Gallisepticum Vaccine Research Articles

An F-Strain Mycoplasma gallisepticum Inoculation at Twelve Weeks of Age Does Not Modify the Effects of Fasting During Lay on the Blood Characteristics of Commercial Egg Laying Hens

The interactive effects of an F-strain Mycoplasma gallisepticum (FMG) inoculation at 12 wk of age with those of a 24 h fast during lay on the BW, mortality, egg production and blood characteristics of commercial egg laying hens at 34 and 46 wk of age were investigated. Blood parameters measured were whole blood hematocrit; plasma protein concentration (PP); serum total cholesterol, triglycerides and calcium concentrations; and percentage serum cholesterol recovered in very low, low and high density lipoprotein fractions. There were no interactive effects involving FMG inoculation and fasting (inoculation x fasting or age x inoculation x fasting) on any of the parameters investigated. These results suggest that a pre-lay (12 wk of age) FMG inoculation does not influence the effects of a 24 h fast during lay (34 and 46 wk of age) on the performance and blood characteristics of commercial layers.

Effects of F-Strain Mycoplasma gallisepticum Inoculation at Twelve Weeks of Age on Serum Vitellogenin Concentrations in Commercial Egg Laying Hens

Effects of F-Strain Mycoplasma gallisepticum Inoculation at Twelve Weeks of Age on Serum Vitellogenin Concentrations in Commercial Egg Laying Hens

The Efficacy of Three Commercial Mycoplasma gallisepticum Vaccines in Laying Hens

The Efficacy of Three Commercial Mycoplasma gallisepticum Vaccines in Laying Hens

A Comparative Study of Live Attenuated F Strain–Derived Mycoplasma gallisepticum Vaccines

Commercially available attenuated strains of Mycoplasma gallisepticum (MG) are commonly used within the layer industry to control MG-induced mycoplasmosis. Among these are two live MG vaccines derived from the moderately pathogenic MG "chick F" strain. In the present study, the commercially available F strain derivatives were compared for their ability to elicit seroconversion, persist in vivo, and protect against virulent MG-induced airsacculitis. In addition, a noncommercial laboratory-derived high-passage F strain isolate was included in the study. Commercial (Hy-Line W-36) layers were placed in biological isolation units at 9 wk of age (woa). At 10 woa, birds within each biological isolation unit were treated via eye-drop application with one of the three F strain-derived vaccines at one of four levels (1x, 10(-1)x, 10(-2)x, or 10(-3)x). For the commercially available F strain derivatives, 1x equaled the manufacturer's recommended dose. The 1x dose of the noncommercial laboratory-maintained F strain derivative equaled 20 microl of a 48 hr culture. For wk 1-6 postvaccination (p.v.), sera were collected weekly from each bird, and seroconversion was assessed via serum plate agglutination (SPA). Virulent MG (strain R(low)) challenge occurred via intratracheal inoculation at 7 wk p.v. Necropsies were subsequently performed to assess challenge-associated airsacculitus. For each F strain derivative applied at 1x and 10(-1)x, 100% seroconversion, as measured by SPA, was demonstrated by 6 wk p.v., and rates at the 10(-2)x dosage were 10% and 90% for the commercial vaccines and 60% for the laboratory-derived strain in this period. Following challenge, airsacculitis was observed in 66.67% of the nontreated controls but not in any 1x- or 10(-1)x-treated bird independent of applied F strain derivative.

The Efficacy of Three Commercial Mycoplasma gallisepticum Vaccines in Laying Hens

The efficacy of three commercial Mycoplasma gallisepticum (MG) immunizing agents-a bacterin, a recombinant fowlpox-MG vaccine, and a live F-strain vaccine-was compared in specific-pathogen-free hens in egg production. Three groups of 25 chickens were vaccinated with one of the vaccines at 10 wk of age and 25 birds were not vaccinated. At 25 wk of age (and approximately 50% egg production), 20 birds from each of the three vaccinated groups and 15 nonvaccinated controls were challenged with virulent R-strain via aerosol; the birds were necropsied and evaluated at 10 days post-challenge. The MG bacterin and live F-strain vaccinations were both protective and resulted in significant differences in air sac lesions, tracheal lesions, and ovarian regression compared to the nonvaccinated controls and the recombinant fowlpox-MG vaccine (P < or = 0.05). The evaluation of ovarian regression is a useful method of testing the efficacy of MG vaccines in laying hens.

