Title: Comparative genomic sequence analysis of the Marek’s disease vaccine SB-1 Authors
|Schat, Karel -|
Submitted to: Herpesvirus International Workshop
Publication Type: Proceedings
Publication Acceptance Date: April 2, 2010
Publication Date: July 24, 2010
Citation: Spatz, S.J., Schat, K. 2010. Comparative genomic sequence analysis of the Marek’s disease vaccine SB-1. Herpesvirus International Workshop. 1(1):9-32. Technical Abstract: Marek’s disease virus (MDV) is one of the most oncogenic herpesviruses known and induces a rapid onset T-cell lymphoma and demyelinating disease in chickens. Since the 1970s the disease has been controlled through mass vaccination with the meleagrid herpesvirus type 1 (MeHV-1). Since then the efficacy of the vaccine has decrease and in the 1980 a divalent vaccine consisting of MeHV-1 and a noncogenic gallid herpesvirus (GaHV-3) known as SB-1 was introduced to control this hideous pathogen. The complete DNA sequence of this strain was recently determined using 454 pyrosequencing. The genome consists of 165,994 base pairs with an overall gene organization typical of avian class E herpesviruses. A total of 521 open reading frames (ORFs) (>25 amino acids) were examined for homology to protein sequences present in GenBank (E-values <0.9). Of the 128 ORFs hits, 75 ORFs showed homology to the well characterized alphaherpesviral proteins of the unique long region (UL1 through UL54), the unique short region (US1, US10, US2, US3, US6, US7 and US8) and ICP4 within the repeat long regions. Overall the gene organization is more similar to that of meleagrid herpesvirus type 1 and gallid herpesvirus 2, than gallid herpesvirus type 1. Phylogenetically, this strains partitions in its own branch along with the GaHV-3 strain HPRS24. In comparison between the two GaHV-3 strains, 21 ORF’s differ in the number of amino acids, of these eight (UL3.5, UL5, UL9, UL28, UL30, UL36, UL37 and UL50) encode well characterized alphaherpesviral proteins. To confirm these differences, selective regions within the genomes of other GaHV-3 strains were sequenced in order to generate a consensus of the number of genes and their sizes within these members of the genus Mardivirus.