Structure and function of herpesvirus genomes. I. comparison of five HSV-1 and two HSV-2 strains by cleavage their DNA with eco R I restriction endonuclease

Characteristics of the a sequence of the duck Plague virus genome and specific cleavage of the viral genome based on the a sequence

During the replication process, the herpesvirus genome forms the head-to-tail linked concatemeric genome, which is then cleaved and packaged into the capsid. The cleavage and packing process is carried out by the terminase complex, which specifically recognizes and cleaves the concatemeric genome. This process is governed by a cis-acting sequence in the genome, named the a sequence. The a sequence and genome cleavage have been described in some herpesviruses, but it remains unclear in duck plague virus. In this study, we analysed the location, composition, and conservation of a sequence in the duck plague virus genome. The structure of the DPV genome has an a sequence of (DR4)m-(DR2)n-pac1-S termini (32 bp)-L termini (32 bp)-pac2, and the length is 841 bp. Direct repeat (DR) sequences are conserved in different DPV strains, but the number of DR copies is inconsistent. Additionally, the typical DR1 sequence was not found in the DPV a sequence. The Pac1 and pac2 motifs are relatively conserved between DPV and other herpesviruses. Cleavage of the DPV concatemeric genome was detected, and the results showed that the DPV genome can form a concatemer and is cleaved into a monomer at a specific site. We also established a sensitive method, TaqMan dual qRT‒PCR, to analyse genome cleavage. The ratio of concatemer to total viral genome was decreased during the replication process. These results will be critical for understanding the process of DPV genome cleavage, and the application of TaqMan dual qRT‒PCR will greatly facilitate more in-depth research.

Toll-like receptor 3 (TLR3) plays a major role in the formation of rabies virus Negri Bodies

Human neurons express the innate immune response receptor, Toll-like receptor 3 (TLR3). TLR3 levels are increased in pathological conditions such as brain virus infection. Here, we further investigated the production, cellular localisation, and function of neuronal TLR3 during neuronotropic rabies virus (RABV) infection in human neuronal cells. Following RABV infection, TLR3 is not only present in endosomes, as observed in the absence of infection, but also in detergent-resistant perinuclear inclusion bodies. As well as TLR3, these inclusion bodies contain the viral genome and viral proteins (N and P, but not G). The size and composition of inclusion bodies and the absence of a surrounding membrane, as shown by electron microscopy, suggest they correspond to the previously described Negri Bodies (NBs). NBs are not formed in the absence of TLR3, and TLR3^−/− mice—in which brain tissue was less severely infected—had a better survival rate than WT mice. These observations demonstrate that TLR3 is a major molecule involved in the spatial arrangement of RABV–induced NBs and viral replication. This study shows how viruses can exploit cellular proteins and compartmentalisation for their own benefit.

Viruses are obligate parasites. The progression of their life cycle depends on their hijacking the cellular metabolism and machinery. Human neurons produce TLR3, a protein involved in early host defence mechanisms and the modulation of neuronal survival. Rabies virus is a neurotropic virus, infecting mainly neurons. In this study, we showed that rabies virus exploits TLR3 function to store viral proteins and viral genomic material in particular areas of the cell where virus multiplication occurs. We found that, during the course of infection, large (1–3 µm) spherical inclusions were formed within the region around the nucleus. These inclusions were composed of an inner core of aggregated TLR3 surrounded by a coat of viral proteins and genomic material. These inclusions were revealed to be the previously described Negri Bodies (NBs). In absence of TLR3, NBs were no longer formed and virus multiplication rate decreased. Mice deficient in TLR3 were more resistant to rabies and had lower levels of infection in their brains. This study shows how neurotropic viruses, such as rabies virus, hijack normal functions of neuronal proteins and use cell compartmentalisation to promote viral multiplication.

Virus infection switches TLR-3-positive human neurons to become strong producers of beta interferon

To study the capacity of human neurons to mount innate immunity responses to viral infections, we infected cells of a human postmitotic neuron-derivative cell line, NT2-N, with rabies virus (RABV) and herpes simplex type 1 (HSV-1). Changes in neuronal gene expression were analyzed by use of Affymetrix microarrays. Applying a twofold cutoff, RABV increased the transcription of 228 genes, and HSV-1 increased the transcription of 263 genes. The most striking difference between the two infections concerns genes involved in immunity. These genes represent 24% of the RABV-upregulated genes and only 4.9% of the HSV-1-upregulated genes. Following RABV infection, the most upregulated genes belong to the immunity cluster and included almost exclusively genes for beta interferon (IFN-beta) primary and secondary responses as well as genes for chemokines (CCL-5, CXCL-10) and inflammatory cytokines (interleukin 6 [IL-6], tumor necrosis factor alpha, interleukin 1 alpha). In contrast, HSV-1 infection did not increase IFN-beta gene transcripts and triggered the production of only IL-6 and interferon regulatory factor 1 mRNAs. The microarray results were confirmed by real-time PCR, immunocytochemistry, and enzyme-linked immunosorbent assay. Human neurons were found to express Toll-like receptor 3. They produced IFN-beta after treatment with poly(I:C) but not with lipopolysaccharide. Thus, human neurons can mount an innate immunity response to double-stranded RNA. These observations firmly establish that human neurons, in absence of glia, have the intrinsic machinery to sense virus infection.

