Viral DNA synthesis is required for the efficient expression of specific herpes simplex virus type 1 mRNA species

Expression of recombinant genes containing herpes simplex virus delayed-early and immediate-early regulatory regions and trans activation by herpesvirus infection

The promoter-regulatory regions from the herpes simplex virus type 1 (HSV-1) gene for the immediate-early, 175,000-molecular-weight (175K) protein and the HSV-2 delayed-early gene for a 38K protein were linked to the readily assayable bacterial gene for the enzyme chloramphenicol acetyltransferase (CAT). Unexpectedly, in measurements of the constitutive expression of the recombinant genes 40 to 50 h after transfection of Vero cells, enzyme levels expressed from the delayed-early 38K-promoter-CAT construct (p38KCAT) were at least as high as those from the immediate-early 175K-promoter-CAT construct (p175KCAT). In contrast, enzyme levels expressed after transfection of a similar recombinant gene containing a second delayed-early promoter region, that of the HSV-1 thymidine kinase gene, were ca. 20-fold lower. The amounts of enzyme expressed from both p38KCAT and p175KCAT could be increased by up to 20- to 40-fold after infection of the transfected cells with HSV. In comparison, virus infection had no significant effect on enzyme levels expressed from recombinant CAT genes containing the simian virus 40 early promoter region, with or without the 72-base-pair enhancer element. Experiments with the temperature-sensitive mutants HSV-1 tsB7 and HSV-1 tsK indicate that induction of expression from p175KCAT was mediated by components of the infecting virus particle, whereas that from p38KCAT required de novo expression of virus immediate-early proteins. In addition, we show that functions required to induce expression from both p175KCAT and p38KCAT could also be provided by infection with pseudorabies virus and cytomegalovirus.

Transactivation of a late herpes simplex virus promoter

We have asked whether the promoter for the gene encoding the major capsid protein (VP5) of herpes simplex virus functions in uninfected mouse cells. Our experimental strategy was to first fuse the VP5 promoter to the herpes simplex virus thymidine kinase (TK) structural sequence and then to use the resulting hybrid gene to transform TK- cells to TK+. The recombinant gene transferred TK at an extremely low frequency by comparison with the wild-type TK gene, and the TK transcripts present within the resulting rare transformants initiated within the TK structural gene, rather than in the vicinity of the VP5 promoter. However, after infection with herpes simplex virus, large amounts of RNA driven from the VP5 promoter accumulated. We conclude that the VP5 promoter does not function in uninfected cells but is efficiently activated by virally coded factors, most likely one or more immediate-early proteins.

Transactivation of a late herpes simplex virus promoter

We have asked whether the promoter for the gene encoding the major capsid protein (VP5) of herpes simplex virus functions in uninfected mouse cells. Our experimental strategy was to first fuse the VP5 promoter to the herpes simplex virus thymidine kinase (TK) structural sequence and then to use the resulting hybrid gene to transform TK- cells to TK+. The recombinant gene transferred TK at an extremely low frequency by comparison with the wild-type TK gene, and the TK transcripts present within the resulting rare transformants initiated within the TK structural gene, rather than in the vicinity of the VP5 promoter. However, after infection with herpes simplex virus, large amounts of RNA driven from the VP5 promoter accumulated. We conclude that the VP5 promoter does not function in uninfected cells but is efficiently activated by virally coded factors, most likely one or more immediate-early proteins.

Transcriptional and genetic analyses of the herpes simplex virus type 1 genome: coordinates 0.29 to 0.45

We have constructed a map of the genes encoded by a 23,000-nucleotide-pair region of herpes simplex virus type 1. This region, defined by the three adjacent EcoRI fragments N (map coordinates 0.298 to 0.315), F (0.315 to 0.421), and M (0.421 to 0.448), has previously been shown by genetic analysis to contain the genes for thymidine kinase, nucleocapsid protein p40, glycoprotein B, DNA-binding protein, and DNA polymerase. We report the identification and mapping of RNAs defining 13 viral genes encoded by the region 0.298 to 0.448. The transcriptional pattern shows families of overlapping messages, similar to those observed in other regions of the viral genome. We also isolated mutants representing four distinct complementation groups and physically mapped several of the mutations to regions within EcoRI fragment F by marker rescue. Mutations representing complementation groups 1-9 (glycoprotein B), 1-1 (DNA-binding protein), and 1-3 (DNA polymerase) were mapped to coordinates 0.361 to 0.368 to 0.411, and 0.411 to 0.421, respectively. A fourth previously undefined complementation group was mapped to the region between glycoprotein B and DNA-binding protein. Comparing the transcription mapping with marker rescue data suggests that the genes for glycoprotein B, DNA-binding protein, DNA polymerase, and nucleocapsid protein p40 are expressed as 3.3-, 4.2-, 4.3- or 4.2- or both, and 2.4-kilobase mRNAs, respectively.

