1,721,075 research outputs found
SPATIAL AND TEMPORAL DYNAMICS OF PESTIVIRUS, CRIMEAN-CONGO HEMORRHAGIC FEVER AND HEPATITIS E VIRUS: A PHYLOGENETIC APPROACH
Full text linkThe general aim of the PhD project was to apply phylogenetic analysis to viral sequences obtained in different geographic areas at different times, in order to reconstruct the most probable places of origin and pathways of dispersion of infections. Viral population growth and evolution leave a measurable imprint on the genome of viruses over the course of years, months or even days and occur simultaneously with geographic dispersal (Holmes, 2008; Pybus & Rambaut, 2009). This interaction characterizes a spatial phylodynamic process that can be recovered from genomic data using phylogeographic analyses (Faria et al., 2011). The research activity has been focused on Pestivirus genus, that includes pathogens of livestock (Bovine viral diarrhea virus - BDV) and wildlife (Border disease virus - BDV), and on zoonotic emerging diseases, involving in their epidemiological cycle both livestock and wildlife (Crimean-Congo hemorrhagic fever - CCHF, Hepatitis E virus- HEV).
Concerning BDV, since 2001 several outbreaks of disease have been reported in Pyrenean chamois in Spain, France and Andorra. These outbreaks have decimated several Pyrenean chamois populations, with mortalities ranging from 40% to 85%. The infection has become endemic in the Central and Eastern Pyrenees. The aim of this study was to clarify the origin and dispersion of the Pyrenean chamois BDV genetic variant by reconstructing the spatial and temporal dynamics of BDV 5’ UTR sequences of Pyrenean chamois, 10 novel sequences and 41 retrieved from public databases and Sheep BDV sequences (n=44) from Spain and France were also retrieved. The phylogenetic analysis was performed using a Bayesian Markov chain Monte Carlo (MCMC) method implemented in the BEAST v.1.74 package. The chamois clade originated from sheep BDV genotype 4, generating a founder effect due to intra-species spread and spatial dispersion. The time of the most recent common ancestor estimates for the chamois clade dated back to a time span between 1974 and 1996, with a mean estimation falling in 1988. The pathway of dispersion of isolates suggests a complex exchange between neighboring Pyrenean chamois populations, still going on such as Western direction.
Genetic typing of bovine viral diarrhea virus (BVDV) has distinguished BVDV-1 and BVDV-2 species and an emerging putative third species (HoBi-like virus), recently detected in southern Italy, signaling the occurrence of natural infection in Europe. Recognizing the need to update the data on BVDV genetic variability in Italy for mounting local and European alerts, a wide collection of 5’ UTR sequences (n = 371) was selected to identify the frequency of genotypes and subtypes at the herd level. BVDV-1 had the highest frequency, followed by sporadic BVDV-2. No novel HoBi-like viruses were identified. Four distribution patterns of BVDV-1 subtypes were observed: highly prevalent subtypes with a wide temporal-spatial distribution (1b and 1e), low prevalent subtypes with a widespread geographic distribution (1a, 1d, 1g, 1h, and 1k) or a restricted geographic distribution (1f), and sporadic subtypes detected only in single herds (1c, 1j, and 1l). BVDV-1c, k, and l are reported for the first time in Italy. Italy is one of the countries with the highest genetic diversity of BVDV worldwide. Northern Italy ranked first for BVDV introduction, prevalence, and dispersion. Nevertheless, the presence of sporadic variants in other restricted areas suggests the risk of different routes of BVDV introduction.
CCHF is a zoonosis mainly transmitted by ticks that causes sporadic cases and severe hemorrhagic fever of acute human disease with a mortality rate of 5-60% and it has recently emerged in the Balkans and eastern Mediterranean areas. In order to reconstruct the origin and pathway of the worldwide dispersion of the virus at global and regional (eastern European) level, we investigated the phylogeography of the infection by analysing 121 publicly available CCHFV S gene sequences including two recently characterised Albanian isolates. The spatial and temporal phylogeny was reconstructed using a Bayesian Markov chain Monte Carlo approach.
CCHFV phylogeographic reconstruction suggests that the disease originated about one thousand years ago from a common ancestor probably located in Africa. The virus then spread to Asia in the XV century and entered Europe on at least two occasions: the first in the early 1800s and the second in the early 1900s. The most probable location for the origin of the European clade was Russia, but Turkey played a central role in spreading the virus throughout Europe. Our data suggest that the movement of wild and domestic ungulates from endemic areas probably represent the main cause of virus dissemination in Eastern Europe.