Virus infection switches TLR-3-positive human neurons to become strong producers of beta interferon

To study the capacity of human neurons to mount innate immunity responses to viral infections, we infected cells of a human postmitotic neuron-derivative cell line, NT2-N, with rabies virus (RABV) and herpes simplex type 1 (HSV-1). Changes in neuronal gene expression were analyzed by use of Affymetrix microarrays. Applying a twofold cutoff, RABV increased the transcription of 228 genes, and HSV-1 increased the transcription of 263 genes. The most striking difference between the two infections concerns genes involved in immunity. These genes represent 24% of the RABV-upregulated genes and only 4.9% of the HSV-1-upregulated genes. Following RABV infection, the most upregulated genes belong to the immunity cluster and included almost exclusively genes for beta interferon (IFN-beta) primary and secondary responses as well as genes for chemokines (CCL-5, CXCL-10) and inflammatory cytokines (interleukin 6 [IL-6], tumor necrosis factor alpha, interleukin 1 alpha). In contrast, HSV-1 infection did not increase IFN-beta gene transcripts and triggered the production of only IL-6 and interferon regulatory factor 1 mRNAs. The microarray results were confirmed by real-time PCR, immunocytochemistry, and enzyme-linked immunosorbent assay. Human neurons were found to express Toll-like receptor 3. They produced IFN-beta after treatment with poly(I:C) but not with lipopolysaccharide. Thus, human neurons can mount an innate immunity response to double-stranded RNA. These observations firmly establish that human neurons, in absence of glia, have the intrinsic machinery to sense virus infection.

Detection and differentiation of primate alpha-herpesviruses by PCR

A rapid method for detection and differentiation of 5 primate alpha-herpesviruses (human herpes simplex virus types 1 and 2 [HSV1, HSV2], green monkey simian agent 8, baboon herpesvirus 2 [HVP2], and macaque B virus [BV]) was developed utilizing the polymerase chain reaction (PCR). PCR primers were located in conserved regions of the gene encoding the glycoprotein B, which flanks an intervening region that is highly divergent among the 5 viruses. Amplified PCR products from the 5 viruses were readily differentiated by their unique restriction enzyme digestion patterns. No variation in digestion patterns was noted among strains of HSV1, HSV2, or HVP2. One clinical isolate of BV exhibited variation in a single restriction site, but its overall restriction pattern remained typical of BV. This method (PCR/RFLP) allowed the presence of herpesvirus DNA in clinical swabs from primates to be readily detected and the virus unambiguously identified.

Herpesvirus papio 2, an SA8-like alpha-herpesvirus of baboons

Several SA8 isolates obtained from baboons were compared to the prototype SA8 herpesvirus of African green monkeys. SDS-PAGE and restriction enzyme analyses revealed definite differences between green monkey and baboon isolates. DNA and amino acid sequences of the gB, gD and gJ glycoprotein genes exhibited substantial differences in variable regions. For the gB and gD, the amount of amino acid substitutions between SA8 and the baboon viruses was comparable to levels observed between analogous genes of SA8 & B virus or HSV1 & HSV2. Although a high degree of antigenic cross-reactivity was apparent, virus-specific antigenic determinants were also readily detected. Phylogenetic analyses supported separation of the baboon isolates and SA8 as distinct viruses. Taken together these results suggest that although closely related to SA8, the baboon viruses represent a distinct simian alpha-herpesvirus which we propose be designated Herpesvirus papio 2.

Preparation of herpes simplex virus type 1 genomic markers to differentiate strains of predominant genotypes

Analyses of restriction fragment length polymorphism (RFLP) of herpes simplex virus type 1 (HSV-1) isolated in Japan using restriction endonucleases recognizing 6-base pairs revealed the presence of two predominant genotypes of F1 and F35. Therefore, the possibility that the two predominant genotypes may differ in clinical manifestations had to be considered. To address the question of whether differences in genotype would reflect clinical presentations of HSV-1 infection, RFLP markers to differentiate strains of predominant genotypes are required. In the present work, DNAs of 66 HSV-1 strains were analyzed, using restriction endonucleases recognizing 4-base pairs of HaeIII, HhaI, and MboI, the objective being to detect a large number of RFLP. The relationship between the 154 identified RFLPs and each predominant genotype of F1 and F35 was traced. RFLPs closely related to each predominant genotype were manifested, as the first case of a set of RFLPs diagnostic for the predominant genotypes. These diagnostic RFLPs will facilitate knowledge on association of predominant genotypes with clinical manifestations by efficiently identifying HSV-1 strains of a genotype, and, in addition, HSV-1 strains of a predominant genotype derived from a common ancestor.

