnolase, rEF-Tu, rLP78, and rMSPB conferred significant protection against MS infection, as indicated by significantly lower DNA copies in the trachea, lower scores of air sac lesions, and lesser tracheal mucosal thickness than that in the challenge control. Especially, rEnolase provided the best protective efficacy, followed by rEF-Tu, rMSPB, and rLP78. Our finds demonstrate that the subunit vaccines and bacterin can only reduce the lesions caused by MS infection, but not prevent colonization of the organism. Our findings may contribute to the development of novel vaccine agents against MS infection.

Biofilm formation and correlations with drug resistance in Mycoplasma synoviae

Infectious synovitis in chickens caused by Mycoplasma synoviae infections are characterized by exudative synovial joint membranes and tenosynovitis. We isolated M. synoviae from chickens on farms in Guangdong, China and identifed 29 K-type and 3 A-type strains using vlhA genotyping and all displayed decreased susceptibilities to enrofloxacin, doxycycline, tiamulin and tylosin compared with the type strain WVU1853 (ATCC 25204). M. synoviae biofilms were present after staining as block or continuous dot shape morphologies and these appeared as tower-like and mushroom-like structures in scanning electron micrographs. The optimal temperature for biofilm formation was 33 °C and these biofilms enhanced the resistance of M. synoviae to all 4 antibiotics we tested and minimum biofilm inhibitory concentration for enrofloxacin and biofilm biomass were significantly negatively correlated (r < 0, 0.3 ≤|r|<0.5, P < 0.05). This work is the first study of the biofilm formation ability of M. synoviae and provides the foundation for further investigations.

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.

Bacterial communities of the oviduct of turkeys

Bacterial communities in the reproductive tract of avian species play an important role in keeping birds healthy and encouraging growth. Infection can occur during egg formation with pathogens that can be transmitted to the embryo. In this study, we investigated the bacterial composition in the turkey reproductive tract using a taxa identification based on the amplicon sequence of the V3–V4 region of the 16S rRNA gene. The microbial composition and relative abundance of bacteria differed between individual birds. Among the 19 phyla detected in turkey oviduct were unique taxa like Planctomycetes or Petescibacteria. Differences in composition of bacterial diversity were found at the family and genus level. Oviducts contained also several genus with well-recognized avian pathogens like Escherichia-Shigella, Enterococcus, Staphylococcus, and Ornithobacterium. Some of the bacteria described in this study have not been so far identified in turkeys. The objective of this study was to identify bacterial communities in the turkey oviduct and compared the composition of the oviduct with that in chickens broadening the knowledge of the microbial composition in the reproductive tract of poultry.

The Monitoring of Mycoplasma gallisepticum Minimum Inhibitory Concentrations during the Last Decade (2010–2020) Seems to Reveal a Comeback of Susceptibility to Macrolides, Tiamulin, and Lincomycin

Mycoplasma gallisepticum (Mg) is a highly contagious avian pathogen responsible for significant economic losses for the poultry industry. In some circumstances, antimicrobial treatment is useful to contain clinical signs of Mg infection in birds. However, antimicrobial resistance emergence is now common among animal pathogens, becoming a worldwide health concern. The collection of minimum inhibitory concentration (MIC) data is fundamental for an appropriate antimicrobial use and for fighting antimicrobial resistance emergence. However, MIC data can only be generated in specialized laboratories, and therefore they are not regularly available. MICs of 67 non-vaccine-derived Mg isolates collected in Italy between 2010 and 2020 were obtained. Although 79.1% of the Mg isolates showed enrofloxacin MICs ≥ 8 µg/mL, a statistically significant trend toward low MICs of erythromycin, tylosin, tilmicosin, spiramycin, tiamulin, and lincomycin was observed, indicating a comeback to susceptibility of Mg toward these drugs. Doxycycline proved to be slightly more effective than oxytetracycline. The present study shows that Mg changed its susceptibility toward many of the drugs most commonly used for its containment over a ten-year period.

A Cross-Sectional Seroepidemiological Study on Infectious Bursal Disease in Backyard Chickens in the Mymensingh District of Bangladesh

Infectious bursal disease (IBD) is a highly contagious disease that causes significant economic loss in chickens. A cross-sectional study was conducted in the Mymensingh district of Bangladesh to determine the seroprevalence of IBD virus (IBDV) antibodies in backyard chickens and their association with different epidemiological risk factors. A total of 460 serum samples were randomly collected from backyard chickens that had not been previously vaccinated against IBDV. The collected sera were examined using an enzyme-linked immunosorbent assay (ELISA). Data on epidemiological risk factors were collected through face-to-face interviews with owners and subjected to both uni- and multivariable risk analyses to determine their association with IBDV infection. Using ELISA, the overall seroprevalence of IBDV antibodies in backyard chickens was 83.4% (95% confidence interval: 79.8%-86.6%), among which, a significantly higher seroprevalence was recorded in females (83.4%, 345/350), 4-6 weeks age group (95.3%, 244/256), and unhealthy (95.0%, 57/60) backyard chickens than those of males, other age groups, and healthy chickens, respectively. Furthermore, chickens reared in free-ranging housing systems (93.3%, 280/300) and poor-conditioned houses (98.0%, 147/150) showed a significantly higher seropositivity of IBDV antibodies than those reared in separated housing systems and other hygienic-conditioned houses, respectively. Moreover, compared with their counterparts, a higher but nonsignificant seroprevalence of IBDV antibodies was observed in backyard chickens that were selected from Fulbaria Upazila (88.8%; 80/90) and which were brought from the marketplace (85.7%, 60/70). A higher seropositivity of IBDV antibodies was shown to be statistically associated with various critical epidemiological risk factors, indicating that field strains of IBDV were exposed in backyard chickens and could be readily transferred horizontally. Proper prevention and control methods, villagers' awareness of IBD, and the rapid and widespread use of seroepidemiological investigations could help to reduce the spread of IBDV infection in backyard chickens.

