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Table 3 Virulence of the A. pleuropneumoniae S-8clpPapxIIC mutant in pigs

From: Attenuated Actinobacillus pleuropneumoniae double-deletion mutant S-8∆clpP/apxIIC confers protection against homologous or heterologous strain challenge

Group Strain for challenge Challenge dosea (CFU) Temperature (°C) b Appetitec Lethargyc Dyspneac Lung lesion score d
1 S-8clpPapxIIC 1.0 × 107 39.2 ± 0.3 0.2 ± 0.4* 0.1 ± 0.2** 0.2 ± 0.2** 1.8 ± 3.0**
2 S-8 1.0 × 107 40.1 ± 0.4 1.8 ± 1.3 1.7 ± 0.7 1.9 ± 0.7 16.2 ± 8.5
3 S-8clpPapxIIC 1.0 × 109 39.4 ± 0.5 0.4 ± 0.5* 0.3 ± 0.3** 0.4 ± 0.4** 3.0 ± 2.2**
4 S-8 1.0 × 109 40.2 ± 0.6 2.4 ± 1.6 2.2 ± 0.6 2.5 ± 0.5 21.8 ± 5.8
5 PBS 0 39.4 ± 0.3 0 0 0 0
  1. a Groups of five pigs were given intranasal inoculations with 1 mL of bacterial suspension containing various quantities of A. pleuropneumoniae strains. Survival was recorded for 14 days after infection
  2. b The average temperature value for each piglet during the observation period was calculated and the mean temperature value for each group was determined
  3. c Clinical signs were scored as described by Jolie et al [24]. Appetite was scored as follows: 0, did eat; and 1, did not eat. The total score equaled the number of 12-h periods of not eating over the 36-h observation period. Lethargy was scored as follows: 0, normal; 1, slight inactivity; 2, moderate; and 3, severe. Dyspnea was scored as follows: 0, normal; 1, slight; 2, moderate; and 3, severe. The final scores were obtained from the average of all of the data within the observation time and are expressed as arithmetic means ± SD; *, significance at a P value of <0.05; **, significance at a P value of <0.01
  4. d The lung lesion score was determined as described by Hannan et al [25]