RESUMEN
Twenty two Mycoplasma isolates were recoverd from 120 Coturuix coturuix quails at Ismailia governorate. Identification and serotyping of these isolates revealed 9 M. gallisepticum [MG], 8M. gallinarum, and 5M. pullorum. Experimental infection was designed where 10 chicks [one week old] were inoculated intranasally with 0.2 ml 10[7] CFU/ml M. gallisepticum isolated from quails, 10 chicks were inoculated with M. gallisepticum S6 strain and 10 chicks were considered as control negative. Post mortem [PM] lesions were milder in chicks inoculated with M. gallisepticum isolated from quail compared to those inoculated with M. gallisepticum S6 strain and presented by congested lungs and liver, turbidity, and thickening of air sacs. Histopathological examination showed that the lungs of chicks infected with M. gallisepticum isolated from quail showed oedema with mononuclear leucocytic inflammatory cells infiltration in the interlobular connective tissue stroma. The grade of histopathological examination of tracheas of chicks infected with M.G. isolated from quail showed local lymphoid cell aggregation of leucocytic inflammatory cells in the lamina propria underneath the epithelial mucosa was mild. Mycoplasma gallisepticum could be reisolated and identified from challenged. Serologic antibody response was less in sera of chicks infected with M. gallisepticum isolated from quails. Polymerase chain reaction confirmed that the Mycoplasma isolates were M. gallisepticum