First Molecular Survey to Detect Mycoplasma gallisepticum and Mycoplasma synoviae in Poultry Farms in a Strategic Production District of Sicily (South-Italy)

Simple Summary

Avian mycoplasmosis is caused by several pathogenic mycoplasmas of which Mycoplasma gallisepticum (MG) and M. synoviae (MS) are the most important. These bacteria may cause both respiratory disease and synovial infections in poultry, resulting in severe economic losses. The aim of this work was to determine the occurrence of MG and MS among commercial and rural laying hens located in Ragusa province (South Italy), using a duplex real time PCR. Four hundred tracheal swabs were collected from seven commercial and 25 rural farms without any clinical disease history. The prevalence in the studied flocks was 28.6% (commercial) and 40% (rural) for MG, and 42.8% (commercial) and 44% (rural) for MS. The overall prevalence at animal level was 12.5% for MG and 23.25% for MS. Data obtained show a lower prevalence of MG than MS in the studied farms. Moreover, both pathogens were spread in rural and commercial farms underlining the importance of surveillance and control of these infections.

Abstract

Mycoplasmas are recognized as avian pathogens, which may cause both respiratory disease and synovial infections in poultry, resulting in severe economic losses. Our study aims to determine the occurrence of Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) among commercial and rural laying hens located in Ragusa province (South Italy), using a duplex real time PCR. Four hundred tracheal swabs were collected from seven commercial (200 swabs) and 25 rural (200 swabs) farms without any clinical disease history. Out of 400 swabs collected, 50 (12.5%) and 93 (23.25%) were positive for MG and MS, respectively. In particular, 9 (18%) and 22 (23.65%) positive swabs for MG and MS, respectively, originated from commercial farms, compared to 41 (82%) and 71 (76.34%) obtained from rural farms. Data obtained show a lower prevalence of MG than MS in the studied farms. Moreover, both pathogens were spread in rural and commercial farms. PCR could be concluded as a rapid and sensitive method for the identification of MG and MS in areas where commercial farms that are declared Mycoplasma-free and rural flocks coexist. These data highlight the importance of surveillance also in rural poultry to monitoring the occurrence of mycoplasmas strains in strategic productive districts.

Investigation of Serotype Prevalence of Escherichia coli Strains Isolated from Layer Poultry in Greece and Interactions with Other Infectious Agents

Colibacillosis is the most common bacterial disease in poultry and it is caused by avian pathogenic Escherichia coli (APEC), which is assigned to various O-serogroups. Previous studies have shown that APEC strains are more often related to certain O-serogroups such asO78, O2 and O1. E. coli has been reported to act either as a primary or secondary agent in complicating other infections. The aim of this study was to investigate the occurrence of and characterize the O-serogroups of E. coli strains isolated from commercial layer and layer breeder flocks showing macroscopic lesions of colibacillosis and increased or normal mortality in Greece. Furthermore, we attempted to assess the interaction between infectious agents such as Mycoplasma gallisepticum (MG), Mycoplasma synoviae (MS), infectious bronchitis (IBV) and infectious laryngotracheitis (ILT) with E. coli infections in layer flocks with increased mortality. Our study revealed that in addition to the common serogroups (O78, O2), many other, and less common serogroups were identified, including O111. The O78, O111 and O2 serogroups were frequently detected in flocks with lesions of colibacillosis and increased mortality whereas O2, O88 and O8 were reported more commonly in birds with colibacillosis lesions but normal mortality rates. These data provide important information for colibacillosis monitoring and define preventative measures, especially by using effective vaccination programs because E. coli vaccines are reported to mainly offer homologous protection. Finally, concerning the association of the four tested infectious agents with E. coli mortality, our study did not reveal a statistically significant effect of the above infectious agents tested with E. coli infection mortality.

Mycoplasma synoviae dihydrolipoamide dehydrogenase is an immunogenic fibronectin/plasminogen binding protein and a putative adhesin

Mycoplasma synoviae (M. synoviae) is an important avian pathogen that causes arthritis and airsacculitis in young chickens and turkeys. Infection by M. synoviae results in considerable economic losses to the poultry industry worldwide. Cytoadherence is a crucial stage during mycoplasma infection. Dihydrolipoamide dehydrogenase (PdhD) is a flavin-dependent enzyme that is critical for energy metabolism and redox balance. To date, its role in cytoadherence is poorly understood. In this study, recombinant PdhD from M. synoviae (rMSPdhD) was expressed in the supernatant component of E. coli BL21 and rabbit anti-rMSPdhD serum was prepared. rMSPdhD was shown to be an immunogenic protein by immunoblot assays, while the mycoplasmacidal assay revealed that the rabbit anti-rMSPdhD serum had a high complement-dependent mycoplasmacidal rate (88.5 %). Using a suspension immunofluorescence assay and subcellular localization analysis, MSPdhD was shown to be a surface-localized protein distributed in both the cytoplasm and cell membrane of M. synoviae. The enzymatic activity of rMSPdhD was determined by measuring its ability to reduce lipoamide to dihydrolipoamide and convert NADH to NAD⁺. Using an indirect immunofluorescence assay, rMSPdhD was shown to adhere to DF-1 chicken embryo fibroblast cells. Furthermore, the attachment of M. synoviae to DF-1 cells was significantly inhibited by rabbit anti-rMSPdhD serum. Western blot and ELISA binding assays confirmed that rMSPdhD also bound to fibronectin (Fn) and plasminogen (Plg) in a dose-dependent manner. In conclusion, our data show that MSPdhD is not only a biological enzyme, but also an immunogenic surface-exposed protein that can bind to Fn and Plg as well as adhere to host cells. In addition, we show that rabbit anti-rMSPdhD serum can inhibit the adhesion of M. synoviae to DF-1 cells and has a significant complement-dependent bactericidal activity. Our findings suggest that MSPdhD may be involved in the pathogenesis of M. synoviae.