Genomic characterization of two predominant genotypes of herpes simplex virus type 1

Genomic profiles of 66 strains of herpes simplex virus type 1 (HSV-1) isolated in Japan were investigated with regard to restriction fragment length polymorphism (RFLP) and length variation of fragments containing reiterations. There were two predominant genotypes of F1 and F35, and the genomic characteristics of each were studied. The nucleotide change between F1 and F35 was estimated to be 1.5%. An RFLP marker (VR23) peculiar to genotype F35 was identified as the first case of genomic marker specific to a predominant genotype of HSV-1, and is the diagnostic marker of F35. The a sequences (repeating in an HSV-1 genome and containing reiterations) of F35 were cleaved by SacII on the DR4 (direct repeat 4) stretch, while a sequences of F1 had a rearranged DR4 and were resistant to SacII digestion. Thus, analyses of fragments containing reiterations, such as a sequences, can serve to classify HSV-1 strains as well as for purpose of differentiation. The proportion of strains derived from primary infection to those from recurrent infection was higher in strains of F35 than in those of F1, and this genotypic difference within HSV-1 may possibly influence clinical manifestations.

A rapid method for purification of herpesvirus DNA

A rapid and reliable method for purification of herpesvirus DNA from cell cultures is described. The method is based on the isolation of virus particles and/or nucleocapsids by differential centrifugation and exploits the solubilizing and denaturing capabilities of cesium trifluoroacetate during isopycnic centrifugation, so that phenol/chloroform extractions can be omitted. The method was used for the purification of DNA from several members of the Alfaherpesvirinae subfamily.

Reiterated sequences of herpes simplex virus type 1 (HSV-1) genome can serve as physical markers for the differentiation of HSV-1 strains

The stability of regions containing tandemly reiterated sequences in the S component of the herpes simplex virus type 1 (HSV-1) genome was determined, by comparing restriction fragments of the regions among sets of HSV-1 isolates derived from a single source. The 6 reiterations examined were grouped into three. Reiteration VII (within protein coding regions of genes US10 and US11) and reiteration IV (within introns of genes US1 and US12) were stable between the isolates (group 1). Regions containing one of four other reiterations were detected as a set of ladder-like fragments. Reiteration II (between "a" sequence and IE 175 gene) and reiteration VI (within an intergenic region on the 3' side of the 3' co-terminal family of genes US10, US11, and US12) (group 3) were more unstable than reiteration I (within "a" sequence) and reiteration III (between "a" sequence and IE175 gene) (group 2). The mode of fluctuation of the reiterations observed within a set of HSV-1 strains isolated from an individual was similar to that observed between HSV-1 single-plaque clones separated in cultured cells. These reiterations, except for group 3, can serve as sensitive and convenient markers for differentiating HSV-1 strains.

Discrimination between twenty isolates of herpesvirus simiae (B virus) by restriction enzyme analysis of the viral genome

Twenty isolates, obtained from adult breeding monkeys, were all identified as herpesvirus simiae (B virus) by neutralisation with polyclonal B virus antiserum. Subsequent analysis of restriction enzyme profiles produced by digestion of DNA from the isolates enabled discrimination to be made between them. In particular Cynomolgus monkey isolates could be distinguished from those of Rhesus animals. One isolate (isolate 9) could not be typed either as B virus or as the antigenically related herpesvirus SA8, despite neutralisation by B virus antiserum. Unlike herpes simplex virus, B virus isolates could not be divided into oral and genital types on the basis of restriction enzyme profiles.

Comparison of genomes of malignant catarrhal fever-associated herpesviruses by restriction endonuclease analysis

The restriction endonuclease DNA cleavage patterns of eight isolates of malignant catarrhal fever-associated herpesviruses were examined using the restriction endonucleases HindIII and EcoRI. The eight viruses could be assigned to two distinct groups. Virus isolates from a blue wildebeest, a sika deer and an ibex had restriction endonuclease DNA cleavage patterns that were in general similar to each other. The restriction pattern of these three viruses was distinct from the other five. Of these five, four were isolated from a greater kudu, a white tailed wildebeest, a white bearded wildebeest, and a cape hartebeest. The fifth isolate C500, was isolated from a domestic cow with malignant catarrhal fever. These five viruses had similar DNA cleavage patterns.

DNA polymorphism in strains of the genus Brucella

Preparations of DNA from 23 Brucella strains including 19 reference strains were compared by restriction endonuclease analysis. Pulsed-field gel electrophoresis resulted in optimal resolution of fragments generated by digestion with low-cleavage-frequency restriction enzymes such as XbaI. By this technique, five electrophoretypes were distinguished in five reference strains of the different species, i.e., B. abortus, B. melitensis, B. suis, B. canis, and B. ovis. Minor profile differences allowed us to discriminate between most biovars within a species. However, the differences in the DNA patterns of different field strains of biovar 2 of B. melitensis were not sufficient to serve as markers for epidemiological studies. From the XbaI fragments, we were able to estimate the size of the genomes of B. abortus 544T and B. melitensis 16 MT. This method revealed a relationship between DNA fingerprints, species, and pathovars which could shed light on problems concerning the classification and evolution of members of the genus Brucella.

Genome isomerism in two alphaherpesviruses: Herpesvirus saimiri-1 (Herpesvirus tamarinus) and avian infectious laryngotracheitis virus. Brief report

Genome isomerism of avian infectious laryngotracheitis virus (ILT) and Herpesvirus saimiri-1 (HVS-1) (formerly H. tamarinus) was investigated using restriction endonuclease analysis and scanning densitometry. ILT DNA was found to have 2 isomers with a molecular weight of 109 X 10(6). HVS-1 DNA was found to have four isomers with a molecular weight of 102 X 10(6).

