After amplification and purification, PCR products from the iap gene of different Listeria monocytogenes serovars were subjected to sequencing to define the intraspecific differences within the gene encoding for the associated invasive protein. Nucleotide sequence analysis of the tested serovars demonstrated a division into serovar-groups obtained by using restriction enzyme analysis and single strand conformation polymorphism. Three groups were identified: the first included serovars 1/2a and 3a, the second serovars 1/2b, 3b and 4b, and the third serovar 1/2c.
