Survey of respiratory disease associated with Mycoplasma gallisepticum in British gamebirds (2016-2019): In vitro antibiotic sensitivity, pathology and detection of other pathogens

BACKGROUND

The causes of respiratory disease in British gamebirds were investigated during 2016-2019 following concerns about poorer responses to antibiotic treatment. Emphasis was placed on Mycoplasma gallisepticum, but other possible bacterial and viral causes were included, along with gross and histopathological examination.

METHODS

Clinical respiratory disease outbreaks were investigated.

RESULTS

Mycoplasma gallisepticum was detected by PCR in 65 of 69 outbreaks in pheasants and partridges and isolated from 56 of these. Partial mgc2 gene sequences from 28 M. gallisepticum isolates were compared, and 26 proved identical, suggesting the prevalence of a dominant sequence type. Minimum inhibitory concentration values for tiamulin, tylosin, tylvalosin, doxycycline and tetracycline were significantly higher than the reference strain but could not be correlated with treatment failures. Other bacterial species were isolated from sinuses but were not consistently correlated with disease. RT-PCRs detected coronaviruses in 18% of 49 outbreaks and avian metapneumovirus in 8%. Histopathological lesions were typical of M. gallisepticum sinusitis and significantly associated with M. gallisepticum PCR outbreak positivity.

CONCLUSION

Mycoplasma gallisepticum remains an important cause of respiratory disease in gamebirds. Synergism with other pathogens may have played a role in some outbreaks. Specific reasons for variable responses to antibacterial treatment were not identified.

Mycoplasma anserisalpingitidis sp. nov., isolated from European domestic geese (Anser anser domesticus) with reproductive pathology

In 1983, Mycoplasma sp. strain 1220 was isolated in Hungary from the phallus lymph of a gander with phallus inflammation. Between 1983 and 2017, Mycoplasma sp. 1220 was also identified and isolated from the respiratory tract, liver, ovary, testis, peritoneum and cloaca of diseased geese in several countries. Seventeen studied strains produced acid from glucose and fructose but did not hydrolyse arginine or urea, and all grew under aerobic, microaerophilic and anaerobic conditions at 35 to 37 ˚C in either SP4 or pleuropneumonia-like organism medium supplemented with glucose and serum. Colonies on agar showed a typical fried-egg appearance and transmission electron microscopy revealed a typical mycoplasma cellular morphology. Molecular characterization included analysis of the following genetic loci: 16S rRNA, 23S rRNA, 16S-23S rRNA ITS, rpoB, rpoC, rpoD, uvrA, parC, topA, dnaE, fusA and pyk. The genome was sequenced for type strain 1220^T. The 16S rRNA gene sequences of studied strains of Mycoplasma sp. 1220 shared 99.02-99.19 % nucleotide similarity with M. anatis strains but demonstrated ≤95.00-96.70 % nucleotide similarity to the 16S rRNA genes of other species of the genus Mycoplasma. Phylogenetic, average nucleotide and amino acid identity analyses revealed that the novel species was most closely related to Mycoplasma anatis. Based on the genetic data, we propose a novel species of the genus Mycoplasma, for which the name Mycoplasma anserisalpingitidis sp. nov. is proposed with the type strain 1220^T (=ATCC BAA-2147^T=NCTC 13513^T=DSM 23982^T). The G+C content is 26.70 mol%, genome size is 959110 bp.

First description of two moderately halophilic and psychrotolerant Mycoplasma species isolated from cephalopods and proposal of Mycoplasma marinum sp. nov. and Mycoplasma todarodis sp. nov