Pooled molecular occurrence of Mycoplasma gallisepticum and Mycoplasma synoviae in poultry: A systematic review and meta-analysis

Worldwide, Mycoplasma gallisepticum (MG) and M. synoviae (MS) are the main agents responsible for chronic respiratory disease in poultry. Therefore, we conducted a systematic review and meta-analysis to estimate their occurrence. We searched electronic databases to find peer-reviewed publications reporting the molecular detection of MG and MS in poultry and used meta-analysis to estimate their pooled global occurrence (combined flock and individual), aggregating results at the regional and national levels. We performed a subgroup meta-analysis for subpopulations (broilers, layers, breeders and diverse poultry including turkeys, ducks and ostriches) and used meta-regression with categorical modifiers. We retrieved 2294 publications from six electronic databases and included 85 publications from 33 countries that reported 62 studies with 22,162 samples for MG and 48 studies with 26,413 samples for MS. The pooled global occurrence was 38.4% (95% CI: 23.5-54.5) for MS and 27.0% (20.4-34.2) for MG. Among regions, Europe and Central Asia had the lowest occurrence for both pathogens, while MG and MS were highly prevalent in South Asia and sub-Saharan Africa, respectively. At the national level, MG occurrence was higher in Algeria, Saudi Arabia and Sudan, whereas China, Egypt and Ethiopia reported higher values of MS. Among the poultry subpopulations, MS and MG were more prevalent in the breeders and layers (62.6% and 31.2%, respectively) than in diverse poultry. The year of publication, the sample size and the level of ambient air pollution (measured indirectly by PM2.5) were associated with the occurrence of both mycoplasmas. Our study revealed high and heterogeneous occurrence values of MG and MS and justifies the need for early detection and improved control measures to reduce the spread of these pathogens.

Occurrence of Mycoplasma spp. in wild birds: phylogenetic analysis and potential factors affecting distribution

Different Mycoplasma species have been reported in avian hosts. However, the majority of studies focus on one particular species of Mycoplasma or one host. In our research, we screened a total of 1141 wild birds representing 55 species, 26 families, and 15 orders for the presence of mycoplasmas by conventional PCR based on the 16S rRNA gene. Selected PCR products were sequenced to perform the phylogenetic analysis. All mycoplasma-positive samples were tested for M. gallisepticum and M. synoviae, which are considered the major pathogens of commercial poultry. We also verified the influence of ecological characteristics of the tested bird species including feeding habits, habitat types, and movement patterns. The presence of Mycoplasma spp. was confirmed in 498 birds of 29 species, but none of the tested birds were positive for M. gallisepticum or M. synoviae. We found possible associations between the presence of Mycoplasma spp. and all investigated ecological factors. The phylogenetic analysis showed a high variability of Mycoplasma spp.; however, some clustering of sequences was observed regarding particular bird species. We found that wild migratory waterfowl, particularly the white-fronted goose (Anser albifrons) and mallard (Anas platyrhynchos) could be reservoirs and vectors of mycoplasmas pathogenic to commercial waterfowl.

Clinical expression, epidemiology and monitoring of Mycoplasma gallisepticum and Mycoplasma synoviae: an update

Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) are of clinical and economic importance for the global poultry industry. Many countries and integrations are involved in monitoring programs to control both mycoplasma species. This review provides an extensive historic overview of the last seven decades on the development of the knowledge regarding the factors that influence the clinical expression of the disease, the epidemiology and monitoring of both MG and MS. This includes the detection of new virulent strains, studies unravelling the transmission routes, survival characteristics and the role of other avian hosts. Also the role of molecular typing tests in unravelling epidemiology, and factors that complicate the interpretation of test results such as heterologous mycoplasma infections, use of heterologous oil-emulsion vaccines, use of antibiotic treatments, occurrence of MG and MS strains with low virulence, and last but not least the use of live and/or inactivated MG and MS vaccines are discussed.

Characterization of pyruvate dehydrogenase complex E1 alpha and beta subunits of Mycoplasma synoviae

Mycoplasma synoviae (MS) is an important pathogen which causes huge economic losses to the poultry industry worldwide, and research on MS can provide the foundation for diagnosis, prevention, and treatment of MS infection. In this study, primers designed based on the sequences of pyruvate dehydrogenase complex (PDC) E1 alpha and beta subunit genes (pdhA and pdhB, respectively) of MS 53 strain(AE017245.1) in GenBank were used to amplify the pdhA and pdhB genes of MS WVU1853 strain through PCR. Subsequently, the prokaryotic expression vectors pET-28a(+)-pdhA and pET-28a(+)-pdhB were constructed and expressed in Escherichia coli BL21(DE3) cells. The recombinant proteins rMSPDHA and rMSPDHB were purified, and anti-rMSPDHA and anti-rMSPDHB sera were prepared by immunizing rabbits, respectively. Subcellular localization of PDHA and PDHB in MS cells, binding activity of rMSPDHA and rMSPDHB to chicken plasminogen (Plg) and human fibronectin (Fn), complement-dependent mycoplasmacidal assays, and adherence and adherence inhibition assays were accomplished. The results showed that PDHA and PDHB were distributed both on the surface membrane and within soluble cytosolic fractions of MS cells. The rMSPDHA and rMSPDHB presented binding activity with chicken Plg and human Fn. The rabbit anti-rMSPDHA and anti-rMSPDHB sera had distinct mycoplasmacidal efficacy in the presence of guinea pig complement, and the adherence of MS to DF-1 cells pretreated with Plg was effectively inhibited by treatment with anti-rMSPDHA or anti-rMSPDHB sera. These findings indicated that surface-associated MSPDHA and MSPDHB were adhesion-related factors of MS and that the binding between MSPDHA/MSPDHB and Plg/Fn contributed to MS adhesion to DF-1 cells.

Bacterial communities of the upper respiratory tract of turkeys

The respiratory tracts of turkeys play important roles in the overall health and performance of the birds. Understanding the bacterial communities present in the respiratory tracts of turkeys can be helpful to better understand the interactions between commensal or symbiotic microorganisms and other pathogenic bacteria or viral infections. The aim of this study was the characterization of the bacterial communities of upper respiratory tracks in commercial turkeys using NGS sequencing by the amplification of 16S rRNA gene with primers designed for hypervariable regions V3 and V4 (MiSeq, Illumina). From 10 phyla identified in upper respiratory tract in turkeys, the most dominated phyla were Firmicutes and Proteobacteria. Differences in composition of bacterial diversity were found at the family and genus level. At the genus level, the turkey sequences present in respiratory tract represent 144 established bacteria. Several respiratory pathogens that contribute to the development of infections in the respiratory system of birds were identified, including the presence of Ornithobacterium and Mycoplasma OTUs. These results obtained in this study supply information about bacterial composition and diversity of the turkey upper respiratory tract. Knowledge about bacteria present in the respiratory tract and the roles they can play in infections can be useful in controlling, diagnosing and treating commercial turkey flocks.

