Table 1 Strains and plasmids used in this study

 C48–1

Avian P. multocida C48–1. Capsulated and virulent

China Veterinary Culture Collection Center

 △aspA::kan

aspA mutant strain of Avian P. multocida C48–1

This work

 C△aspA::kan

Complemented strain of △aspA::kan

This work

 △aspA::kan (pAL99S)

aspA mutant strain harboring an empty vector

This work

 pBC-Tn903

Suicide vector, Cm^R, Kan^R

[39]

 pBC-aspA

Containing left and right arms of aspA, Cm^R

This work

 pBC-aspA-kan

Constructing aspA gene deletion mutants, Cm^R, Kan^R

This work

 pAL99S

P. multocida expression plasmid, derivative of pAL99, Spec^R

[40]

 pAL99S-aspA

Containing the intact aspA, Spec^R

This work

 pET-28a

Amplifing the kanamycin resistance cassette, Kan^R

Our Lab