Identification of the coding region for a second Epstein-Barr virus nuclear antigen (EBNA 2) by transfection of cloned DNA fragments.

SUMMARYThe BamHI WYH region of the Epstein-Barr virus (EBV) genome encodes a protein localized to the nucleus of the infected cell, the EBV-determined nuclear antigen EBNA2. We have constructed a series of recombinant vectors that carried the complete EBNA2 gene, or the gene modified so as to contain defined deletions involving presumed exons and regulatory elements of the gene. The recombinant vectors were transfected into COS-I cells which permit the replication of simian virus 40 origin-containing plasmids to a high copy number, and the transient expression of EBNA2 was analysed. A recombinant plasmid that carried a BglII-NotI subfragment of the BamHI WYH region (nucleotides 44 664 to 50 628) contained all the information necessary for inducing the expression of a full length EBNA2 polypeptide. Moreover, EBV DNA sequences between nucleotides 45442 and 48 337 could be deleted without interfering with the ability of the vectors to induce EBNA2. On the other hand the loss of the left one-third of the BgllI-NotI fragment completely abolished the EBNA2-inducing capacity of the vector. A rightward promoter consensus sequence in the BamHI W part of the BgllI-NotI fragment was functional in COS-1 ceils expressing EBNA2 and essential for EBV-specific RNA synthesis. The results indicated that transcription of the EBNA2 gene was initiated in the BamHI W fragment, that the transcript was spliced and that all of EBNA2 was encoded within the continuous long open reading frame in the BamHI Y and H fragments.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Identification of Sequences in Epstein-Barr Virus DNA Required for the Expression of the Second Epstein-Barr Virus-determined Nuclear Antigen in COS-1 Cells

Ricksten

Svensson²,

Welinder

et al. 1987

“…Subsequently the cloning of DNA fragments from the non-homologous regions of the M-ABA (a B95-8-1ike isolate) (Polack et al, 1984) and the Jijoye (Adldinger et al, 1985) virus genomes has provided probes which can distinguish all EBV isolates as either 'type A' (B95-8-1ike) or 'type B' (Jijoye-like) in the BarnHI WYH region. These differences in fact stem from sequence divergence within the open reading frame encoding the nuclear antigen EBNA 2 (Hennessy & Kieff, 1985;Dillner et al, 1985 ;Rymo et al, 1985 ;Muller-Lantzsch et al, 1985). Thus the EBNA 2 type B protein found in Jijoye and in AG876 cells is significantly smaller (75K tool.…”

Section: Introductionmentioning

confidence: 99%

New Type B Isolates of Epstein--Barr Virus from Burkitt's Lymphoma and from Normal Individuals in Endemic Areas

Young

Yao

Rooney

et al. 1987

191

105

SUMMARYAll Epstein-Barr virus (EBV) isolates can be classified as type A or type B depending upon the identity of their EBV nuclear antigen (EBNA) 2 protein. The great majority of isolates examined to date encode an EBNA 2A protein like that of the reference type A strain B95-8. Type B virus strains, encoding an antigenically distinct EBNA 2B protein, have as yet only been rescued from rare Burkitt's lymphoma (BL) cell lines of African origin (Jijoye, AG876). Our recent finding that type B isolates are less efficient than type A in in vitro transformation assays prompted us to determine (i) the relative contribution the two types of virus make to the incidence of BL in endemic areas of Africa (Kenya) and New Guinea and (ii) the relative incidence of infection with these two types in the normal population in these same areas. On the first point, EBNA 2 gene typing using specific DNA probes showed that four of ten recently established Kenyan BL cell lines and two of four BL cell lines from New Guinea carried type B virus isolates. To address the second point, spontaneous lymphoblastoid cell lines were established from the blood of normal virus carriers and typed for EBNA 2 at the protein level; a significant proportion (> 20 ~) of the normal population in both the above BLendemic areas were infected with type B isolates. This is the first indication of the widespread nature of type B virus infection in any community and the first isolation of such viruses from a non-BL source. The reproducible size of the EBNA 2B protein encoded by all type B isolates irrespective of their geographical origin, and of the EBNA 1 protein encoded by all type B isolates from one area, contrasted markedly with the extreme variability in the size both of EBNA 2A and of EBNA 1 seen generally among type A isolates. This suggests that the number of type B virus strains in existence worldwide could be quite limited. Most importantly, the data suggest that type B viruses, despite their relatively poor performance in in vitro transformation assays, can contribute at least as efficiently as can type A viruses to the pathogenesis of BL.

“…These include a species originally termed EBNA (Epstein-Barr nuclear antigen). In fact, three separate nuclear proteins are now recognized: EBNA1 (the original), EBNA2 and EBNA3 (Mueller-Lantzsch et al, 1985 ;Rymo et al, 1985;Hennessy et al, 1985). Yates et al (1985) and Lupton & Levine (1985) showed that EBNA1 alone is sufficient for maintenance of OriP plasmids, so that plasmids carrying OriP and an active EBNA1 gene replicate in many cell types not carrying EBV.…”

Section: Replication Of Epstein-barr Virus Dna In Latently Infected Cmentioning

confidence: 99%

Some Highlights of Animal Virus Research in 1985

McGeoch¹,

Halliburton²,

Meulen³

et al. 1986

For some time, the Editors of The Journal of General Virology have sought a format for presenting accounts of advances and notable events in virology, in a broader and more flexible manner than is afforded by the traditional review of a topic in depth. This article represents an experiment in such presentation. Its aim is to look at advances in virus research, and to present brief accounts of the most important and interesting work published within a calendar year. Subject to evaluation of the success of this first essay, an annual feature is envisaged.Implementation of these fine notions, however, has demanded some compromises. Virology comprises such an awesome range of techniques and objectives, with such a disparate assembly of virus types, that rigorous limits were necessary. Thus, we have confined our attention to animal viruses, and explicitly avoided any pretension to constructing a systematic review of all virology; the idea of selectivity was pre-eminent. In addition, this initial account has been very largely composed by one author, and so reflects one particular set of interests. Molecular and genome structural aspects are emphasized, and little overt attention is paid, for instance, to immunity and pathogenesis. The true high points of published research are relatively easy to identify, and their perception is probably not much affected by personal interests. The choice of lesser topics, however, is increasingly subjective; in particular, defining a cut-off point was not trivial. Our dealings are with 1985 as far as is practicable, but research advances do not really respect such clean divisions and so some flexibility has been exercised.Our final qualification concerns the nature of scientific advance: a 'highlight' is a phenomenon of a surface, and thus can exist only with an underlying structure. In our analogy, most research papers are considered part of this substratum. They also are an essential part (indeed, the major part) of overall advance, but their existence is only implicit in the present account.For this review, we consider that the major highlights of 1985 were analysis of the structures of two picornaviruses and research on the acquired immune deficiency syndrome (AIDS), and these are presented first. We then describe in succession selected aspects of work on genome organization, virus gene expression, genome replication and virus proteins, and finish with two topics at the edge of virology, namely, work on scrapie and on retrotransposons. The structures of two picornavirusesThe single and definitive high point of animal virus research in 1985 was the publication of two papers on X-ray crystallographic determination of the three-dimensional (3D) virion 0000-7094 © 1986 SGM