title: Molecular attenuation of vaccinia virus: mutant generation and animal characterization.
abstract: These studies demonstrated that the inbred BALB/c mouse strain can be optimized for the assessment of vaccinia virus virulence, growth, and spread from the site of inoculation and immune protection from a lethal vaccinia virus challenge. The studies established that manipulation of the vaccinia virus genome generated mutants exhibiting a wide range of attenuated phenotypes. The nine NYCBH vaccinia virus mutants had intracranial 50% lethal doses that ranged from 2 to greater than 7 log10 units. The decreased neurovirulence was due to decreased replication in brain tissue. Three mutants had a decreased ability to disseminate to the lungs, brains, livers, and spleens of mice after intranasal infection. One mutant had a decreased transmission from mice infected by tail scarification to naive cage mates. Although the mutants, with one exception, grew to wild-type titers in cell culture, they showed a growth potential on the scarified skin of mice that was dramatically different from that of the wild-type virus. Consequently, all of the mutants had significantly compromised immunogenicities at low virus immunization doses compared with that of the wild-type virus. Conversely, at high immunization doses most mutants could induce an immune response similar to that of the wild-type virus. Three Wyeth vaccine strain mutants were also studied. Whereas the thymidine kinase, ribonucleotide reductase, and hemagglutinin mutants had a reduced virulence (50% lethal dose), only the thymidine kinase mutant retained its immunogenicity.
authors.affiliation: Applied bioTechnology, Inc., Cambridge, Massachusetts 02142.
authors.forename: M S
authors.initials: MS
authors.lastname: Lee
authors.forename: J M
authors.initials: JM
authors.lastname: Roos
authors.forename: L C
authors.initials: LC
authors.lastname: McGuigan
authors.forename: K A
authors.initials: KA
authors.lastname: Smith
authors.forename: N
authors.initials: N
authors.lastname: Cormier
authors.forename: L K
authors.initials: LK
authors.lastname: Cohen
authors.forename: B E
authors.initials: BE
authors.lastname: Roberts
authors.forename: L G
authors.initials: LG
authors.lastname: Payne
mesh_terms: D000281:Administration, Intranasal; D000818:Animals; D000914:Antibodies, Viral; D001921:Brain / Q000382:microbiology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D006388:Hemagglutinins / Q000235:genetics; D006790:Host-Parasite Interactions; D007110:Immunity, Active; D036341:Intercellular Signaling Peptides and Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D016296:Mutagenesis; D009928:Organ Specificity; D010455:Peptides / Q000235:genetics; D012264:Ribonucleotide Reductases / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics; D014615:Vaccinia / Q000235:genetics* / Q000276:immunology / Q000635:transmission; D014616:Vaccinia virus / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity*; D014774:Virulence
chemical_list: D000914:Antibodies, Viral; D006388:Hemagglutinins; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; C051087:vaccinia growth factor; D012264:Ribonucleotide Reductases; D013937:Thymidine Kinase