Herpes simplex virus mutants defective in the virion-associated shutoff of host polypeptide synthesis and exhibiting abnormal synthesis of alpha (immediate early) viral polypeptides

Six mutants isolated from herpes simplex virus type 1 were judged to be defective with respect to the virion-associated function acting to rapidly shut off host polypeptide synthesis in herpes simplex virus-infected cells. The mutants were capable of proper entry into the cells, but, unlike the parent wild-type virus, they failed to shut off host polypeptide syntehsis in the presence of actinomycin D. They were consequently designated as virion-associated host shutoff (vhs) mutants. In the presence of actinomycin D, three of the mutants, vhs1, -2, and -3, failed to shut off the host at both 34 and 39 degrees C, whereas vhs4, -5, and -6 exhibited a temperature-dependent vhs phenotype. Since the mutants were capable of growth at 34 degrees C, it appeared that the vhs function was not essential for virus replication in cultured cells. Temperature-shift experiments performed with the vhs4 mutant showed that an active vhs function was required throughout the shutoff process and that, once established, the translational shutoff could not be reversed. In the absence of actinomycin D, the mutants induced a generalized, secondary shutoff of host translation, which required the synthesis of beta (early) or gamma (late) viral polypeptide(s). The vhs mutants appeared to be defective also with respect to post-transcriptional shutoff of alpha (immediate early) viral gene expression, since (i) cells infected with mutant viruses overproduced alpha viral polypeptides, (ii) there was an increased functional stability of alpha mRNA in the vhs1 mutant virus-infected cells, and (iii) superinfection of vhs1-infected cells with wild-type virus, in the presence of actinomycin D, resulted in a more pronounced shutoff of alpha polypeptide synthesis from preformed alpha mRNA than equivalent superinfection with vhs1 virus. The data suggest that the synthesis of alpha polypeptides in wild-type virus infections is subject to a negative post-transcriptional control involving viral gene product(s) present in infected cell lysates constituting virus stocks. The vhs1 mutant and possibly other vhs mutants contain a mutation in the gene encoding this function.

Identification of a subset of herpesvirus saimiri polypeptides synthesized in the absence of virus DNA replication

The effects of phosphonoacetic acid on the synthesis of herpesvirus saimiri-specific polypeptides in productively infected cells were examined. At concentrations that inhibited virus DNA synthesis (greater than or equal to 150 micrograms/ml), phosphonoacetic acid prevented the synthesis of the majority of virus-specific polypeptides while allowing the synthesis of a subset of virus proteins (i.e., 110,000 [110K], 76K, 72K, 51K, 48K, 29K, 24K, and 20K or 21K) and the protracted synthesis of host-specified polypeptides. Other inhibitors of DNA synthesis (e.g., cytosine arabinoside) showed the same selective inhibition of late virus protein synthesis and identified the same resistant subset of early virus-specific polypeptides. This DNA synthesis-independent subset included the 51K phosphoprotein, which, together with the 110K, 48K, and 31K polypeptides, accumulated in the nuclear fraction of infected cells.

Detailed analysis of the portion of the herpes simplex virus type 1 genome encoding glycoprotein C

We previously showed that the right third of HindIII fragment L (0.59 to 0.65) of herpes simplex virus type 1 (HSV-1) encodes a family of mRNAs some members of which appear to be related by splicing. In the experiments described in this communication, we determined the nucleotide sequence of the DNA encoding this mRNA family and precisely located the mRNAs associated with this DNA sequence. The major mRNA species is unspliced and encoded by a 2.520-nucleotide region. Just upstream of the 5' end are TATA and CAT box sequences characteristic of HSV-1 promoters. The 3' end maps near a region containing a nominal polyadenylation signal. Three minor species (2,400, 2,200, and 1,900 bases, respectively) appear to share a very short leader sequence with the 5' end of the major mRNA and are then encoded by uninterrupted DNA sequences beginning about 100, 400, and 625 bases downstream of the 5' end of the major unspliced mRNA. These positions map at or very near positions which agree reasonably well with consensus splice acceptor sequences. The fourth mRNA is encoded by a contiguous 730-nucleotide sequence at the 3' end of the major unspliced mRNA and has its 5' end just downstream of recognizable TATA and CAT box sequences. We suggest that this mRNA is controlled by its own promoter. The nucleotide sequence data, in combination with the mRNA localization, demonstrate four potential polypeptides encoded by the region. The largest is 1,569 bases long and defines a 523-amino acid protein with sequence features characteristic of a glycoprotein. This was confirmed to be HSV-1 glycoprotein C by immune precipitation of the in vitro translation product of the major unspliced mRNA, performed with a polyspecific antibody to HSV-1 envelope glycoproteins (anti-env-1 serum), and by comparison of tryptic peptides of this translation product with those of authentic HSV-1 glycoprotein C. Polypeptides encoded by some of the minor species also were tentatively identified.

