Economic impact of Mycoplasma gallisepticum and M. synoviae in commercial layer flocks

An egg-production function was constructed, using data collected from 366 commercial layer flocks in California, to predict the impact of Mycoplasma gallisepticum (MG) and M. synoviae (MS) on egg production while controlling for confounding factors. In the first and second cycles, respectively, an MG-infected flock produced 12 and 5 fewer eggs per hen than an uninfected flock. Flocks that became infected with MG after F-strain vaccination produced 6 eggs/hen more than unvaccinated infected flocks in the first cycle, but no significant difference was observed between such groups in the second cycle. No association was found between MS-infection and egg production. Commercial layer producers in Southern California lost an estimated 127 million eggs because of MG in 1984. This lost egg production and associated MG-control-program costs amounted to an estimated financial loss of approximately $7 million. This represented a loss of approximately $6 million in consumer surplus.     

Characterization of Escherichia coli isolates from peritonitis lesions in commercial laying hens

Five clinically normal chickens from three farms (farm A, farm B, and farm C), for a total of 15 clinically normal chickens, were examined bacteriologically. In a similar manner, five dead chickens with lesions of peritonitis from each of the same three commercial egg-laying operations were selected for bacterial culturing. Escherichia coli were isolated from the cloaca in 14 of 15 healthy chickens and from all 15 chickens with peritonitis. Oviducts of normal chickens did not contain E. coli (0/15) whereas oviducts from 13 of 15 hens with peritonitis were positive for this pathogen. No lesions and no E. coli (0/15) were found in the peritoneal cavity of healthy hens, but peritonitis lesions from 13 of 15 dead chickens yielded E. coli. On farm A and farm B, a flock consisted of all chickens within a single house and all chickens in each flock were of the same age and same genetic strain. In flock 1 from farm A, all five E. coli isolates from the oviduct and all five isolates from the peritoneal cavity were serogrouped as O78; contained the virulence genes iroN, sitA, iutA, tsh, and iss; and belonged to phylogenetic group A. In flock 2 from farm B, all four E. coli isolates from the oviduct and all four isolates from the peritoneal cavity were serogrouped as O111; contained virulence genes iroN, sitA, iutA, traT, iss, and ompT; and belonged to phylogenetic group D. These data suggest that all chickens with peritonitis in a single flock on farms A and B were likely infected by the same E. coli strain. Escherichia coli isolates from the magnum and peritoneum had the same serogroup, virulence genotype, and phylogenetic group, which is consistent with an ascending infection from the oviduct to the peritoneal cavity.     

Escherichia coli salpingitis and peritonitis in layer chickens: an overview

Escherichia coli can induce salpingitis and/or peritonitis, a major cause of mortality in layer hens, but also other localized and systemic infections. E. coli infections have also been described in turkeys, geese, and ducks and are thought to be the cause of significant economic losses. However little is known about the real economic impact of the disease in layer chickens. The pathogenesis of E. coli salpingitis and peritonitis has not been elucidated yet. Three routes of infection have been discussed in the literature: ascending faecal contamination from the cloaca, bacterial translocation from the respiratory tract (air sac and lungs) and bacterial translocation from the intestinal lumen. Only one study has reported the occurrence of ascending faecal contamination from the cloaca to the oviduct and subsequently to the peritoneum. Regarding bacterial translocation, the only models available are for mammals, and these have not been applied to chickens so far Animal models could prove valuable to elucidate the pathogenesis of E. coli-induced salpingitis and peritonitis, and for assessing the value of preventive and curative intervention strategies. Little is known about risk factors for E. coli salpingitis and peritonitis. In contrast to colibacillosis in broilers, recent research has failed to demonstrate an association between several pathogens of the respiratory tract and the occurrence of E. coli pathology in layer chickens. The distance between poultry farms and the hen density in the cages were recently proposed as important risk factors for outbreaks ofcolibacillosis in flocks of layer hens, while in the past hormonal factors were implicated. The latter is an area of research that deserves more attention. Several methods for the molecular typing of E. coli have been described and might prove useful to study the epidemiology ofE. coli outbreaks in poultry, about which little is known. The presumptive diagnosis E. coli salpingitis and peritonitis is rather simple to establish, based on the anamnesis, clinical symptoms, and macroscopic findings at post-mortem. However; bacteriological analysis is required to establish a definite diagnosis because other pathogens can also cause salpingitis and peritonitis in layer hens. Antibiotics, chosen on the basis of sensitivity testing and their pharmacokinetic properties can be used as therapy; however residues in eggs may occur. Autovaccines are often used as prevention because in practice effective protection is only achieved against homologous E. coli serotypes.     

