Circulation of infectious bronchitis virus strains from Italy 02 and QX genotypes in Slovenia between 2007 and 2009.

Fourteen infectious bronchitis viruses (IBVs) detected in broiler, broiler breeder, and layer flocks in Slovenia between 2007 and 2009 were molecularly analyzed by reverse transcription-PCR and direct sequencing of the S1 gene. Phylogenetic analyses based on partial S1 gene sequences revealed that seven strains were classified as the Italy 02 genotype, a genetic group of IBV that has not previously been detected in Slovenia. Another seven strains were classified as the QX genotype. The results of phylogenetic analyses and epidemiologic investigations revealed that the genetic classification correlates with the geographic origins of the IBV strains. Greater genetic variability (maximum nucleotide and amino acid divergences were 4.8% and 9.9%, respectively) was observed within the Slovenian strains from the Italy 02 genotype detected between 2007 and 2009 than within strains from the QX genotype isolated in 2008 and 2009 (1.2% and 1.3%, respectively). The Slovenian strains classified as the Italy 02 genotype form a separate genetic cluster. These strains shared five specific amino acid substitutions that became fixed during the period of surveillance. Strains from the QX genotype that shared one specific amino acid substitution also form a separate genetic cluster.