First molecular characterization of canine parvovirus strains in Sardinia, Italy.

Canine parvovirus type 2 (CPV-2) is responsible of acute hemorrhagic gastroenteritis in young dogs. CPV-2 emerged in 1978 in the USA, but new antigenic types, CPV-2a, 2b and 2c, have completely replaced the original type. In this study, we analyzed 81 animals collected in Sardinia, Italy. The VP2 sequence analysis of 27 positive samples showed that all antigenic CPV-2 types are circulating. CPV-2b seems to be the most widespread variant, followed by CPV-2a. Furthermore, 12 CPV-2b strains displayed further amino acid substitutions and formed a separate cluster in a phylogenetic tree, indicating regional genetic variation.

Improved Strategy for Molecular Characterization of African Swine Fever Viruses from Sardinia, Based on Analysis of p30, CD2V and I73R/I329L Variable Regions.

African swine fever virus (ASFV) is the aetiological agent of a highly lethal haemorrhagic disease affecting pigs that inflicts significant economic damage on the swine industry. ASF is present in many African countries, in several eastern and central European countries and in Sardinia (Italy). Sequence analyses of variable genomic regions have been extensively used for molecular epidemiological studies of ASFV isolates. Previous sequencing data of genes that codify for viral protein p54, p72 and the central variable region (CVR) within the B602L gene revealed that Sardinian isolates show a very low level of variability. To achieve a finer level of discrimination among such closely related viruses, in this study, we have chosen three different genome regions to investigate the within-genotype relationships and to provide a more accurate assessment of the origin of outbreaks. The analysis of p30 and I73R/I329L sequences obtained from ASFV collected in Sardinia over a 13-years period confirms a remarkable genetic stability in these regions. The sequence comparison of the protein encoded by the EP402R gene (CD2v), carried out on various strains from 1978 to 2014, revealed a temporal subdivision of Sardinian viruses into two subgroups: one group includes the historical isolates from 1978 to 1990, and the second one is comprised of the viruses collected from 1990 until 2014. These data, together with those obtained from CVR within the B602L gene analysis, demonstrated that the viruses circulating in Sardinia belong to p72 genotype I, but have undergone genetic variations in two different regions of the genome since 1990. We proposed the cytoplasmic region of CD2v protein as a new genetic marker that could be use to analyse ASFVs from different locations to track virus spread. Our study reaffirms the need to analyse other genome regions in order to improve the molecular characterization of ASFV.

Temporal and spatial patterns of African swine fever in Sardinia.

Temporal patterns and spatial distribution of African swine fever (ASF) were studied through the analysis of routinely collected data in the ASF-endemic area of the Province of Nuoro, Sardinia. During 1993-1996, ASF outbreaks were reported from 45 out of the 82 municipalities of the study area. Overall farm-level incidence rate (IR) was 1.3 outbreaks per 100 farms-year. ASF peaked in 1995 (IR = 1.8) and declined in 1996 (IR = 0.82). Significant (P < 0.05) spring peaks of ASF outbreaks and affected municipalities were detected using statistical methods for circular distributions. Spatial clustering of ASF-affected municipalities, as evaluated by join-count statistics, was significant in 1993 (Zjc = -3.0, P < 0.01) and 1994 (Zjc = -3.2, P < 0.01) but not in 1995 (Zjc = -0.6, P = 0.55) and 1996 (Zjc = -1.2, P = 0.23). Extensive pig farming and ASF were spatially co-distributed (kappa = 0.51, 95% CI = 0.33-0.70).

Epidemiology of classical swine fever in Sardinia: a serological survey of wild boar and comparison with African swine fever.

A serological survey was carried out to establish the distribution of classical swine fever among wild boar in Sardinia, where that disease and African swine fever have been endemic in free-ranging domestic pigs and wild boar living in the mountainous areas of the province of Nuoro for several years. Blood samples were collected from 4752 wild boar shot during the period December 1988 to January 1992. An overall prevalence of 11 per cent was observed and the almost constant rate of about 9.8 per cent detected in the past three years indicates that the infection is well established. Wild boar seropositive to classical swine fever were found not only in the areas of the province of Nuoro where they share their habitat with free-ranging domestic pigs but also in other areas of the island where contacts between wild and domestic pigs are unlikely to occur. Therefore, transmission from wild boar to wild boar seems to play an important role in the spread and persistence of classical swine fever virus. In contrast, African swine fever virus is probably unable to persist in the wild boar population in the absence of the risk factor represented by their cohabitation with domestic free-ranging pigs infected with African swine fever.