Two moderately halophilic and psychrotolerant new Mycoplasma species were isolated from common cephalopods. Three strains were isolated in pure culture from two individual European flying squid (Todarodes sagittatus), and two individual octopuses (Octopus vulgaris). The strains showed optimal growth at 25 °C and a salinity of 3% (w/v) NaCl. Molecular analyses revealed that the isolates belonged to two new, but phylogenetically related species, divergent from all previously described Mollicutes, representing the first marine isolates of the class, and also the first Mycoplasma strains for which NaCl requirement has been demonstrated. A genome search against all available marine metagenomes and 16S rRNA gene databases indicated that these two species represent a novel non-free-living marine lineage of Mollicutes, specifically associated with marine animals. Morphology and physiology were compatible with other members of this group, and genomic and phenotypic analyses demonstrated that these organisms represent two novel species of the genus Mycoplasma, for which the names Mycoplasma marinum sp. nov. and Mycoplasma todarodis sp. nov. are proposed; the type strains are PE^T (DSM 105487^T, CIP 111404^T) and 5H^T (DSM 105,488^T, CIP 111405^T), respectively.

Mycoplasma tullyi sp. nov., isolated from penguins of the genus Spheniscus

A mycoplasma isolated from the liver of a dead Humboldt penguin (Spheniscus humboldti) and designated strain 56A97^T, was investigated to determine its taxonomic status. Complete 16S rRNA gene sequence analysis indicated that the organism was most closely related to Mycoplasma gallisepticum and Mycoplasma imitans(99.7 and 99.9 % similarity, respectively). The average DNA-DNA hybridization values between strain 56A97^T and M. gallisepticum and M. imitans were 39.5 and 30 %, respectively and the Genome to Genome Distance Calculator gave results of 29.10 and 23.50 %, respectively. The 16S-23S rRNA intergenic spacer was 72-73 % similar to M. gallisepticum strains and 52.2 % to M. imitans. A partial sequence of rpoB was 91.1-92 % similar to M. gallisepticum strains and 84.7 % to M. imitans. Colonies possessed a typical fried-egg appearance and electron micrographs revealed the lack of a cell wall and a nearly spherical morphology, with an electron-dense tip-like structure on some flask-shaped cells. The isolate required sterol for growth, fermented glucose, adsorbed and haemolysed erythrocytes, but did not hydrolyse arginine or urea. The strain was compared serologically against 110 previously described Mycoplasma reference strains, showing that, except for M. gallisepticum, strain 56A97^T is not related to any of the previously described species, although weak cross-reactions were evident. Genomic information, serological reactions and phenotypic properties demonstrate that this organism represents a novel species of the genus Mycoplasma, for which the name Mycoplasma tullyi sp. nov. is proposed; the type strain is 56A97^T (ATCC BAA-1432^T, DSM 21909^T, NCTC 11747^T).

Pathogenicity of Mycoplasma imitans in mixed infection with infectious bronchitis virus in chickens

Mycoplasma imitans (Mim) has been isolated from ducks, geese and partridges, and is closely related to Mycoplasma gallisepticum (Mg). The pathogenicity of Mim for chicks was investigated in single and mixed infections with infectious bronchitis virus (IBV) by giving IBV strain M41 at 1-day-old and Mim 2 days later. Single infections with IBV or Mim were also performed. No clinical signs or gross lesions were seen in chicks infected with Mim or uninfected control chicks, but they were seen in the other two groups. Clinical scores were consistently higher in birds with mixed infections than those infected with IBV alone, and were significantly higher (P < 0.05) between days 7 and 14. More birds developed sinusitis, tracheitis and airsacculitis (with greater severity) in the mixed than the single IBV infections. Mim was recovered more frequently and in greater numbers from the respiratory tract of birds with mixed than single infections. It was recovered from the lower trachea, air sacs and lungs only in mixed infections. Seroconversion to Mim occurred by day 14 in mixed infections, but not until day 21 in single infections. It appears that Mim can act synergistically with IBV in young chickens in a similar manner to Mg, although Mg may act as a primary pathogen under some circumstances.

