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1.
Genetic typing of recent classical swine fever virus isolates from Croatia   总被引：1，自引：0，他引：1  
During a period of 5 years (1997-2001) several outbreaks of classical swine fever (CSF) were recorded in Croatia. For genetic typing, fragments of 150 nucleotides within the 5'-non-translated region (5'-NTR) and 190 nucleotides within the E2 glycoprotein coding gene of nine field isolates that were derived from domestic pigs and wild boars were used. For better epizootiological understanding, isolates from other European countries were included in the study. The results show that the isolates belong to subgroups 2.1 and 2.3 of CSF virus. Isolates from subgroup 2.1 were collected from domestic pigs during sporadic outbreaks in June 1997 and are genetically closely related. A genomic similarity between these isolates and CSF virus isolates from pigs in other European countries from the same year could also be confirmed. In contrast, the isolate from October 1997 was found to be a member of subgroup 2.3, and is closely related to European CSF virus isolates from outbreaks in the last decade in Western and Central European countries. These results show that two different sources of CSF virus caused outbreaks in Croatia during the same year. Furthermore, a close relationship was found between an isolate from a domestic pig in 1999 and isolates of subgroup 2.3 that originated from Croatian wild boars.  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.
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   

4.
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   

5.
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   

6.
Emergence of classical swine fever virus in Israel in 2009   总被引：1，自引：0，他引：1  
Classical swine fever (CSF) re-emerged in Israel in February 2009 after an absence of 62 years. The outbreak occurred on a domestic pig farm in northern Israel and affected domestic pigs and wild boar. On the basis of phylogenetic analysis of a 190 base pair fragment of the E2 glycoprotein gene, the Israeli CSF virus strain belonged to genotype 2.1 and was genetically most similar to a Chinese CSF virus strain.  相似文献   

7.
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   

8.
Genetic typing of classical swine fever viruses--a review   总被引：2，自引：0，他引：2  
Classical swine fever (CSF) is a notifiable disease of domestic pigs and wild boar. It is caused by the highly contagious CSF virus and in its acute form the disease generally results in high morbidity and mortality. Due to the great economical impact an outbreak can cause to the pig industry it is one of the most important swine diseases worldwide. To limit the damage in the case of a new outbreak it is necessary to identify the virus as fast as possible. This information helps epidemiologists to trace the origin of the virus and to follow the virus spread. Genetic typing revealed that CSF virus genotypes, subgroups and types show a regional distribution making it an important tool for epidemiologists. Meanwhile, besides epidemiological data and nucleotide sequences from European isolates, information from isolates from South- and Central America, the Caribbean, Asia and recently from South Africa have become available. The data are stored in a database in the EU Reference Laboratory for CSF, accessible by the WWW (http://viro08.tiho-hanno ver.de). A new module was implemented that allows efficient automated genotyping.  相似文献   

9.
Classical swine fever--an update   总被引：8，自引：0，他引：8  
Classical swine fever (CSF) is a serious and contagious viral disease of pigs and wild boar with a widespread worldwide distribution. The immunopathology of the disease is poorly understood, but the ability of the CSF virus to infect cells without triggering apoptosis and to kill uninfected cells is probably highly significant. The virus may be spread by various direct and indirect methods, but in most cases the exact mechanisms involved in local spread between farms are not known. Excellent diagnostic tools and typing methods are available, but tests that could be performed on-farm, in pre-clinically infected pigs or on meat would also be advantageous. A more complete picture of the viruses circulating in different parts of the world is needed. There is great interest to develop and use marker vaccines for the control of CSF in domestic pigs and in wild boar. Epidemiological modelling is increasingly used to evaluate control options.  相似文献   

10.
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   

11.
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   

12.
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   

13.
A molecular epidemiological approach was applied to establishing a possible role for the wild boar as a natural reservoir of Mycobacterium bovis in Sierra de Villuercas, Western Spain; an area free of farmed cattle and wild deer populations. Spoligo and VNTR typing were used over a three year period to study the epidemiological relationship between the occurrence of bovine tuberculosis (TB) in extensively bred Iberian pigs and indigenous wild boar. The 37 sampled wild boar showed different degree of calcified granulomatous lesions in retropharyngeal, mediastinal and pulmonary lymph nodes. The 25 sampled Iberian pigs showed calcified lesions, mainly in the respiratory tract. Lesions located in the mesenteric lymph nodes appeared secondarily. M. bovis was isolated from all affected animals. Twenty-five and 37 isolates of M. bovis were obtained from domestic pigs and wild boar, respectively. Our findings provide evidence that supports the possibility of cross infection between wild boar and domestic pig populations. This is contrary to the generally held belief that swine represent an epidemiological dead end host and play no role in the epidemiology of M. bovis.  相似文献   

