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

Abstract

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 (<39.5 °C insulation), as well as to confirm the transmission of isolated strain from the hens to their progeny. The minimum inhibitory concentrations (MIC ₁₀₀) were calculated. Isolates of MS from 40 ts+ MS−H‑vaccinated Hy−Line ® breeder hens and 20 unvaccinated female progenies with and without Infectious synovitis (IS) were produced 39.5 °C. Random amplification of polymorphic DNA was performed on the isolates at 39.5 °C, and the same ts- MS−H strains were identified in the breeder hens and their progeny. The isolates from breeder hens and their progeny showed non-significant differences in five antimycoplasmic MIC ₁₀₀ values (P > 0.05). This investigation demonstrated the reversal of the thermosensitivity, pathogenicity, and vertical transmission of the MS−H strain.

Keywords: RAPD, reversal pathogenicity, MS-H, Vaxsafe®, enrofloxacin