Differentiation of Salmonella Gallinarum biovar Gallinarum from Salmonella Gallinarum biovar Pullorum by PCR-RFLP of the fimH gene.

In our studies on FimH adhesins expressed by different Salmonella serovars, we cloned and sequenced the fimH genes from Salmonella enterica ssp. Enterica ser. Gallinarum biovar Gallinarum and S. enterica ssp. Enterica ser. Gallinarum biovar Pullorum. Comparison of the nucleotide sequences revealed the presence of a single-nucleotide polymorphism (SNP) at position 544 bp from the A of the start codon of the fimH open reading frame (ORF). Further analysis of the restriction enzyme sites in fimH gene showed that the SNP at this position is responsible for a sequence specifically recognized by SacI in S. Gallinarum biovar Gallinarum only, making it possible to differentiate both biovars with the use of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Digestion of PCR amplicons of the fimH gene from S. Gallinarum biovar Gallinarum strains with SacI gave two DNA fragments of 554 and 472 bp and only one fragment of 1026 bp for S. Gallinarum biovar Pullorum. This allows a clear differentiation between these two biovars.