Anatomic location of Mycoplasma mycoides subsp. capri and Mycoplasma agalactiae in naturally infected goat male auricular carriers

Mycoplasma mycoides subspecies capri, an uncommon mastitis and respiratory pathogen isolated in a German flock of goats

Mycoplasma mycoides ssp. capri (Mmc) is one of the etiological microorganisms of contagious agalactia, which is among the diseases causing the highest economical losses in small ruminants. We report a disease outbreak in a German flock that led to significant suffering of goats characterized by mastitis, arthritis, pleuropneumonia and sudden deaths. Mmc was persistently isolated from many animals both from milk, and from a number of different swab and tissue samples. A number of closely related Mycoplasma spp. have to be taken into consideration to rule out important animal epizootics listed by European Animal Health Law and the World Organisation for Animal Health (WOAH). Some goats developed cross-reacting antibodies against Mycoplasma mycoides ssp. mycoides. Although Mmc is believed to be an uncommon microorganism in Germany, this study highlights that veterinarians should consider this pathogen in their work during herd health monitoring in Central Europe. Although eradication was not fully achieved, autogenous vaccination significantly seemed to improve animal health and welfare.

In Vitro Interaction between Mycoplasma agalactiae and Small Ruminants' Endogenous Bacterial Strains of Enterococcus spp. and Coagulase-Negative Staphylococcus

Recently, an antimicrobial effect on Mycoplasma agalactiae (Ma), the main etiological agent of contagious agalactia (CA), was reported in vitro with strains of Enterococcus spp. from ovine and caprine milk. The aim of this work was to evaluate the interaction of Ma with the same Enterococcus spp. isolated from other anatomical locations (vagina) and other bacterial populations present in milk, such as coagulase-negative staphylococci (CNS). The vaginal Enterococcus strains and the raw milk CNS were isolated from sheep and goats. Experimental in vitro conditions were prepared to assess the growth of Ma with and without the presence of these strains. The selected vaginal strains were identified as Enterococcus (E.) hirae and E. mundtii, and the strains of CNS were identified as Staphylococcus petrasii. Different interactions of Ma with ovine and caprine wild vaginal strains of Enterococcus and dairy strains of CNS are described for the first time: Ma can grow exponentially during 15 h with the selected strains, although with certain strains, its optimal growth can be negatively affected (p < 0.05). The colonization and/or excretion of Ma could, therefore, be influenced by certain endogenous bacterial strains. Our results increase the knowledge about possible bacterial ecology dynamics surrounding CA.

Antibacterial potential of commercial and wild lactic acid bacteria strains isolated from ovine and caprine raw milk against Mycoplasma agalactiae

Introduction

The complexity of fighting contagious agalactia (CA) has raised the necessity of alternative antimicrobial therapies, such as probiotics. Lactic acid bacteria (LAB) are present in the mammary gland of small ruminants and their antimicrobial effect have been previously described against species like Mycoplasma bovis but never against Mycoplasma agalactiae (Ma). This in vitro study aims to evaluate the antimicrobial activity against Ma of ovine and caprine LAB strains and a human commercial probiotic (L2) of Lactobacillus spp.

Methods

A total of 63 possible LAB strains were isolated from nine ovine and caprine farms in Spain, three isolates (33B, 248D, and 120B) from the 63 strains were selected, based on their capacity to grow in a specific medium in vitro, for an in vitro experiment to assess their antimicrobial activity against Ma in Ultra High Temperature (UHT) processed goat milk (GM). A women commercial vaginal probiotic was also included in the study. The inoculum of L2 was prepared at a concentration of 3.24 × 10⁸  CFU/mL and the average concentration of the inoculum of the wild LAB varied from 7.9 × 10⁷ to 8.4 × 10⁸  CFU/mL.

Results

The commercial probiotic L2 significantly reduced the concentration of Ma to 0.000 log CFU/mL (p < 0.001), strain 33B reduced it from 7.185 to 1.279 log CFU/mL (p < 0.001), and 120B from 6.825 to 6.466 log CFU/mL (p < 0.05). Strain 248D presented a bacteriostatic effect in GM. Moreover, the three wild strains and the commercial probiotic produced a significative reduction of the pH (p < 0.001).

Discussion

This is the first in vivo report of the antimicrobial potential of LAB strains against Ma and its interaction. Our results support possible future alternative strategies to antibiotic therapy, previously not contemplated, to fight CA in small ruminants. Further studies are necessary to elucidate the action mechanisms through which these LAB are able to inhibit Ma and to assess the safety of using these strains in possible in vivo studies.