Minimal inhibitory concentration of seven antimicrobials to Mycoplasma gallisepticum and Mycoplasma synoviae isolates from six European countries

Mycoplasma gallisepticum and Mycoplasma synoviae are bacterial pathogens that cause disease in poultry, adversely affecting their health and welfare, and are a financial burden on producers. This manuscript describes the results of the MycoPath project that is the first international antimicrobial susceptibility programme for mycoplasma pathogens isolated from poultry. Improved comparative analysis of minimal inhibitory concentration (MIC) results from participating countries was facilitated by using one laboratory determining all MICs. Chicken and turkey isolates were obtained from France, Germany, Great Britain, Hungary, Italy and Spain during 2014-2016. One isolate per farm was retained. The MIC of seven antimicrobial agents was determined using a broth microdilution method, with Friis Medium (M. gallisepticum) or Modified Chanock's Medium (M. synoviae). Of the 222 isolates recovered, 82 were M. gallisepticum and 130 were M. synoviae. M. gallisepticum MIC_50/90 values were 0.12/0.5, 2/8, 0.5/4, 0.12/>64, 0.008/0.062, 0.008/32, 0.062/4 mg/l for doxycycline, enrofloxacin, oxytetracycline, spiramycin, tiamulin, tilmicosin and tylosin, respectively. For M. synoviae, the values were 0.5/1, 8/16, 0.5/1, 0.5/8, 0.25/0.5, 0.062/2 and 0.062/16 mg/l respectively. A bimodal MIC distribution for the fluoroquinolone (enrofloxacin) and the macrolides (spiramycin, tilmicosin and tylosin) indicate that both species have sub-populations that are less susceptible in vitro to those antimicrobials. Some differences in susceptibilities were observed according to host species, Mycoplasma species, and country of origin. This study provides a baseline of novel data for future monitoring of antimicrobial resistance in poultry Mycoplasma species. Additionally, this information will facilitate the selection of the antimicrobial agents most likely to be effective, thus ensuring their minimal use with targeted and correct therapeutic treatments.Highlights First large-scale pan-European collection of representative Mg and Ms isolates.MIC values assessed in central laboratory for Mg and Ms from chickens and turkeys.Range of MIC values for 82 Mg and 130 Ms isolates to seven licenced antibiotics shown.Data can be used to help determine Mg and Ms veterinary-specific breakpoints.

Seroprevalence and prevalence of Mycoplasma synoviae in laying hens and broiler breeders in Spain

Mycoplasma species are worldwide recognized poultry pathogens, with Mycoplasma synoviae being the second most important species from the clinical point of view that causes considerable economic losses in the poultry industry. The aim of this study was to assess the seroprevalence, prevalence, and phylogenetic variants of M. synoviae present in layers and broiler breeders' farms of Gallus gallus species located in eastern Spain. Thus, 19 and 23 flocks of layers and broiler breeders, respectively, were analyzed at 3 different ages. To assess seroprevalence, sera samples were analyzed by ELISA. Tracheal swabs were tested by PCR to assess the prevalence. A M. synoviae seroprevalence of 95 and 74% was detected in layers and broiler breeders, respectively. Regarding age-wise analysis, the positive rates obtained seemed to be higher as the age of sampling increased. As per PCR results, a prevalence of 95% in layers and 35% in broiler breeders was obtained. The genetic analysis showed that the strains present in broilers breeders were vaccine strains (MS H strain). In contrast, 6 different field strains were detected in layer hens. In conclusion, this study carried out in eastern Spain showed a higher seroprevalence and prevalence of M. synoviae field strains in layer flocks regarding broiler breeders, highlighting the usefulness of monitoring flocks to control this poultry pathogen. Moreover, our findings suggest M. synoviae vaccination in broiler breeders could be an effective prevention strategy.

Decrease of Mycoplasma gallisepticum seroprevalence and introduction of new genotypes in Dutch commercial poultry during the years 2001-2018

Almost two decades ago, in addition to a compulsory M. gallisepticum (Mg) monitoring programme of breeding stock based on European Union regulations, the Dutch poultry industry added national regulations to further reduce the Mg prevalence in Dutch commercial poultry. Currently, all commercial chicken and turkey flocks except broilers are monitored for Mg. All breeding flocks on a farm where one or more flocks tested Mg positive are culled. Mg positive layer pullets are channelled and layer pullets placed on Mg positive multi-age farms are vaccinated. The monitoring data obtained were analysed covering a period of 17 years. Moreover, 31 Dutch Mg isolates from the same period were analysed by multilocus sequence typing (MLST) and compared to available PubMLST data. The results show that in breeding stock the seroprevalence decreased from 1.6% to 0.0%, in commercial layers from 6.3% to 1.9%, and in meat turkeys from 17.6% to 2.4%. The MLST results showed the presence of closely related and identical sequence types (STs) within the different Dutch poultry types. Similar STs were found in Northern and Southern Europe only. The results show a fast decline in the Mg prevalence since 2001, although in layers the Mg prevalence has stabilized and suggests backyard poultry might pose a risk for commercial poultry. The need for Mg control across poultry sectors and in trade was confirmed by the similarity in STs found in different types of poultry and regions. These results from the Dutch poultry industry can be extrapolated to Mg control in general.