A Comparative Study of Live Attenuated F Strain–Derived Mycoplasma gallisepticum Vaccines

A Comparative Study of Live Attenuated F Strain–Derived Mycoplasma gallisepticum Vaccines

Evaluation of Mycoplasma gallisepticum K-Strain as a Live Vaccine in Chickens

We evaluated the pathogenicity of three live Mycoplasma gallisepticum (MG) vaccine candidates by infection via aerosol of 3-wk-old chickens with log phase broth cultures (trial 1). Two of the candidates (K3020 and K4649A) colonized only 10% and 20% of the chickens, respectively, unlike K2101 (K-strain), which was reisolated from all of the vaccinated chickens tested. K-strain inoculation did not result in significant air sac or tracheal lesions in chickens at 10 and 39 days postinfection (P < or = 0.05). The efficacy of K-strain as a live vaccine was evaluated in trial 2, by challenge of vaccinated chickens with virulent R-strain via aerosol at 6 wk postvaccination. K-strain vaccination resulted in significant protection from air sac and tracheal lesions (P < or = 0.05). The K-strain was further investigated to evaluate transmissibility (trial 3), colonization and persistence of infection following aerosol administration (trial 4), genetic and phenotypic stability following back passage through chickens (trial 5), and vertical transmission (trial 6). The K-strain had a low rate of horizontal transmission; it remained primarily in the respiratory system of inoculated birds and persisted in the upper respiratory tract for the duration of the trial 4 (5 mo). There was no increase in virulence of K-strain when it was back passaged five times through chickens, and no vertical transmission of K-strain was detected. K-strain showed great potential as a safe and effective live MG vaccine.

Serologic Response of Roosters to Gradient Dosage Levels of a Commercially Available Live F Strain-Derived Mycoplasma gallisepticum Vaccine Over Time

Spray application is a commonly used, time- and labor-efficient means to deliver live Mycoplasma gallisepticum (MG) vaccine to laying hens in commercial production facilities. The dosage of vaccine received by spray-vaccinated birds can vary due to variation in the spray plume and the vaccine suspension droplet trajectory. In this study, a total of 48 Hy-Line W-36 males were placed individually in isolation units following eye-drop application of gradient levels (1 x, 10(-1) x, 10(-2) x, 10(-3) x, 10(-4) x, 10(-5) x, 10(-6) x, and unvaccinated control) of the MG vaccine. The determined titer associated with a 1 x dose was 2 x 10(6) colony-forming units/dose. Serologic response was assessed weekly following vaccination via serum plate agglutination (SPA) for weeks one through seven postvaccination (p.v.). In addition, immunologic response was assessed at 5, 6, and 7 wk p.v. via MG enzyme-linked immunosorbent assay (ELISA). As indicated by SPA analyses, a 1 x dose of vaccine resulted in 100% seroconversion, and dose levels of 10(-1) x and 10(-2) x resulted in 75% and 37.5% seroconversion, respectively, at 6 wk p.v. The MG ELISA results at 6 wk p.v. demonstrated immunologic responses in 100%, 57.1%, and 28.6% of the 1 x, 10(-1) x, and 10(-2) x dosed birds, respectively. The lower dosage levels of 10(-3) x, 10(-4) x, 10(-5) x, and 10(-6) x did not elicit a response from any bird at 6 wk p.v. Utilizing the SPA data, a logistic regression model was used to determine the relationship between dosage level and seroconversion rate (R2 = 0.999 with a standard error of prediction of 1.6%). The model predicted a required effective dosage of 0.26 x for 90% seroconversion at 6 wk p.v. under test conditions.

Serologic Response of Roosters to Gradient Dosage Levels of a Commercially Available Live F Strain-Derived Mycoplasma gallisepticum Vaccine Over Time

Serologic Response of Roosters to Gradient Dosage Levels of a Commercially Available Live F Strain-Derived Mycoplasma gallisepticum Vaccine Over Time

Development and immunogenicity of recombinant GapA+Mycoplasma gallisepticum vaccine strain ts-11 expressing infectious bronchitis virus-S1 glycoprotein and chicken interleukin-6

