Interaction Of Herpes Simplex Virus Research Articles

LB1.5 Initial interactions of herpes simplex virus with human skin dendritic cells

Introduction The mechanism by which immunity to herpes simplex virus (HSV) is initiated is not completely defined. HSV initially infects the stratified squamous epithelium of the anogenital mucosa prior to entering nerve endings. We have recently reported that topical application of HSV-1 to human foreskin explants results in infection of epidermal Langerhans cells (LCs) which then emigrate into the dermis where they expressed the maturation marker CD80 and formed large cell clusters with BDCA3+ subsets of DC-SIGN+ and dermal dendritic cells (DCs) and. HSV-expressing LC fragments were observed inside the dermal DCs/macrophages. No other infected epidermal cells interacted with the dermal DCs (Kim et al. Plos Pathogens, 2015). Methods Therefore, we isolated LCs and dermal DCs from large abdominal skin specimens by collagenase digestion and flow sorting. LCs were pulsed with fluorescent tagged HSV and co-cultured with a subset of (BDCA3+) dermal DCs. Results All infected LCs showed markers of apoptosis at 18 hr p.i. Approximately 50% of BDCA3+ DCs co-localised with infected LCs and in some cases fragments of infected LCs were observed within the dermal DC cytoplasm. Such colocalizaton of HSV antigen bearing LCs and dermal DC subsets, was also detected within biopsies of initial genital herpes lesions. The mechanism of interaction of apoptotic LCs and dermal DCs, and uptake by phagocytosis are being determined. Conclusion Thus, a viral antigen relay takes place where HSV infected LCs slowly die by apoptosis during migration to the dermis and are taken up by dermal DCs by phagocytosis for subsequent antigen presentation. This provides a rationale for targeting these dermal DCs for mucosal or perhaps intradermal HSV immunisation. Disclosure of interest statement No pharmaceutical grants were received in the development of this study.

Host nectin-1 is required for efficient Chlamydia trachomatis serovar E development.

Interaction of Herpes Simplex Virus (HSV) glycoprotein D (gD) with the host cell surface during Chlamydia trachomatis/HSV co-infection stimulates chlamydiae to become persistent. During viral entry, gD interacts with one of 4 host co-receptors: HVEM (herpes virus entry mediator), nectin-1, nectin-2 and 3-O-sulfated heparan sulfate. HVEM and nectin-1 are high-affinity entry receptors for both HSV-1 and HSV-2. Nectin-2 mediates HSV-2 entry but is inactive for HSV-1, while 3-O-sulfated heparan sulfate facilitates HSV-1, but not HSV-2, entry. Western blot and RT-PCR analyses demonstrate that HeLa and HEC-1B cells express nectin-1 and nectin-2, but not HVEM. Because both HSV-1 and HSV-2 trigger persistence, these data suggest that nectin-1 is the most likely co-receptor involved. Co-infections with nectin-1 specific HSV-1 mutants stimulate chlamydial persistence, as evidenced by aberrant body (AB) formation and decreased production of elementary bodies (EBs). These data indicate that nectin-1 is involved in viral-induced chlamydial persistence. However, inhibition of signal transduction molecules associated with HSV attachment and entry does not rescue EB production during C. trachomatis/HSV-2 co-infection. HSV attachment also does not activate Cdc42 in HeLa cells, as would be expected with viral stimulated activation of nectin-1 signaling. Additionally, immunofluorescence assays confirm that HSV infection decreases nectin-1 expression. Together, these observations suggest that gD binding-induced loss of nectin-1 signaling negatively influences chlamydial growth. Chlamydial infection studies in nectin-1 knockdown (NKD) HeLa cell lines support this hypothesis. In NKD cells, chlamydial inclusions are smaller in size, contain ABs, and produce significantly fewer infectious EBs compared to C. trachomatis infection in control HeLa cells. Overall, the current study indicates that the actions of host molecule, nectin-1, are required for successful C. trachomatis development.