A novel fusion protein candidate for the serodiagnosis of Mycoplasma agalactiae infection

BACKGROUND

The aim of current study was to construct, express, purify and immunogenicity evaluate of a novel recombinant fusion protein including Pyruvate dehydrogenase beta subunit (PDHB) and high antigenic region of lipoprotein P80 of Mycoplasma agalactiae. Using bioinformatics tools, antigenicity and physiochemical properties of fused protein were assessed.

MATERIAL AND METHODS

The recombinant fusion protein of GST-PDHB-P80 were expressed in pGEX4T-1 and purified then verified by Western blot assay. The purified protein was successfully used for immunization of mice. 30 female BALB/c mice were divided into three groups (10 mice per each group) injected with GST-PDHB-P80, inactivated bacteria vaccine and PBS as negative control, separately.

RESULTS

Western blot analysis confirmed the interaction between the immunized mice serum and the blotted recombinant protein GST-PDHB-P80, demonstrating the immunogenicity of this protein. Moreover, the sera of vaccinated mice with inactivated bacteria vaccine, containing whole cell proteins, detected the recombinant protein GST-PDHB-P80 confirming the antigenicity of PDHB-P80. Negative control displayed no reactivity with GST-PDHB-P80.

CONCLUSION

We proposed a novel designed chimeric protein of Mycoplasma agalactiae as a potential marker for serodiagnostic assays but still further field research is required.

Influence of natural and climatic conditions on the distribution and forms of contagious agalactia in sheep in Bessarabia, Ukraine

Introduction

Contagious agalactia of ruminants is an endemic disease caused by Mycoplasma agalactiae in flicting significant losses on farms in deaths and forced slaughter of sick animals, abortions, births of sick young animals, and reduced milk and wool production. The aim of the study was to determine the influence of hydrometeorological conditions on the distribution and forms of contagious agalactia in sheep in Bessarabia, Ukraine.

Material and Methods

The epizootic situation regarding contagious agalactia was studied during 2011–2021 on sheep farms in the south of the Odesa region in Bessarabia. Over two million blood samples from sheep aged 1–6 years were serologically investigated and the prevalence of agalactia was correlated with Selyaninov’s hydrothermal coefficient for each sampling year.

Results

High rates of infection of sheep with contagious agalactia (from 13.1% to 14.4%) were registered in 2012, 2016 and 2021, years which according to the hydrothermal coefficient of 1.0 were sufficiently moist. The lowest incidence rates, from 6.5% to 7.4%, were registered in the very dry 2013, 2014 and 2019 with hydrothermal coefficients of 0.5‒0.6. In sufficiently moist years, contagious agalactia of sheep manifested itself in the mastitic form, while in the dry period the mastitic form was half as prevalent, and the mixed, articular and ocular forms of the disease proliferated.

Conclusion

The results indicate the circulation of Mycoplasma agalactiae among small ruminants in Bessarabia, and that the prevalence and the course of the associated disease depend on the humidity of the climate, i.e. the value of the hydrothermal coefficient.

Detection of Mycoplasma agalactiae in Ticks (Rhipicephalus bursa) Collected by Sheep and Goats in Sicily (South-Italy), Endemic Area for Contagious Agalactia

The aim of this preliminary study was to investigate the presence of Mycoplasma agalactiae (Ma) or other Contagious Agalactia (CA) causative organisms, in hard ticks infesting milking sheep and goats in endemic areas for CA in Sicily (South-Italy). Although there is accumulating evidence to support the role of ticks in the transmission of blood-borne haemoplasmas, information regarding their role in the transmission of CA, remains scarce. Ticks (n = 152) were collected from 25 lactating sheep and goats from three farms with previous outbreaks of CA. Microbiological and biomolecular, as well as serological analysis were performed on milk, tick, and serum samples, respectively. Rhipicephalus bursa species predominated, comprising 84.8% of the sampled ticks. Mycoplasma-like colonies were isolated from 5/56 (8.9%) tick pools and were identified as Ma by specific PCR and 16S rRNA gene sequencing. Unexpectedly, the organism was isolated from R. bursa ticks recovered only from animals whose milk tested negative for the pathogen. This preliminary demonstration suggests the potential role for ticks to act as a reservoir for the organisms, with potential involvement in the spread and maintenance of CA. Further work is required to determine the location of the organisms within the body of the ticks and to assess transmission potential.

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.