Restriction endonucleases recognizing DNA sequences of four base pairs facilitate differentiation of herpes simplex virus type 1 strains

Variation of restriction endonuclease cleavage patterns between herpes simplex virus type 1 (HSV-1) strains was investigated using restriction endonucleases recognizing DNA sequences of four base pairs (4-bp enzymes) (HaeIII, HhaI, Sau3AI). The analysis made feasible identification of variations not heretofore detectable, using enzymes recognizing DNA sequences of six base pairs (BamHI, KpnI, SalI), and proved to be most useful for distinction and classification of HSV-1 strains. Ten of the fifteen strains analysed using 4-bp enzymes were closely related, and were put into group 1, and the other five not so related strains were classed into the non-group 1. The observations suggested a possible common ancestor from which group 1 strains had derived.

Transition from a heterozygous to a homozygous state of a pair of loci in the inverted repeat sequences of the L component of the herpes simplex virus type 1 genome

The behavior of herpes simplex virus type 1 heterozygous isolates, in which the two inverted repeats of the L component (RL) were differentiated by a polymorphism marker (the presence [type B] or absence [type A] of a SalI site), was investigated. The progeny viruses derived from the heterozygote (A/B) consisted of heterozygotes (A/B), type A homozygotes (A/A), and type B homozygotes (B/B). The heterology between RL, albeit tolerated, was unstable, as is the case with heterology between the repeats of the S component. The two repeats TRL (terminal) and IRL (internal) were equipotent in generating homozygotes from a heterozygote. Data obtained from an analysis of 426 progeny viruses derived from heterozygous clones supported the hypothesis that the two loci in RL of a herpes simplex virus type 1 genome are determined as a random combination of the corresponding two loci in RL of the parent virus and that the ratio of heterozygotes/type A homozygotes/type B homozygotes in the progeny viruses from a heterozygote is expected to be 2:1:1. An ephemeral dominance of one type of homozygote over the other was observed in subclones from several heterozygous clones.

Putative glycoprotein gene of varicella-zoster virus with variable copy numbers of a 42-base-pair repeat sequence has homology to herpes simplex virus glycoprotein C

A strain variation of varicella-zoster virus that maps to the UL region of the genome was found to be due to different copy numbers of a high GC 42-base-pair repeat. DNA sequence analysis of this variable region showed the sequence to be 5-GCGGGATCGGGCTTTCGGG(A/T)AGCGGCCGAGGTGGGCGCGACG-3. Strains Scott and Webster both contain 7 and 32/42 copies of the repeat, whereas strain Oka has exactly 4 copies less. Microheterogeneity exists within the repeated sequences, depending on the strain and the repeat number. Sequencing of the entire EcoRI P fragment (which contains the repeated sequences) and part of the adjacent EcoRI M and EcoRI Q fragments from strain Scott showed that the repeats are part of a large open reading frame that could code for a polypeptide core with a molecular weight of 66,000. Several potential TATA boxes exist upstream and two polyadenylation signals are found downstream of the open reading frame. The predicted protein bears several characteristics of a glycoprotein. The region is transcriptionally active in varicella-zoster virus-infected cells, specifying at least three RNA species of 1.7, 1.95, and 2.5 kilobases, which are transcribed from the same DNA strand. Part of the predicted protein has a high degree of homology to the herpes simplex virus type 1 glycoprotein gC.

Possible relationship between antigenic properties and isolation history of HSV-1 strains

29 monoclonal anti-herpes simplex virus (HSV)-1 antibodies were produced and characterized with regard to virus neutralizing activity, intracellular or cell-surface location of viral antigens and, where possible, molecular weight of the viral protein recognized. 13 antibodies recognized viral antigens expressed on the surface of infected cells and 16 were directed to intracellular viral components. Only two antibodies exhibited virus neutralizing activity. Application of these antibodies to an antigenic comparison of standard laboratory HSV-1 strains F, HFEM, mP, Glasgow-17 and MAC revealed unique antigenic differences among these strains. The antibodies were further used in an antigenic comparison of 45 human HSV-1 isolates with defined isolation history. Except for two paired isolates from left and right trigeminal ganglia of two human cadavers, the antibody panel revealed antigenic differences among all isolates, including paired isolates from three additional cadavers. Overall, isolates from different human donors showed greater antigenic dissimilarity from each other in cell-surface associated than in intracellular antigens. The data suggest the possibility of a correlation between antigenic and biologic properties of HSV-1.

Study of herpes simplex virus type 1 populations obtained from recurrences and primary infections

The analysis of 23 clinical isolates of herpes simplex virus type 1 (HSV-1) showed that 15 of 15 isolates that had undergone a few passages in tissue culture (fresh isolates) and two of eight isolates that had never been passaged (new isolates) were composed of a mixed population with respect to plaque morphology in Vero cells. Cloning and characterization of 10 large plaque viruses (L variants) and nine small plaque viruses (S variants), obtained from seven different isolates, showed the following. BamHI DNA restriction patterns of the L and the S variants from a single isolate differed only with respect to the electrophoretic mobility of the fragments that contain reiteration of specific sequences; they did not differ regarding the presence or the absence of restriction endonuclease cleavage sites. The L and S variants differed with respect to the electrophoretic profiles of infected cell glycoproteins, thermosensitivity of growth and plaquing efficiency at 39 degrees C, and, at least in the case of the two couples of variants that we tested, pathogenicity for the mouse. The hypothesis that the L variants might arise from the S variant during in vivo replication is discussed.