Post-transcriptional control of human cytomegalovirus gene expression

During the immediate-early, early, and late phases of human cytomegalovirus infection in human fibroblasts, transcripts accumulated, respectively, from approximately 20, 75, and 90% of the sequences on the genome. Not all of the sequences which accumulated during the immediate-early and early phases were represented on polysomes, however. Four transcripts synthesized in cycloheximide-treated cells were studied in detail. A 2.2-kb transcript (0.713-0.733 map units) represented 95% of the polysome-associated RNA in cycloheximide-treated cells and was the first to be detected on polysomes at 2 hr postinfection in untreated cells. A second, less abundant, transcript of 5.2 kb (0.670-0.733 map units) was also found on polysomes in cycloheximide-treated cells, and preliminary evidence suggested that this transcript may be spliced during processing. A 3.25-kb transcript (0.190-0.217 map units) was identified also as a minor polysome-associated species of RNA. One transcript of 4.8 kb (0.630-0.670) remained associated with the nucleus and was not processed into mRNA in cycloheximide-treated cells. Differential stability between the various transcripts was observed, the 2.2-kb transcript being the most stable. The results showed that in human cytomegalovirus-infected cells controls exist at the level of transcript accumulation, transport into the cytoplasm, preferential association with polysomes, and relative stability of RNAs.

Transcription of herpes simplex virus genes in vivo: overlap of a late promoter with the 3' end of the early thymidine kinase gene

We identified in herpes simplex virus type 1-infected cells six cytoplasmic transcripts which were complementary to BamHI restriction endonuclease fragment Q. Two transcripts appeared in major amounts compared with the other four. One major transcript of about 1.4 kilobases was the mRNA for the viral thymidine kinase, was synthesized at intermediate times, and was classified as a beta transcript. The other major transcript was synthesized at late times and was classified as a gamma transcript. This late transcript was about 3 kilonucleotides long and was transcribed in the same direction as the gene for thymidine kinase. The 5' end of this late RNA was located by RNA sequence analysis and was 23 nucleotides downstream from the polyadenylation site for the thymidine kinase mRNA. This finding led to the conclusion that the control region for the 3-kilobase gamma transcript is contained within the 3' untranslated region of the thymidine kinase transcript.

Herpes simplex virus mRNA species mapping in EcoRI fragment I

We described the detailed characterization and high-resolution mapping of nine herpes simplex virus type 1 mRNAs encoded in EcoRI fragment I. Four of these mRNAs are partially colinear and encode the same sized polypeptide in vitro. Nucleotide sequence analysis of the DNA around the 5' ends of these mRNAs suggested that the larger may encode a small (ca. 100-dalton) polypeptide not resolvable by in vitro translation.

DNA sequence of an immediate-early gene (IEmRNA-5) of herpes simplex virus type I

We describe a 2560 base pair herpes simplex virus type 1 (HSV-1) DNA sequence containing the entire immediate-early mRNA-5 (IEmRNA-5) gene. The 3' and 5' termini of IEmRNA-5 were mapped within this DNA sequence by single-strand specific endonuclease protection experiments. The IEmRNA-5 gene contains DNA sequences from both the unique (Us) and reiterated (TRs/IRs) regions of the HSV-1 DNA short component and is interrupted by a single intron mapping in TRs/IRs. A search of the transcribed DNA sequence revealed no initiator codon within TRs/IRs. The first ATG was located 6 bases into Us sequences and this reading frame (316 codons) was also observed in the 3' transcribed region. The oligonucleotide sequences adjacent to the IEmRNA-5 termini are discussed in relation to those of the HSV-1 thymidine kinase gene and other genes transcribed by RNA polymerase II.