Sialidase activity in Mycoplasma synoviae

Eleven strains of the avian pathogen Mycoplasma synoviae were evaluated for the presence of sialidase activity with the use of the fluorogenic substrate 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid and the sialidase inhibitor 2-deoxy-2,3- didehydro-N-acetylneuraminic acid. The kinetics of in vitro growth in modified Frey medium were also assessed for each strain. Five strains had been isolated from clinically symptomatic chickens, and strains WVU 1853T and K3344 have been demonstrated to be capable of reproducing disease in specific-pathogen-free chickens. All strains exhibited sialidase activity, although the amount varied 65-fold among strains (P < 0.0001) from 1.3 x 10(-7) to 2.0 x 10(-9) activity units per colony-forming unit. Strains originally isolated from clinically symptomatic birds had more (P < 0.05) sialidase activity than strains from asymptomatic birds. Strain WVU1853T exhibited the most sialidase activity (P < 0.0001) and grew to the highest culture density (P < 0.0001) among strains, but across strains, the rank correlation of growth rate with sialidase activity was not significant. Negligible activity was detected in conditioned culture supernatant fluid. This is the first report of sialidase activity in pathogenic strains of M. synoviae, which suggests a potential enzymatic basis for virulence of the organism.     

Isolation of Mycoplasma synoviae from the brains of commercial meat turkeys with meningeal vasculitis

Mycoplasma synoviae (MS) was isolated from the brains of 22-week-old commercial meat turkeys displaying severe synovitis and infrequent central nervous system signs. Histological examination of the brains revealed mild-to-severe meningeal vasculitis. The vasculitis ranged from fibrinoid necrosis with little inflammation to a marked infiltration of lymphocytes and plasma cells disrupting the architecture of the vessel wall, accumulating as perivascular cuffs, and involving surrounding meninges. Occasional arteries were undergoing thrombosis. Similar lesions were occasionally seen in renal, synovial, and splenic vessels. MS isolates from the brain, trachea, and joint showed similar protein-banding patterns by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, the protein profile differed markedly from the standard MS reference strain, WVU 1853. This is the first known field case of MS isolation from the brains of turkeys.     

Prevalence of Mycoplasma gallisepticum and M. synoviae in commercial layers in southern and central California

The prevalence of Mycoplasma gallisepticum (MG) and M. synoviae (MS) in commercial pullet and layer flocks in Southern and Central California was estimated by testing serum and egg-yolk samples from 360 sample flocks in Southern California and 41 sample flocks in Central California. Data relating to potential risk factors associated with MG and MS infections were collected. The estimated true prevalence rate of MG was 73% in Southern California and 3% in Central California. The estimated true prevalence rate of MS was 91% in Southern California and 32% in Central California. Compared with uninfected flocks, MG-infected flocks in Southern California were significantly older and were medicated less (P less than 0.05). More managements were under a multiple-age system, more flocks had molted, more were vaccinated with F-strain, and more had concurrent infection with MS (P less than 0.05). Only one sample flock in Central California was MG-infected; none were vaccinated with F-strain. In Southern California, MS-infected flocks were older than uninfected flocks, more had molted, more were medicated, and more had concurrent infection with MG (P less than 0.05). In Central California, MS-infected flocks did not differ significantly from uninfected flocks in any factor examined; the lack of statistical significance may be due to small sample size.     

Lyophilization of Mycoplasma synoviae hemagglutination antigen

Two hemagglutination (HA) antigens produced from Mycoplasma synoviae isolates WVU-1853m and FMT grown in Frey's mycoplasma broth were lyophilized for HA preservation. Some increase in the HA titer occurred following lyophilization.     

Detection of Mycoplasma synoviae in clinically normal pheasants

Mycoplasma synoviae was isolated from the tracheas of seven clinically normal pheasants found in the vicinity of a chicken farm infected with M synoviae, but not from 120 pheasants and partridges with respiratory disease. When specimens were examined by the polymerase chain reaction only two additional pheasants infected with M synoviae were identified, one healthy and one diseased.     