Mycoplasma gallisepticum (MG) is a major pathogen of poultry that causes chronic respiratory disease in chickens and infectious sinusitis in turkeys. A live attenuated vaccine, ts-11, has been used for the control of MG in several countries. The efficacy of this vaccine is highly dose dependent and the flock antibody response is weak. To improve the functionality of the vaccine and investigate its potential as a delivery vector for foreign antigens and immunomodulatory proteins, we developed a derivative of ts-11 expressing infectious bronchitis virus-S1 glycoprotein (IBV-S1) and releasing chicken interleukin-6 into the extracellular milieu (MG ts-11 C3 (+CS)) using a transposon-based delivery vector. Following administration of MG ts-11 C3 (+CS) to chickens by eye-drop, an antibody response to MG and IBV-S1, as determined by the rapid serum agglutination test (RSA) and Western blotting, respectively, could be detected. Birds inoculated with the recombinant vaccine had significantly enhanced weight gain and were partially protected against damage by pathogenic IBV. These results indicate that the ChIL-6 released by MG ts-11 C3 (+CS) may have had a non-specific effect on growth rate. They also suggest that ts-11 is a promising vaccine vector, capable of delivering heterologous protective antigens, and may also provide non-specific benefits when engineered to express immunomodulatory proteins. With some improvements in the expression system, it could be used to induce a targeted immune response against specific mucosal pathogens, and co-expression of several antigens would allow development of a novel multivalent vaccine.

Effects of single and combined Mycoplasma gallisepticum vaccinations on blood electrolytes and acid-base balance in commercial egg-laying hens

A previous study from our laboratory on F-strain Mycoplasma gallisepticum-inoculated layers showed a significant increase in arterial partial pressure of oxygen (pO(2)), which is generally associated with an oxygen-dependent improvement in tissue oxygenation. The aim of this study was to determine whether a killed (bacterin) and live TS-11-strain M. gallisepticum (TS-11-MG) vaccine treatment combination could further enhance the arterial pO(2) levels in layer chickens. The experiment was conducted in 2 trials and arranged in a completely randomized experimental design with 4 treatments. The treatments consisted of a control M. gallisepticum, bacterin, TS-11-MG, and bacterin + TS-11-MG combined, with all treatments receiving the R low strain of MG at 30 wk of age (WOA). In each of the 2 trials, 160 one-day-old MG-free pullets were raised to 10 WOA and were transported to a poultry disease isolation facility. Sixteen isolation units were divided into 4 treatment groups, and each of the 4 treatment groups had 4 replication units, with 10 birds/unit (40 birds/treatment). Venous blood samples were collected at the termination of the study at 56 WOA. The TS-11-MG-vaccinated chickens had a higher (P ≤ 0.05) blood pO(2) and a lower (P ≤ 0.05) partial pressure of CO(2) when compared with the control and combined MG-vaccinated groups. However, no significant blood pO(2) differences were observed between the bacterin and TS-11-MG treatment groups. Hematocrit and blood concentrations of hemoglobin were not statistically different among treatments, but were numerically higher in the TS-11-MG treatment group. There was a significant (P ≤ 0.05) treatment effect on blood concentrations of Na(+), Ca(2+), and anion, but no significant effect on glucose, cholesterol, triglyceride, or osmolality. These data suggest that the inoculation of layers with TS-11-MG was more effective in elevating pO(2) than was inoculation with TS-11-MG + bacterin combined.

Eye Surface Area and Dosage Rates for Spray Vaccination

Spray application of Mycoplasma gallisepticum (MG) vaccines is a labor- and time-saving means of mass vaccination of layer chickens. Recent assessment of spray characteristics of nozzles commonly used to apply MG vaccine in layer chicken operations has shown that the amount of respirable droplets (< 5 microm) is negligible. Topical application of vaccine onto the eye surface has been suggested as a route of vaccination, but no estimates of vaccine load delivered via spray application were found in the literature. Estimates of eye surface area were developed using digital imaging; 24 layer pullets were used for analysis, and the mean eye surface area, corrected for corneal curvature, was found to be 0.609 cm2. This surface area was then used to estimate vaccine load for commercially available live MG vaccine sprayed through popular nozzles. Less than 3000 colony-forming units can be expected for direct deposition onto the surface of an eye.