Therapeutic Efficacy of a Herpes Simplex Virus With Radiation or Temozolomide for Intracranial Glioblastoma After Convection-enhanced Delivery

The herpes simplex virus-1 (HSV-1)-infected cell protein 0 (ICP0) is an E3 ubiquitin ligase implicated in cell cycle arrest and DNA repair inhibition. Convection-enhanced delivery (CED) of either the replication-defective, ICP0-producing HSV-1 mutant, d106, or the recombinant d109, devoid of all viral genome expression, was performed to determine the in vivo efficacy of ICP0 in combination with ionizing radiation (IR) or systemic temozolomide (TMZ) in the treatment of glioblastoma multiforme (GBM). Intracranial U87-MG xenografts were established in athymic nude mice. Animal survival was determined after mice underwent intracranial CED of either the replication-defective d106 or d109 viruses, or Hanks' balanced salt solution (HBSS), before a single session of whole-brain irradiation or TMZ treatment. Median survival for animals that underwent treatment with HBSS alone, d109 alone, d106 alone, HBSS + IR, HBSS + TMZ, d109 + IR, d106 + IR, and d106 + TMZ was 28, 35, 41, 39, 44, 39, 68 (P < 0.01), and 66 days (P < 0.01), respectively. Intracerebral d106 CED resulted in a significant increase in athymic nude mouse survival when combined with IR or TMZ. d106 CED allows for distribution of HSV-1 in human GBM xenografts and persistent viral infection.

Structural Rearrangement within an Enveloped Virus upon Binding to the Host Cell

We have made the surprising discovery that the interactions of herpes simplex virus with its initial cell attachment receptor induce a rapid and highly efficient structural change in the tegument, the region of the virion situated between the membrane and the capsid. It has been known for nearly a decade that viruses can trigger host signaling pathways when they bind to receptors on the cell surface; however, until now there has been no evidence that a signal can be sent in reverse--from the "outside in"--across a viral membrane. Evidence for this signaling event was found during studies of UL16, a tegument protein that is conserved among all the herpesviruses. Previous work has demonstrated that UL16 is bound to capsids isolated from the cytoplasm of infected cells, but this interaction is destabilized during subsequent egress steps, leading to release of the extracellular virion. Pretreatment with N-ethylmaleimide, a small, membrane-permeating compound that covalently modifies free cysteines, restabilizes the interaction, thereby permitting the capsid-UL16 complex to be isolated following disruption of virions with NP-40. In the experiments described here, we found that the natural signal for release of UL16 from capsids is sent when virions merely bind to cells at 4 degrees C. The internal change was also observed upon binding to immobilized heparin in a manner that requires viral glycoprotein C. This represents the first example of signaling across a viral envelope following receptor binding.

The Interaction of Herpes Simplex Virus 1 Regulatory Protein ICP22 with the cdc25C Phosphatase Is Enabled In Vitro by Viral Protein Kinases U S 3 and U L 13

Earlier studies have shown that ICP22 and the U(L)13 protein kinase but not the U(S)3 kinase are required for optimal expression of a subset of late (gamma(2)) genes exemplified by U(L)38, U(L)41, and U(S)11. In primate cells, ICP22 mediates the disappearance of inactive isoforms of cdc2 and degradation of cyclins A and B1. Active cdc2 acquires a new partner, the viral DNA synthesis processivity factor U(L)42. The cdc2-U(L)42 complex recruits and phosphorylates topoisomerase IIalpha for efficient expression of the gamma(2) genes listed above. In uninfected cells, the cdc25C phosphatase activates cdc2 by removing two inhibitory phosphates. The accompanying report shows that in the absence of cdc25C, the rate of degradation of cyclin B1 is similar to that occurring in infected wild-type mouse embryo fibroblast cells but the levels of cdc2 increase, and the accumulation of a subset of late proteins and virus yields are reduced. This report links ICP22 with cdc25C. We show that in infected cells, ICP22 and U(S)3 protein kinase mediate the phosphorylation of cdc25C at its C-terminal domain. In in vitro assays with purified components, both U(L)13 and U(S)3 viral kinases phosphorylate cdc25C and ICP22. cdc25C also interacts with cdc2. However, in infected cells, the ability of cdc25C to activate cdc2 by dephosphorylation of the inactive cdc2 protein is reduced. Coupled with the phosphorylation of cdc25C by the U(S)3 kinase, the results raise the possibility that herpes simplex virus 1 diverts cdc25C to perform functions other than those performed in uninfected cells.