Herpes simplex virus type 1 HindIII fragment L encodes spliced and complementary mRNA species

We have used DNA bound to cellulose to isolate and translate in vitro herpes simplex virus type 1 (HSV-1) mRNA's encoded by HindIII fragment L (mapping between 0.592 and 0.647), and 8.450-base-pair (8.45-kb) portion of the long unique region of the viral genome. Readily detectable, late mRNA's 2.7 and 1.9 kb in size encoding 69,000- and 58,000-dalton polypeptides, respectively, were isolated. A very minor late mRNA family composed of two colinear forms, one 2.6 kb and one 2.8 kb, was isolated and found to encode only an 85,000-dalton polypeptide. A major early mRNA, 1.8 kb in size encoding a 64,000-dalton polypeptide, was also isolated. High-resolution mapping of these mRNA's by using S1 nuclease and exonuclease VII digestion of hybrids between them and 5' and 3' end-labeled DNA fragments from the region indicated that the major early mRNA contained no detectable splices, and about half of its 3' end was complementary to the 3' region of the very minor 2.6- to 2.8-kb mRNA's encoded on the opposite strand. These mRNA's also contained no detectable splices. The major late 2.7-kb mRNA was found to be a family made up of members with no detectable splices and members with variable-length (100 to 300 bases) segments spliced out very near (ca. 50 to 100 bases) the 5' end.

Identification and mapping of two polypeptides encoded within the herpes simplex virus type 1 thymidine kinase gene sequences

mRNA's homologous to the herpes simplex virus type 1 DNA restriction endonuclease fragment BamHI p, which contains the thymidine kinase gene, have been identified and mapped by hybrid-arrested translation and mRNA selection. Such mRNA's, when translated in vitro, directed the synthesis of polypeptides of apparent molecular weights 43,000 (VI43) and 39,000 (VI39). mRNA for enzymatically active thymidine kinase was enriched by more than 20-fold after selection. Mapping was carried out with restriction endonuclease fragments of BamHI p, and locations of the 5' and 3' termini of VI43 mRNA were deduced. Analysis of nucleotide sequences around the 5' terminus revealed several consensus sequences commonly found at the start of eucaryotic mRNA's and which are presumably involved in initiation of transcription by RNA polymerase II. Translation of mRNA's for VI43, VI39, and the thymidine kinase enzyme was arrested only by a 1,170-base-pair region of BamHI p. Since this region is insufficient for adjacent genes, coding sequences for VI43 and VI39 must overlap; the possible relationship of these two polypeptides is discussed. A virus-induced product equivalent to VI39 was detected in infected cells.

Characterization of a major late herpes simplex virus type 1 mRNA

A major, late 6-kilobase (6-kb) mRNa mapping in the large unique region of herpes simplex virus type 1 (HSV-1) was characterized by using two recombinant DNA clones, one containing EcoRI fragment G (0.190 to 0.30 map units) in lambda. WES.B (L. Enquist, M. Madden, P. Schiop-Stansly, and G. Vandl Woude, Science 203:541-544, 1979) and one containing HindIII fragment J (0.181 to 0.259 map units) in pBR322. This 6-kb mRNA had its 3' end to the left of 0.231 on the prototypical arrangement of the HSV-1 genome and was transcribed from right to left. It was bounded on both sides by regions containing a large number of distinct mRNA species, and its 3' end was partially colinear with a 1.5-kb mRNA which encoded a 35,000-dalton polypeptide. The 6-kb mRNA encoded a 155,000-dalton polypeptide which was shown to be the only one of this size detectable by hybrid-arrested translation encoded by late polyadenylated polyribosomal RNA. The S1 nuclease mapping experiments indicated that there were no introns in the coding sequence for this mRNA and that its 3' end mapped approximately 800 nucleotides to the left of the BglII site at 0.231, whereas its 5' end extended very close to the BamHI site at 0.266.

Gene expression of herpes simplex virus. III. Effect of arabinosyladenine on viral polypeptide synthesis

Arabinosyladenine, an established antiherpetic drug, was used to block herpes simplex virus type 1 DNA synthesis quantitatively in infected xeroderma pigmentosum cells. Kinetic analyses of viral polypeptides synthesized in the presence and absence of this drug revealed that there were at least six distinct kinetic classes of polypeptides. These differed in time of appearance after infection, time of maximum rate of synthesis, kinetics of turnoff, and sensitivity to arabinosyladenine. This study showed that arabinosyladenine had the following three main effects on herpes simplex virus type 1 gene expression. (i) The turnon of immediate early and delayed early polypeptides (kinetic classes 1 and 2) was retarded. (ii) The turnoff of early (immediate early and delayed early) polypeptides (classes 1 through 3) was delayed. (iii) The synthesis of late polypeptides (class 4 through 6) was inhibited by arabinosyladenine, with class 6 severely (80 to 90%) inhibited. The kinetic data presented here, along with the findings of other workers on the effects of inhibition of viral DNA synthesis, suggest that viral DNA replication is required for optimum synthesis of late viral polypeptides.