Mycoplasma bovis in Spanish Cattle Herds: Two Groups of Multiresistant Isolates Predominate, with One Remaining Susceptible to Fluoroquinolones

Mycoplasma bovis is an important bovine pathogen causing pneumonia, mastitis, and arthritis and is responsible for major economic losses worldwide. In the absence of an efficient vaccine, control of M. bovis infections mainly relies on antimicrobial treatments, but resistance is reported in an increasing number of countries. To address the situation in Spain, M. bovis was searched in 436 samples collected from beef and dairy cattle (2016–2019) and 28% were positive. Single-locus typing using polC sequences further revealed that two subtypes ST2 and ST3, circulate in Spain both in beef and dairy cattle, regardless of the regions or the clinical signs. Monitoring of ST2 and ST3 isolates minimum inhibitory concentration (MIC) to a panel of antimicrobials revealed one major difference when using fluoroquinolones (FQL): ST2 is more susceptible than ST3. Accordingly, whole-genome sequencing (WGS) further identified mutations in the gyrA and parC regions, encoding quinolone resistance-determining regions (QRDR) only in ST3 isolates. This situation shows the capacity of ST3 to accumulate mutations in QRDR and might reflect the selective pressure imposed by the extensive use of these antimicrobials. MIC values and detection of mutations by WGS also showed that most Spanish isolates are resistant to macrolides, lincosamides, and tetracyclines. Valnemulin was the only one effective, at least in vitro, against both STs.

The Addition of Lactobacillus spp., Enrofloxacin or Doxycycline Negatively Affects the Viability of Mycoplasma bovis in Diluted Bovine Semen

Simple Summary

Mycoplasma bovis is an important infectious agent in cattle. The pathogen may cause a wide range of clinical signs, including mastitis, arthritis, pneumonia and reproductive disorders. Artificial insemination with contaminated semen may be a source of infection in infection-free areas or herds. Hence, the antimicrobials used in the preparation of seminal doses should be re-evaluated, or alternative measures to antimicrobials should be tested. This in vitro study aims to evaluate novel strategies to reduce the risk of the transmission of the pathogen through contaminated semen during artificial insemination. Hence, we assess the effect of the addition of (1) the antimicrobial enrofloxacin, (2) the antimicrobial doxycycline, or (3) a probiotic of human origin that contains acid lactic bacteria of the genus Lactobacillus, on the viability of Mycoplasma bovis in diluted bull semen in a Tris-citrate-fructose medium. The data show that the pathogen is negatively affected by the addition of 0.125 μg/mL of enrofloxacin, 0.0625 μg/mL of doxycycline, or the probiotic at a concentration of 3.24 × 10⁶ or 3.24 × 10⁸ colony-forming units/mL in diluted semen. Our results are promising in the field, as they may support new strategies to reduce the risk of the transmission of Mycoplasma bovis through artificial insemination.

Abstract

Mycoplasma bovis is an important etiologic agent of bovine mycoplasmosis in cattle. Different transmission routes have been described, including those related to reproduction. The presence of mycoplasma in semen has led to its appearance in infection-free areas through artificial insemination (AI). Semen was recently reported to be the initial source of two M. bovis mastitis outbreaks in two closed dairy herds in Finland. This questions the effectiveness of the antimicrobials currently used in semen extenders to control the pathogens in contaminated semen. They should be re-evaluated, or alternative measures to antimicrobials should be tested to obtain M. bovis-free semen. This in vitro study aimed to assess different strategies to reduce the risk of transmission of M. bovis through AI technologies. The viability of M. bovis (PG45, NCTC 10131) in bull semen diluted (DS) in a Tris-citrate-fructose solution was tested, after the addition of enrofloxacin, doxycycline or a Lactobacillus spp.-based probiotic. The data show the susceptibility of the pathogen to the addition of 0.125 μg/mL of enrofloxacin or 0.0625 μg/mL of doxycycline and to the addition of the probiotic at a concentration of 3.24 × 10⁶ colony forming units (CFU)/mL or 3.24 × 10⁸ CFU/mL in DS. The Tris-citrate-fructose medium negatively affected the viability of M. bovis, although this effect was lower than that observed after the addition of the probiotic and antimicrobials (p < 0.05). Our results may support new strategies for reducing the risk of M. bovis transmission through AI.

Use of Probiotics in Intravaginal Sponges in Sheep: A Pilot Study

Simple Summary

The use of intravaginal devices may generate retention of vaginal secretions and abnormal discharges at device withdrawal, which may create changes in the normal vaginal bacterial microbiota. These changes in vaginal microbiota could allow the growth of opportunistic pathogenic bacteria which can require antibiotic treatment. The addition of antibiotics on sponges poses a risk of milk contamination. In dairy cows, it has been observed that the use of lactic acid bacteria (LAB) confers a health benefit to the reproductive tract against bacterial infections. However, LAB use in intravaginal sponges in sheep has not been reported. The aims of this study were to describe the dynamics of the ewes’s vaginal cultivable microbiota during a classic long-term estrous synchronization protocol and to develop a model of probiotic infusion in vaginal sponges in order to study their influence in ewe’s vaginal microbiota, general health status, fertility and prolificity. The present results suggest that LAB infusion in the ewe’s vagina do not affect general health status and did not reduce fertility during natural mating.

