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1.
Molecular epidemiology of classical swine fever in Italy   总被引：5，自引：0，他引：5  
To gain an insight into the molecular epidemiology of classical swine fever (CSF) in Italy, virus isolates originating from outbreaks that occurred between 1985 and 2000 in wild boar or in domestic pigs in mainland Italy and in Sardinia were analysed by genetic typing. For this, a fragment (190 nucleotides) of the E2 glycoprotein gene was sequenced and phylogenetic analyses were performed, including older Italian isolates and isolates from recent outbreaks in Europe for comparison. The results show that in mainland Italy, several independent epidemiological events occurred in the last decade. In the north of the country, viruses of genotype 2.2 have persisted in wild boar, causing sporadic outbreaks in domestic pigs. In contrast, viruses of subgroups 2.1 and 2.3 appeared only intermittently in different regions of the mainland. In 1997, classical swine fever virus (CSFV) isolates belonging to the subgroup 2.1 and genetically and epidemiologically related to the Dutch isolate in Venhorst, affected domestic pigs exclusively. The isolates of subgroup 2.3, derived from wild boar as well as from domestic pigs were closely related to isolates from Germany and Poland. In Sardinia, CSF is an endemic in wild boar and affects domestic pigs also. Genetic typing showed that viruses of subgroups 1.1 and 2.3 have been present, the last ones being unrelated to the mainland viruses of the same subgroup. Due to the large quantities of pig and wild boar meat imported in some parts of Italy, it cannot be established if these viruses were always present in either the mainland or Sardinia, or if they represent recent introductions.  相似文献   

2.
During the last decade several outbreaks of classical swine fever (CSF) occurred in Germany in domestic pigs and in wild boar, respectively. Two major epidemics which also affected other EU Member States were recorded. To support epidemiological investigations genetic typing was applied and virus isolates originating from different outbreaks in Germany were assigned to groups and virus types. Two genomic regions were selected for the phylogenetic analysis, namely 150 nucleotides from the 5' non-translated region (5'-NTR) and 190 nucleotides from the E2 glycoprotein gene. All German CSF virus isolates of the nineties (Group 2) were distinct from former reference strains (Group 1). Within Group 2 both genomic regions allowed to distinguish three subgroups, namely 2.1, 2.2 and 2.3. Within subgroup 2.3 five virus types could be discriminated using the 5'-NTR sequences. These are 2.3*Uelzen and 2.3*Spreda, mainly with isolates from Lower Saxony, as well as 2.3*Rostock, 2.3*Güstrow and 2.3*Spante, mainly with isolates from Eastern Germany. Analysis of the E2 gene fragment allowed a better discrimination between single isolates, but only two virus types could be defined: 2.3*MV/BB, comprising the isolates from Eastern Germany, and 2.3*NI, with the isolates from Lower Saxony. Genetic typing allowed to discriminate between isolates involved in different CSF epidemics, and was useful for tracing the origin and spread of CSF viruses. Due to the close relationship between German CSF virus isolates, epidemiological data are a prerequisite for the interpretation of the results obtained by genetic typing. In addition, at least both genomic regions suggested here should be analysed to determine the identity of a new isolate.  相似文献   

3.
Background: Limited studies are available on molecular epidemiology of classical swine fever virus (CSFV) in India and are restricted to domestic pigs. These studies show the presence of 1.1. genotype.

Hypothesis/objectives: The aim of the present study was to subgenotype four CSFV isolates, two each from the outbreaks of CSF in wild (Sus scrofa) and domestic pigs of Mizoram state, India, in 2011.

Animals and methods: CSFV isolates were subjected to nucleotide sequencing in E2 and NS5B genomic regions. Phylogenetic analysis of the isolates in both genomic regions was carried out with 39 Indian isolates (4 isolates from the present study of Mizoram state and 35 isolates from the other states of India) and 57 reference sequences retrieved from the GenBank database. Two of the 39 isolates from India were collected from wild boar and were subgenotyped as 2.1. Out of 37 isolates from domestic pigs, only two were subgenotyped as 2.1.

Results: The analysis revealed the emergence of 2.1. subgenotype of CSFV in both wild and domestic pigs in India.