A Chronicle of Serologic Response in Commercial Layer Chickens to Vaccination with Commercial F Strain Mycoplasma gallisepticum Vaccine

A Chronicle of Serologic Response in Commercial Layer Chickens to Vaccination with Commercial F Strain Mycoplasma gallisepticum Vaccine

A Chronicle of Serologic Response in Commercial Layer Chickens to Vaccination with Commercial F Strain Mycoplasma gallisepticum Vaccine

Vaccination of multi-age layer operations, wherein one million plus commercial layer chickens are housed, has been spurious until the development of a self-propelled, constant-speed spray vaccinator. Still, even with its use, live Mycoplasma gallisepticum (MG) vaccinations have been questionable in terms of seroconversion. Using the vaccinator as a research tool over the past 5 yr, factors have been elucidated which impact seroconversion to one live MG vaccine in particular, the F strain of MG (FMG). These factors include the type of nozzle used to spray the vaccine, the temperature of the water used to rehydrate and administer the vaccine, and the pH and osmolarity of the fluid used to apply the vaccine. In the present study, one farm was monitored for its seroconversion rates over 4 1/2 yr, during which time the FMG vaccination protocol was amended as factors were identified that enhanced seroconversion rates. The results of this study showed that implementation and inclusion of the optimized factors into the vaccination protocol for FMG enhanced seroconversion rates because they went from an initial 50%-55% positive seroconversion rate to a consistent 100% positive seroconversion rate over the 56-mo study period.

A safety assessment of a fowlpox-vectored Mycoplasma gallisepticum vaccine in chickens

A recombinant fowlpox virus vaccine expressing key protective Mycoplasma gallisepticum antigens could facilitate in the prevention both of fowlpox virus and M. gallisepticum infections. Vectormune FP-MG vaccine, a recombinant fowlpox virus expressing both M. gallisepticum 40k and mgc genes, was assessed for its safety in 8-wk-old specific-pathogen-free White Leghorn chickens. The vaccine virus was serially passaged 5 times by wing-web inoculation. Based on the postinoculation clinical observation, gross pathological examination of air sacs and peritoneum, genetic stability evaluation, virus shedding and tissue distribution detection, horizontal transmission ability determination, and protection against fowlpox virus challenge, the Vectormune FP-MG vaccine possesses a high level of safety.

Effects of vaccination with F-strain Mycoplasma gallisepticum on egg production and quality parameters of commercial layer hens previously vaccinated with 6/85-strain Mycoplasma gallisepticum

This study was conducted to determine the effect of overlaying (revaccinating) F-strain Mycoplasma gallisepticum at 22 or 45 wk of age on commercial leghorn hens previously vaccinated with 6/85-strain M. gallisepticum at 10 wk of age. The treatment groups included unvaccinated hens (group 1), hens receiving 6/85-strain M. gallisepticum only (group 2), and hens receiving 6/85-strain M. gallisepticum followed by F-strain M. gallisepticum at either 22 (group 3) or 45 (group 4) wk of age. There was no significant effect on egg production or egg size distribution between any of the treatment groups, unlike previous studies looking at F-strain vaccination only. Egg quality parameters, including eggshell strength, Haugh unit score, and blood-meat spot were similar between the different treatment groups. There was a difference in the rate of pimpling at postpeak production for the treatment group receiving F-strain M. gallisepticum at 22 wk of age, consistent with previously published results. This work suggests that hens previously vaccinated with 6/85-strain M. gallisepticum can be safely revaccinated with F-strain M. gallisepticum to increase protection from field strains while ameliorating the adverse effects associated with F-strain M. gallisepticum vaccination in layers post onset of lay.

Influence of supplemental dietary poultry fat on the digestive and reproductive organ characteristics of commercial layers inoculated before or at the onset of lay with F-strainMycoplasma gallisepticum

Effects of F-strain Mycoplasma gallisepticum (FMG) inoculation and 1.5% supplemental dietary poultry fat (PF) on the digestive and reproductive organ characteristics of commercial layers at 58 wk of age were investigated. Sham and FMG inoculations were administered at 12 (before lay) and 22 (early in lay) wk of age, and dietary treatments (basal control diets and basal control diets with PF) were initiated at 20 wk of age. Supplemental PF increased BW and decreased isthmal length relative to total oviduct length in hens. Various oviduct segments were also affected by the type and age of inoculation, and these effects were further influenced by the use of PF. In comparison to their time-specific sham-inoculated controls, infundibulum weight relative to BW was increased when birds were inoculated with FMG at 22 wk, whereas isthmus weight relative to total oviduct weight was increased by FMG inoculation at 12 wk of age. However, PF affected infundibulum length relative to total oviduct length only in sham-inoculated birds, and PF increased magnum weight relative to total oviduct weight only in birds inoculated at 22 wk of age (sham or FMG). Furthermore, PF decreased isthmus weight relative to total oviduct weight only in birds that were sham-inoculated (12 or 22 wk). In conclusion, the inoculation of FMG at 12 or 22 wk may increase the relative contributions of the isthmus and infundibulum, respectively, to the total mass of the oviduct. In addition, PF may decrease the relative length of the isthmus and increase the relative weight of the magnum in the oviducts of birds that have been inoculated at 22 wk of age (sham or FMG). Previous studies have shown 1.5% supplemental dietary PF to influence feed consumption throughout lay and performance early in lay in hens that were inoculated with FMG at 12 wk of age. However, the current results suggest that these influences are associated with gross changes in the oviduct but not the digestive tract of layers.