Herpes simplex virus type 1 restriction fragment polymorphism determined using southern hybridization

Regions of herpes simplex virus type 1 (HSV-1) DNA with variation in the size of restriction endonuclease fragments were identified by comparison of the BamHI, KpnI or SalI restriction endonuclease digestion patterns among 15 HSV-1 isolates after hybridization with specific 32P-labeled cloned HSV-1 DNA fragments. Of the types of restriction fragment polymorphism identified, one was a strain with a distinctly different restriction fragment than the prototype (loss or gain of restriction sites). Another type, the specific fragment varied only in size among strains. Thirteen distinct variations were identified. Ten were mapped to the unique sequence of the L component; two to the inverted repeat of the L component and one to the inverted repeat of the S component. The presence of a common ancestor from which some isolates of HSV-1 might derive was deduced from an analysis of the distribution of the thirteen variations among the 15 HSV-1 isolates.

Comparison of Chlamydia psittaci isolates by DNA restriction endonuclease analysis

Preparations of DNA from 12 Chlamydia psittaci isolates and one Chlamydia trachomatis strain were compared by restriction endonuclease analysis. Polyacrylamide gel electrophoresis, followed by silver staining, resulted in optimal resolution of fragments generated by digestion. By this technique, four distinct electropherotypes were demonstrated when ovine abortion, ovine arthritis, and avian and Cal10 strains of C. psittaci were examined. Minor profile differences allowed the discrimination of avian isolates derived from psittacine and columbiforme species, and the Cal10 DNA electropherotype was shown to have features in common with these profiles. However, there were no detectable differences in the DNA patterns of eight ovine abortion isolates.

Comparison of a commercial ELISA system with restriction endonuclease analysis for typing herpes simplex virus

Isolates of herpes simplex virus which had previously been typed by restriction enzyme analysis were typed again with a commercial ELISA system using polyclonal antibodies. There was complete correlation between the two techniques. Although restriction is more precise and definitive, when typing only is required the simplicity of ELISA makes it the preferred technique.

Structural organization of human herpesvirus DNA molecules

The herpesviruses are among the largest and most complex of all DNA viruses, and their genomes display an astonishing diversity in size, structure, and organization. In 1974, the features of large inverted repeats and structural isomerization were first discovered, and these proved to be characteristic properties of many herpesvirus genomes. Since then, research using the powerful techniques of modern molecular biology has revealed a great deal of comparative structural information about the arrangement of repetitive sequences and the location, structure, and primary nucleotide sequences of the genes for several easily assayed or abundantly expressed gene products. Extensive restriction enzyme cleavage maps and complete sets of cloned DNA fragments have been constructed for each of the five human herpesviruses, HSV-1, HSV-2, CMV, EBV, and VZV, and the entire 175,000-bp nucleotide sequence of EBV DNA has been determined. Based on these maps and reagents, the procedures of "DNA fingerprinting" and "dot hybridization" are proving useful at a clinical level for characterization of isolates and studying herpesvirus epidemiology. Strain differences, localized heterogeneity, tandem-repeat-defective genomes, and sites of cell-virus DNA homology have been described in some detail. The attention of basic researchers is now turning to equating structure with function, and rapid progress is expected in studies aimed at a better understanding of the mechanisms of viral DNA replication, maintenance of the latent state, reactivation, transformation, packaging, and regulation of the lytic cycle, etc using cloned functionally active DNA fragments, isolated intact genes and promoters, and DNA transfection and in vitro expression systems.

Restriction endonuclease cleavage analysis of herpes simplex virus isolates obtained from three pairs of siblings

Cleavage of herpes simplex virus type 1-infected cell DNA with restriction endonucleases showed that profiles of paired isolates obtained from three groups of siblings were essentially identical. This finding is different from that for profiles of other paired isolates that are epidemiologically unrelated. One set of paired isolates of the three had completely identical profiles. However, two other sets of paired isolates yielded minor heterogeneity in fragments derived from the regions spanning the unique repeat junction and repeated regions of the herpes simplex virus type 1 genome. This suggests that the regions of the herpes simplex virus genome are variable during viral DNA replication. This finding also supports the hypothesis that the same variants tend to be transmitted and thereafter perpetuate within a family cluster.

The use of monoclonal antibodies to differentiate isolates of herpes simplex types 1 and 2 by neutralisation and reverse passive haemagglutination tests

Monoclonal antibodies specific for herpes simplex type 1 or type 2 were used in reverse passive haemagglutination tests or infectivity neutralisation tests to serotype 100 isolates of herpes simplex virus (HSV). All isolates were independently serotyped by measuring their sensitivity to bromovinyl deoxyuridine. Reverse passive haemagglutination tests with type-specific antibodies directed against the HSV glycoprotein D and major DNA binding protein gave results in perfect agreement with the results of drug-sensitivity measurement. A single isolate behaved anomalously in the neutralisation test with a type 1-specific antibody directed against glycoprotein A/B. Restriction-enzyme analysis of virus DNA suggests that this isolate contains a variant glycoprotein A/B. The two methods used for serotyping proved very sensitive, giving adequate results with samples containing as little as 100 plaque forming units (pfu) of HSV. The reverse passive haemagglutination test has the additional advantages of speed and simplicity.