Conclusions and clinical importance: The isolates from domestic pigs of Mizoram state (CSF/MZ/KOL/73 and CSF/MZ/AIZ/115) were grouped in genotype 1 and subgenotype 1.1., thus confirming that the source of CSF outbreaks in domesticated pigs in Mizoram was not from wild pigs. The current study forms an essential step for better understanding of the epidemiology of 2.1 subgroup as well as the movement and spread of the disease in India.  相似文献   

4.
A big epidemic of classical swine fever (CSF) occurred in the European Community in 1997. The first case was reported at the beginning of January 1997 from Germany. The disease presumably spread to the Netherlands, and from there to Italy, Spain and eventually to Belgium. About 30 isolates from these outbreaks were analysed by comparison of the nucleotide sequence data generated from fragments of both the E2 glycoprotein gene (190 nucleotides) and from the 5'-nontranslated region (5'-NTR; 150 nucleotides). By combining epidemiological data with genetic typing, it was found that the outbreaks were related and caused by a virus belonging to the genetic subgroup 2.1. As this type of virus had been reported infrequently in Europe and not at all since 1993, we postulate that it was newly introduced into the European Union (EU).  相似文献   

5.
In May 1998, wild boars with classical swine fever (CSF) symptoms were detected in the southern part (Canton Ticino) of Switzerland. CSF virus was isolated from the submitted samples and RT-PCR followed by direct nucleotide sequencing of the 5' non-translated region showed that this virus was identical to the isolate previously recognized in wild boars from the area of Varese (Italy). In most animals, antibodies to CSF virus were detected as well. An immediate measurement was taken by limiting the movement of pigs and identifying both risk and surveillance zones. In order not to disturb potentially infected wild boars within their habitat a complete hunting prohibition for 2 months was enforced. The different possibilities of the control of CSF outbreaks in wild boars are discussed.  相似文献   

6.
Classical swine fever (CSF) is a highly contagious systemic hemorrhagic viral disease of pigs. Wild boar plays a crucial role in the epidemiology of CSF. Between 2010 and 2014, samples were collected nationwide from 6,654 wild boars hunted in South Korea. Anti-CSF antibodies were identified in 0.59% (39 of 6,654) of the wild boar samples using a virus neutralization test and were primarily detected in wild boars living close to the demilitarized zone and the area of the Taebaek Mountains surroundings. The CSF virus (subgroup 2.1b) was isolated from two wild boars captured in a nearby border area. The criteria used to define high-risk areas for targeted CSF surveillance in South Korea should be further expanded to include other regions nationwide.  相似文献   

7.
A classical swine fever virus (CSFV) field isolate originating from wild boar was investigated on its virulence in domestic pigs and wild boar. Three weaner pigs and two wild boars (yearlings) were intranasally inoculated with the isolate "Spante" and tested for clinical, virological, hematological and serological findings until day 31 after infection (p. i.). One day p. i. the piglets were put in contact to three sentinel pigs. During a period of 31 d neither the domestic pigs nor the wild boars showed clinical signs specific for CSF. Two infected weaner pigs became transiently viraemic, transmitted CSFV in nasal secretions, showed a slight leukopenia and reacted serologically positive. The contact infection resulted in a viraemia in two sentinel piglets on day 30. Only one contact animal developed antibodies. None of the wild boars became viraemic, excreted CSFV in nasal secretions or developed antibodies. The CSFV isolate "Spante" represents a low virulent virus. Referring to a significant higher percentage of virologically positive tissue samples after nested PCR compared with the virus isolation, persistence of CSFV is discussed.  相似文献   

8.
Hepatitis E is considered an emerging human viral disease in industrialized countries. Studies from Switzerland report a human seroprevalence of hepatitis E virus (HEV) of 2.6–21%, a range lower than in adjacent European countries. The aim of this study was to determine whether HEV seroprevalence in domestic pigs and wild boars is also lower in Switzerland and whether it is increasing and thus indicating that this zoonotic viral infection is emerging. Serum samples collected from 2,001 pigs in 2006 and 2011 and from 303 wild boars from 2008 to 2012 were analysed by ELISA for the presence of HEV‐specific antibodies. Overall HEV seroprevalence was 58.1% in domestic pigs and 12.5% in wild boars. Prevalence in domestic pigs was significantly higher in 2006 than in 2011. In conclusion, HEV seroprevalence in domestic pigs and wild boars in Switzerland is comparable with the seroprevalence in other countries and not increasing. Therefore, prevalence of HEV in humans must be related to other factors than prevalence in pigs or wild boars.  相似文献   

