Classical Swine Fever and Related Viral Infections

The history of research on hog cholera (HC)/classical swine fever (CSF) can be roughly divided into three phases which are characterized by the methods available at the time for demonstrati ng the causati ve agent. Phase covered the period before the viral etiology of HC was discovered by de Schweinitz and Dorset (1904)*. Thereafter (Phase II) the detection of HC virus (HCV) was accomplished by laborious, time-consuming and costly pig inoculation experiments. This explains the extensive search for methods not only for detection but also for accurate infectivity titration as well as for applicable serological techniques to solve urgent problems concerning the pathogenesis, diagnosis, epidemiology and prophylaxis of HC. It was not before the late fifties that HC research entered Phase III when fluorescent antibody techniques offered not only the means for detection and titration of HCV in porcine cell cultures but also for more intensive research on hog cholera and its virus. And yet, there are a number of questions to be answered, e. g. on the genetic and antigenic relation of HCV to bovine viral diarrhea (BVD) virus. There are indications that Phase IV of HC research will bear the stamp of biotechnology. In view of this development it appears appropriate to give an up-dating and summarizing account of HC/CSF including comparative aspects of infections caused by structurally related viruses. The editIon of the present volume would have been impossible without the cooperation of several known scientists who instantly agreed when asked for contribution.

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1. Description of the virus infection.- 1. Introduction.- 2. Viral and host determinants of virulence.- 3. Infections with high-virulent virus strains.- 4. Infections with moderate-virulent virus strains.- 5. Infections with low-virulent virus strains.- 6. Infections with avirulent virus strains.- 7. Concluding remarks.- 2. Pathology and pathogenesis of the disease.- 1. Introduction.- 2. Pathology of classical swine fever.- 3. Light and electron microscopical changes.- 4. Haematological findings.- 5. Blood coagulation disorders.- 6. Foetal and neonatal pathology.- 7. Congenital persistent HC virus infection.- 8. Pathogenesis of HC virus infection.- 9. Concluding remarks.- 3. Characteristics of the virus.- 1. Virion morphology.- 2. Physico-chemical properties.- 3. Isolation and cultivation.- 4. Viral strains.- 5. Serological relationship to other pestiviruses.- 4. Molecular biology of the virus.- 1. Introduction.- 2. Taxonomy.- 3. Molecular biology of the togaviruses.- 4. Ribonucleic acid of pestiviruses.- 5. Structural proteins of pestiviruses.- 6. Replication, strain differences and mutants of pestiviruses.- 7. Conclusions.- 5. Diagnostic procedures.- 1. Introduction.- 2. Laboratory diagnosis.- 3. Characteristics of isolates from field outbreaks.- 4. Concluding remarks.- 6. Serology.- 1. Introduction.- 2. Serologic reactions used for humoral antibody detection.- 3. Application of serological methods.- 4. Concluding remarks.- 7. Immunological aspects of the infection.- 1. Introduction.- 2. Humoral immune response.- 3. Cellular immune response.- 4. Effects of HCV infections on immune functions.- 5. Discussion and concluding remarks.- 8. Principles of vaccination.- 1. Introduction.- 2. Types of vaccines.- 3. Properties of modern live virus vaccines.- 4. Immunity induced by modern live virus vaccines.- 5. Use of modern live virus vaccines.- 6. Vaccination failures.- 7. Appraisal of vaccination: Epizootiological and economic impact.- 9. Vaccines.- 1. Introduction.- 2. Production of HCV vaccines.- 3. Properties of HCV vaccines.- 4. Conclusions.- 10. Epizootiology of hog cholera.- 1. Introduction.- 2. Distribution and economic impact.- 3. Transmission.- 4. Reservoirs.- 5. Factors influencing the epizootiology.- 6. Tracing of herds infected with HC.- 7. Concluding remarks.- 11. Control of classical swine fever.- 1. Introduction.- 2. The epidemiologic situation.- 3. The structure of the pig production.- 4. Public control of CSF.- 5. The legislation of the EEC on CSF.- 6. Legal measures against CSF in case of emergency situations.- 7. The EEC programme for eradication of CSF.- 8. The CSF epizootic in Belgium, the Netherlands and the Federal Republic of Germany.- 9. Concluding remarks.- 12. The comparative biology of classicle swine fever.- 1. Introduction.- 2. Prenatal infection.- 3. The legacy of intra-uterine infection.- 4. Acute postnatal infections.- 5. Epidemiology and control.