J. D. Evans

Effects of live and killed vaccines against Mycoplasma gallisepticum on the performance characteristics of commercial layer chickens

Different vaccine strains of Mycoplasma gallisepticum have been used on multiple-age commercial layer farms in an effort to protect birds against virulent field-strain infections. Use of the F-strain of M. gallisepticum (FMG), as an overlay vaccine during lay, may be necessary because of the lower level of protection afforded by M. gallisepticum vaccines of low virulence given before lay. Two replicate trials were conducted to investigate effects of live and killed M. gallisepticum vaccines administered individually and in combination before lay, in conjunction with an FMG vaccine overlay after peak egg production (EP), on the performance characteristics of commercial layers. The following treatments were utilized at 10 wk of age (woa): 1) control (no vaccinations); 2) ts11 strain M. gallisepticum (ts11MG) vaccine; 3) M. gallisepticum-Bacterin vaccine (MG-Bacterin); and 4) ts11MG and MG-Bacterin vaccines combination. At 45 woa, half of the birds were overlaid with an FMG vaccine. Hen mortality, BW, egg weight, percentage hen-day EP, egg blood spots, and egg meat spots were determined at various time periods between 18 and 52 woa. The data from each trial were pooled. Treatment did not affect performance in interval I (23 to 45 woa). However, during interval II (46 to 52 woa), the EP of control and MG-Bacterin-vaccinated birds that later received an FMG vaccine overlay was lower than that in the other treatment groups. Furthermore, treatment application reduced bird BW during interval II. Despite the effects on BW and EP, no differences were observed for egg blood or meat spots among the various treatments. It is suggested that the vaccination of commercial layers before lay with ts11MG, but not MG-Bacterin, may reduce the negative impacts of an FMG overlay vaccination given during lay. These results establish that the vaccination of pullets with ts11MG in combination with the vaccination of hens with an FMG overlay, for continual protection against field-strain M. gallisepticum infections, may be used without suppressing performance.

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.

Proteomics inference of genes involved in host adaptation of Mycoplasma gallinarum.

Different from most other host-specific mycoplasmas, Mycoplasma gallinarum has been isolated from various hosts, such as poultry, pig, cattle, and sheep. The wide distribution among different hosts, the low pathogenesis, and the weak host immunological responses suggest this mycoplasma has a unique host adaptation mechanism. In this study, we applied two-dimensional liquid chromatography electrospray ionization tandem mass spectrometry (2D LC-MS/MS) to characterize the protein profiling of M. gallinarum. Our results suggest that M. gallinarum possesses homologs of cytadhesin proteins found in other mycoplasmas lacking an organized tip organelle. Our results showed that there are possibly multiple aminopeptidase gene homologs present in M. gallinarum, which might be involved in nutrient acquisition of M. gallinarum. The information present here would be useful for future studies to identify genes responsible for the colonization and host adaptation properties of M. gallinarum.

Mycoplasma gallisepticum transmission: Comparison of commercial F-strain vaccine versus layer complex-derived field strains in a tunnel ventilated house

Two simultaneous trials were conducted using a commercially available, live, F strain Mycoplasma gallisepticum (FMG) vaccine (trial 1) or 2 inocula of layer complex-derived MG strains (LCD-MG; trial 2). In each of the 2 trials, 4 commercial turkeys were housed in each of 2 adjoining pens immediately adjacent to air inlets. The turkeys (8/trial) were inoculated in the right eye with either a 1× dose of FMG (trial 1) or with 0.02 mL of 1 of 2 actively growing LCD-MG inocula (4 turkeys/inoculum; trial 2). In each of the 2 trials, one pen housing 4 inoculated turkeys was maintained without the addition of other poultry, whereas 16 MG-free broilers and 4 MG-free layers were added to the other pen of 4 inoculated turkeys. Within each of the trials and at increasing intervals, either 4 layers (3 pens) or 4 turkeys (3 pens) were placed down-airstream from the inoculated pens. The distance of the first pen from the inoculated turkeys was separated by the width of one pen that was empty. Succeeding down-airstream pens were situated such that the empty distance (absence of any poultry) between pens that contained poultry doubled from one pen to the next such that the final pen that contained poultry had 4 empty pens between it and the next up-airstream pen that also contained poultry. At 106 d postinoculation, all poultry were bled, swabbed for MG from the choanal cleft, and then euthanized and necropsied. No commingled poultry in trial 1 (FMG), whether inoculated (turkeys) or commingled (layers and broilers), died during the course of the trial, and 5 of the 8 FMG-vaccinated turkeys exhibited serological but not cultural evidence of mycoplasmosis. In trial 2 (LCD-MG), 2 commingled broilers died and no inoculated turkeys exhibited either serological or cultural evidence of mycoplasmosis. In both trials, no poultry housed down-airstream from the inoculated poultry showed evidence of clinical signs of mycocplasmosis and none showed either serological or cultural evidence of mycoplasmosis.