Hepatitis E virus is classified into four genotypes that have different geographical and host distributions. The main cause of sporadic autochthonous type E acute hepatitis in developed countries is genotype 3, which has a worldwide distribution and widely infects pigs. The aim of this study was to make hypotheses concerning the origin and global dispersion routes of this genotype by reconstructing the spatial and temporal dynamics of 208 HEV genotype 3 ORF-2 sequences (retrieved from public databases) isolated in different geographical areas. The evolutionary rates, time of the most recent common ancestors (tMRCAs), epidemic growth and phylogeography of HEV-3 were co-estimated using a MCMC Bayesian method. On the basis of time-scaled phylogeographical reconstruction, we hypothesise that HEV-3, after originating in the early 1800s in Europe, reached Asia in the first decades of 1900, and then moved to America probably in the 1970s-1980s. Analysis of the skyline plot showed a sharp increase of the number of infections between the 1980s and 2005, suggesting the intervention of new and highly efficient routes of transmission, possibly related to changes in the pig industry
Controllo delle Infezioni da BVDV, realizzazione ed applicazione di un piano a livello provinciale
No full textBVD control program in Lecco and Como provinces (Italy) : herd risk categories to modulate interventions
No full textGenotypic characteristics of Bovine viral diarrhea virus 2 strains isolated in northern Italy
No full textTwo strains of Bovine viral diarrhea virus 2 (BVDV-2) were isolated from calves in northern Italy. Variations in the 5'-untranslated region (UTR) of the genome were studied by primary structure alignment and neighbor-joining method based phylogenetic tree analyses and by palindromic nucleotide substitutions at the three variable loci in the 5'-UTR. Genetic analysis indicated their appurtenance to genovar BVDV-2a. Nucleotide sequence at the 5'-UTR of strain BS-95-II, one of the Italian isolates from healthy calves, showed 98% homology to that of the Japanese isolate OY89, a cytopathic strain derived from cattle with mucosal disease
Monticazione ovi-caprina nelle Alpi Orobie e rischi sanitari per il patrimonio faunistico
No full textSheep and goats alpine summer grazing and sanitary risk for wildlife- A three-years survey was carried out in sheep and goats during summer pasturing in the Orobie Alps (North Italy) within an Interreg III A project aimed to recovering tetraonids habitat. Selected pathogens of zoonotic and wildlife importance were tested. Antibodies against to Tick-Borne Encephalitis Virus (TBEV) and Mycobacterium avium subsp. paratuberculosis (MAP) were not detected. Two
among 266 goats and one among 182 sheep resulted seropositive for Q-fever. A prevalence of 4% and 10,9% for Pestivirus was detected respectively in goats and sheep, with only adult animals affected and no seroconvertion through three years. Antibodies against Bovine respiratory
syncitial virus (BRSV) were detected in young and adult animals with seroprevalences of 19,6 in goats and 79,1% in sheep and no seroconvertion through three years. The role of the above pathogens are discussed in an alpine sustainable land use perspective
Bovine respiratory syncytial virus seroprevalence and risk factors in endemic dairy cattle herds
No full textThe herd seroprevalence of bovine respiratory syncytial virus (BRSV) was studied in 59 dairy cattle herds using serology on random selected animals stratified by two age classes (heifers, cows). Risk factors for primary infections in heifers were investigated using a questionnaire on management conditions and data on bovine viral diarrhoea (BVD) status. At least one seropositive cow was present in all the herds. In 25% of the herds all individual were seropositive and 22% of herds had all heifers seronegative. Analysis of the influence of risk factors retained summer pasture and BVD status. In particular, absence of summer pasture and the BVD positive status of heifers were associated with an increased risk of BRSV infection in heifers group
In vitro replication activity of Bovine Viral Diarrhea Virus in an epithelial cell line and in bovine peripheral blood mononuclear cells
No full textThe present study focused on the in vitro infection of Madin Darby Bovine Kidney (MDBK) cells and bovine peripheral blood mononuclear cells (PBMCs) from naïve animals with non-cytopathic (ncp, BVDV-1b NY-1) and cytopathic (cp, BVDV-1a NADL) strains. Infections with 0.1 and 1 multiplicity of infections (MOI) and incubation times of 18 and 36 hr were compared. Twelve BVDV naïve heifers were enrolled to collect PBMCs. The viral loads in MDBK cells and in PBMCs after in vitro infections were measured by Real-Time Polymerase Chain Reaction (PCR) assays. The highest viral loads were measured at 1 MOI and 36 hr post-infection in both the cell systems and the lowest at 0.1 MOI and 18 hr with the exception of the cp strain NADL in PBMCs, where the highest viral load was observed at 0.1 MOI and 36 hr. Viral load mean values were higher for the cp strain than the ncp one irrespectively of the extent of the infection period and MOI. The models of infection studied uncovered different replication activities respectively to the biotype of virus, the cell substrate and the lasting of infection. Replication tends to be higher in PBMCs, particularly at low MOIs and for the ncp strain
Real-time PCR per la quantificazione del virus della diarrea virale bovina in PBMC di bovino infettate in vitro
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