Submitted to: International Marek's Disease Symposium Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 14, 2004
Publication Date: July 14, 2004
Citation: Fadly, A.M., Silva, R.F., Hunt, H.D. 2004. Isolation of subgroup A avian leukosis virus from commercial Marek's disease vaccines [abstract]. International Marek's Disease Symposium Abstracts and Proceedings. Paper No. P.8. Technical Abstract: Commercial Marek's disease (MD) vaccines were submitted to USDA-ARS Avian Disease and Oncology Laboratory for testing for possible contamination with avian leukosis virus (ALV). Samples of MD vaccines manufactured by two different companies (A & B) were received from a breeder company; samples were also received directly from vaccine company B. Initially, samples tested positive by virus isolation for subgroup E (endogenous) ALV. However, upon re-passage, the vaccines also tested positive for exogenous (subgroup A) ALV. PCR and DNA sequencing of the envelope of isolated ALVs confirmed the results obtained from virus isolation assays that in addition to endogenous subgroup E ALV, an exogenous subgroup A ALV was also present in the vaccines tested. Although the source of this contamination of MD vaccines with exogenous subgroup A ALV has not be determined, the data presented in this paper should be of interest to vaccine manufacturers, suppliers of specific-pathogen-free (SPF) eggs as well as scientists from academia and government.