Detailed characterization of the mRNA mapping in the HindIII fragment K region of the herpes simplex virus type 1 genome

We have isolated as recombinant DNA clones, in the plasmid pBR322, regions of the herpesvirus type 1 genome spanning the region between 0.53 and 0.6 on the prototypical arrangement. This 11,000-base-pair region corresponds to 10% of the large unique region and encodes five major and several minor mRNA species abundant at different times after infection, which range in length from 7 to 1 kilobase. In this report, we have used RNA transfer blots and S1 nuclease digestion of hybrids between viral DNA and polyribosomal RNA to precisely localize (+/- 0.1 kilobase) these mRNA's. Comparison of neutral and alkaline gels of S1 nuclease-digested hybrids indicates no internal introns in the coding sequences of these mRNA's, although noncontiguous leader sequences near (ca. 0.1 kilobase) the 5' ends of any or all mRNA's could not be excluded. The 5' ends of several late mRNA's that are encoded opposite DNA strands map very close to one another, and the 3' ends of a major late and a major early mRNA, which are partially colinear, terminate in the same region. In vitro translation of the viral mRNA's isolated by hybridization with DNA bound to cellulose and fractionation of mRNA species on denaturing agarose gels allowed us to assign specific polypeptide products to each of the mRNA's characterized. Among other results, it was demonstrated unequivocally that two major late mRNA's, which partially overlap, encode the same polypeptide.

Epstein-Barr virus polypeptides: effect of inhibition of viral DNA replication on their synthesis

After Epstein-Barr virus superinfection of the human lymphoblastoid cell line Raji, a Burkitt lymphoma-derived line that contains Epstein-Barr virus genomes in an episomal form, at least 40 polypeptides could be resolved by polyacrylamide gel electrophoresis. Eleven of the 40 polypeptides were immunoprecipitable by early antigen+/viral capsid antigen+ antiserum. The polypeptides could be divided into six classes, immediate-early, early, intermediate, late, very late, and persistent, depending upon the time of synthesis. Ten of the 40 polypeptides appeared to preexist before superinfection and persisted despite general cessation of host protein synthesis; none of the persistent proteins was immunoprecipitated by the Epstein-Barr virus antibody-containing serum. When viral DNA replication was blocked by a variety of inhibitors of DNA synthesis, a number of different patterns of polypeptide synthesis could be detected. The synthesis of six polypeptides was blocked by the most virus-specific inhibitors, acyclovir and phosphonoacetic acid. Additionally, in the presence of 1-beta-D-arabinofuranosylcytosine, 1-beta-D-arabinofuranosyladenine, and methotrexate, seven polypeptides showed oversynthesis.

Structures of two spliced herpes simplex virus type 1 immediate-early mRNA's which map at the junctions of the unique and reiterated regions of the virus DNA S component

We have examined the structures of two herpes simplex virus type 1 immediate-early (IE) RNAs (IE mRNA-4 and IE mRNA-5) which map at the junctions of the unique (Us) and reiterated regions (TRs/IRs) of the virus DNA short component. Hybrids between IE cytoplasmic RNA and herpes simplex virus type 1 DNA restriction fragments were digested with single-strand-specific nucleases S1 and exonuclease VII, and the products were analyzed by agarose gel electrophoresis. Data obtained with the nuclease digestion technique were confirmed by electron microscopy of R-loop structures formed with polyadenylated IE RNA and virus DNA fragments. It was found that both IE mRNA-4 and IE mRNA-5 contained a 260-base 5'-terminal cotranscript which mapped at equivalent loci within TRs/IRs. These 5'-terminal sequences were shown to be spliced to 3'-terminal cotranscripts of 1,450 bases (for IE mRNA-4) and 1,540 bases (for IE mRNA-5). The 3'-terminal cotranscripts contained sequences encoded by both TRs/IRs and opposite ends of Us, indicating that the introns contained by the IE mRNA-4 and IE mRNA-5 genes, found to be approximately 150 base pairs in size, mapped entirely within the reiterated sequences. The data suggest that these genes may contain common and unique components, and the implications of this model are discussed.