9.
The virulence of two isolates of the classical swine fever virus (CSFV) was studied in experimentally infected wild boars of different ages. The isolates, originating from wild boars shot in Mecklenburg-Western Pomerania (isolate '1829-NVP') and in Rhineland-Palatinate (isolate '11722-WIL'), belong to the genetic subgroup 2.3 Rostock. Clinical picture, transient viraemia, virus excretion and gross lesions at necropsy as well as a failure of virus detection at the end of the experiment revealed that this virus subtype was only moderately virulent. Whereas one subadult wild boar and both 7-week-old wild boar piglets infected intranasally became sick and died, only one of three 8-week-old animals which survived after contact infection remained CSFV positive until the end of the experiment [34 days post infection (dpi)], although neutralizing antibodies were present. This underlines the role of young boars in CSF epidemics. The isolate '11722-WIL' was shed by an infected adult wild boar and was transmitted to susceptible piglets. Interestingly, all animals which became sick and died also were found to be infected with a secondary pathogen. Therefore, we assume that after infection with moderately virulent CSFV simultaneous infections with other pathogens may be important for the clinical course and the outcome of the disease as well as for a spread of the virus in field.  相似文献   

10.
OBJECTIVE: To determine susceptibility of European wild boars (Sus scrofa) to infection with pseudorabies virus (PrV) and to characterize the virulence of a wildboar PrV isolate for wild and domestic pigs. ANIMALS: 18 wild boars and 16 domestic pigs. PROCEDURE: Three groups of 4 wild boars were inoculated with PrV Bartha, Kaplan, and a wild-boar isolate (BFW1) and housed with uninfected pigs. Two groups of domestic pigs (4 and 8 pigs/group, respectively) were inoculated with various doses of BFW1. Animals were observed daily for clinical signs, and samples were tested for PrV excretion and homologous antibodies. After reactivation of latent infection by induced immunosuppression, PrV was detected in tissues of necropsied animals, using cell culture and a polymerase chain reaction (PCR). RESULTS: Clinical signs depended on virulence of the PrV strain and dose of inoculum. Only infection with PrV Kaplan resulted in severe disease and death. Virus was isolated from nasal and genital swab specimens. Antibodies were first detected on day 7 after inoculation; a specific humoral immune response was delayed in BFW1-infected animals. Virus was isolated from various tissues of Kaplan-infected wild boars, whereas mainly viral DNA was detected in a few tissues of Bartha- and BFW1-infected animals, using PCR after immunosuppression. CONCLUSIONS AND CLINICAL RELEVANCE: European wild boars are susceptible to transmission of PrV infection from domestic pigs and vice-versa. The PrV isolate BFW1 is of low virulence and seems to be adapted to the wild boar population from which it was isolated.  相似文献   

11.
The virulence genes and plasmid profiles of 23 Rhodococcus equi isolates from 258 lymph nodes from domestic pigs (129 nodes with lesions and 129 without lesions) and 120 lymph nodes from slaughtered wild boars (60 nodes with lesions and 60 without) were characterized. R. equi was obtained from 19 lymph nodes of domestic pigs, 17 with, and two without lesions, and from four lymph nodes with lesions, from wild boars. The 23 isolates were tested for the presence of vapA and vapB genes, responsible for the 15–17 and 20 kDa virulence-associated proteins, respectively, by PCR in order to characterize as virulent (VapA), intermediately virulent (VapB) and avirulent. Plasmid DNAs were isolated and analyzed by digestion with restriction endonucleases to estimate size and compare their polymorphisms. Of the 19 domestic pigs strains, seven (36.8%) were avirulent and 12 (63.2%) were intermediately virulent, with the intermediately virulent isolates being plasmid types 8 (8 isolates), 10 (2 isolates), 1 (1 isolate) and 29 (1 isolate). The plasmid type of four strains isolated from wild boars was also intermediately virulent type 8. None of the domestic pigs and wild boar isolates showed the vapA gene. These findings demonstrate a high occurrence of plasmid type 8 in isolates from pigs and wild boars, and the similarity of plasmid types in the domestic pigs, wild boars and human isolates in Brazil.  相似文献   