Abstract

Sheep estrous synchronization is mainly based on progestagen-impregnated sponges which could cause vaginitis. Several species of Lactobacillus used as probiotics are commonly used in the treatment or prevention of urogenital infections in humans. However, no studies have been performed to analyze the potential use of probiotics to prevent urogenital infections in sheep. A randomized controlled clinical trial was conducted with 21 one-year-old ewes to develop a model of probiotic infusion in vaginal sponges in order to study their influence in ewe’s vaginal microbiota, general health status, fertility and prolificity. Synchronization of estrus was based on intravaginal sponges for 14 days. Bacterial communities (Enterobacteriaceae and lactic acid bacteria) were highly fluctuating over time and between animals. The safety of probiotic infusion (mix of Lactobacillus spp. 60% L. crispatus, 20% L. brevis and 20% L. gasseri) in the vagina of healthy ewes was firstly confirmed. Neutrophils were observed in 80% (8/10) of the control ewes compared to 36% (4/11) of the ewes in the probiotic group 2 days after sponge removal (p = 0.056). Fertility in the control and probiotic groups was 60% (6/10) and 91% (10/11), respectively p = 0.097. These results suggest that Lactobacillus spp. infusion in the ewe’s vagina does not affect general health status or fertility.

Contagious agalactia monitoring in caprine herds through regular bulk tank milk sampling

Surveillance and control of Mycoplasma spp. responsible for contagious agalactia (CA) in caprine herds are important challenges in countries with a large small-ruminant dairy industry. In the absence of any clinical signs, being able to determine the potential circulation of mycoplasmas within a herd could help to prevent biosecurity issues during animal exchanges between farms and improve health management practices. The objective of this study was to determine whether regular sampling of bulk tank milk was suitable for such surveillance. Twenty farms were sampled once a month for 2 yr and CA-responsible mycoplasmas were detected by real-time PCR on DNA extracted from milk, using 3 different DNA extraction methods. The pattern of mycoplasma excretion in bulk tank milk was assessed over time and several herd characteristics were recorded together with any event occurring within the herds. In general, the results obtained with the different detection methods were comparable and mainly agreed with the culture results. Several patterns of excretion were observed but were not related to herd characteristics (size, breed, and so on). Recurrence of the same (sub)species and same pulsed-field gel electrophoresis subtype during the 2-yr period is indicative of the considerable persistence of mycoplasmas. This persistence was associated with intermittent excretion. In conclusion, bulk tank milk sampling could be valuable for controlling CA in caprine herds provided it is repeated several times, yet to be defined, per year and analyzed using an appropriate methodology and the right cut-off for interpretation.

Mycoplasma conjunctivae in insect vectors and anatomic locations related to transmission and persistence

Mycoplasma conjunctivae is an obligate microparasite that causes Infectious Keratoconjunctivitis (IKC) in Caprinae species. IKC is a long-recognised disease, but little attention has been paid to the mechanisms of transmission of the mycoplasma and its occurrence in locations other than the eyes. In this study, the presence of M. conjunctivae is assessed in the eyes, external ear canals (EEC), nasal cavity, and vagina of host species as well as in potential vectors, which may be involved in the transmission and persistence of infection within the host. M. conjunctivae was detected by qPCR in 7.2 % (CI 95% 4.7-11.0) of the ear swabs and 9.5 % (CI 95% 6.4-13.9) of the nasal swabs from Pyrenean chamois, Iberian ibex, domestic sheep and mouflon without statistical differences between species. Mycoplasma detection in nasal swabs was mostly associated with ocular infection (95.6%), but this was not the case for EEC (52.6%). Among the eye-positive ruminants, 27.3% were positive in ear swabs and 64.7% in nasal swabs, and the threshold cycle values of the qPCR were correlated only between eye and nasal swabs (p < 0.01; r₂ = 0.56). M. conjunctivae was detected in 1.7% - 7.1 % of Musca spp. captured during an IKC outbreak in Iberian ibex and in one out of three endemic sheep flocks. The results indicate that the transmission of M. conjunctivae may occur by direct contact with eye or nasal secretions and/or indirectly through flies. The M. conjunctivae DNA detection in EEC suggests that it can colonise the auditory tract, but the significance for its persistence within the host should be further assessed.

