Virulence plasmid-borne spvB and spvC genes can replace the 90-kilobase plasmid in conferring virulence to Salmonella enterica serovar Typhimurium in subcutaneously inoculated mice.
In a mouse model of systemic infection, the spv genes carried on the Salmonella enterica serovar Typhimurium virulence plasmid increase the replication rate of salmonellae in host cells of the reticuloendothelial system, most likely within macrophages. A nonpolar deletion in the spvB gene greatly decreased virulence but could not be complemented by spvB alone. However, a low-copy-number plasmid expressing spvBC from a constitutive lacUV5 promoter did complement the spvB deletion. By examining a series of spv mutations and cloned spv sequences, we deduced that spvB and spvC could be sufficient to confer plasmid-mediated virulence to S. enterica serovar Typhimurium. The spvBC-bearing plasmid was capable of replacing all of the spv genes, as well as the entire virulence plasmid, of serovar Typhimurium for causing systemic infection in BALB/c mice after subcutaneous, but not oral, inoculation. A point mutation in the spvBC plasmid preventing translation but not transcription of spvC eliminated the ability of the plasmid to confer virulence. Therefore, it appears that both spvB and spvC encode the principal effector factors for Spv- and plasmid-mediated virulence of serovar Typhimurium.
Matsui
H
H
Laboratory of Infectious Diseases and Immunology, Center for Basic Research, The Kitasato Institute, Tokyo, Japan.
Bacot
C M
CM
Garlington
W A
WA
Doyle
T J
TJ
Roberts
S
S
Gulig
P A
PA
D036002:ADP Ribose Transferases / Q000235:genetics* / Q000502:physiology; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D018387:Codon, Initiator; D004269:DNA, Bacterial; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000502:physiology*; D007279:Injections, Subcutaneous; D051379:Mice; D008807:Mice, Inbred BALB C; D016296:Mutagenesis; D010957:Plasmids; D011995:Recombination, Genetic; D012486:Salmonella typhimurium / Q000235:genetics / Q000472:pathogenicity*; D014774:Virulence; D037521:Virulence Factors
D001426:Bacterial Proteins; D018387:Codon, Initiator; D004269:DNA, Bacterial; D037521:Virulence Factors; D036002:ADP Ribose Transferases; C415223:spvB protein, Salmonella enterica virulence plasmid