14.
Denmark has no free-range wild-boar population. However, Danish wildlife organizations have suggested that wild boar should be reintroduced into the wild to broaden national biodiversity. Danish pig farmers fear that this would lead to a higher risk of introduction of classical swine fever virus (CSFV), which could have enormous consequences in terms of loss of pork exports. We conducted a risk assessment to address the additional risk of introducing and spreading CSFV due to the reintroduction of wild boar. In this paper, we present the part of the risk assessment that deals with the spread of CSFV between the hypothetical wild-boar population and the domestic population. Furthermore, the economic impact is assessed taking the perspective of the Danish national budget and the Danish pig industry. We used InterSpreadPlus to model the differential classical swine fever (CSF) risk due to wild boar. Nine scenarios were run to elucidate the effect of: (a) presence of wild boar (yes/no), (b) locations for the index case (domestic pig herd/wild-boar group), (c) type of control strategy for wild boar (hunting/vaccination) and (d) presence of free-range domestic pigs. The presence of free-range wild boar was simulated in two large forests using data from wildlife studies and Danish habitat data. For each scenario, we estimated (1) the control costs borne by the veterinary authorities, (2) the control-related costs to farmers and (3) the loss of exports associated with an epidemic. Our simulations predict that CSFV will be transmitted from the domestic pig population to wild boar if the infected domestic pig herd is located close to an area with wild boar (<5 km). If an outbreak begins in the wild-boar population, the epidemic will last longer and will occasionally lead to several epidemics because of periodic transfer of virus from groups of infected wild boar to domestic pig herds. The size and duration of the epidemic will be reduced if there are no free-range domestic pig herds in the area with CSF-infected wild boar. The economic calculations showed that the total national costs for Denmark (i.e. the direct costs to the national budget and the costs to the pig industry) related to an outbreak of CSF in Denmark will be highly driven by the reactions of the export markets and in particular of the non-EU markets. Unfortunately, there is a substantial amount of uncertainty surrounding this issue. If hunting is used as a control measure, the average expenses related to a CSF outbreak will be 40% higher if wild boar are present compared with not present. However, a vaccination strategy for wild boar will double the total costs compared with a hunting strategy.  相似文献   

15.
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   

16.
The ability to discriminate between various classical swine fever virus (CSFV) strains and isolates is a prerequisite for following the spread of the virus after an outbreak. To determine the relatedness between Russian CSFV isolates from different geographical regions, three fragments of the viral genome (5' NTR, the variable region of the E2 gene and a fragment of the NS5B gene) were sequenced and used for genetic typing. Thirty-one field isolates were obtained from CSF outbreaks which occurred between 1994 and 1999. In addition, three attenuated strains were included in the study, namely the LK and CS vaccine strains, and the moderately virulent 238H isolate. The vaccine strains have been used in Russia for more than 30 years. Our results showed that all field isolates are in subgroup 1.1 together with Alfort 187 and with the highly virulent strain Shimen. In contrast, the CS and LK vaccine strains belong to subgroup 1.2. While there is no evidence for the reversion of the two vaccine strains to wild type, it is feasible that the highly virulent Shimen strain, which has been used as a challenge strain for many years, contributed to field strain generation. The Russian field isolates from the 1990s can be distinguished from the CSF virus isolates which occurred in the EU Member States in the same decade, as here all outbreaks were caused by CSF viruses belonging to subgroup 2.  相似文献   

17.
Epidemiology of classical swine fever in Germany in the 1990s   总被引：10，自引：0，他引：10  
In Germany, 424 outbreaks of CSF in domestic pigs and a great number of cases in wild boar were recorded between 1990 and 1998. Most of the federal states ('Bundesl?nder') were affected. Epidemiological data from field investigations combined with genetic typing allowed to distinguish seven unrelated epidemics and a number of sporadic outbreaks in domestic pigs. Detailed epidemiological data was available for 327 outbreaks. It was found that 28% of these were primary outbreaks. Most of them were due to indirect or direct contact to wild boar infected with CSF virus or swill feeding. Infected wild boar remain the main risk for domestic pigs. The most frequent sources of infection in secondary or follow up outbreaks were the trade with infected pigs, neighbourhood contacts to infected farms and other contacts via contaminated persons and vehicles, respectively. An increased risk of virus transmission from infected herds to neighbourhood farms was observed up to a radius of approximately 500m. More than two thirds of the infected herds were discovered due to clinical signs. About 20% were identified by epidemiological tracing on and back. These were scrutinised because contacts to infected herds were evident. In conclusion, tracing of contact herds and clinical examination combined with carefully targeted virological testing of suspicious animals is likely to be the most important measure to immediately uncover secondary outbreaks. Obligatory serological screening in the surveillance and the restriction zones do not seem to be efficient measures to detect follow-up outbreaks.  相似文献   

18.
Classical swine fever (CSF) is a highly contagious multi-systemic haemorrhagic viral disease of pigs. Not only domestic pigs, but also wild boar appear to play a crucial role in the epidemiology of CSF. Spleen (n = 739) and blood coagulum (n = 562) sampled from wild boars (Sus scrofa) shot in 2002, and serum samples from 746 wild boar shot in 2003 and 2004, were tested throughout Slovenia. In 2002, 17 samples were positive on enzyme-linked immunosorbent assay (ELISA) test for antibodies against classical swine fever virus (CSFV). Positive ELISA test was confirmed by a virus neutralization test. All other samples were negative. This is the first report that describes the epidemiology of CSFV from 2002 on, and the monitoring of the wild boar population in Slovenia at present.  相似文献   

19.
房强 《猪业科学》2020,37(12):42-44
2018年8月3日,农业农村部发布辽宁沈阳发生全国首例非洲猪瘟。至今,全国32个省、自治区、直辖市、特别行政区公布共发生149起非洲猪瘟疫情,超过116万头猪只被扑杀。面对前所未有的非洲猪瘟,目前尚无有效的药物和疫苗预防,养猪行业面临种种危机。文章对非洲猪瘟及其危害做了简要介绍,并提出了防控非洲猪瘟的措施和建议。  相似文献   

20.
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   

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