A diagnostic polymerase chain reaction for Mycoplasma iowae using primers located in the intergenic spacer region and the 23S rRNA gene

Mycoplasma iowae is primarily a pathogen of turkeys and, although uncommon, it still persists in some areas of the world, where it may cause embryo mortality and leg lesions. A species-specific diagnostic polymerase chain reaction was developed using a forward primer based in the intergenic spacer region between the 16S rRNA and the 23S rRNA ribosomal genes and a reverse primer located within the 23S rRNA gene. The polymerase chain reaction proved to be both sensitive and specific. It detected M. iowae DNA in the six reference strains of serotypes I, J, K, N, Q and R and in 28 field isolates. With the six serotypes the test detected between 1 and 5 pg of M. iowae DNA. There were no non-specific reactions with the other avian Mycoplasma species. When the closest phylogenetically related species were checked, a weak reaction with Mycoplasma muris was observed that disappeared when the annealing temperature was increased by 2°C.

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

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

Poultry mycoplasmas: sophisticated pathogens in simple guise

Mycoplasmas are a genus within the class Mollicutes (trivial name mollicutes), which are the smallest known prokaryotes capable of self-replication. They have a very small genome, and have evolved to this 'minimalist' status by losing non-essential genes, including those involved in cell wall synthesis. The mollicutes exploit their limited genetic material to the maximum and many are successful pathogens in man, animals, birds and plants. Most of those of veterinary importance are in the genus Mycoplasma and include 4 poultry pathogens of economic importance: Mycoplasma gallisepticum, Mycoplasma synoviae, Mycoplasma meleagridis and Mycoplasma iowae. The pathogenetic mechanisms of mycoplasmas are not fully understood, but they are successful pathogens because they can enter the host and multiply, evade the defence mechanisms, cause damage and escape to infect new hosts. M. gallisepticum is one of several motile species and possesses a terminal tip structure that mediates adherence to its target tissues. For some species, including M. gallisepticum, some of the organisms may become intracellular. Some Mycoplasma species, including the pathogenic poultry species, have a remarkable ability to vary their major surface antigens, a mechanism that is thought to help them to persist in their host by evading the immune response. The molecular and cellular events that lead to the development of lesions and clinical disease are still obscure. Some lesions appear to be the result of indirect damage from the host's inflammatory and cellular responses. Despite short survival times in the environment, mycoplasmas are able to transmit successfully to new hosts. In poultry flocks there is both horizontal and vertical transmission, the former being encouraged by intensive husbandry and stress factors. Establishing the pathways of transmission and the possible role of other birds, such as game and wild birds, as intermediate vectors between poultry flocks is now greatly aided by the availability of modern molecular methods for strain typing.

Effects of cyclosporin A on the immune responses and pathogenesis of a virulent strain of Mycoplasma gallisepticum in chickens

Immune responses to the virulent S6 strain of Mycoplasma gallisepticum in immunocompetent and cyclosporin A (CsA)-treated specific pathogen free chickens were investigated, and pathogenesis of the M. gallisepticum strain was also examined. Ten-day-old specific pathogen free chickens were inoculated by eye-drop with M. gallisepticum, and a control uninfected group was inoculated with mycoplasma broth. Blood was collected weekly for 4 weeks from five birds in each group and whole blood lymphocyte transformation assayed against concanavalin A and lipopolysaccharide. Blood samples were also collected at intervals for serological assays. Live body weight, clinical signs and lesions were monitored, and recovery of M. gallisepticum was attempted from choanal cleft of live birds and also from various sites at necropsy. In parallel to the aforementioned groups, another set of two groups of chicks treated with CsA was infected with M. gallisepticum S6 or mycoplasma broth. These groups were subjected to the same experimental procedures. In the immunocompetent chickens, M. gallisepticum caused temporary T-cell suppression at 2 weeks post-infection. Comparison of the clinical signs and macroscopic lesions produced in immunocompetent and CsA-treated chickens indicated that T cells may not play an active role in disease development. The percentage of birds with mycoplasma isolation and the load of mycoplasmas suggested that T cells may have some role in resisting mycoplasma colonization or in the elimination of the infection.