A miniaturised and simplified technique for typing and subtyping herpes simplex virus

A miniaturised, simplified and rapid method for typing and subtyping herpes simplex virus by restriction enzyme analysis of radioactively labelled DNA is described. This method requires far less label than those described previously, giving advantages in both cost and safety and therefore in its suitability for use in a routine laboratory. It produces results indistinguishable from those obtained by the parent method.

Genetic variability of herpes simplex virus: development of a pathogenic variant during passaging of a nonpathogenic herpes simplex virus type 1 virus strain in mouse brain

Herpes simplex virus type 1 ANG (HSV-1 ANG) is originally nonpathogenic for inbred mice upon intraperitoneal intravenous, or intravaginal inoculation. In contrast, mice died of encephalitis within 4 to 5 days after intracerebral inoculation with this strain. HSV-1 ANG was serially passaged in mouse brains. In two independent series, peripherally pathogenic virus variants had developed and accumulated in the virus progeny after 12 to 15 intracerebral passages. In mixed infections both nonpathogenic and pathogenic viruses replicated at the primary site of infection and spread to various organs. However, only the pathogenic phenotype could be recovered from the spinal cord and the brain. Comparison of the restriction enzyme cleavage patterns of pathogenic ANG and nonpathogenic ANG virus DNAs revealed distinct alterations in the S-segment (US) sequences bounded by coordinates 0.953 and 0.958 in the prototype orientation and by coordinates 0.862 to 0.867 in the IS orientation of the viral genome. However, it is not known whether these alterations are physiologically relevant to the observed changes in pathogenicity. When coinjected intraperitoneally at 50 to 100-fold excess, the nonpathogenic HSV-1 ANG protected mice against its own pathogenic variant as well as against other pathogenic HSV-1 strains. Pathogenic HSV-1 ANG proved to be genetically and phenotypically stable for at least 25 serial passages in tissue culture at either high or low multiplicity of infection.

A simple and practical method for typing and strain differentiation of herpes simplex virus using infected cell DNAs

A simple and practical method for typing and strain differentiation of herpes simplex virus (HSV) isolates, based upon analysis of the restriction endonuclease cleavage patterns of viral DNAs, was established by using unlabeled infected cell DNAs. The preparation of infected cell DNA is technically easier than that of purified viral DNA or of radiolabeled viral DNA. The method provides a powerful and practical tool for epidemiological and clinical studies of HSV infection, which can be performed in most diagnostic laboratories. In order to select suitable restriction endonucleases for the study of HSV isolates, the cleavage patterns of viral DNAs (strains MacIntyre, HF, UW-268, and SAV) with 12 enzymes were analyzed. Several enzymes, Bam HI, Kpn I, Pst I, Sal I, Sst I, and Xho I, were found to be useful for both typing and strain differentiation. With this method, HSV isolates from different individuals and from the same individual were analyzed by digestion of their infected cell DNAs with Bam HI. Six isolates from epidemiologically unrelated individuals were readily typed and differentiated from each other. Three isolates from the same individual showed very similar patterns. However, there was a small degree of difference between the first two isolates and the third isolate.

Herpes simplex virus variants restraint to high concentrations of acyclovir exist in clinical isolates

Acyclovir (ACV) has been shown to inhibit the replication of herpes simplex virus (HSV) in vitro. We examined a wide variety of HSV clinical isolates for the presence of naturally occurring ACV-resistant (ACVr) variants. Although the ACV doses that inhibited 50% of these isolates were within the range of doses inhibiting 50% of the ACV-susceptible wild-type strains, we successfully isolated variants resistant to high ACV concentrations (25 to 75 microM) from each virion population even in the absence of prior drug exposure. Furthermore, we demonstrated, by fluctuation analysis of two encephalitis strains, that the ACVr variants were clonally distributed in the virus populations before exposure to ACV and did not result from rapid adaptation to ACV. All variants isolated after a single exposure to a high dose of ACV were true ACVr variants, as demonstrated by their plating efficiencies in the presence of ACV. We found that 36 and 50% of the ACVr variants of the two strains examined in detail displayed plating efficiencies in phosphonoacetic acid of greater than 0.1, possibly indicating that many of the ACVr variants contained alterations in the DNA polymerase gene locus. Because the distribution of ACVr variants in natural populations is relatively high (10(-4), these results suggest that selection of ACVr strains during ACV therapy is possible.

Isolation of infectious bovine rhinotracheitis virus from the soft-shelled tick, Ornithodoros coriaceus

Infectious bovine rhinotracheitis virus was isolated from the soft-shelled tick (Ornithodoros coriaceus). Serological identification of the isolated viruses was confirmed by restriction endonuclease digestion of purified virus DNA. These isolations indicate that the soft-shelled tick may be a vector for infectious bovine rhinotracheitis virus. This may be the first reported isolation of mammalian herpesvirus from an arthropod vector.

