TABLE 5

Serology, air sac lesion scores, and reisolation rates in infectivity and virulence study

GroupInoculumNo. of birds positive for antibody against M. gallisepticum/no. examinedaNo. of birds positive/no. examineda,b
Air sac lesionsAgar cultureBroth culturec
Air sacsTracheaAir sacsTrachea
1Medium0/20A0/20A (0–0)d0/20A0/20A0/20A0/20A
2Mutant 03-11/20A1/20A,B (0–0.25)0/20A2/20A,B0/20A5/20B,C
3Mutant 18-120/20B5/20B (0.5–3.5)5/20B,C17/20C7/20B19/20D
4Mutant 20-120/20B6/20B (0.5–4.0)7/20C20/20C8/20B20/20D
5Mutant 22-10/19A0/19A (0–0)0/19A1/19A,B0/19A3/19A,B
6Mutant 26-10/20A4/20A,B (0.5–1.0)1/20A,B6/20B1/20A10/20C
7Wild-type Ap3AS18/18B11/18C (0.5–8.5)9/18C18/18C10/18B15/18D
  • a Data in the same column marked with the same superscript letter were not significantly different.

  • b One bird in group 5 and two birds in group 7 died before necropsy.

  • c The only signature tag detected in each group was that carried by the mutant used to infect that group. No signature tags were detected in cultures from groups 1 and 7.

  • d Data in parentheses represent the range of scores.