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Journal ArticleDOI

Feather follicle epithelium: a source of enveloped and infectious cell-free herpesvirus from Marek's disease.

01 May 1970-Avian Diseases (Avian Dis)-Vol. 14, Iss: 2, pp 219-233
About: This article is published in Avian Diseases.The article was published on 1970-05-01. It has received 330 citations till now. The article focuses on the topics: Marek's disease & Mardivirus.
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Journal ArticleDOI
TL;DR: HVT gives substantial protection against the development of MD yet is nonpathogenic and noncontagious, all of which are important characteristics of vaccine viruses.
Abstract: SUMMARY Studies were conducted to determine whether a herpesvirus isolated from turkeys (HVT) would protect chickens against subsequent challenge with the virulent JM strain of Marek's disease herpesvirus (MDHV). HVT administered intra-abdominally at doses as low as 600 plaque-forming units per one-day-old chick gave protection against Marek's disease (MD). The virus would protect when birds were challenged with MDHV by intra-abdominal inoculation at 3 weeks or by contact exposure as early as 2 weeks postvaccination. Chickens inoculated with HVT and observed for 17 to 20 weeks did not develop lesions. Birds produced antibody and infection persisted throughout this period, however, as indicated by reisolation of the virus. Furthermore, HVT did not spread to chickens in direct contact with vaccinated birds. Thus HVT gives substantial protection against the development of MD yet is nonpathogenic and noncontagious, all of which are important characteristics of vaccine viruses.

413 citations

Journal ArticleDOI
14 Jan 1977-Science
TL;DR: Comparison of inoculated sibs in backcross-families revealed that the B alloalleles characterizing the two lines accounted for an eightfold difference in tumor incidence.
Abstract: Lines of chickens selected from a common ancestral population for either resistance or susceptibility to Marek's disease developed contrasting frequencies of particular B alloalleles. Comparison of inoculated sibs in backcross-families revealed that the B alloalleles characterizing the two lines accounted for an eightfold difference in tumor incidence. This genetic difference in tumorigenesis associated with the alloalleles of the major histocompatibility complex is probably expressed through the cell-mediated immune system.

362 citations

Journal ArticleDOI
TL;DR: A Marek's disease virus of low pathogenicity was isolated from a flock of chickens and was designated strain CVI 988 and gave excellent protection on subsequent challenge with a virulent virus, even if this challenge was performed shortly after vaccination.
Abstract: A Marek's disease virus of low pathogenicity was isolated from a flock of chickens and was designated strain CVI 988. On primary isolation, this virus did not cause disease in susceptible chicks and gave excellent protection on subsequent challenge with a virulent virus, even if this challenge was performed shortly after vaccination. The virus occasionally caused minor microscopic lesions in antibody-free MD susceptible chicks but on further passage in DEF cultures the virus became completely avirulent while retaining its A antigen, spreading capacity and immunizing potentials. Chicks vaccinated by contact exposure developed a high degree of MD resistance after the 5th week but immunity was induced more rapidly when 3-week-old seeder chicks, which were actively shedding vaccine virus, were used as the source of exposure. However, by any procedure, contact-vaccinated chicks required several weeks for the development of solid immunity. High passage virus did not become virulent after 5 subsequent passages in antibody-free MD susceptible chicks. Vaccinated birds produced antibody which remained at a high level through observation periods of 2 years. Viremia and virus-shedding persisted throughout this period in a considerable number of birds. Rhesus monkeys inoculated with the virus did not develop any lesions during a one year observation period and no seroconversion could be detected.

335 citations

Book ChapterDOI
B. W. Calnek1
TL;DR: This chapter will concern itself with the spectrum of sequential events triggered by infection with MD virus (MDV), and the consequences of those events at both the cellular and host level.
Abstract: The term pathogenesis is most simply defined as the development of disease. Many uncomplicated infectious diseases proceed in a direct fashion from infection to a specific pathologic expression. However, other diseases are relatively complex in terms of pathogenesis; Marek’s disease (MD) most certainly belongs in this category. This chapter will concern itself with the spectrum of sequential events triggered by infection with MD virus (MDV), and the consequences of those events at both the cellular and host level. It will also consider the many factors that affect the potential manifestations of MD. Attention will be given to mechanisms and interactions associated with those factors. Major emphasis will be placed on the lymphomagenic nature of the disease.

299 citations

Journal ArticleDOI
TL;DR: In this paper, an rMd5DeltaMeq virus was generated by deleting both copies of the meq gene from the genome of a very virulent strain of MDV.
Abstract: Marek's disease virus (MDV) causes an acute lymphoproliferative disease in chickens, resulting in T cell lymphomas in visceral organs and peripheral nerves. Earlier studies have determined that the repeat regions of oncogenic serotype 1 MDV encode a basic leucine zipper protein, Meq, which structurally resembles the Jun/Fos family of transcriptional activators. Meq is consistently expressed in MDV-induced tumor cells and has been suggested as the MDV-associated oncogene. To study the function of Meq, we have generated an rMd5DeltaMeq virus by deleting both copies of the meq gene from the genome of a very virulent strain of MDV. Growth curves in cultured fibroblasts indicated that Meq is dispensable for in vitro virus replication. In vivo replication in lymphoid organs and feather follicular epithelium was also not impaired, suggesting that Meq is dispensable for lytic infection in chickens. Reactivation of the rMd5DeltaMeq virus from peripheral blood lymphocytes was reduced, suggesting that Meq is involved but not essential for latency. Pathogenesis experiments showed that the rMd5DeltaMeq virus was fully attenuated in chickens because none of the infected chickens developed Marek's disease-associated lymphomas, suggesting that Meq is involved in lymphocyte transformation. A revertant virus that restored the expression of the meq gene, showed properties similar to those of the parental virus, confirming that Meq is involved in transformation but not in lytic replication in chickens.

212 citations