title: Safety of a temperature-sensitive clone of Mycoplasma synoviae as a live vaccine.
abstract: A temperature-sensitive (ts+) clone derived from the Australian Mycoplasma synoviae (MS) field isolate 86079/7NS was produced by chemical mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine and assessed for safety as a live vaccine. This clone, designated MS-H, was assessed for pathogenicity in three different models with air sac lesions as the criterion. No air sac lesions were observed when MS-H was administered to specific-pathogen-free hybrid white leghorn (HWL) chickens by eyedrop at 10 times the normal dose or directly into the thoracic air sacs or as an aerosol administered to specific-pathogen-free Webster white leghorn chickens with concurrent intratracheal T-strain infectious bronchitis virus (IBV). MS-H did not revert to virulence or lose the ts+ phenotype when passaged through five in vivo and 10 in vitro passages. No adverse effects were seen when HWL chickens were vaccinated concurrently with MS-H and combinations of Mycoplasma gallisepticum ts-11 vaccine, IBV vaccine, and infectious laryngotracheitis virus vaccine. Lateral transmission of MS-H was found to occur when vaccinated HWL chickens were mixed with unvaccinated chickens 2 wk after vaccination. At 1 wk after mixing, one out of two unvaccinated chickens had seroconverted to MS and was culture positive for MS. At 2 wk after mixing, both contact chickens were positive for MS by culture and serology.
authors.affiliation: School of Veterinary Science, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: J F
authors.initials: JF
authors.lastname: Markham
authors.forename: C J
authors.initials: CJ
authors.lastname: Morrow
authors.forename: P C
authors.initials: PC
authors.lastname: Scott
authors.forename: K G
authors.initials: KG
authors.lastname: Whithear
mesh_terms: D000400:Air Sacs / Q000382:microbiology / Q000473:pathology; D000818:Animals; D001428:Bacterial Vaccines / Q000009:adverse effects; D002645:Chickens; D018352:Coronavirus Infections / Q000150:complications / Q000276:immunology / Q000662:veterinary; D001351:Infectious bronchitis virus; D008769:Methylnitronitrosoguanidine; D016296:Mutagenesis; D009174:Mycoplasma / Q000235:genetics / Q000276:immunology*; D009175:Mycoplasma Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D011201:Poultry Diseases / Q000276:immunology* / Q000517:prevention & control; D012449:Safety; D013047:Specific Pathogen-Free Organisms; D013696:Temperature; D014132:Trachea / Q000382:microbiology / Q000821:virology
chemical_list: D001428:Bacterial Vaccines; D008769:Methylnitronitrosoguanidine