Location: Poultry Research
Title: Mycoplasma gallisepticum transmission: Comparison of commercial F-strain vaccine versus layer complex-derived field strains in a tunnel ventilated house Authors
|Pharr, G -|
|Peebles, E -|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 30, 2012
Publication Date: November 15, 2012
Citation: Purswell, J.L., Evans, J.D., Leigh, S.A., Collier, S.D., Olanrewaju, H.A., Kim, E.J., Pharr, G.T., Peebles, E.D., Branton, S.L. 2012. Mycoplasma gallisepticum transmission: Comparison of commercial F-strain vaccine versus layer complex-derived field strains in a tunnel ventilated house. Poultry Science. 91:3072-3079. Interpretive Summary: Some states, in particular Arkansas, North Carolina, do not allow the use of F strain Mycoplasma gallisepticum (FMG) vaccine within their borders. Many other states have limitations on the vaccine’s usage which is granted through the individual State Veterinarian within each state. Much of the restriction is based on anecdotal evidence concerning transmission of the live FMG vaccine. This vaccine is the only one of four live MG vaccines that has been demonstrated to be capable of displacing field or wild strains of MG. Granted the live organism is pathogenic for turkeys but the results of this study shows that transmission via movement of ventilated air for both wild or field strains of MG as well as for the FMG vaccine is non-existent. These findings are extremely important to states which have significant poultry dense regions wherein broilers, turkeys and layer chickens are in close geographic proximity as they provide data which refutes the idea that MG is readily moved from one poultry location to another via the air.
Technical Abstract: Two simultaneous trials were conducted using a commercially available, live, F strain Mycoplasma gallisepticum (FMG) vaccine [Trial 1] or two inocula of layer complex-derived MG strains (LCD-MG) [Trial 2]. In each of the two trials, four commercial turkeys were housed in each of two adjoining pens immediately adjacent to air inlets. The turkeys (eight/trial) were inoculated in the right eye with either a 1X dose of FMG (Trial 1) or with 0.02 mL of one of two actively growing, LCD-MG inocula (four turkeys/inoculum) [Trial 2]. In each of the two trials, one pen housing four inoculated turkeys was maintained without the addition of other poultry while sixteen MG-free broilers and four MG-free layers were added to the other pen of four inoculated turkeys,. Within each of the trials and at increasing intervals, either four layers (three pens) or four turkeys (three 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 which itself 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 four empty pens between it and the next up-airstream pen that also contained poultry. At 106 days post-inoculation, 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 five of the eight FMG vaccinated turkeys exhibited serological but not cultural evidence of mycoplasmosis. In Trial 2 (LCD-MG) two 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 evidenced clinical signs of mycocplasmosis and none showed either serological or cultural evidence of mycoplasmosis.