Molecular typing of Mycobacterium bovis strains isolated in Italy from 2000 to 2006 and evaluation of variable-number tandem repeats for geographically optimized genotyping.

Spoligotyping and exact tandem repeat (ETR) analysis of Mycobacterium bovis and M. caprae isolated strains has been routinely carried out in Italy since 2000 to obtain a database of genetic profiles and support traditional epidemiological investigations. In this study, we characterized 1,503 M. bovis and 57 M. caprae isolates obtained from 2000 to 2006 in 747 cattle herds mainly located in northern Italy. We identified 81 spoligotypes and 113 ETR profiles, while the combination of spoligotyping/ETR analysis differentiated 228 genotypes, with genotypic diversity indices of 0.70 (spoligotyping), 0.94 (ETR-A to -E typing), and 0.97 (spoligotyping/ETR-A to -E typing), respectively. Despite the high degree of resolution obtained, the spoligotyping/ETR methods were not discriminative enough in the case of genotypes characterized by the combination of SB0120, the predominant spoligotype in Italy, with the most common ETR profiles. To obtain a more informative subset of typing loci, 24 mycobacterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR) markers were evaluated by analyzing a panel of 100 epidemiologically unrelated SB0120 isolates. The panel was differentiated into 89 profiles with an overall genotypic diversity of 0.987 that could be also achieved by using a minimal group of 13 loci: ETR-A, -B, and -E; MIRU 26 and 40; and VNTR 2163a, 2163b, 3155, 1612, 4052, 1895, 3232, and 3336. The allelic diversity index and the stability of single loci was evaluated to provide the most discriminative genotyping method for locally prevalent strains.

Characterization of Newcastle disease virus isolates obtained from Eurasian collared doves (Streptopelia decaocto) in Italy.

Eurasian collared doves (Streptopelia decaocto) are thought to originate from India and they have colonized, throughout the centuries, the Middle East and, more recently, Mediterranean countries such as Italy and Spain. In the present paper we report of the isolation and characterization of Newcastle disease viruses (NDV) obtained from Eurasian collared doves during 2000-2001, and compare them to isolates obtained from feral pigeons (Columba livia) during the same period. All isolates could be classified as avian paramyxovirus type 1 (APMV1) and belonged to the pigeon variant group (PPMV1), as their haemagglutinating activity was inhibited by mAb 161/617 which is specific for PPMV1. The intracerebral pathogenicity indices ranged from 0.68 to 1.38 and all isolates contained multiple basic amino acids at the deduced cleavage site of the fusion protein, which is a typical feature of virulent viruses. Phylogenetic analysis of the isolates indicate that 18/20 of these form a separate cluster from the isolates obtained from pigeons in the same period. These findings suggest that different lineages are circulating in feral pigeon populations, and that a separate lineage affects Eurasian collared doves.

Genetic analysis of canine parvovirus isolates (CPV-2) from dogs in Italy.

Genetic and antigenic properties of 62 field isolates of canine parvovirus (CPV-2) collected from 1994 to 2001 in Italy were investigated. Antigenic characterisation was conducted using specific monoclonal antibodies (Mabs). The VP1\VP2 gene was amplified by PCR and characterised with restriction endonucleases to detect the 297 and 265 variant. The VP2 gene of 16 isolates was sequenced and molecular genetic analysis was conducted. The antigenic type prevalent among our isolates is type 2a as well as the 297 variant, which is also prevalent in the rest of Europe. Only the 9.7% of the isolates have the T265P mutation. The VP2 sequences of CPV-2 isolates were very similar to recent Asian isolates. In the threefold spike of CPV-699 a coding change was detected in the 440 residue where threonine was substituted by alanine: the same mutation has been found in two Asian CPV-2 isolates from leopard cats [Virology 278 (2000) 13]. Phylogenetic analysis revealed that the Italian CPV-2 strains followed the same evolution as observed in other countries and they gave no indication of a separate lineage.

Analysis of canine parvovirus sequences from wolves and dogs isolated in Italy.

The VP2 genes of Italian canine parvovirus (CPV) type 2 strains isolated from dogs and wolves were sequenced and a three-dimensional model of the VP2 capsid protein was constructed. Two mutations were detected in the VP2 sequences of the Italian strains: one at residue 297 and one at residue 265. Variant 297 is the predominant CPV isolate in Europe, whereas variant 265 has never been detected before. The mutation at residue 265 causes a disruption in a G strand of the beta-barrel in the VP2 protein. Data on strains isolated from wolves demonstrated that the same strain of CPV can circulate among domestic and wild canids; therefore, this result leads us to exclude the possibility that a separate parvovirus pool exists in wild populations.