In vitro evaluation of various antimicrobials against Mycoplasma gallisepticum and Mycoplasma synoviae by the micro-broth method, and comparison with a commercially-prepared test system

The efficacy of danofloxacin, a new quinolone antimicrobial agent, was tested in vitro by the micro-broth method with nine field strains of Mycoplasma gallisepticum (Mg) and eight of M. synoviae (Ms) and comparison was made with oxytetracycline and tylosin tartrate. The virulent S6 strain of Mg was also included for reference. All Mycoplasma strains, including a strain of Mg that was resistant to tylosin tartrate, were susceptible to danofloxacin with minimal inhibitory concentrations ranging from pound 0.008 to 0.5 microg/ml. A commercially produced test system (Sensititre), using micro-plates whose wells were predosed with antimicrobial agents and then dried, was also investigated. Results with the same three antimicrobials were in agreement with those obtained by the micro-broth method. With the exception of the tylosin resistant strain, the Mg strains were more susceptible to erythromycin than the Ms strains. Conversely, Ms strains were susceptible to apramycin, while the Mg strains appeared to be resistant.

Investigations into the survival of Mycoplasma gallisepticum, Mycoplasma synoviae and Mycoplasma iowae on materials found in the poultry house environment

Following preliminary experiments to determine suitable methods for studying mycoplasma survival, suspensions of Mycoplasma gallisepticum (four strains), Mycoplasma synoviae (two strains) or Mycoplasma iowae (two strains) were seeded onto replicate samples of cotton, rubber, straw, shavings, timber, food, feathers and human hair. The organisms were also seeded onto human skin, ear and nasal mucosa. All samples were cultured for viability after 4, 8, 12 and 24 h, and then daily up to 6 days. The identity of recovered mycoplasmas was confirmed by indirect immunofluorescence. All three Mycoplasma species survived for the longest time on feathers with M. gallisepticum surviving between 2 and 4 days and M. synoviae 2 to 3 days. The type strain of M. iowae remained viable for 5 days on feathers, while the field strain was still viable at the end of the 6-day experiment. This strain also survived for at least 6 days on human hair and several other materials. M. gallisepticum survived on human hair up to 3 days and one recent field isolate also survived in the nose for 24 h. Survival times of the organisms were generally less on other materials although M. gallisepticum could be isolated from straw, cotton and rubber samples after 2 days.

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

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

Isolation of Mycoplasma cloacale from a number of different avian hosts in great Britain and France

Following the original isolation of Mycoplasma cloacale from a turkey in Great Britain, only one further turkey isolate has been obtained whereas the mycoplasma has been recovered from 2 species of wild ducks in Britain, and from 2 breeds of domestic ducks and from domestic geese in France. A few isolations have also been made from wild and exotic birds but M. cloacale has not been found in chickens.

The response of chickens to experimental infection 'em ovo' with Mycoplasma synoviae

Embryonated chicken eggs were inoculated at 18 days of incubation with a broth culture of Mycoplasma synoviae and the infected chicks were hatched and reared in isolation. Control chicks were hatched following inoculation of eggs with sterile mycoplasma broth. Both groups were closely observed for clinical signs and, at intervals up to 6 weeks infected and control chicks were killed and examined for gross lesions and for isolation of M. synoviae. Four of the 35 infected chicks developed synovitis but there were no other clinical signs. Airsacculitis was encountered in 44% of birds at postmortem examination but M. synoviae was not consistently isolated from affected air sacs. The organism was recovered most frequently from the trachea and lung but sporadic isolations were made from other sites including infraorbital sinus, heart, kidney, liver, spleen and blood. M. synoviae was also isolated consistently from the tracheas of 10 live infected birds until the end of the experiment at 23 weeks. However, the serum plate agglutination test, using a commercial antigen was positive for only half these birds up to ten weeks, and it was not until 15 and 23 weeks that 90% to 100% of the samples were positive.