Influence of supplemental dietary poultry fat on the yolk characteristics of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum

Effects of F-strain Mycoplasma gallisepticum (FMG) inoculation and 1.5% supplemental dietary poultry fat (PF) on the egg yolk characteristics of commercial layers at 24, 34, 44, 50, and 58 wk of age were investigated. Sham and FMG inoculations were administered at 12 and 22 wk of age and dietary treatments (basal control and basal control with 1.5% supplemental PF) were initiated at 20 wk of age. Yolk lipid concentration was reduced on wk 24 in birds that had been inoculated at 12 or 22 wk of age with FMG. The use of 1.5% supplemental PF increased percentage of yolk weight and yolk:albumen ratio across age and inoculation treatment. At 58 wk of age, concentrations of yolk palmitic acid increased and those of oleic and linolenic acid decreased when sham inoculations were given at 22 rather than at 12 wk of age. However, FMG inoculations given at 22 rather than at 12 wk increased palmitoleic acid and decreased stearic acid yolk concentrations. At 12 wk of age, FMG inoculations decreased yolk palmitoleic, oleic, and linolenic acid concentrations while causing increased yolk stearic and arachidonic acid levels when compared with sham inoculations. Furthermore, 1.5% supplemental PF decreased concentrations of palmitic and oleic acid and increased those of linoleic acid in the yolk at 58 wk of age. Despite the interaction of 1.5% supplemental PF with the prelay inoculation of FMG on early (18 to 26 wk) layer performance noted in a previous report, the effects of a prelay FMG inoculation and 1.5% supplemental PF on the egg yolk characteristics examined in the current study were independent of each other. This suggests that 1.5% supplemental PF is not effective in modulating the effects of an FMG inoculation at 12 wk of age on hen egg yolk characteristics between 24 and 58 wk of age and that the combined effects of PF supplementation and FMG inoculation on performance do not influence egg yolk characteristics.

Effect of Dosage and Vaccination Route on Transmission of a Live Attenuated Mycoplasma gallisepticum Vaccine: A Broiler Model *

Effect of Dosage and Vaccination Route on Transmission of a Live Attenuated Mycoplasma gallisepticum Vaccine: A Broiler Model *

Effect of Dosage and Vaccination Route on Transmission of a Live Attenuated Mycoplasma gallisepticum Vaccine: A Broiler Model

Mycoplasma gallisepticum (MG) is an economically significant pathogen of poultry species. Among the table egg sector of the poultry industry, live attenuated strains of MG are commonly used to limit production losses associated with MG-induced disease. These vaccines, however, may be problematic to broiler- and turkey-related industries because of associated virulence; therefore, an understanding of the transmissibility of the live MG vaccines is of particular importance. In the present study, a broiler model addresses the effect of vaccine application route and dosage on the transmission of the MG vaccine FVAX-MG to commingled unvaccinated subjects for 7 wk postvaccination. Vaccinations occurred at 2 wk of age via eyedrop or spray application at 1 x (4 x 10(6) colony-forming units [cfu]), 10(-3) x (4 x 10(3) cfu), or 10(-6) x (4 cfu) of the manufacturer's recommended dosage, and subsequent transmission to unvaccinated subjects was measured. The serologic response to MG antigen and the presence of MG DNA indicated FVAX-MG transmission only within the 1 x FVAX-MG eyedrop treatment. Among no other treatment was transmission of FVAX-MG detected. The results of the present study demonstrate that the dosage and vaccination route may have direct implications on subsequent transmission of FVAX-MG.