12.
Classical swine fever (CSF) is a severe multi-systemic disease that can affect both domestic pigs and wild boar. Past outbreaks in European wild boar involved high-virulent CSF virus (CSFV) strains and were mostly self-limiting. In these cases, morbidity and mortality rates were high in the affected regions. In contrast, endemic infections have been observed in several European wild boar populations in recent decades. Morbidity and mortality rates were much lower despite the fact that outbreaks were still detected via diseased or fallen animals. The virus strains involved were mostly classified as genotype 2.3 strains of moderate virulence causing age-dependent disease outcomes. The mechanisms leading to the establishment and perpetuation of endemicity are still not fully understood, but the factor "moderate virulence" seems to be of considerable importance. In this study, we aim to clarify whether the perception of declined 'CSF severity' could hypothetically reflect the adaptation of an initially high-virulent virus or whether this might be better explained as a misinterpretation of observations. A mechanistic eco-epidemiological model was employed to follow up a highly virulent strain of CSFV introduced into large connected wild boar populations. In the model, the virulence of the CSF virus is represented by case mortality and life expectancy after lethal infection. Allowing for small stochastic variation, these two characteristics of the virus are passed on with every new simulated infection that occurs. Model analysis revealed a decrease from high to moderate case mortality within a few years of simulated perpetuation of the virus. The resulting mortality corresponded to the level where the population average of the infectious period and the basic reproduction number of the disease were maximal. This shift in virulence was sufficient to prolong virus circulation considerably beyond the epidemic phase of the simulated outbreaks. Alternative mechanistic explanations for the decrease in disease severity in a CSF-affected wild boar population were evaluated in the light of the simulation experiments and the available epidemiological or virological evidence. In conclusion, the current virus isolates of subgroup 2.3 might be the ideally adapted variants of the CSF virus for long-term perpetuation in wildlife and indeed may have evolved (once) during past outbreaks in large populations. A repeated perception of a declining severity of disease pattern during the course of a CSF outbreak, however, favours the explanation based on monitoring and detection biases rather than repeated observation of selection against highly virulent virus during the time of virus perpetuation.  相似文献   

13.
Although classical swine fever (CSF) has been well known for decades and epidemics still occur, clinical diagnosis continues to cause problems for veterinary practitioners. This is due to the extensive differential diagnosis, further complicated by the emergence of new diseases such as porcine reproductive and respiratory syndrome (PRRS) and porcine dermatitis and nephropathy syndrome (PDNS). In addition, acute, chronic and prenatal courses of CSF have to be distinguished. As a cause of considerable economical losses within the EU, control of CSF requires knowledge of the primary outbreaks and spread of the disease. Genetic typing of CSF virus isolates has proved to be a potent method of supporting epidemiological investigations. Phylogenetic analysis of CSF virus strains and isolates originating from different continents has allowed three genetic groups and several subgroups within these groups to be distinguished. Whereas isolates belonging to group 3 seem to occur solely in Asia, all CSF virus isolates of the 1990s isolated in the EU belonged to one of the subgroups within group 2 (2.1, 2.2, or 2.3) and were clearly distinct from former CSF reference viruses, which belong to group 1. Within the EU, different strategies are followed for the eradication of CSF in domestic pigs and in wild boar. While a strict non-vaccination policy is followed for domestic pigs, eradication of the disease in wild boar is more complex, and oral immunisation together with special hunting strategies have been applied. Recently, marker vaccines with a companion discriminatory test designed to allow differentiation between vaccinated animals and animals having recovered from field virus infection have been developed. Preliminary studies indicated that the discriminatory tests had a reduced sensitivity and specificity. Further improvements are therefore necessary before marker vaccines can be considered for emergency use in EU Member States. Prevention of CSF remains the main objective within the EU.  相似文献   

14.
In Germany, eleven outbreaks of CSF in domestic pig holdings were reported in 2002. They occurred exclusively in regions where CSF virus circulated in the wild boar population. In ten cases the phylogenetic analysis revealed that the isolates from domestic pigs and wild boar had identical sequences in the 5' non-translated region (5'NTR). However, in one case a subtype was isolated which was slightly different from the virus subtype found in the wild boar population of that region. This case is decribed in detail. The epidemiological significance of different diagnostic methods is discussed, in particular the genetic typing of CSF virus isolates.  相似文献   