Effects of different vaccine combinations against Mycoplasma gallisepticum on the internal egg and eggshell characteristics of commercial layer chickens

Live F-strain Mycoplasma gallisepticum (FMG) vaccines are presently being used to help control field-strain MG outbreaks. However, they may exert some adverse effects on egg production. Live strains of MG of lesser virulence as well as killed vaccines have little or no effect on egg production, but afford lower levels of protection. This has led to research investigating their use in combination with a subsequent overlay vaccination of FMG given later in the production cycle. In the present study, 2 trials were conducted to investigate the effects of prelay vaccinations of live and killed MG vaccines or their combination, in conjunction with an FMG vaccine overlay after peak production, on the egg characteristics of commercial layers. The following vaccination treatments were administered at 10 wk of age (woa): 1) unvaccinated (Control), 2) MG-Bacterin (MGBac) vaccine, 3) ts-11 strain MG (ts11MG) vaccine, and 4) MGBac and ts11MG combination (MGBac + ts11MG). At 45 woa, half of the birds were overlaid with an FMG vaccine. In each trial, internal egg and eggshell parameters including egg weight (EW), Haugh unit score (HU), eggshell breaking strength (EBS), percentage yolk weight (PYW), percentage albumen weight (PAW), percentage eggshell weight (PSW), eggshell weight per unit surface area (SWUSA), percentage yolk moisture (PYM), and percent total lipids (PYL) were determined at various time periods between 21 and 52 woa. At 28 woa, SWUSA was lower in the ts11MG and MGBac + ts11MG groups compared to the Control group. Conversely, at 43 woa, SWUSA was higher in the ts11MG than in the MGBac group. Between 23 and 43 woa, PYL was higher in the MGBac and ts11MG groups in comparison to the Control group. In conclusion, vaccination with MGBac alone or in combination with ts11MG at 10 woa with or without an FMG vaccine overlay at 45 woa does not adversely affect the internal egg or eggshell quality of commercial layers throughout lay.

Impact of fowlpox-vectored Mycoplasma gallisepticum vaccine Vectormune FP MG on layer hen egg production and egg quality parameters

This study was conducted to determine the impact of vaccination with Vectormune FP MG on egg production and egg quality characteristics of Single Comb White Leghorn hens. Due to questions of the efficacy of this vaccine in preventing Mycoplasma gallisepticum-mediated pathology, the ability of this vaccine to protect against postproduction-peak egg losses associated with F-strain M. gallisepticum (FMG) vaccination was also investigated. Vaccination with Vectormune FP MG did not result in any significant change in egg production or egg quality parameters compared with control (unvaccinated) hens. Subsequent revaccination with FMG at 45 wk of age (woa) yielded no impact on egg production or egg quality parameters of Vectormune FP MG vaccinated hens, unlike prior results for postproduction-peak vaccination of M. gallisepticum-clean hens with FMG, which exhibited a drop in egg production of approximately 6%. No difference in egg size distribution was observed for any of the treatment groups before or after FMG revaccination. These results suggest that hens can be safely vaccinated with Vectormune FP MG as pullets and can be revaccinated with a live M. gallisepticum vaccine such as FMG at a later date with no deleterious effects on egg production or egg or eggshell quality parameters.

The impact of deposition site on vaccination efficiency of a live bacterial poultry vaccine

Vaccines are utilized within the poultry industry to minimize disease-associated losses and spray vaccination is a commonly utilized means for the mass application of poultry vaccines. During this process, vaccine-laden particles are deposited upon target areas (e.g., eyes, nares, and oral cavity) resulting in the direct internalization of the vaccine. However, particles are also deposited on nontarget areas such as the exterior of the subject and its surrounding environment. To better determine the fate of particles deposited upon nontarget areas and the impact of deposition site on the efficiency of vaccine application, a live bacterial poultry vaccine (AviPro(®) MG F) was applied via spray using a spray cabinet with a slotted partition allowing for head-only, body-only, and whole-bird spray application. At 11 wk age, Hy-Line(®) W-36 pullets (n = 280) were allocated equally among 7 treatments including: nonvaccinated controls, pullets spray-vaccinated at the manufacturers recommended dose (1X) in a site-specific manner (head-only, body-only, and whole-bird), pullets spray-vaccinated at 5X the recommended level (body-only), pullets vaccinated by manual eye-drop application (1X), and pullets eye-drop vaccinated at a level approximating that achieved during the spray vaccination process (1/700X). At 6 to 7 wk postvaccination, vaccination efficiency was assessed via serological-based assays [serum plate agglutination (SPA) and ELISA] and the detection of vaccine-derived in vivo populations. Results indicate an additive contribution of the vaccine deposited on the body to the overall vaccination efficiency of this live bacterial live poultry vaccine.

Application of a micro-aerosolized disinfectant to clear Mycoplasma gallisepticum from contaminated facilities1

Abstract Infectious agents and their associated diseases can be significant barriers in the production of poultry and zoonotic agents associated with poultry flocks can ultimately endanger consumers. To this end, poultry producers employ a variety of strategies to minimize associated risks. Disinfectants are widely utilized in the poultry industry to limit encounters with avian pathogens and zoonotic agents. These disinfectants are readily applied by a variety of means to both equipment and facilities to reduce pathogenic populations and minimize their associated risk. While a variety of disinfectants and application means are currently available, the search for more efficacious products and technologies continues. Recently, technology has been developed that may be applicable to the poultry industry for pathogen reduction. The NebuPure™ disinfecting system was developed as a means to decontaminate facilities harboring human pathogens. The system utilizes a novel dispersal unit to suspend an electrochemically activated solution in enclosed facilities and allows for largely automated decontamination. To test the NebuPure™ disinfecting system for poultry‐related applications, a research facility was seeded with plate cultures of the avian respiratory pathogen Mycoplasma gallisepticum (MG). The facility was then treated with the NebuPure™ disinfecting system with exposure times of 1 or 4 h. Following incubation, no growth was observed among exposed plates, while control plates were 100% positive for MG. The research demonstrates the efficacy of the NebuPure™ disinfecting system for disinfecting MG‐contaminated facilities and indicates that the system may be used against other poultry‐associated pathogens.