Dual infection with Mycoplasma synoviae and a tenosynovitis-inducing reovirus in chickens

One group of embryonated chicken eggs was inoculated with sterile myco-plasma broth and another with a broth culture of Mycoplasma synoviae. Each group was subdivided into two and the chicks were hatched in four isolation pens. At 1 day of age one uninfected and one M. synoviae infected group were inoculated with a reovirus known to cause tenosynovitis. Birds were closely observed, and some were killed for sampling as chicks (1-5 weeks) and the remainder as adults (25-30 weeks). Clinical signs related to both organisms were seen in the dual-infected chicks and were more pronounced than in either of the corresponding single infections. There were significant weight differences between the infected and control chicks, except in single M. synoviae infection, and the mean weight of the birds with mixed infection was less than those with either single infection. Gross and histological lesions were observed in the hocks and livers of chicks in each infected group although with a higher incidence and severity in the dual-infection. Microscopic lesions were seen in the hearts of some birds in all three groups. Leg lesions associated with the reovirus infection persisted to maturity and another observation in mature, virus-infected birds was impaired egg production and fertility. M. synoviae was reisolated consistently from tracheas of single and dual-infected birds of all ages and reovirus from the tendons of inoculated birds for 4 weeks. Antibodies to both agents persisted throughout the period of the experiment.

Pathogenicity of Mycoplasma iowae for chick embryos

An investigation was carried out into the pathogenicity of four strains of Mycoplasma iowae for chick embryos. Doses ranging from approximately 10(6) to 10 colony-forming units of M. iowae per egg were inoculated via the yolk sac at 7 days of incubation. Groups of 10 or more eggs per dose were used. The eggs were incubated through to hatch, and dead embryos and hatched chicks were examined for abnormalities and mycoplasma recovery. All four strains of M. iowae caused embryo mortality but two were especially virulent - one killed all the embryos while the other killed all but one. Most deaths occurred towards the end of incubation and the main abnormalities were dwarfing and congestion. Some embryos were oedematous, especially around the head, and livers and spleens were often mustard-coloured. Hatched chicks had a low incidence of air sac lesions. Mycoplasmas, identified by immunofluorescence as M. iowae were isolated from almost every exposed embryo and chick, and from almost every site sampled. No mycoplasmas were isolated from broth-inoculated controls.

Pathogenicity of latent infectious laryngotracheitis virus in chickens

Groups of specific pathogen-free chickens were inoculated with the same dose of a field strain of infectious laryngotracheitis virus that had either been isolated from tracheal swabs taken from infected birds during acute phase shedding, or that had been isolated during an episode of virus shedding after a latent period of 12 to 17 weeks. Birds in both groups developed characteristic clinical signs of ILT including difficulty in breathing, rales and sneezing. Thus, ILT virus shed after a latent period is capable of causing disease in susceptible birds similar to that seen in the field.

Exacerbation of Mycoplasma gallisepticum infection in turkeys by rhinotracheitis virus

Groups of 1-day-old turkey poults from a parent flock free of antibodies to turkey rhinotracheitis virus (TRTV) and the pathogenic mycoplasmas, were infected by eyedrop with virulent TRTV, with Mycoplasma gallisepticum (Mg) or with both agents together. Dual infection resulted in increased morbidity compared with those groups given single infections. The presence of the Mg in the dual infection had no apparent effect on the pathogenesis of the virus, but the virus caused the Mycoplasma to be more invasive. Mg infection caused a transient depression in TRTV ELISA antibody titres at 29 days post-inoculation. At 14 days post-infection Mg haemagglutination inhibition (HI) and rapid serum agglutination (RSA) titres were higher (P <0.01) in the mixed infection group compared with those infected with Mg alone, but there was no significant difference between ELISA antibody titres of these two groups.

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

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

Survey of campylobacter, salmonella and mycoplasmas in house crows (Corvus splendens ) in Malaysia

House crows (Corvus splendens) in Selangor, Malaysia were examined for the presence of Campylobacter species, Salmonella species, Mycoplasma gallisepticum and Mycoplasma synoviae by serology, culture and pcr. For the detection of Campylobacter and Salmonella species swabs were taken either from the intestine or cloaca. For the detection of mycoplasmas, swabs were taken either from the choanal cleft or trachea for culture and pcr and serum samples were tested by the rapid serum agglutination (rsa) and monoclonal antibody-blocking elisa (mbelisa) for antibodies to M gallisepticum and M synoviae. For campylobacter, 25.3 per cent of the crows were positive by culture, and the species identified were Campylobacter jejuni and Campylobacter coli. No Salmonella species were isolated. Four of 24 swabs were positive for M gallisepticum dna but none gave positive results for M synoviae dna. No M gallisepticum or M synoviae antibodies were detected by rsa but 60 per cent of the sera gave positive reactions for M gallisepticum and 13 per cent gave positive reactions for M synoviae by mbelisa.

