DNA sequence and organization of genes in a 5{middle dot}5 kbp EcoRI fragment mapping in the short unique segment of Marek's disease virus (strain RB1B)

Abstract

The DNA sequence of a 5.5 kbp EcoRI fragment located in the short unique region (Us) of the 'highly oncogenic' strain RB1B of Marek's disease virus (MDV) was determined. The sequence contained six open reading frames (ORFs), four of which were homologous to proteins mapping in the Us region of herpes simplex virus type 1 (HSV-1). These include the homologues of HSV-1 protein kinase, glycoprotein D (gD), glycoprotein I (gI) and US2 which is of unknown function. The MDV ORFs had a marked bias for A or T in the third codon position and analysis of the dinucleotide frequencies showed a marginal deficit in ApG/CpT but no overall deviation of CpG from random expectations. Comparison of genes in the Us region of MDV to he~esvirus proteins confirmed and extended our previous observation that MDV is more closely related to alphaherpesviruses than to gammaherpesviruses. We also showed that MDV possessed a homologue of HSV-1 gD which is lacking in varicellazoster virus (VZV) but that MDV probably lacked homologues of US4 and US5 of HSV-1. These results show that in contrast to the genes in the long unique region which were grossly collinear in HSV, VZV and MDV, those mapping in Us show greater diversity.Marek's disease virus (MDV) DNA is a linear, 175 kbp double-stranded molecule consisting of unique long (UL) and unique short (Us) segments flanked by inverted repeats (IRs) (Cebrian et al., 1982). Recently, Buckmaster et al. (1988) identified 35 MDV genes by comparing the translated sequence of random fragments of MDV DNA with the amino acid sequences of known herpesvirus proteins. Most of the genes identified mapped in the UL region and were coUinear with genes of the alphaherpesviruses herpes simplex virus (HSV) and varicella-zoster virus (VZV). Moreover, the random sequencing study showed that MDV was more closely related to alphaherpesviruses than to beta-and gammaherpesviruses on the basis of amino acid sequence conservation. Genes of MDV that have been sequenced fully so far map in UL (Coussens & Velicer, 1988;Scott et al., 1989). In this paper we report on the DNA sequence and organization of predicted open reading frames (ORFs) in approximately half of the Us segment of MDV strain RB1B (Schat et al., 1982). We were particularly interested in determining whether MDV had a homologue of the HSV glycoprotein D (gD) and the nature and arrangement of genes adjacent to gD.Initially, random fragments of MDV DNA derived from a 23 kbp BamHI A fragment of the GA strain of MDV (Fukuchi et al., 1984) containing part of Us and most of the IRs (Fig. 1) were sequenced and the TRL

Characterization of the herpes simplex virus type 2 (HSV-2) US2 gene product and a US2-deficient HSV-2 mutant.

“…The US2 gene of HSV-2 is predicted to encode a 291-amino-acid protein with a molecular mass of 33 kDa (McGeoch et al, 1987), and homologues of the US2 protein are encoded by many alphaherpesviruses and unclassified herpesviruses of birds, including HSV-1 (McGeoch et al, 1985), pseudorabies virus (van Zijl et al, 1990), Marek's disease virus (MDV) (Ross et al, 1991 ;Sakaguchi et al, 1992 ;Brunovskis & Velicer, 1995), equine herpesvirus type 1 (EHV-1) (Telford et al, 1992) and type 4 (EHV-4) (Nagesha et al, 1993), herpesvirus of turkeys (HVT) (Zelnı! k et al, 1993), bovine herpesvirus type 1 (LeungTack et al, 1994) and infectious laryngotracheitis virus (ILT) (Wild et al, 1996).…”

Properties and evolutionary relationships of the Marek's disease virus homologues of protein kinase, glycoprotein D and glycoprotein I of herpes simplex virus

“…A search for amino acid similarities using FASTP showed that ORF3 of MDV Us (Ross et al, 1991) was more closely related to the protein kinase of alphaherpesviruses mapping in Us than to any other sequence in the PIR database. Moreover, the conserved sequences were located within the catalytic domain of protein kinase as defined by Hanks et al (1988).…”

“…In view of the recent report of McGeoch (1990) that alphaherpesvirus genes mapping in Us may have been generated by a process of gene duplication and independent evolution, we have examined our sequence data for possible relationships not only between the MDV glycoprotein genes and their mammalian herpesvirus counterparts, but have also searched for similarities between the MDV genes themselves. Although we were unable to demonstrate a relationship between MDV ORF4 and other 0000-9949 © 1991 SGM herpesvirus proteins using FASTP (Lipman & Pearson, 1985) in our previous study (Ross et al, 1991) we now report that ORF4 is probably the homologue of HSV-1 gG and that it is also related to MDV gD. We present here an analysis which shows that MDV and mammalian alphaherpesvirus glycoproteins in Us constitute a family of inter-related genes.…”

“…The sequence of the 5-5 kbp EcoRI fragment of MDV DNA (RB1B strain) was obtained from the accompanying paper (Ross et al, 1991).…”

“…In the accompanying paper (Ross et al, 1991) we have reported the sequence of six open reading frames (ORFs) mapping to a 5-5 kbp EcoRI fragment within the short unique segment (Us) of Marek's disease virus (MDV) DNA. We showed that four of these ORFs were collinear in herpes simplex virus (HSV) but that MDV appeared to lack homologues of HSV US4 and US5.…”