Molecular Differentiation of Mycoplasma gallisepticum Outbreaks: A Last Decade Study on Italian Farms Using GTS and MLST

Mycoplasma gallisepticum (MG) infects many avian species and leads to significant economic losses in the poultry industry. Transmission of this pathogen occurs both horizontally and vertically, and strategies to avoid the spread of MG rely on vaccination and the application of biosecurity measures to maintain breeder groups as pathogen-free. Two live attenuated MG vaccine strains are licensed in Italy: 6/85 and ts-11. After their introduction, the implementation of adequate genotyping tools became necessary to distinguish between field and vaccine strains and to guarantee proper infection monitoring activity. In this study, 40 Italian MG isolates collected between 2010–2019 from both vaccinated and unvaccinated farms were genotyped using gene-targeted sequencing (GTS) of the cythadesin gene mgc2 and multilocus sequence typing (MLST) based on six housekeeping genes. The discriminatory power of GTS typing ensures 6/85-like strain identification, but the technique does not allow the identification ts-11 strains; conversely, MLST differentiates both vaccine strains, describing more detailed interrelation structures. Our study describes MG genetic scenario within a mixed farming context. In conclusion, the use of adequate typing methods is essential to understand the evolutionary dynamics of MG strains in a particular area and to conduct epidemiological investigations in the avian population.

Isolation and Antimicrobial Sensitivity of Mycoplasma synoviae and Mycoplasma gallisepticum from Vaccinated Hens in Mexico

Mycoplasma synoviae (MS) and Mycoplasma gallisepticum (MG) strains were isolated at 39.5 °C to rule out temperature-sensitive strains (ts+) and identified using random amplification of polymorphic DNA. Then, their minimum inhibitory concentrations (MIC₁₀₀) were calculated in isolated strains from broiler breeders and laying hens vaccinated with ts+ MS-H and ts+ MG TS-11 vaccines in Mexico. We sampled 631 lots of hens. A total of 28 of the 123 MS isolates and 12 of the 23 MG isolates were analyzed using random amplification of polymorphic DNA, of which 24 and 3 matched the DNA banding patterns of the MS-H and MG-F strains, respectively. The isolated MS and MG strains were sensitive to tiamulin and tylosin and showed intermediate sensitivity or resistance to lincomycin, florfenicol, erythromycin, enrofloxacin, and curcumin. Although both the MS and MG strains were sensitive to the same antibiotics (MIC₁₀₀ lower than 1 mg mL⁻¹), the MG strains were 5 to 10 times more sensitive than the MS strains. MS is the most frequently isolated mycoplasma in Mexican poultry production. The MS vaccine used (ts+ MS-H) could reverse its thermosensitivity and therefore could regain its virulence. MS was less sensitive to tiamulin and tylosin compared to MG.

Mutations potentially associated with decreased susceptibility to fluoroquinolones, macrolides and lincomycin in Mycoplasma synoviae

Mycoplasma synoviae is one of the economically most significant avian Mycoplasma species. It can cause great financial losses to the poultry industry by inducing respiratory diseases, infectious synovitis, or eggshell apex abnormalities. There are different approaches to control M. synoviae infection. Although antimicrobial therapy cannot replace long-term solutions, like eradication and vaccination, this strategy can be effective in the short term, as adequate antibiotic treatment can relieve economic losses through the attenuation of clinical signs and reduction of transmission. Using broth microdilution method, minimal inhibitory concentration (MIC) values to fourteen antibiotics related to eight antimicrobial groups were determined in 96 M. synoviae strains. Whole genome sequencing and sequence analysis revealed mutations potentially associated with decreased susceptibility to fluoroquinolones, macrolides and lincomycin. Molecular markers responsible for the high MICs to fluoroquinolones were found in the gyrA, gyrB, parC and parE genes. Besides, single nucleotide polymorphisms identified in genes encoding the 23S rRNA were found to be responsible for high MICs to the 50S inhibitor macrolides and lincomycin, while amino acid change in the 50S ribosomal protein L22 could be associated with decreased susceptibility to macrolides. The revealed mutations can contribute to the extension of knowledge about the genetic background of antibiotic resistance in M. synoviae. Moreover, the explored potentially resistance-related mutations may serve as targets for molecular biological assays providing data of antibiotic susceptibility prior to the laborious and time-consuming isolation of M. synoviae strains.

Investigation on eggshell apex abnormality (EAA) syndrome in France: isolation of Mycoplasma synoviae is frequently associated with Mycoplasma pullorum

BACKGROUND

Mycoplasma synoviae (MS) is known to cause Eggshell Apex Abnormality (EAA) syndrome characterized by an altered shell surface with increased translucency on the apex. However, no large-scale studies have been conducted to obtain prevalence data of EAA and MS isolates associated to this syndrome. This manuscript reports the results of two field studies performed in the French poultry industry (2015-2017): focusing mainly on investigation of presence and prevalence of EAA in different types of laying hen flocks (phase 1), and isolation of MS strains from EAA-infected flocks (phase 2).

RESULTS

The first survey included 77 farms of commercial layers in three French egg-production regions, hosting 40 flocks in alternative systems (ALT) and 56 in furnished cages (FC). Seven flocks (4 FC and 3 ALT) presented EAA clinical signs, giving a prevalence of 7.3% in this studied sample. A second independent field study was conducted to identify MS by in vitro cultivation and PCR in samples from 28 flocks with clinical signs of EAA. Different types of biological specimens were collected in EAA-affected flocks and submitted to the laboratory. M. synoviae was detected in 25/28 flocks, from both production systems (5/5 ALT and 20/23 FC). Detection of MS was significantly higher in tracheal swabs (59%) than in cloacal (10.5%), albumen (3.6%) and egg yolk (1.1%) swabs. It is worth to mention that attempts to clone MS from positive samples were often hampered by the presence of another Mycoplasma species, which showed fast growing behaviour in the selective media used in this study (Frey Medium 4 and Frey Medium 4 supplemented with erythromycin). The use of MALDI-TOF mass spectrometry in combination with next-generation sequencing (NGS) results allowed the identification of this fast growing mycoplasma as Mycoplasma pullorum, which was detected in 14 of the 25 (56%) MS-positive flocks.

CONCLUSIONS

These results confirmed the presence of the EAA syndrome in MS-positive flocks of layers in France, reared in different regions and in different production systems (ALT and FC). Studies need to be conducted to test whether M. pullorum may influence the expression of clinical signs of EAA in MS-infected layer farms.