北京市鸡毒支原体和滑液囊支原体血清学调查

为了解北京市鸡毒支原体(Mycoplasma galliscepticum,MG)和滑液囊支原体(Mycoplasma synoviae,MS)感染情况,2019年从北京市10个区127个养鸡场(户),采集3 910份鸡血清样品,采用酶联免疫吸附试验(ELISA)进行MG和MS感染抗体检测。结果显示:北京市10个区均有不同程度的MG和MS感染,场群阳性率分别介于78.95%～100%、68.42%～100%,样品阳性率分别介于59.35%～93.13%、50.0%～94.53%,平均场群阳性率分别为89.0%和86.6%,平均样品阳性率分别为79.0%和75.6%;第三季度的场群阳性率和第二季度的样品阳性率最高,第四季度场群阳性率和样品阳性率最低(P0.01);110～180日龄的MG样品阳性率、251～320日龄的MS样品阳性率最高,462日龄以上均最低(P0.01);规模化商品鸡场的MG和MS场群阳性率和样品阳性率均最高(P0.01);蛋鸡的MG和MS样品阳性率均高于肉鸡(P0.01)。结果表明,北京市MG和MS感染较为严重,第二、三季度高发,110～320日龄鸡群、规模化商品鸡场和蛋鸡群感染尤其严重。结果提示,应采取包括加强生物安全管理、种鸡净化、疫苗预防和药物治疗在内的综合管理措施,有效控制该地区MG、MS的流行。     

Pathogenicity of Mycoplasma synoviae in chicken embryos.

Pathogenicity of Mycoplasma synoviae (MS) was examined in specific-pathogen-free (SPF) white leghorn chicken embryos. Six isolates of MS were inoculated into 7-day embryos via the yolk sac. Isolates were evaluated for gross and microscopic lesions through 19 days' incubation and for embryo lethality through 20 days' incubation. Isolates in decreasing order of lethality, from lowest to highest 50% embryo lethal dose, were WVU 1853, K1968, K1858, FMT, 92D8034, and F10-2AS. Embryo lethality was consistent with lesion incidence and severity. Embryo lethality did not correlate with previous results regarding pathogenicity of these same six isolates in SPF broiler chickens.     

Evaluation of factors associated with infection of commercial layers with Mycoplasma gallisepticum and M. synoviae

Information on factors possibly associated with the risk of infection with Mycoplasma gallisepticum (MG) or M. synoviae (MS) were collected from nearly 400 layer flocks in California. Factors associated with the probability of flock infection with either MG or MS were identified, and their magnitude was quantified by statistical analysis. More frequent administration of several vaccines was associated with decreased probability of both MG and MS infection of flocks. Also identified were housing or hygiene factors and system of management (i.e., multiple-age status) that could reduce the probability of infection of flocks with mycoplasma. The change in probability of MG infection resulting from modifying certain management factors was examined.     

Restriction endonuclease analysis of Mycoplasma synoviae strains

A diverse group of Mycoplasma synoviae strains from various hosts, pathological processes, and geographic areas collected over about 25 years were analyzed by restriction endonuclease analysis. The results suggest that restriction endonuclease analysis of M. synoviae strains may be a useful strain identification tool to study epidemiological problems.     

Experimental infection of ducks with Mycoplasma synoviae

Specific-pathogen-free ducks 24 and 180 days old were inoculated intranasally with the WVU 1853 strain of Mycoplasma synoviae (MS). No significant gross lesions were found in the infraorbital sinus, trachea, or air sacs at 7 or 28 days postinfection (PI), although MS was recovered from all these organs. A few ducks responded serologically by developing agglutinating antibodies. MS multiplied in embryonated duck eggs but to lower titers than in embryonated chicken eggs.     