Novel role of Vpmas as major adhesins of Mycoplasma agalactiae mediating differential cell adhesion and invasion of Vpma expression variants

Mycoplasma agalactiae exhibits antigenic variation by switching the expression of multiple surface lipoproteins called Vpmas. Although implicated to have a significant influence on the pathogenicity, their exact role in pathogen-host interactions has not been investigated so far. Initial attachment to host cells is regarded as one of the most important steps for colonization but this pathogen lacks the typical mycoplasma attachment organelle. The aim of this study was to determine the role of Vpmas in adhesion of M. agalactiae to host cells. 'Phase-Locked' Mutants (PLMs) steadily expressing single well-characterized Vpma lipoproteins served as ideal tools to evaluate the role of each of the six Vpmas in cytadhesion, which was otherwise not possible due to the high-frequency switching of Vpmas in the wildtype strain PG2. Using in vitro adhesion assays with HeLa and sheep mammary epithelial (MECs) and stromal (MSCs) cells, we could demonstrate differences in the adhesion capabilities of each of the six PLMs compared to the wildtype strain. The PLMV mutant expressing VpmaV exhibited the highest adhesion rate, whereas PLMU, which expresses VpmaU showed the lowest adhesion values explaining the reduced in vivo fitness of PLMU in sheep during experimental intramammary and conjunctival infections. Furthermore, adhesion inhibition assays using Vpma-specific polyclonal antisera were performed to confirm the role of Vpmas in M. agalactiae cytadhesion. This led to a significant decrease (p<0.05) in the adhesion percentage of each PLM. Immunofluorescence staining of TX-114 phase proteins extracted from each PLM showed binding of the respective Vpma to HeLa cells and MECs proving the direct role of Vpmas in cytadhesion. Furthermore, as adhesion is a prerequisite for cell invasion, the ability of the six PLMs to invade HeLa cells was also evaluated using the gentamicin protection assay. The results showed a strong correlation between the adhesion rates and invasion frequencies of the individual PLMs. This is the first report that describes a novel function of Vpma proteins in cell adhesion and invasion. Besides the variability of these proteins causing surface antigenic variation, the newly identified phenotypes are likely to play critical roles in the pathogenicity potential of this ruminant pathogen.

Mycoplasmas: Brain invaders?

Mycoplasmas of humans and animals are usually associated with respiratory, autoimmune, genital and joint diseases. Human mycoplasmas have also been known to affect the brain. Severe central nervous system (CNS) diseases, such as encephalitis, have been linked to Mycoplasma pneumoniae and ureaplasma infections. Less well known is the sheep and goat pathogen, Mycoplasma agalactiae, which has been found in large quantities in the brain where it may be responsible for non-purulent encephalitis as well as ataxia in young animals. Experimental intra-mammary infections of sheep with this mycoplasma have resulted in histopathological changes in the CNS. The cattle pathogen, M. bovis, has been reported occasionally in the brains of calves and adult cattle showing a range of histopathological lesions including abscesses and fibrinous meningitis. Two avian pathogens, M. gallisepticum and M. synoviae have been isolated from the brains of poultry showing meningeal vasculitis and encephalitis. There have been no reported detections of two other avian pathogens, M. meleagridis or M. iowae in the CNS. Over the last few decades, mycoplasmas have been isolated from the brains of sea mammals dying in large numbers in the North Sea although it was concluded that their role may be secondary to underlying viral disease. Finally, evidence has been advanced that certain Spiroplasma species may have a role in the development of the transmissible spongiform encephalopathies (TSE). Invasion of the brain by mycoplasmas may be as a result of direct entry following damage to the inner ear as seen with M. bovis or across the blood brain barrier by mechanisms as yet uncertain.

Antimicrobial susceptibility and multilocus sequence typing of Mycoplasma capricolum subsp. capricolum

Mycoplasma capricolum subsp. capricolum is one of the causative agents of contagious agalactia (CA). Nevertheless, there is still a lack of information about its antimicrobial susceptibility and genetic characteristics. Therefore, the aim of this work was to study the antimicrobial and genetic variability of different Mycoplasma capricolum subsp. capricolum field isolates. For this purpose, the growth inhibition effect of 18 antimicrobials and a multilocus sequence typing (MLST) scheme based on five housekeeping genes (fusA, glpQ, gyrB, lepA and rpoB) were performed on 32 selected field isolates from Italy and Spain.The results showed a wide range of growth inhibitory effects for almost all the antimicrobials studied. Macrolides presented lower efficacy inhibiting Mcc growth than in previous works performed on other CA-causative mycoplasmas. Erythromycin was not able to inhibit the growth of any of the studied strains, contrary to doxycycline, which inhibited the growth of all of them from low concentrations. On the other hand, the study of the concatenated genes revealed a high genetic variability among the different Mcc isolates. Hence, these genetic variations were greater than the ones reported in prior works on other mycoplasma species.