Persistence in Livestock Mycoplasmas—a Key Role in Infection and Pathogenesis

Purpose of Review

Mycoplasma, economically important pathogens in livestock, often establishes immunologically complex persistent infections that drive their pathogenesis and complicate prophylaxis and therapy of the caused diseases. In this review, we summarize some of the recent findings concerning cellular and molecular persistence mechanisms related to the pathogenesis of mycoplasma infections in livestock.

Recent Findings

Data from recent studies prove several mechanisms including intracellular lifestyle, immune dysregulation, and autoimmunity as well as microcolony and biofilm formation and apoptosis of different host cell types as important persistence mechanisms in several clinically significant Mycoplasma species, i.e., M. bovis, M. gallisepticum, M. hyopneumoniae, and M. suis.

Summary

Evasion of the immune system and the establishment of persistent infections are key features in the pathogenesis of livestock mycoplasmas. In-depth knowledge of the underlying mechanisms will provide the basis for the development of therapy and prophylaxis strategies against mycoplasma infections.

Rate of false positive reactions in 11 M. gallisepticum and M. synoviae serological tests in samples obtained from SPF birds inoculated with heterologous mycoplasma species

No recent information is available on the specificity of current M. synoviae (Ms) and M. gallisepticum (Mg) serological tests. In this study the performance of a currently available Mg and Ms Rapid Plate Agglutination (RPA) test, and three Mg, three Ms and three Mg/Ms combination ELISAs were evaluated on SPF sera that were obtained from days (D) 0-28 after M. gallinarum, M. imitans or M. gallinaceum inoculation, after sham inoculation and without inoculation. Tracheal swabs for mycoplasma culture were obtained before inoculation (D0), 7 and 28 days post inoculation (d.p.i.) in all groups except the sham inoculated group. The different mycoplasma species colonized well. In the early stage after inoculation (7-14 d.p.i.) with heterologous mycoplasma species, the specificity varied from 85% to 100% in the Mg RPA test and from 70% to 85% in the Ms RPA test. The specificity of both Mg and Ms RPA test was 100% in the sham inoculated samples and ruled out the effect of sham medium. In the late stage (21-28 d.p.i.) specificity was 100% for both RPA tests. The test specificity was 100% for seven ELISAs except for two combination ELISAs where a specificity of 95% was found in the late stage after inoculation. However, this was not significantly different from the specificity of all other tests in the late stage of these groups. These results show that it is not advisable to establish Mg and Ms seromonitoring programmes on the Mg and Ms RPA test alone as other mycoplasma species frequently occur in poultry.

Rapid and visible detection of Mycoplasma synoviae using a novel polymerase spiral reaction assay

In this study, a rapid, specific, and sensitive detection assay for Mycoplasma synoviae (MS) was established using a polymerase spiral reaction (PSR) method. A pair of primers were designed according to the conserved region of the vlhA gene of MS, and PSR results were assessed using agarose gel electrophoresis and color rendering with a dye indicator. The optimum reaction temperature and time for PSR using the specific primers were 62°C and 40 min in a water bath, respectively. The sensitivity of the PSR assay for MS detection was 100 times more than that of the polymerase chain reaction assay based on agarose gel electrophoresis results and color change detected by the naked eye. Further experiments demonstrated that the primers specifically detected MS and showed no cross-reaction with other prevalent avian pathogens. Clinical sample testing confirmed that the MS-PSR assay is simple, rapid, specific, and sensitive, and thereby very suitable for application and promotion in the field and laboratories of grassroots units.

Evaluation of Minimum Inhibitory Concentrations for 154 Mycoplasma synoviae isolates from Italy collected during 2012-2017

Mycoplasma synoviae (MS) is a highly prevalent bacterial species in poultry causing disease and severe economic losses. Antibiotic treatment is one of the control strategies that can be applied to contain clinical outbreaks in MS-free flocks, especially because this bacterium can be transmitted in ovo. It becomes, then, very important for veterinarians to know the antibiotic susceptibility of the circulating strains in order to choose the most appropriate first-line antibiotic molecule as a proactive role in fighting antibiotic resistance. We evaluated the Minimum Inhibitory Concentrations (MICs) of enrofloxacin, oxytetracycline, doxycycline, erythromycin, tylosin, tilmicosin, spiramycin, tiamulin, florfenicol and lincomycin for MS isolates collected between 2012 and 2017 in Italy. A total of 154 MS isolates from different poultry commercial categories (broiler, layer, and turkey sectors) was tested using commercial MIC plates. All MS isolates showed very high MIC values of erythromycin (MIC90 ≥8 μg/mL) and enrofloxacin (MIC90 ≥16 μg/mL). MIC values of doxycycline and oxytetracycline obtained were superimposable to each other with only a one-fold dilution difference. Discrepancies between MIC values of tylosin and tilmicosin were observed. Interestingly, seven isolates showed very high MIC values of lincomycin and tilmicosin, but not all of them showed very high MIC values of tylosin. Most of the MS isolates showed low MIC values of spiramycin, but seven strains showed a MIC ≥16 μg/mL. In the observation period, the frequency of the different MIC classes varied dependently on the tested antibiotic. Interestingly, tilmicosin MICs clearly showed a time-dependent progressive shift towards high-concentration classes, indicative of an on-going selection process among MS isolates. Until standardized breakpoints become available to facilitate data interpretation, it will be fundamental to continue studying MIC value fluctuations in the meantime in order to create a significant database that would facilitate veterinarians in selecting the proper drug for treating this impactful Mycoplasma.

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.

Application of different laboratory techniques to monitor the behaviour of a Mycoplasma synoviae vaccine (MS-H) in broiler breeders

Background

Mycoplasma synoviae (MS) is a major poultry pathogen which causes severe economic losses in all the productive sectors. The prevalence of MS in European countries has increased in the last few years, leading to greater attention to the available methods to prevent its spread. The main strategy currently applied for its containment is the development and maintenance of MS-free breeder flocks. A live MS vaccine (MS-H) obtained by mutagenizing an Australian field strain has recently been introduced in Italy. The aim of the present study was to evaluate the vaccine behaviour in broiler breeder groups at different production stages and the effectiveness of the available laboratory tests in discriminating the MS-H from a field strain.

