New flagellin gene for Salmonella enterica serovar Typhi from the East Indonesian archipelago

Phase variation is a property unique of some Salmonella enterica serovar Typhi strains from Indonesia. Salmonella Typhi isolates from Indonesia have been described that in addition to the phase 1 Hd flagellin gene contain a second flagellin gene named z66. S. Typhi isolates from Indonesia with a mutant Hd gene named Hj have also been described. Here, we have identified another flagellin gene of S. Typhi, named Ind, showing a closest homology with the flagellin gene of Serratia marcescens. The Ind gene was detected in 21.8% of the S. Typhi isolates from the East Indonesian archipelago, all of which contained the Hd gene. The Hj gene was not detected. The z66 gene was present in 15.4% of the isolates. The presence of these "foreign" flagellin genes could be associated with an increased risk for developing severe disease.