Detecting asymptomatic rams infected with Mycoplasma agalactiae in ovine artificial insemination centers

Mycoplasma agalactiae (Ma) is the main causative agent of ovine contagious agalactia, which is a serious disease of small ruminants. In endemic areas, its most common clinical situation consists of chronically infected herds, and asymptomatic infected individuals represent an epidemiological risk regarding the transmission of this disease. The aim of this work was to detect the presence of asymptomatic rams infected with Ma in different artificial insemination centers, and to determine the most effective way to identify these individuals so as to implement adequate surveillance protocols. For this purpose, 215 rams and 14 teaser sheep were sampled taking auricular, nasal, and vaginal swabs and serum samples. In addition, ejaculates from 147 rams were analyzed. These samples were subjected to specific culture and molecular techniques to isolate and identify mycoplasmas, and to a serological test to detect antibodies against Ma. Mycoplasma agalactiae was detected in 47 (4.4%) of the 1077 samples analyzed, and also one individual resulted seropositive. Thus, 37 (17.2%) of the 215 studied rams were infected with Ma. The specimens which proportionally yielded the greatest number of positive results for this pathogen were semen samples (13.6%), followed by nasal swabs (5.8%). In contrast, the sampling of the external auricular canal and the serological analyses resulted insufficient to effectively detect infected individuals. Asymptomatic rams infected with Ma were detected in all the analyzed artificial insemination centers, highlighting the need to implement adequate surveillance protocols to prevent the presence of these individuals in these centers, reducing the risk of transmitting contagious agalactia.

Mycoplasma agalactiae Induces Cytopathic Effects in Infected Cells Cultured In Vitro

Mycoplasma agalactiae is the etiological agent of the contagious agalactia syndrome in sheep and goats and causes significant economic losses worldwide. Yet the mechanism of pathogenesis is largely unknown. Even whole-genome sequence analysis of its pathogenic type strain did not lead to any conclusions regarding its virulence or pathogenicity factors. Although inflammation and tissue destruction at the local site of M. agalactiae infection are largely considered as effects of the host immune response, the direct effect of the agent on host cells is not completely understood. The aim of this study was to investigate the effect of M. agalactiae infection on the quality and viability of host cells in vitro. Changes in cell morphology including cell elongation, cytoplasm shrinkage and membrane blebbing were observed in infected HeLa cells. Chromatin condensation and increased caspase-3 cleavage in infected HeLa cells 48 h after infection suggests an apoptosis-like phenomenon in M. agalactiae-infected cells. In compliance with these results, decreased viability and cell lysis of M. agalactiae-infected HeLa cells was also observed. Measurement of the amount of LDH released after M. agalactiae infection revealed a time- and dose-dependent increase in HeLa cell lysis. A significant decrease in LDH released after gentamicin treatment of infected cells confirmed the major role of cytadherent M. agalactiae in inducing host cell lysis. This is the first study illustrating M. agalactiae's induction of cytopathic effects in infected HeLa cells. Further detailed investigation of infected host tissue for apoptotic markers might demonstrate the association between M. agalactiae-induced host cell lysis and the tissue destruction observed during M. agalactiae natural infection.

Presence of Mycoplasma agalactiae in semen of naturally infected asymptomatic rams

The purpose of the present study was to assess the presence of Mycoplasma agalactiae (Ma), the main causative agent of ovine contagious agalactia (CA), in semen of naturally infected rams. Therefore, semen samples from 167 rams residing in three different artificial insemination (AI) centers of a CA-endemic area were studied by microbiological and molecular techniques. In addition, serial ejaculates from the same rams were evaluated to determine the excretion dynamics of Ma. Of the 384 samples studied, Ma was detected in 56 (14.58%) which belonged to 44 different rams (26.35%). These findings confirm the ability of Ma to be excreted in semen of asymptomatic rams. Furthermore, these results also evidence the presence of these asymptomatic carriers of Ma in ovine AI centers, representing a serious health risk regarding the spread and maintenance of CA, especially in endemic areas. Moreover, the excretion of Ma in semen also points to the risk of venereal transmission of this disease. The current results highlight the need to implement control measures to prevent the admission of infected rams in AI centers and the necessity to continuously monitor semen samples to effectively detect infected individuals.

Sensitivity of two methods to detect Mycoplasma agalactiae in goat milk

BACKGROUND

Laboratory diagnostic techniques able to detect Mycoplasma agalactiae are essential in contagious agalactia in dairy goats. This study was designed: 1) to determine the detection limits of PCR and culture in goat milk samples, 2) to examine the effects of experimental conditions including the DNA extraction method, PCR technique and storage conditions (fresh versus frozen stored milk samples) on these methods and 3), to establish agreement between PCR and culture techniques using milk samples from goats with mastitis in commercial dairy herds. The study was conducted both on artificially inoculated and field samples.

