Isolation and Progeny Transmission of Non-Temperature-Sensitive MS-H Vaccine Strains of <i>Mycoplasma synoviae</i> from Temperature-Sensitive MS-H-Vaccinated Laying Breeder Hens

This pilot study reports the vertical transmission and reverse thermosensitivity of MS-H vaccine strain Mycoplasma synoviae (MS) by RAPD in commercial breeders their progeny. At two weeks age, were vaccinated with ts+ strain. 9 an outbreak infectious synovitis (IS) was detected Tracheal swab samples collected from at 24, 39, 48, 70 age. weeks, pullets elbow joints collected. performed on isolates 39.5°C, same ts- strains identified breeder hens swabs negative to MS isolation 37°C 39.5°C 24- 39-weeks. recovered tracheal 9/10 10/10 48- 70- week. age progeny, isolated non-IS pullets. samples. The progeny showed non-significant differences five antimycoplasmic MIC100 values; otherwise, enrofloxacin presented a significant difference value (p -H Consequently, it is crucial contemplate danger reversing pathogenicity when applying