title: Temperature-sensitive mutants of Actinobacillus pleuropneumoniae induce protection in mice.
abstract: Temperature-sensitive mutants of Actinobacillus pleuropneumoniae 4074, serotype 1, were isolated after treatment with nitrosoguanidine and enrichment with penicillin and D-cycloserine. Of the four temperature-sensitive mutants evaluated in mice, one (A-1) had a tight phenotype (i.e., it ceased replication immediately after transfer to the nonpermissive temperature [37 degrees C]) and three (1-2, 4-1, and 12-1) were coasters that continued replication for up to three generations after transfer to 37 degrees C. The reversion frequencies ranged from 10(-6) to 10(-9), and cutoff temperatures ranged from 33 to 35 degrees C. No major changes were detected in the biochemical profiles; agglutination reactions; electrophoretic profiles of the lipopolysaccharides, outer membrane proteins, and hemolysin proteins; hemolytic titers; or CAMP factor reactions of the mutants and the wild-type bacteria. Groups of 3- to 5-week-old, female ICR mice were immunized intranasally with three doses of 3.5 x 10(6) CFU of the mutants over 3 weeks and subsequently challenged intranasally with 5 50% lethal doses of the parental wild-type. Protection was induced by both the tight and the coaster mutants, with the 4-1 and 12-1 coasters eliciting greater protection (67 and 82%, respectively) than that induced by the A-1 tight mutant (57%). Intranasal immunization with both phenotypes induced serum antibody responses against the surface antigens and the hemolysin protein.
authors.affiliation: Department of Microbiology, Miami University, Oxford, Ohio 45056, USA.
authors.forename: W
authors.initials: W
authors.lastname: Byrd
authors.forename: A M
authors.initials: AM
authors.lastname: Hooke
mesh_terms: D016977:Actinobacillus pleuropneumoniae / Q000276:immunology* / Q000378:metabolism; D000818:Animals; D001428:Bacterial Vaccines / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007114:Immunization; D051379:Mice; D008813:Mice, Inbred ICR; D009154:Mutation; D013696:Temperature
chemical_list: D001428:Bacterial Vaccines