Results

The vaccine diffused extensively through the population, shown by the wide serological response (over 80% of positive samples in RSA and 85% in ELISA), the high serological titres, the positivity of all the tracheal samples collected during the production phase by MS PCR and the positivity by cultivation from tracheal swabs at the end-point (55 weeks after vaccination). In contrast, only one swab from a sternal bursa was positive in MS PCR, while all the joint and oviduct samples were negative. There was no evidence of vertical transmission. Different genotyping techniques were used to achieve a clear classification of the MS positive samples. The vlhA and the obg gene analysis showed that most of the strains were homologous with the vaccine, but some ambiguous samples were further investigated with the multi locus sequence typing (MLST) scheme which confirmed the homology.

Conclusions

The development of a multi-technique approach to monitor vaccinated avian flocks, based both on serological and biomolecular methods, is advised as well as the use of effective genotyping techniques to analyse the MS strains circulating in high densely populated poultry areas.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1669-8) contains supplementary material, which is available to authorized users.

Co-circulation of genetically diverse population of vaccine related and unrelated respiratory mycoplasmas and viruses in UK poultry flocks with health or production problems

Respiratory diseases continue to have a major impact on poultry health, welfare and productivity. However, little information is available on their current status in UK poultry flocks. We investigated the presence of four economically important respiratory pathogens in healthy or problematic flocks; infectious bronchitis virus (IBV), avian metapneumovirus (aMPV), Mycoplasma gallisepticum (Mg) and Mycoplasma synoviae (Ms). Samples from 131 UK poultry flocks were received during the 12 month study period. Oropharyngeal (OP) swabs were taken from eight birds per flock and accompanied with flock health information. The study included 118 chicken, 6 pheasant and 5 turkey flocks, and 1 quail and 1 partridge flock. Chicken flocks were of layers (n = 98), broilers (n = 15), breeders (n = 3) and undisclosed (n = 2). Flock ages ranged from 3 to 72 weeks old, and the average flock size was 17,633 birds. PCR detected 65 (49.6%), 59 (45%) and 8 (6.1%) flocks as positive for IBV, Mg/Ms and aMPV respectively. Analysis of the mgc2 gene of the Mg isolates revealed high similarities to Mg TS-11 and Mg 6/85. Further gene analysis found that the TS-11-like isolates were unrelated to the TS-11 vaccine. Multi-locus sequence typing (MLST) analysis identified the majority of positive Ms as ST21, along with ST2 (MS-H-like), ST6 and ST43. IBV S1 gene sequencing identified strains as 793B (66.7%), Arkansas (23.8%) and Massachusetts (9.5%). All aMPV positive samples belonged to subtype B. Findings indicate that over half of the flocks sampled were positive for at least one of the four vaccine or field strains of mycoplasmas or viruses.

Genome analysis of Mycoplasma synoviae strain MS-H, the most common M. synoviae strain with a worldwide distribution

BACKGROUND

The bacterial pathogen Mycoplasma synoviae can cause subclinical respiratory disease, synovitis, airsacculitis and reproductive tract disease in poultry and is a major cause of economic loss worldwide. The M. synoviae strain MS-H was developed by chemical mutagenesis of an Australian isolate and has been used as a live attenuated vaccine in many countries over the past two decades. As a result it may now be the most prevalent strain of M. synoviae globally. Differentiation of the MS-H vaccine from local field strains is important for epidemiological investigations and is often required for registration of the vaccine.

RESULTS

The complete genomic sequence of the MS-H strain was determined using a combination of Illumina and Nanopore methods and compared to WVU-1853, the M. synoviae type strain isolated in the USA 30 years before the parent strain of MS-H, and MS53, a more recent isolate from Brazil. The vaccine strain genome had a slightly larger number of pseudogenes than the two other strains and contained a unique 55 kb chromosomal inversion partially affecting a putative genomic island. Variations in gene content were also noted, including a deoxyribose-phosphate aldolase (deoC) fragment and an ATP-dependent DNA helicase gene found only in MS-H. Some of these sequences may have been acquired horizontally from other avian mycoplasma species.

CONCLUSIONS

MS-H was somewhat more similar to WVU-1853 than to MS53. The genome sequence of MS-H will enable identification of vaccine-specific genetic markers for use as diagnostic and epidemiological tools to better control M. synoviae.

Antibiotic susceptibility profiles of Mycoplasma synoviae strains originating from Central and Eastern Europe

BACKGROUND

Mycoplasma synoviae causes infectious synovitis and respiratory diseases in chickens and turkeys and may lead to egg shell apex abnormalities in chickens; hence possesses high economic impact on the poultry industry. Control of the disease consists of eradication, vaccination or medication. The aim of the present study was to determine the in vitro susceptibility to 14 different antibiotics and an antibiotic combination of M. synoviae strains originating from Hungary and other countries of Central and Eastern Europe.

RESULTS

Minimal inhibitory concentration (MIC) values of a total of 41 M. synoviae strains were determined by the microbroth dilution method. The strains were collected between 2002 and 2016 and originated from Hungary (n = 26), Austria (n = 3), the Czech Republic (n = 3), Slovenia (n = 3), Ukraine (n = 3), Russia (n = 2) and Serbia (n = 1). Tetracyclines (with MIC50 values of 0.078 μg/ml, ≤0.25 μg/ml and 0.5 μg/ml for doxycycline, oxytetracycline and chlortetracycline, respectively), macrolides (with MIC50 values of ≤0.25 μg/ml for tylvalosin, tylosin and tilmicosin), pleuromutilins (with MIC50 values of 0.078 μg/ml and ≤0.039 μg/ml for tiamulin and valnemulin) and the combination of lincomycin and spectinomycin (MIC50 1 μg/ml (0.333/0.667 μg/ml)) were found to be the most effective antibiotic agents against M. synoviae in vitro. High MIC values were detected in numerous strains for fluoroquinolones (with MIC50 values of 1.25 μg/ml and 2.5 μg/ml for enrofloxacin and difloxacin), neomycin (MIC50 32 μg/ml), spectinomycin (MIC50 2 μg/ml), lincomycin (MIC50 0.5 μg/ml) and florfenicol (MIC50 4 μg/ml). Nevertheless, strains with elevated MIC values were detected for most of the applied antibiotics.