Immunoglobulin G Fc receptors of Mycoplasma synoviae

The objective of the study was to demonstrate and characterize IgG Fc receptors of Mycoplasma synoviae. Two IgG Fc receptors were recognized with molecular weights (MW) of 80,000 and 90,000 and isoelectric focusing points (pI) of 5.3 and 4.3, respectively. The activity of the IgG Fc receptors was eliminated by exposure to 0.1 unit of protease for 10 minutes. Mild reduction in activity was observed with trypsin between 100 to 1000 units for 10 minutes. The IgG Fc receptors were resistant to exposure to 60 C for 60 minutes and to 100 C for 20 minutes. The M. synoviae IgG Fc receptors were strongly reactive to affinity-purified Fc Fragment of chicken IgG; affinity-purified chicken IgG; and serum IgG of chicken, quail, pigeon, and turkey. A moderate reaction was detected to human affinity-purified IgG, and weak reactions were detected to affinity-purified IgG of cat, cow, dog, goat, guinea pig, horse, and rabbit. No reaction occurred with IgG of duck, goose, mouse, pig or rat.     

Epidemiological study on Mycoplasma synoviae infection in layers

Mycoplasma synoviae infection occurs worldwide in commercial poultry flocks and may result in severe economic losses. The prevalence of this mycoplasma in standard layers older than 60 weeks was studied in a French department and the characteristics of infected or free flocks were compared. The genomic profiles of isolates from 36 infected flocks were studied by pulsed-field gel electrophoresis and random amplified polymorphic DNA methods in order to investigate possible routes of transmission. The minimum inhibitory concentrations of antibiotics were determined. Results showed that infection was more frequent in multi-age farms. Egg production and mortality of infected flocks were respectively lower and higher than in non-infected flocks but the differences were not statistically significant. The genomic profiles of isolates were quite homogeneous, a feature which does not facilitate the understanding of routes of transmission. All isolates were susceptible to tetracyclines, macrolides (except erythromycin), spectinomycin and fluoroquinolones.     

Airsacculitis in turkeys exposed to Mycoplasma synoviae membranes

In studies to investigate the pathogenesis of mycoplasmal airsacculitis, exudative lesions were produced in turkeys by intra-air-sac inoculation with Mycoplasma synoviae cell membranes and viable organisms. Membrane inocula containing 5 mg of protein produced more severe lesions than inocula containing either 2.5 mg or 1 mg protein. Turkeys exposed to 5 mg of membrane protein developed moderately severe airsacculitis; those exposed to viable organisms developed markedly severe airsacculitis. Microscopic examinations revealed that membrane-induced lesions were generally similar to those resulting from infection but were less severe. At the termination of the study, 8 days after exposure, M. synoviae was isolated from respiratory tract tissues of all turkeys exposed to live organisms, but it was not isolated from any of those exposed to membranes or from unexposed control turkeys. Antibody against M. synoviae was demonstrated with the tube agglutination test in sera from turkeys exposed to membranes and those exposed to live organisms, but it was not demonstrated in sera from unexposed control turkeys.     

应用多重套式PCR检测鸡毒支原体和鸡滑液囊支原体

根据已发表的鸡毒和鸡滑液支原体血凝素基因序列pMGA和vlhA各设计两对引物,建立鉴别诊断两种支原体的多重套式PCR方法,对其进行温度条件、Ⅱ步模板浓度优化及特异性、敏感性实验。该方法在两步PCR后能特异性地扩增出MG(408 bp)和MS(688 bp)两个目的片段。应用于临床样品检测,与支原体分离、SPA检测比较结果PCR灵敏度高于病原分离。     

Characterization of Escherichia coli strains obtained from layer chickens affected with colibacillosis in a commercial egg-producing farm

The present study reports colibacillosis of layer chickens in a commercial egg-producing farm in western Japan. Three flocks of chicken at 18-21 weeks of age were affected during the initiation of egg lay. Postmortem examination revealed pericarditis, perihepatitis, airsacculitis, subcutaneous inguinal lesion, and injured cloaca. Escherichia coli was isolated from the lesions of the affected birds. Twenty-two of 26 E. coli isolates (84.6%) obtained from 18 birds in the 3 flocks showed pulsed-field gel electrophoresis (PFGE) patterns that were considered to be closely associated to each other and arbitrarily designated as pattern A. All the 22 isolates with the PFGE pattern A harbored the putative virulence genes, astA, iss, iucD, tsh, and cva/cvi. Additional 2 PFGE patterns (B and C) were also found in E. coli isolates obtained from the affected flocks and had the putative virulence genes in combinations different from those in the pattern A strains. The results suggested that certain E. coli virulence genes and host factors, such as initiation of egg lay may be associated with occurrence of colibacillosis.