RESULTS

Our findings indicate that culture is able to detect M. agalactiae in goat milk at lower concentrations than PCR. Qualitative detection of M.agalactiae by culture and PCR was not affected by sample freezing, though the DNA extraction method used significantly affected the results of the different PCR protocols. When clinical samples were used, both techniques showed good agreement.

CONCLUSIONS

The results from this study indicate that both culture and PCR are able to detect M. agalactiae in clinical goat mastitis samples. However, in bulk tank milk samples with presumably lower M. agalactiae concentrations, culture is recommended within the first 24 h of sample collection due to its lower limit of detection. To improve the diagnostic sensitivity of PCR in milk samples, there is a need to increase the efficiency of extracting DNA from milk samples using protocols including a previous step of enzymatic digestion.

Sheep primary cells as in vitro models to investigate Mycoplasma agalactiae host cell interactions

Appropriate infection models are imperative for the understanding of pathogens like mycoplasmas that are known for their strict host and tissue specificity, and lack of suitable cell and small animal models has hindered pathogenicity studies. This is particularly true for the economically important group of ruminant mycoplasmas whose virulence factors need to be elucidated for designing effective intervention strategies. Mycoplasma agalactiae serves as a useful role model especially because it is phylogenetically very close to M. bovis and causes similar symptoms by as yet unknown mechanisms. Here, we successfully prepared and characterized four different primary sheep cell lines, namely the epithelial and stromal cells from the mammary gland and uterus, respectively. Using immunohistochemistry, we identified vimentin and cytokeratin as specific markers to confirm the typical cell phenotypes of these primary cells. Furthermore, M. agalactiae’s consistent adhesion and invasion into these primary cells proves the reliability of these cell models. Mimicking natural infections, mammary epithelial and stromal cells showed higher invasion and adhesion rates compared to the uterine cells as also seen via double immunofluorescence staining. Altogether, we have generated promising in vitro cell models to study host–pathogen interactions of M. agalactiae and related ruminant pathogens in a more authentic manner.

The study is an important step forward in developing in vitro models that will facilitate analyses of Mycoplasma agalactiae and related ruminant mycoplasmas' host–pathogen interactions at the molecular level.

Simultaneous Identification of Potential Pathogenicity Factors of Mycoplasma agalactiae in the Natural Ovine Host by Negative Selection

Mycoplasmas possess complex pathogenicity determinants that are largely unknown at the molecular level. Mycoplasma agalactiae serves as a useful model to study the molecular basis of mycoplasma pathogenicity. The generation and in vivo screening of a transposon mutant library of M. agalactiae were employed to unravel its host colonization factors. Tn4001mod mutants were sequenced using a novel sequencing method, and functionally heterogeneous pools containing 15 to 19 selected mutants were screened simultaneously through two successive cycles of sheep intramammary infections. A PCR-based negative selection method was employed to identify mutants that failed to colonize the udders and draining lymph nodes in the animals. A total of 14 different mutants found to be absent from ≥ 95% of samples were identified and subsequently verified via a second round of stringent confirmatory screening where 100% absence was considered attenuation. Using this criterion, seven mutants with insertions in genes MAG1050, MAG2540, MAG3390, uhpT, eutD, adhT, and MAG4460 were not recovered from any of the infected animals. Among the attenuated mutants, many contain disruptions in hypothetical genes, implying their previously unknown role in M. agalactiae pathogenicity. These data indicate the putative role of functionally different genes, including hypothetical ones, in the pathogenesis of M. agalactiae. Defining the precise functions of the identified genes is anticipated to increase our understanding of M. agalactiae infections and to develop successful intervention strategies against it.

Development of loop-mediated isothermal amplification test for the diagnosis of contagious agalactia in goats

Contagious agalactia is a highly infectious disease affecting sheep and goats, mainly caused by Mycoplasma agalactiae. Although various tests are available for diagnosis of contagious agalactia, none of them is credited with the capacity to provide rapid and cost-effective diagnosis. This article reports the development of loop-mediated isothermal amplification (LAMP) test targeting the p40 gene of M. agalactiae, for the diagnosis of classical contagious agalactia. Optimum amplification was obtained at 58 °C in 70 min. The developed test was found to be 100-fold more sensitive than PCR and detected up to 20-fg level of DNA. The test was also superior to conventional PCR in detecting from artificially contaminated milk, i.e. 10(4)-fold more sensitive. The developed LAMP test could detect up to 10 cfu/ml of artificially contaminated milk, indicating its potential for being developed as a field test for rapid and sensitive diagnosis.

