Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/14/2002
Publication Date: 12/31/2002
Citation: Reddy, S.M., Lupiani, B., Gimeno, I., Lee, L.F., Silva, R.F., Witter, R.L. 2002. Rescue of a pathogenic marek's disease virus with overlapping cosmid dnas: use of a pp38 mutant to validate the technology for the study of gene function. Proceedings of the National Academy of Sciences. 99:7054-7059. Interpretive Summary: Marek's disease (MD), a virus induced cancer-like disease of chickens, is considered as a major disease problem in commercial poultry. Vaccination has dramatically reduced the incidence of the disease, but very little is known about the basic mechanisms involved in the induction of disease. The objective of this research was to generate a new technology to introduce specific changes into the pathogen. The information provided in this report shows how to manipulate this pathogen to modify its disease causing ability. This important information about manipulation of MD virus will undoubtedly help scientists in academia and industry understand how to modify this virus and eventually lead to better control of the disease.
Technical Abstract: Five overlapping cosmid DNAs containing the entire sequence of a very virulent Marek's disease virus (MDV), Md5, were constructed. Transfection of duck embryo fibroblast (DEF) with the five overlapping cosmid DNAs resulted in the generation of infectious MDV, rMd5 (recombinant Md5). The pp38 gene specific for MDV was deleted from one of the cosmids and was used to generate a recombinant MDV, rMd5Dpp38. The mutant virus grew at a rate similar to that of parental rMd5 in cultured cells. Inoculation of 15I5x7 birds with parental Md5, rMd5 and rMd5Dpp38, resulted in the replication in all the inoculated birds. The biological properties of rMd5 were similar to that of highly virulent parental Md5. In the absence of pp38, early cytolytic infection was impaired however; the virus did not loose the ability to transform lymphocytes. The procedure described here will be very useful to study genes involved in cytolytic, latent, and tumor phases of MDV pathogenesis.