Primers with restriction enzyme used for the construction of the E. ictaluri mutants.

aRE: restriction enzyme sequence added to the 5′ end of the primer sequence.bBold letters at the 5′ end of the primer sequence represent RE site. AA nucleotides were added to the end of each primer containing a RE site to increase the efficiency of enzyme cut. Underlined bases in internal primer (rflp) indicate reverse complemented internal primer (lfrp) sequence.