Incidence of herpes simplex virus types 1 and 2 isolated in patients with herpes genitalis in Sheffield

Thirty-one strains of herpesvirus (HSV), isolated from patients presenting with the clinical features of herpes genitalis, were typed by polypeptide analysis of virus proteins in sodium dodecyl sulphate polyacrylamide gels. Nineteen (61.3%) of the isolates were shown to be HSV type 1 and 12 (38.7%) HSV type 2. There was no obvious difference in the incidence of HSV-1 in primary or recurrent infections and no apparent correlation between the genital site of isolation and virus type. The high incidence of genital HSV-1 infection in this group of patients is probably due to the increased practice of oro-genital contact and has possible implications for the future development of drugs and vaccines in the control of genital herpes.

Characterization of coliphage lambda hybrids carrying DNA fragments from Herpes simplex virus type 1 defective interfering particles

We describe the characterization of 34 hybrid lambda bacteriophages carrying EcoRI fragments obtained from DNA of defective interfering particles of the Patton strain of Herpes simplex virus type 1 (HSV-1). All cloned fragments contained S region terminal repeat sequences (TRs) fused to unique HSV-1 DNA. Several fragments contained deletions and rearrangements not described previously for DNA of HSV-1 defective interfering particles. A model describing the generation of defective interfering DNA based on recombination events involving the terminal "a" sequence as presented.

Differences in the morphology of herpes simplex virus infected cells. II. Type specific membrane alterations of HSV-1 and HSV-2 infected cells

The two types of herpes simplex virus (HSV-1, HSV-2) induced significantly different alterations in the morphology and permeability of infected cells. HEp-2 cells infected with HSV-1 (strain THEA) were characterized by the formation of polynuclear syncytia. In contrast, after infection with HSV-2 (strain D316, DD), the cells were rounded up. The HSV-1 strains KOS and LS5039 and the HSV-2 strain 196 induced both types of cytopathic effect. As shown by comparative scanning and transmission electron microscopy newly synthesized virus particles of the various strains of HSV-1 were generally found to be restricted to smooth areas of the cell surface. In these areas the number of microvilli was reduced in comparison to uninfected cells. However, the progeny viruses of the strains of HSV-2 were mainly connected with protrusions of the cell membrane (microvilli and filopodia). The morphological changes in cells infected with either type of HSV were associated with different functional alterations of the cell membrane. The membranes of HEp-w cells became more stable after infection with HSV-1. This is characterized by a reduced permeability for 51Cr as well as by a decreased sensitivity to the detergent Triton-X-100. HSV-2 induced opposite effects on the stability of the membrane in infected cells. In contrast to these findings with HEp-2 cells, opposite results were obtained with primary chick embryo fibroblasts: Infection with HSV-1 rendered the cell membrane more permeable for 51Cr and a reduction of the 51Cr-release was achieved by infection with HSV-2. The results show that HSV-cell interactions depend on the type of the virus as well as on the type of the infected cell.

Cloning of herpes simplex virus type 1 sequences representing the whole genome

Sequences representative of the whole genome of herpes simplex virus type 1 (HSV-1) strain KOS were cloned in the plasmid vector pBR325 in the form of EcoRI-generated DNA fragments. The cloned fragments were identified by digestion of the chimeric plasmid DNA with restriction enzymes EcoRI or EcoRI and BglII followed by comparison of their electrophoretic mobilities in agarose gels with that of similarly digested HSV-1 virion DNA. The cloned fragments showed the same migration patterns as the corresponding fragments from restricted virion DNA, indicating that no major insertions or deletions were present. The presence of HSV-1 sequences in the chimeric plasmids was confirmed by hybridization of plasmid DNA to HSV-1 virion DNA. Additionally, some of the cloned fragments were shown to be biologicaly active in that they efficiently rescued three HSV-1 temperature-sensitive mutants in cotransfection marker rescue experiments.

Immune response after exposure to varicella zoster virus: characterization of virus-specific antibodies and their corresponding antigens

Fourteen varicella zoster virus antigens were identified that induce antibodies during primary and recurrent infections. These antigens, which included the major nucleocapsid polypeptide (molecular weight, 155,000) and three glycoproteins (molecular weights, 130,000, 88,000, and 60,000, respectively) plus a number of minor antigens, were identified in radioimmunoprecipitation assays, using [35S]methionine-labeled extracts of cells infected with varicella zoster virus and sera from patients with primary and recurrent viral infections. No significant and reproducible differences were observed between early convalescent sera from cases with natural chicken pox and sera from cases with zoster in their ability react with viral antigens. Sera that were taken many years after episodes of chicken pox still retained their ability to react with the major viral antigens.

Variations in herpes simplex virus isolated from human ganglia and a study of clonal variation in HSV-1

Growth of human sensory ganglia in culture has led to the reactivation of herpes simplex virus from over 50% of cases studied. Infected cell polypeptide and restriction enzyme analysis has led to the conclusion that each individual has one unique latent strain of HSV-1 that can be present in more than one ganglion in the body. Analysis of 91 isolates has shown that the long region of the genome is variable in terms of DNA restriction sites, DNA sequences, and in coding for the majority of variable polypeptides. The short region is stable with only polypeptides Vmw 21 and 22, restriction sites HindIII-(M-N) and BglII-(G-H) and the DNA sequence BamHI-1' having been found to vary. The insertion and deletion of small DNA sequences at specific locations allows individual reactivation events to be distinguished. Detection of information able to complement and produce ts+ virus on superinfection of otherwise negative ganglia with ts mutants, has led to the conclusion that ganglion cells may harbor herpes virus-related information that is only detectable by use of such genetic probes.

