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Viruses of the genus Pestivirus, family Flaviviridae, are believed to be among the main factors causing economic losses in cattle and pig breeding. Their genomes, consisting of single-stranded RNA with positive polarity and a length of approximately 12.3 kb, have one open reading frame that encodes from 11 to 12 proteins. The virion is surrounded by a lipid membrane. According to the official classification, the genus Pestivirus includes four species: bovine viral diarrhea virus-1 (BVDV-1), bovine viral diarrhea virus-2 (BVDV-2), classical swine fever virus (CSFV) and border disease virus (BDV). To date, several genetically related viruses have been identified, but not yet included in the official classification. They include: giraffe pestivirus isolated from an animal with symptoms of mucosal disease and from cell cultures originating from Kenya, Pronghorn virus from an antelope, HoBi-like viruses detected for the first time in fetal bovine serum and Bungowannah virus causing losses in the Australian domestic pig population. It is suspected that new strains detected in Turkish goat and sheep herds and in Tunisian sheep pox vaccines also belong to pestiviruses. Next-generation sequencing has made it possible to identify another atypical pestivirus of pigs, as well as to discover strains infecting other animals beyond the order of Artiodactyla, such as rats or bats. New emerging strains may pose a threat to the livestock industry.
Problems in the reproduction of pigs may be the result of interaction of various factors, both infectious and non-infectious. Among the infectious agents, the greatest economic losses are caused by viral infection of pregnant gilts and sows. In the present study the most important pathogens causing reproductive disorders in pigs, including parvovirus (PPV), porcine reproductive and respiratory syndrome (PRRSV), swine influenza virus (SIV), porcine circovirus type 2 (PCV2), enteroviruses, encephalitis virus (EMCV), Aujeszky’s disease virus (ADV), classical swine fever virus (CSFV), Leptospira spp., Brucella suis and Erysipelotrix rhusiopathiae are characterized. So far, three possible ways of natural infection of the embryo or fetus are identified: via placenta, through the cervical canal, and by infection of the egg cell. The consequences of infection of pregnant females depend on the species of the virus, the gestation period, wherein there is an infection and immune status of pregnant females. The most common changes included: embryo death, resorption of embryos, mummification of fetuses, malformations, abortions, birth of dead or very weak piglets. Because of the importance of the reproduction sector for the competitive production of pigs, the monitoring of the health status of breeding stock, including compliance with all biosecurity rules and vaccination schedules, should be strictly respected by veterinarians taking care of pig breeding herds.
The purpose of the article was to characterize the progress achieved in Europe during the last two decades on the control of classical swine fever (CSF) in domestic pigs and the wild boar population in Europe. RT-PCR and other findings based on molecular biology, improving laboratory diagnosis and enabling the use of DIVA strategy in vaccination, were mentioned. The classical swine fever virus (CSFV) using genome sequencing could be divided into 3 genotypes. Genotype 1 and 2 could be subdivided into 3 subgenotypes, each and genotype 3 in 4 subgenotypes. These results enabled the implementation of tracing the spread of particular strains of CSFV and the definition of the origin of the infection, what earlier was not possible. A special database of these findings is located in the E.U. and OIE Reference Laboratory for CSF in the Institute of Virology, University of Veterinary Medicine in Hannover, Germany. In the second part of the paper the current epidemiological situation concerning CSF in domestic pigs and the wild boar population is characterized. It relates to Germany and France, Slovakia and Hungary, Lithuania and Latvia, Romania, Bulgaria and the Balkan region. Besides E.U. member countries also other European countries are mentioned. It is underlined, that the wild boar population plays a crucial role as the reservoir of CSFV in Europe. In connection with this statement a working group on CSF in wild boar of the Directorate General Health and Consumer Protection (DGSANCO) of the European Commission initiated a common data base on the epidemiology of CSF in wild boar. In parallel to collecting CSFV isolates and sequences data concerning strains from domestic pigs the same information from wild boar is collected. All these data are to disposal of the national Reference Laboratories for CSF worldwide. The paper, at the end, presents recommendations concerning progress in the control and eradication of CSF, mentioning the significant role of vaccination with the use of DIVA strategy particularly for the wild boar population. Despite of the achieved progress, taking into account the present epidemiologic situation in Europe it is stated, that CSF still belongs to the most important viral diseases in pigs in Europe and also worldwide.
Classical swine fever (CSF) is a worldwide economically important, highly contagious disease of swine. Poland has been free of this disease for the last 14 years. However, outbreaks occur in neighboring countries and create serious risks. Therefore, it seems essential to present the progress of laboratory diagnosis and vaccines. Since the CSF virus reservoir in wild boars is important for the infection of domestic swine, this topic has also been presented. The paper also describes diagnostic techniques for identifying the agents and serological tests for detecting the virus - it characterizes specific antibodies, including an assessment of their diagnostic value. Recent developments of CSF vaccines are discussed, including the live, lapinised vaccine, containing the attenuated Chinese C strain of CSF and marker vaccines, developed with the application of molecular biology and genetic engineering techniques. These vaccines, despite being less effective than the C-strain vaccine, enable to discriminate infected animals from vaccinated ones (DIVA strategy) when correspondent diagnostic kits are used. These detect antibodies which are exclusively characteristic for antigens of the vaccine strain or antibodies specific to antigens of the virulent CSF virus. Procedures of controlling CSF in wild boars were described including recommendations of diagnostic tests and oral vaccinations.
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