ISSN:0165-2176    

DOI:10.1080/01652176.1987.9694133

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The paper reviews developments in foot‐and‐mouth disease research with an emphasis on the Netherlands and research developments at the Central Veterinary Institute.

ISSN:0165-2176    

DOI:10.1080/01652176.1987.9694134

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Biological characteristics of Marek's disease virus (MDV) CVI‐988 clone C, of importance for vaccine application, are described. CVI‐988 clone C was shown to be nonpathogenic for highly MD‐susceptible chickens and slightly more effective than prototype CVI‐988 vaccine. During plaque purification and serial cell‐culture passages, reductions were observed in the release of ‘A’ antigen from infected cell cultures, in spreading properties and in virus replication in vivo. Pre‐licensing batches of CVI‐988 clone C vaccine afforded excellent protection against challenge infection with virulent MDV and highly virulent MDV strains. Groups of chickens with bivalent (HVT/ SB‐1) vaccine‐induced maternal antibodies were equally protected by a double dose of CVI‐988 clone C vaccine. Field trials performed in the Netherlands and in the United States confirmed the safety and protective efficacy of monovalent CVI‐988 clone C vaccine.

ISSN:0165-2176    

DOI:10.1080/01652176.1987.9694135

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The results of the first four years of the Dutch national voluntary maedi‐visna control program, which was launched on January 1, 1982, are presented. At the end of the observation period, 1711 breeding flocks representing 70% of the registered breeding flocks participated. The program is based on accreditation of flocks that have passed two successive serological tests with an interval of six months between and post‐accreditation tests every 12 months. The flocks have to conform to a set of specific regulations. Sheep sold from such flocks receive a certificate stating that their origin was accredited. A total of 1212 flocks gained accredition. Of these flocks, 29.5% were free from infection from the beginning, 35.6% were created by total replacement of the original stock, 19.6% employed repeated testing and culling of positives, and 15.3% were created by artificial rearing of colostrum‐deprived lambs. A total of 22 flocks lost accreditation due to detection of 36 seropositives. These positives and their progeny were culled, and all flocks regained accreditation after passing the two negative flock tests required. In a total of seven flocks, an unusual course of events during the pre‐accreditation stage was observed; this was mainly attributed to late seroconversions and uncommon degrees of horizontal transmission.

ISSN:0165-2176    

DOI:10.1080/01652176.1987.9694136

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The efficacy of two inactivated and three attenuated Aujeszky's disease virus (ADV) vaccines was compared in pigs in a standardised test. After vaccination, excretion of attenuated vaccine viruses was not detected. All vaccines were capable of preventing mortality, but none conferred complete protection against challenge with a virulent strain of ADV 3 months after the first vaccination. After a single vaccination, no large differences in vaccine efficacy were observed. Revaccination markedly enhanced protection; however, with one vaccine this was not the case. The two inactivated vaccines induced quite different levels of neutralizing antibodies.

ISSN:0165-2176    

DOI:10.1080/01652176.1987.9694137

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

In countries with an intensive pig production system, swine fever (SF), where present, may be regarded as one of the economically most important pig diseases. Although reservoirs of virus and pathways of transmission are well understood, field experience has shown that the disease is extremely difficult to eradicate, especially in countries with intensive pig breeding.

ISSN:0165-2176    

DOI:10.1080/01652176.1987.9694138

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0165-2176    

DOI:10.1080/01652176.1987.9694132

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor