Table 2.
Infectious dose measurements (50%) of LPS mutants in turkey poults.
| Straina | Plasmidb | Relevant propertiesc genotype (phenotype) |
ID50d(× 106) | Significantly different from parentalg strain |
|---|---|---|---|---|
| 197N | – | Parental strain (WlbA+, WlbL+) | 7 ± 8.7 | NA |
| PAS85 | – | wlbA::Tn5 (WlbA−) | 81 ± 73 | Yes |
| pLAFR5 | wlbA::Tn5 (WlbA−) | 110 | Yes | |
| pLAF-av | wlbA::Tn5/wlbA-L (WlbA+) | 9 | No | |
| PAS78 | – | wlbL::Tn5 (WlbL−) | 1900 ± 1100e | Yes |
| pLAFR5 | wlbL::Tn5 (WlbL−) | > 500f | Yes | |
| pLAF-av | wlbL::Tn5/wlbA-L (WlbL+) | 2 | No |
Strain numbers refer to specific insertion mutant isolates.
Plasmid pLAFR5 refers to the vector; plasmid pLAF-av refers to the pLAFR5 vector containing the wlb locus of B. avium.
The wlb genetic mnemonics refer to LPS biosynthesis genes interrupted by an insertion.
Fifty percent infectious dose (ID50) measurements were performed as previously described (in the text). Averages or individual measurements are indicated. When two or more experiments were performed, the standard deviation of the mean is indicated (+/−).
These ID50 values were extrapolated from colonization rates obtained from birds infected at dose of ~107 and ~108 cfu.
The inequality refers to the fact that no birds were infected at any dose given. The numeric value shown is lowest possible ID50 achievable (i.e. it represents the ID50 value generated if all animals were infected at a dose one order of magnitude higher than the highest dose employed).
ID50 measurements of both mutant strains (PAS85 and PAS78) were found to be significantly different (P < 0.05) from the parental strain using the Student’s t-test. Mutants containing either the vector or complementing plasmid were found to be significantly different (P < 0.05) from the parental strain using the Z-test analysis. NA; not applicable.