New endogenous herpesvirus of guinea pigs: biological and molecular characterization

Two known guinea pig herpesviruses, guinea pig cytomegalovirus (GPCMV) and guinea pig herpes-like virus (GPHLV), and well characterized. A third herpesvirus (GPXV) was originally isolated from leukocytes of healthy strain 2 guinea pigs. Growth of GPXV in guinea pig embryo fibroblastic cells produced a characteristic cytopathic effect. Electron microscopy of guinea pig cells infected with GPXV revealed the morphological development of a herpesvirus. Cross-neutralization tests and immunoferritin electron microscopy demonstrated that GPXV, GPCMV, and GPHLV were serologically distinct herpeviruses of guinea pigs. To confirm the distinction between these three herpesviruses, DNA genomes were compared by CsCl equilibrium buoyant density measurements and restriction endonuclease cleavage analysis. 32P-labeled viral DNA ws obtained from nucleocapsids isolated from virus-infected cells, and the buoyant density of GPXV DNA differed from that of GPCMV and GPHLV. Cleavage of viral DNAs with restriction endonucleases followed by gel electrophoresis revealed distinct patterns for each virus.

Minor base sequence differences between the genomes of two strains of murine cytomegalovirus differing in virulence

Two strains of murine cytomegalovirus (MCMV), differing in virulence towards mice, were compared for possible genetic differences. The two strains behaved identically in cell cultures, although the virulent strain gave higher yields of infectious virus in salivary glands. The viral DNAs displayed identical reassociation kinetics, but minor differences in their base sequences were revealed by restriction endonuclease profiles. The endonuclease profile of the "virulent" strain was conserved during serial high multiplicity infection in vitro.

Molecular epidemiology of DNA viruses: applications of restriction endonuclease cleavage site analysis

Restriction endonucleases which cleave DNA at specific nucleotide sequences can be used to produce a set of DNA fragments of a viral genome which, when separated by gel electrophoresis, gives a characteristic "fingerprint" for that virus genome. This simple technique has been used to identify and classify DNA viruses of the herpes, adeno, and papova virus groups. Small variants within a given type (e.g., herpes simplex type I) are genetically stable and permit study and identification of individual strains of viruses. Such analyses have recently been applied to study the epidemiology of some DNA virus outbreaks. Restriction endonuclease fingerprinting provides a useful addition to methods for virus identification and classification.

Analysis of the DNAs from seven varicella-zoster virus isolates

The 32P-labeled DNAs from seven different clinical isolates of human varicella-zoster virus (VZV) were independently digested with five site-specific restriction endonucleases, EcoRI, HindIII, SmaI, BamHI, and AvaI. The digestion products were analyzed by electrophoresis on 0.5% agarose gels followed by autoradiography of the dried gels. Evaluation of the restriction enzyme cleavage patterns revealed small variations among the VZV DNAs. The VZV DNAs were also compared based on their buoyant densities in CsCl. No significant buoyant density differences were detected among the VZV DNAs.

Strain characteristics and features of ocular infection of herpes simplex virus type 1 isolates

Herpes simplex virus type 1 isolates from 63 patients with herpetic keratoconjunctivitis were investigated. For the purpose of detecting strain differences neurovirulence was determined in mice, and viral DNA's were analyzed by digestion with EcoRI and Hind III restriction endonucleases. Neurovirulence differed by a factor up to 10(5) between individual strains and proved to be independent of the ratio between infectious and noninfectious particles in the stocks used. The endonuclease cleavage patterns revealed differences of the viral DNA structure which permitted us to distinguish seven clusters of strains. Correlations between neurovirulence and DNA markers could not be established nor could correlations be found between these markers and features of disease. The main reason for not finding a relationship in the latter case may be attributed to the significant role of host factors in the course of herpetic diseases.

Herpesviruses

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Detection by complementation of defective or uninducible (herpes simplex type 1) virus genomes latent in human ganglia

Reconstruction experiments have shown that temperature-sensitive (ts) mutants of herpes simplex virus type 1 (HSV-1)(Glasgow strain 17) grow, complement, and recombine with similar efficiency in human nerve ganglion cells, human brain cells, normal human fibroblasts (WI38), and baby hamster kidney (BHK) 21/C13 hamster cells. Cultures of human trigeminal, superior cervical, and vagus ganglia that had failed to release herpes simplex virus spontaneously were superinfected with a range of ts mutants of HSV-1 and incubated at both permissive (31 degrees C) and nonpermissive (38.5 degrees C) temperatures. Progeny virus was assayed at both temperatures to determine if complementation of or recombination with the input genomes had occurred. The results showed that the ganglia from 8 of 14 individuals, which had been consistently negative for spontaneous release of virus, contained information that could be detected or rescued following superinfection with ts mutants of herpes simplex virus. In two additional cases, positive results were obtained after the superinfection of negative ganglia explants, but in each of these herpes simplex virus had previously been spontaneously released from one of six ganglia explanted.