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

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

Mycoplasma amphoriforme sp. nov., isolated from a patient with chronic bronchopneumonia

A mycoplasma was isolated from the sputum of an immunodeficient patient with recurrent bronchitis. The isolate designated strain A39T was very fastidious and atypical for a mycoplasma in its colonial appearance. Classical biochemical tests for mycoplasma speciation could not differentiate the isolate from the pathogens Mycoplasma pneumoniae and Mycoplasma genitalium and serological identification as a recognized Mycoplasma species was lacking. Specific PCR detection for these two species was negative. Subsequently, other strains were isolated from human patients that appeared to be similar to strain A39T in their physiological and genetic characteristics. Analysis of the 16S rRNA gene placed strain A39T and other isolates in the pneumoniae group of mycoplasmas, with the highest sequence similarity to Mycoplasma testudinis (96.8 %), but with only 93.0 % similarity to M. pneumoniae and M. genitalium. Examination of the 16S-23S rRNA internally transcribed spacer sequence, protein electrophoresis profile, genome size and serological reactions indicated that this organism represents a novel species, for which the name Mycoplasma amphoriforme sp. nov. is proposed, with strain A39T (=NCTC 11740T=ATCC BAA-992T) as the type strain.

Isolation of Mycoplasma capricolum-like strains from chickens

Members of the genus Mycoplasma infect a wide range of hosts, but individual Mycoplasma species tend to exhibit a considerable degree of host specificity. We characterized Mycoplasma strain 700, isolated from a kidney of a layer hen in Spain and Mycoplasma strains ULB-A and ULB-B, isolated from the air sac and from the bile of stunted broiler chickens in Slovenia. The serologic examination showed that these three strains are antigenically unrelated to all of the recognized Mycoplasma species of avian origin, but closely related to the ruminant mycoplasma Mycoplasma capricolum subspecies capricolum (M. capricolum). The comparison of their 16S rRNA gene sequences with the sequence of M. capricolum (California kid) revealed 99.66% sequence identity for the strain 700 and 99.59% identity for strains ULB-A and ULB-B. Moreover, the predicted DnaK sequences of the M. capricolum-like strains, isolated from chickens, were identical to DnaK sequences of M. capricolum. Comparison of their dnaK gene sequences with M. capricolum showed 99.64% sequence identity for strain 700 and 99.27% identity for strains ULB-A and ULB-B. In the flock from which M. capricolum-like strains ULB-A and ULB-B were isolated, the majority of chickens (83% of the chickens examined) raised antibodies reacting with M. capricolum antigens. Notably, the infection of chickens with M. capricolum-like strains represents an unusual exception to the range of Mycoplasma species host specificity.

Evaluation of an egg yolk enzyme-linked immunosorbent assay antibody test and its use to assess the prevalence of Mycoplasma synoviae in UK laying hens

The frequency of Mycoplasma synoviae exposure in a convenience sample of commercial layers was established by the presence of antibody in eggs. Chloroform-extracted egg yolks were found to be more suitable than saline-extracted yolks, and were used with a commercial enzyme-linked immunosorbent assay kit, having first established the sensitivity and specificity of the kit with eggs from known M. synoviae-positive and M. synoviae-negative flocks. For the prevalence study, pooled yolks from 12 eggs were obtained from each of 56 randomly selected laying farms in possession of a packing station number in the east of England. This number allowed 95% confidence of detection of antibody in one egg if present in 50% of the flock. Eggs were taken from the oldest flock on each site and were returned with a completed questionnaire. The prevalence of egg antibody to M. synoviae was 78.6% (95% confidence interval, 65.6, 88.4). This study has confirmed that chloroform extraction of yolk antibody is a suitable approach for assessing the flock prevalence of M. synoviae infection in layer hens.

