Location: Avian Disease and Oncology ResearchTitle: Partial attenuation of Marek's disease virus by manipulation of Di-codon bias Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/20/2014
Publication Date: 7/20/2014
Citation: Dunn, J.R., Silva, R.F. 2014. Partial attenuation of Marek's disease virus by manipulation of Di-codon bias [abstract]. In: Proceeding for 10th International Symposium on Marek's Disease and Avian Herpesviruses, July 20-23, 2014, East Lansing, Michigan. p.70. Interpretive Summary:
Technical Abstract: All species studied to date demonstrate a preference for certain codons over other synonymous codons (codon bias), a preference which is also observed for pairs of codons (di-codon bias). Previous studies using poliovirus and influenza virus as models have demonstrated the ability to cause attenuation by replacing frequently used di-codons with infrequently used synonymous di-codons. We analyzed di-codon usage in the 18,742 referenced chicken genes and 86 protein-coding genes in the Md5 strain of Marek’s disease virus (MDV) and found a clear bias for preferential use of some di-codons and rare utilization of other di-codons. In the current study we replaced commonly used di-codons with synonymous uncommonly used di-codons for two MDV genes, UL54 (ICP27), a transactivator of immediate early genes and UL53 (gK), an essential structural gene. The mutant genes were cloned into the MDV Md5B40BAC and inoculated into groups of MD-susceptible maternal antibody negative chickens. Mutations in UL54 led to reduced virus quantity in buffy coats measured 21 days post-challenge despite similar in vitro growth curves compared to positive control Md5B40BAC. This virus also had reduced pathogenicity including a pronounced decrease in visceral tumors and increased survivability compared to the control. Results from additional pathogenicity trials using the gK di-codon mutants will also be presented. Our results demonstrate that altering the di-codon bias of select herpesvirus genes can affect the pathogenicity of the virus and may be useful in the generation of a novel class of herpesviral vaccines.