Process for preparation of improved mutant strain of Bordetella bronchiseptica useful for live attenuated vaccine for protection of B. bronchiseptica infection and live attenuated AR vaccine produced therefrom

Abstract

A process for the preparation of a mutant strain of B. bronchiseptica having chromosomal genetic markers carrying at least temperature-sensitive (grown at 42.degree. C.), nalidixic acid-resistant and heat-labile dermonecrotic toxin producing ability negative markers, suitable for the preparation of live attenuated AR vaccine, which comprises subjecting a strain of B. bronchiseptica to an induced mutation, isolating a mutant having the genetic markers of being at least temperature-sensitive (grown at 42.degree. C.), nalidixic acid-resistant and heat-labile dermonecrotic toxin negative, culturing the isolated strain of B. bronchiseptica on a Bordet-gengou agar plate containing nalidixic acid at 42.degree. C., thereafter picking up an organism morphologically resembling a phase-I organism, repeating the procedures of culturing and picking up, and converting the organisms to a heat-labile dermonecrotic toxin-producing ability negative phase-I organism having a complete capsular antigen.

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