Reverse Thermosensitivity and Vertical Transmission of the MS−H Vaccine Strain of Mycoplasma synoviae in Commercial Laying Hens

The purpose of this research was to isolate and identify non-temperature sensitive (ts-) (≥39.5 °C insulation), vaccine Mycoplasma synoviae (MS) strains from laying breeder hens vaccinated with temperature sensitive (ts+) strains ( 0.05). This investigation demonstrated the reversal of the thermosensitivity, pathogenicity, and vertical transmission of the MS−H strain.