STUDIES INTO AVIRULENT BORDETELLA-BRONCHI SEPTICA STRAINS FOR THEIR SUITABILITY AS LIVE VACCINES - STUDIES INTO PURINE AUXOTROPHIC B-BRONCHISEPTICA MUTANT STRAINS

Four adenine-auxotrophic B. bronchiseptica mutant strains (Ade(-)50, A de(-)51, Ade(-)28 and Ade(-)5026) were studied for their biological pr operties, marker and phase stability in animal models as well as for i nduction of specific antibodies. All of these strains but Ade(-)50 wer e found to be in the avirulent Phase III. Guinea pigs intranasally ino culated with the four strains usually eliminated the auxotrophic patho gens within 14 days without leaving behind any noticeable SLA antibody titre. Pathogen persistence up to 40 days was recorded from rabbits. Out of the four strains examined only Ade(-)28 and Ade(-)50 proved to be of marker and phase stability. In conventional piglets which had be en intranasally inoculated at birth, strain Ade(-)28 was recordable fr om the nasal mucosa up to the 33rd day from inoculation. A second Ade( -)28 colonisaion 66 days after inoculation did not lead to colonisatio n of the mutant strain. When colonisation by strain Ade(-)28 was accom plished on SPF piglets on their first day of age, the pathogen could b e reisolated also from the lungs up to the 28th day from inoculation. Moderately pronounced peribronchial inflammatory alterations were inte rpreted as activation of mucosa-associated lymphatic tissue.