CONCLUSIONS

In the medical control of M. synoviae infections the preliminary in vitro antibiotic susceptibility testing and the careful evaluation of the data are crucial. Based on the in vitro examinations doxycycline, oxytetracycline, tylvalosin, tylosin and pleuromutilins could be recommended for the therapy of M. synoviae infections in the region.

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.

Epidemiological investigation of Mycoplasma Synoviae in native chicken breeds in China

Backgroud

Mycoplasma synoviae (M. synoviae) is widely distributed around the world, and leads to serious economic losses in the world every year. Nevertheless, the incidence and epidemiology of M. synoviae infection in China have remained unclear.

Results

In this study we demonstrate that over 9773 broiler chicken flocks in 16 Chinese provinces were affected by M. synoviae between 2010 and 2015. Our epidemiological study revealed that M. synoviae was widely prevalent in multi-aged Chinese native breeder chickens, and the prevalence of M. synoviae in embryos of breeders reached up to 16.29%. In addition, our data showed that chickens aged 14 days or younger carried simultaneously high levels of maternal antibody against M. synoviae and high M. synoviae infection (10%), and low M. synoviae antibody levels in breeders and high proportion of M. synoviae infection in embryos could increase the chances of incidence in the offspring. Finally, our results also indicated that 3- to 7-week-old chickens might be most the susceptible to M. synoviae and, therefore, might play a key role in the horizontal transmission of M. synoviae.

Conclusion

Our findings suggest that M. synoviae is widely circulating in Chinese native chickens, accordingly, effective control measures are urgently needed to control the spread.

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.

The PK/PD Interactions of Doxycycline against Mycoplasma gallisepticum

Mycoplasma gallisepticum is one of the most important pathogens that cause chronic respiratory disease in chicken. This study investigated the antibacterial activity of doxycycline against M. gallisepticum strain S6. In static time–killing studies with constant antibiotic concentrations [0–64 minimum inhibitory concentration (MIC)], M. gallisepticum colonies were quantified and kill rates were calculated to estimate the drug effect. The half-life of doxycycline in chicken was 6.51 ± 0.63 h. An in vitro dynamic model (the drug concentrations are fluctuant) was also established and two half-lives of 6.51 and 12 h were simulated. The samples were collected for drug concentration determination and viable counting of M. gallisepticum. In static time–killing studies, doxycycline produced a maximum antimycoplasmal effect of 5.62log₁₀ (CFU/mL) reduction and the maximum kill rate was 0.11 h⁻¹. In the in vitro dynamic model, doxycycline had a mycoplasmacidal activity in the two regimens, and the maximum antimycoplasmal effects were 4.1 and 4.75log₁₀ (CFU/mL) reduction, respectively. Furthermore, the cumulative percentage of time over a 48-h period that the drug concentration exceeds the MIC (%T > MIC) was the pharmacokinetic–pharmacodynamic index that best correlated with antimicrobial efficacy (R² = 0.986, compared with 0.897 for the peak level divided by the MIC and 0.953 for the area under the concentration–time curve over 48 h divided by the MIC). The estimated %T > MIC values for 0log₁₀ (CFU/mL) reduction, 2log10 (CFU/mL) reduction and 3log₁₀ (CFU/mL) reduction were 32.48, 45.68, and 54.36%, respectively, during 48 h treatment period of doxycycline. In conclusion, doxycycline shows excellent effectiveness and time-dependent characteristics against M. gallisepticum strain S6 in vitro. Additionally, these results will guide optimal dosing strategies of doxycycline in M. gallisepticum infection.

Evaluation of the Capacity of PCR and High-Resolution Melt Curve Analysis for Identification of Mixed Infection with Mycoplasma gallisepticum Strains

Pathogenicity and presentation of Mycoplasma gallisepticum (MG) infection may differ from one strain to another and this may have implications on control measures. Infection of individual birds with more than one MG strain has been reported. A PCR followed by high resolution melt (HRM) curve analysis has been developed in our laboratory and routinely used for detection and differentiation of MG strains. However the potential of this test for identification of MG strains in a mixed specimen has not been evaluated. In the present study, the capability of PCR-HRM curve analysis technique, targeting vlhA and pvpA genes was assessed for identification of individual MG strains in a mixed population. Different DNA ratios of two MG strains from 1 to 10^-4 ng were tested with some generated conventional and normalized curves distinct from those of individual strains alone. Using genotype confidence percentages (GCP) generated from HRM curve analysis, it was found that vlhA PCR-HRM was more consistent than pvpA PCR-HRM for the detection of MG ts-11 vaccine strain mixed with any of the MG strains 6/85, F, S6 or a field isolate. The potential of vlhA PCR-HRM to detect mixed MG strains in a specimen was found to be primarily dependent on quantity and proportion of the target DNAs in the mixture. This is the first study examining the capacity of PCR-HRM technique for identification of individual MG strains in a mixed strain population.

High seroprevalence of respiratory pathogens in hobby poultry

Seroprevalence studies on respiratory pathogens have been done extensively in commercial laying hens, broilers, and, to a lesser extent, backyard poultry. In Europe, seroprevalence studies in backyard and fancy breed poultry flocks are scarce and limited to a few pathogens, such as Mycoplasma gallisepticum (MG); others, such as Ornithobacterium rhinotracheale (ORT), are missing. A commercial ELISA for detection of antibodies against six selected pathogens was performed on 460 serum samples from chickens across Flanders. Anti-ORT antibodies were, by far, the most prevalent, with a prevalence of 95.4%. Infectious bronchitis virus, Mycoplasma synoviae, and avian metapneumovirus antibodies were found in 75.6%, 76.3%, and 63.5% of the animals, respectively. Antibodies against MG and infectious laryngotracheitis virus were found in 36.7% and 30% of the animals, respectively. These data demonstrate the high seroprevalence of respiratory pathogens among hobby poultry; therefore, it is possible that this group could act as a reservoir for commercially kept poultry.

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.