Open AccessConversion of Salmonella enteritidis phage type 4 to phage type 7 involves loss of lipopolysaccharide with concomitant loss of virulence
Author(s) -
Chart Henrik,
Row Bernard,
Threlfall E.John,
Ward Linda R.
Publication year - 1989
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1989.tb03415.x
Subject(s) - salmonella enteritidis , virulence , microbiology and biotechnology , plasmid , biology , serotype , phage typing , salmonella , virology , enterobacteriaceae , escherichia coli , bacteria , dna , genetics , gene
Abstract Three strains of Salmonella enteritidis phage type 4 (PT4) and 33 strains of S. enteritidis phage type 7 (PT7) were examined for the ability to produce lipopolysaccharide (LPS) and for plasmid carriage. The LPS of all strains of PT4 gave a typical ‘ladder’ pattern by SDS‐PAGE and silver staining, and on serotyping these strains were shown to express the O‐antigens 9, 12. In contrast, strains of PT7 did not express long‐chain LPS and were autoagglutinable. All strains of PT4 and the majority of strains of PT7 carried a single plasmid of 38 MDa, indistinguishable when characterised by restriction endonuclease fragmentation analysis. Epidemiological and experimental observations have demonstrated a relationship between strains of S. enteritidis PT4 and PT7, and our results, using mice, show that the loss of ability of strains of PT4 to sythesise LPS is responsible for the conversion of highly virulent strains of PT4 to avirulent strains of PT7. From epidemiological data of human infections in England and Wales, we suggest that strains of S. enteritidis PT7 may be less virulent for humans.