A putative transposase gene in the 16S–23S rRNA intergenic spacer region of Mycoplasma imitans

Examination of the nucleotide sequences of the 16S–23S intergenic transcribed spacer (ITS) region ofMycoplasma imitansandMycoplasma gallisepticumidentified a putative transposase gene located only in the ITS ofM. imitans, which can be used as a genetic marker to distinguish these two species. The relative size of the PCR products of the ITS region allowed a clear distinction to be made between strains ofM. imitansandM. gallisepticum, both of which could be readily discriminated from the type strains of all the other recognized avianMycoplasmaspecies. In addition, the putative transposase gene assigned in the ITS ofM. imitanswas shown to include a sequence homologous to that of the P75 gene ofM. gallisepticum. This is believed to be the first description of an insertion element in the rRNA operon region of a mycoplasma species.

Sensory properties of articular afferents following Mycoplasma arthritis in the chicken

The physiological properties of joint capsule mechanical nociceptors of monoarthritic chickens (Gallus domesticus) were studied by recording the electrical activity from single C (Group IV) and A-delta (Group III) fibres dissected from the parafibular nerve. By injecting live Mycoplasma gallisepticum cultures into the ankle joint a typical mycoplasma arthritis was induced which was restricted to a single joint. During the early stage of the disease (7-21 days after infection) there was histopathological evidence of an acute synovitis and the fibres showed evidence of sensitisation. Sensitisation was observed in the significantly increased receptive field size, decreased response thresholds, increased response to joint movement both noxious and innocuous, but only in the C-fibres was there an increase in spontaneous activity. During the more chronic stage of the disease (49-56 days after infection) there was pathological evidence of prolonged synovitis but the sensory fibres responded normally to mechanical stimulation and joint movement. These changes in sensitivity of the joint capsule mechanical nociceptors provides peripheral neural evidence of possible pain experienced during the acute stage of the disease but not at the chronic stage when the disease might be in period of remission. The absence of any clear correlation between pathology and receptor activity demonstrates the difficulty of trying to predict nociceptive consequences in animals on the basis of histopathology.

The complex matter of DNA double-strand break detection

To maintain genomic stability, despite constant exposure to agents that damage DNA, eukaryotic cells have developed elaborate and highly conserved pathways of DNA damage sensing, signalling and repair. In this review, we concentrate mainly on what we know about DNA damage sensing with particular reference to Lcd1p, a yeast protein that functions early in DNA damage signalling, and MDC1 (mediator of DNA damage checkpoint 1), a recently identified human protein that may be involved in recruiting the MRE11 complex to radiation-induced nuclear foci. We describe a model for the DNA damage response in which factors are recruited sequentially to sites of DNA damage to form complexes that can amplify the original signal and propagate it to the multitude of response pathways necessary for genome stability.

Infectious agents associated with respiratory disease in pheasants

In a case-control study of the infectious agents associated with natural outbreaks of respiratory disease in pheasants, 28 batches of birds from sites affected by disease and eight batches of birds from unaffected sites were examined by six veterinary laboratories in England, Wales and Scotland, and tested for mycoplasmas, other bacteria and viruses. Sinusitis was the commonest sign of disease and was associated with Mycoplasma gallisepticum as detected by PCR in the trachea (P < 0.05) and conjunctiva (P < 0.01). Sinusitis was also associated with pasteurella cultured from the sinus (P < 0.05), antibody to avian pneumovirus (APV) (P < 0.01) and avian coronaviruses as detected by reverse-transcriptase PCR (P < 0.05); there was no association between disease and APV as detected by PCR. Avian coronaviruses were the most common infectious agents detected. They were genetically close to infectious bronchitis virus (IBV) but differed in their gene sequence from all the serotypes of IBV previously identified in domestic fowl, and serological tests with six known IBV types showed little cross reactivity. Mycoplasma species other than M gallisepticum were cultured in 18 batches of pheasants but, with the exception of Mycoplasma gallinaceum, were not associated with disease.