Survival capacity of Mycoplasma agalactiae and Mycoplasma mycoides subsp capri in the diluted semen of goat bucks and their effects on sperm quality

This study examines the viability of Mycoplasma agalactiae (Ma) and Mycoplasma mycoides subsp capri (Mmc) during 150 minutes of incubation at 37 °C in contaminated diluted semen (DS) doses. The effects of the presence of both microorganisms on sperm viability, motility, and morphology were also examined. In a second experiment, the viability of Ma and its effects on sperm viability were determined in ejaculate samples and skimmed milk semen extender samples. Ma and Mmc were able to survive in DS at concentrations considered infectious, and no significant differences in mean concentrations were detected (7.1 log colony-forming units [CFU]/mL). However, initial concentration of Ma declined (P < 0.05) from 7.5 to 6.9 log CFU/mL and Mmc declined (P < 0.05) from 7.7 to 7.1 log CFU/mL after incubation. Conversely, ejaculate concentrations of Ma increased significantly (from 7.1 to 7.4 log CFU/mL, P < 0.05). These observations suggest that the natural breeding medium is more suitable for Ma than the medium used for artificial insemination (AI). The presence of Mmc slightly reduced sperm viability in the DS (from 21.7% to 16.6%, P < 0.05). The absence of major effects on sperm quality could lead to the unnoticed use of semen contaminated with Ma and Mmc for AI. As both bacteria were able to survive the conditions of ejaculates and semen doses, these findings suggest a risk of venereal transmission of contagious agalactia and support the use of mycoplasma-free semen samples for (AI).

In vitro and in vivo cell invasion and systemic spreading of Mycoplasma agalactiae in the sheep infection model

Generally regarded as extracellular pathogens, molecular mechanisms of mycoplasma persistence, chronicity and disease spread are largely unknown. Mycoplasma agalactiae, an economically important pathogen of small ruminants, causes chronic infections that are difficult to eradicate. Animals continue to shed the agent for several months and even years after the initial infection, in spite of long antibiotic treatment. However, little is known about the strategies that M. agalactiae employs to survive and spread within an immunocompetent host to cause chronic disease. Here, we demonstrate for the first time its ability to invade cultured human (HeLa) and ruminant (BEND and BLF) host cells. Presence of intracellular mycoplasmas is clearly substantiated using differential immunofluorescence technique and quantitative gentamicin invasion assays. Internalized M. agalactiae could survive and exit the cells in a viable state to repopulate the extracellular environment after complete removal of extracellular bacteria with gentamicin. Furthermore, an experimental sheep intramammary infection was carried out to evaluate its systemic spread to organs and host niches distant from the site of initial infection. Positive results obtained via PCR, culture and immunohistochemistry, especially the latter depicting the presence of M. agalactiae in the cytoplasm of mammary duct epithelium and macrophages, clearly provide the first formal proof of M. agalactiae's capability to translocate across the mammary epithelium and systemically disseminate to distant inner organs. Altogether, the findings of these in vitro and in vivo studies indicate that M. agalactiae is capable of entering host cells and this might be the strategy that it employs at a population level to ward off the host immune response and antibiotic action, and to disseminate to new and safer niches to later egress and once again proliferate upon the return of favorable conditions to cause persistent chronic infections.

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

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

Contagious agalactia due to Mycoplasma spp. in small dairy ruminants: epidemiology and prospects for diagnosis and control

Contagious agalactia (CA) is a serious disease of small dairy ruminants that has a substantial economic impact on the goat and sheep milk industries. The main aetiological agent of the disease is Mycoplasma agalactiae, although other species, such as Mycoplasma mycoides subsp. capri, Mycoplasma capricolum subsp. capricolum and Mycoplasma putrefaciens, are pathogenic in goats. There are two clinical-epidemiological states of CA in sheep and goats; herds and flocks may exhibit outbreaks of CA or may be chronically infected, the latter with a high incidence of subclinical mastitis and only occasional clinical cases. The complex epidemiology of CA is related to the genetic characteristics and mechanisms of molecular variation of the Mycoplasma spp. involved, along with presence of CA-mycoplasmas in wild ruminant species. In goats, the situation is particularly complex and asymptomatic carriers have been detected in chronically infected herds. The coexistence of other non-pathogenic mycoplasmas in the herd further complicates the diagnosis of CA and the design of efficient strategies to control the disease. Routes of infection, such as the venereal route, may be involved in the establishment of chronic infection in herds. Current challenges include the need for improved diagnostic methods for detection of chronic and subclinical infections and for the design of more efficient vaccines.