title: A comparative study of live attenuated F strain-derived Mycoplasma gallisepticum vaccines.
abstract: 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.
authors.affiliation: USDA, Agricultural Research Service, Poultry Research Unit, Mississippi State, MS 39762, USA. jeff.evans@ars.usda.gov
authors.forename: J D
authors.initials: JD
authors.lastname: Evans
authors.forename: S A
authors.initials: SA
authors.lastname: Leigh
authors.forename: J L
authors.initials: JL
authors.lastname: Purswell
authors.forename: R
authors.initials: R
authors.lastname: Jacob
authors.forename: E D
authors.initials: ED
authors.lastname: Peebles
authors.forename: S D
authors.initials: SD
authors.lastname: Collier
authors.forename: S L
authors.initials: SL
authors.lastname: Branton
mesh_terms: D000372:Agglutination Tests / Q000662:veterinary; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology*; D002645:Chickens; D004306:Dose-Response Relationship, Immunologic; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D009175:Mycoplasma Infections / Q000517:prevention & control / Q000662:veterinary*; D045686:Mycoplasma gallisepticum / Q000276:immunology* / Q000472:pathogenicity; D011201:Poultry Diseases / Q000517:prevention & control*; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D014774:Virulence
chemical_list: D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D014613:Vaccines, Attenuated