ARS | Publication request: Marek's Disease Viruses Lacking the 132 Bp Repeats Are Oncogenic But Can Still Be Attenuated by Serial in Vitro Cell Culture Passages

Submitted to: American Veterinary Medical Association Abstract
Publication Acceptance Date: July 28, 2004
Publication Date: July 28, 2004
Citation: Silva, R.F., Gimeno, I.M. 2004. Marek's Disease Viruses Lacking The 132 Bp Repeats Are Oncogenic But Can Still Be Attenuated By Serial In Vitro Cell Culture Passages [abstract]. American Veterinary Medical Association. P. 58.

Technical Abstract: Oncogenic Marek's disease virus (MDV) contains two copies of a 132 bp repeat that increases to over 20 copies when MDV is attenuated by repeatedly passing the virus in cell culture. These findings suggest that the expansion may be responsible for the attenuation. To test this hypothesis, we deleted the two copies of the 132 bp repeat in an oncogenic MDV, rMd5(delta132bp), and found the mutant MDV was still oncogenic. In addition, we passed the rMd5(delta132bp) in cell culture for 40 passages (high pass) and found that the high pass deletion mutant was attenuated to the same degree as a wild-type MDV that had been passed 40 times in parallel with rMd5(delta132bp). Characteristics, such as early virus replication, persistent neurological lesions and reactivation from latency were very similar in the high pass wild-type MDV and the high pass rMd5(delta132bp). We conclude that the 132 bp repeat expansion is not responsible for attenuation and that oncogenic MDVs that lack the 132 bp repeats can be attenuated as effectively as wild-type MDVs.