15.
Classical swine fever virus (CSFV) is an economically important pathogen of domestic pigs and wild boar. Due to the highly variable clinical picture of CSF, laboratory methods are essential for an unambiguous diagnosis. Virus isolation using cell culture is still considered the gold standard. It is based on the incubation of permissive cells with organ or leukocyte preparations followed by antigen detection. In the "EU Diagnostic Manual for CSF Diagnosis", the permanent cell line PK(15) (porcine kidney) is recommended. In the European Reference Laboratory (EURL) a clone of this cell line, PK(15)A, and the STE (swine testicular epitheloid) cell line are in use for propagation of CSFV. The aim of this work was to assess the relative ability of eleven permanent cell lines derived from various organs of wild boar and domestic pig, respectively, to support the replication of different strains and isolates in comparison to these cell lines. An avirulent and a highly virulent laboratory CSFV strain, and several recent field isolates from domestic pigs and wild boars were used. Titers were determined after one, two and three virus passages, and after 48 and 120 h of incubation. Of the eleven cell lines analyzed, two were found that replicated all the tested CSFV strains and field isolates. Those may be useful for improving diagnosis of CSFV and for preparing low-passaged virus stocks of new isolates.  相似文献   

16.
Classical swine fever (CSF), a highly contagious viral disease of pigs, is endemic in India. As there is no information concerning the accurate genetic typing of classical swine fever virus (CSFV) isolates in India, 16 CSF viruses isolated during 2005-2007 from domestic pigs in different districts of Assam were typed in 5′ UTR (150 nucleotides). To confirm the genetic typing results and to study the genetic variability, selected viruses were also analyzed in E2 (190 nt) and NS5B gene (409 nt) regions. Phylogenetic analysis revealed that all the 16 CSFV isolates analyzed belonged to group 1 and subgroup 1.1 in contrast to the situation in other Asian countries. Additionally, analysis in E2 and NS5B region placed the Indian isolates in a clearly separated clade within subgroup 1.1. The results suggest that subgroup 1.1 CSF viruses are currently circulating in India, which is important for epidemiology and control of CSF.  相似文献   

17.
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18.
Sylvatic rabies has been present in Croatia for more than three decades, with the red fox (Vulpes vulpes) as the main reservoir. The present epidemic of sylvatic rabies in Croatia started already in 1977 and in the past ten years the disease has become enzootic in the entire country and thus represents a considerable veterinary and public health threat. A genetic characterization and phylogenetic analysis of rabies virus isolates (RABV) from Croatia was performed using panel of 32 selected rabies-positive brain samples from domestic and wild animals collected between 2008 and 2010. Based on the comparison of 367-nucleotide sequences of a conserved region of the nucleoprotein (N) gene (nucleotides 75-441), the phylogenetic analysis revealed a low genetic diversity of currently circulating RABV strains in Croatia. 18 RABV isolates mainly originating from Eastern Croatia clustered with the formerly established Eastern European (EE) lineage, and the rest (14) were identical with the West European (WE) group. Both phylogenetic groups seem to coincide in central regions on both sides along the Save River. A high sequence identity in the N gene of the RABV isolates from neighbouring countries was found.  相似文献   

19.
China is one of the most diverse countries, which have developed 88 indigenous pig breeds. Several studies showed that pigs were independently domesticated in multiple regions of the world. The purpose of this study was to investigate the origin and evolution of Chinese pigs using complete mitochondrial genomic sequences (mtDNA) from Asian and European domestic pigs and wild boars. Thirty primer pairs were designed to determine the mtDNA sequences of Xiang pig, Large White, Lantang, Jinhua and Pietrain. The phylogenetic status of Chinese native pigs was investigated by comparing the mtDNA sequences of complete coding regions and D-loop regions respectively amongst Asian breeds, European breeds and wild boars. The analyzed results by two cluster methods contributed to the same conclusion that all pigs were classified into two major groups, European clade and Asian clade. It revealed that Chinese pigs were only recently diverged from each other and distinctly different from European pigs. Berkshire was clustered with Asian pigs and Chinese pigs were involved in the development of Berkshire breeding. The Malaysian wild boar had distant genetic relationship with European and Asian pigs. Jinhua and Lanyu pigs had more nucleotide diversity with Chinese pigs although they all belonged to the Asian major clade. Chinese domestic pigs were clustered with wild boars in Yangtze River region and South China.  相似文献   

20.
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