TABLE 2.
Virulence of B. avium phage-resistant mutants
| Strain | Ba1 c1 sensitivity | ID50 (106)a | Statistical difference from 197Nb |
|---|---|---|---|
| 197N | + | 8 ± 2 | NA |
| AP104 | − | 3 | − |
| AP99 | − | 9 | − |
| AP108 | − | 12 | − |
| AP103 | − | 81 | + |
| AP101 | − | 150 | + |
| AP107c | − | >900 | + |
| AP105 | − | >3,000 | + |
| AP106 | − | >4,000 | + |
| AP102 | − | >5,000 | + |
ID50 measurements were determined as described in the text. The “greater-than” sign indicates that no turkeys were colonized at any dose given. The numeric value shown after the greater-than sign indicates the lowest possible ID50 achievable (i.e., it represents the ID50 value generated if all birds were colonized at a dose 1 order of magnitude higher than the highest dose employed). The standard deviation of the mean ID50 is indicated for the parental strain (197N) in which the ID50 values for 23 independent and identical experiments were averaged.
The statistical analysis was performed with the log10 ID50 values shown in the table. A plus sign indicates that there was a significant difference; a minus sign indicates there was no significant difference (P > 0.05). The Z-test was employed as described in the text. NA, not applicable.
Strain AP107 was recovered from turkeys at a rate similar to that for the parent. However, all isolates examined were Ba1-sensitive revertants. None of the other strains exhibited reversion to phage sensitivity in vivo.