Susceptibility of Human Female Primary Genital Epithelial Cells to Herpes Simplex Virus, Type-2 and the Effect of TLR3 Ligand and Sex Hormones on Infection1

Genital epithelial cells (ECs) are the first line of defense that sexually transmitted viruses encounter. The mechanism of viral pathogenesis in these cells is not well understood. Here, we show that a primary cell culture model from human reproductive tract tissues can be used as a novel ex vivo model in examining the interaction of herpes simplex virus, type 2 (HSV-2), with female genital mucosa. Confluent, polarized primary cultures of human endometrial and cervical ECs were established and shown to be free from any significant contamination of any other cell type. Both endometrial and cervical ECs were found to be highly susceptible to HSV-2 infection. The kinetic of infection was similar to in vivo infection, with the earliest viral shedding seen at 18 h postinfection. Primary EC monolayers could be infected both apically and basolaterally, but preferential viral shedding was seen on the apical side of cells. Following treatment of the monolayers with poly (I:C), an innate immune activator that acts via TLR3, viral shedding was reduced significantly, comparable to levels seen when an antiviral formulation, acyclovir, was used. Treatment of epithelial and stromal co-cultures with estradiol increased HSV-2 infection in endometrial ECs, but viral shedding decreased following treatment with progesterone. To the best of our knowledge, this is the first study that examines the interaction of primary human female genital ECs with HSV-2, using an ex vivo culture model. The results provide valuable information regarding the susceptibility of women's genital ECs to HSV-2 and the ability of innate immunity and hormones to modify this susceptibility.

Soluble V domain of Nectin-1/HveC enables entry of herpes simplex virus type 1 (HSV-1) into HSV-resistant cells by binding to viral glycoprotein D.

Interaction of herpes simplex virus (HSV) glycoprotein D (gD) with specific cellular receptors is essential for HSV infection of susceptible cells. Virus mutants that lack gD can bind to the cell surface (attachment) but do not enter, implying that interaction of gD with its receptor(s) initiates the postattachment (entry) phase of HSV infection. In this report, we have studied HSV entry in the presence of the gD-binding variable (V) domain of the common gD receptor nectin-1/HveC to determine whether cell association of the gD receptor is required for HSV infection. In the presence of increasing amounts of the soluble nectin-1 V domain (sNec1(123)), increasing viral entry into HSV-resistant CHO-K1 cells was observed. At a multiplicity of 3 in the presence of optimal amounts of sNec1(123), approximately 90% of the cells were infected. The soluble V domain of nectin-2, a strain-specific HSV entry receptor, promoted entry of the HSV type 1 (HSV-1) Rid-1 mutant strain, but not of wild-type HSV-1. Preincubation and immunofluorescence studies indicated that free or gD-bound sNec1(123) did not associate with the cell surface. sNec1(123)-mediated entry was highly impaired by interference with the cell-binding activities of viral glycoproteins B and C. While gD has at least two functions, virus attachment to the cell and initiation of the virus entry process, our results demonstrate that the attachment function of gD is dispensable for entry provided that other means of attachment are available, such as gB and gC binding to cell surface glycosaminoglycans.

Replication and interaction of herpes simplex virus and human papillomavirus in differentiating host epithelial tissue

We have investigated the interactions and consequences of superinfecting and coreplication of human papillomavirus (HPV) and herpes simplex virus (HSV) in human epithelial organotypic (raft) culture tissues. In HPV-positive tissues, HSV infection and replication induced significant cytopathic effects (CPE), but the tissues were able to recover and maintain a certain degree of tissue integrity and architecture. HPV31b not only maintained the episomal state of its genomic DNA but also maintained its genomic copy number even during times of extensive HSV-induced CPE. E2 transcripts encoded by HPV31b were undetectable even though HPV31b replication was maintained in HSV- infected raft tissues. Expression of HPV31b oncogenes (E6 and E7) was also repressed but to a lesser degree than was E2 expression. The extent of CPE induced by HSV is dependent on the magnitude of HPV replication and gene expression at the time of HSV infection. During active HSV infection, HPV maintains its genomic copy number even though genes required for its replication were repressed. These studies provide new insight into the complex interaction between two common human sexually transmitted viruses in an in vitro system, modeling their natural host tissue in vivo.

Interaction of herpes simplex virus with mononuclear phagocytes is dependent on the differentiation stage of the cells.

The interaction of herpes simplex virus (HSV) with mononuclear phagocytes (MP), i.e. monocytes and macrophages, is of importance for the pathogenesis of HSV infections. MP are known to play a significant role in the cellular defence against infections with HSV, but it has also been shown that HSV-1 affects MP. The infection of these cells at different stages of differentiation has different outcomes, and may result in the alteration of important cellular functions. HSV-1 inhibits the morphological differentiation of human monocytes, and this inhibition occurs in spite of the fact that human monocytes are non-permissive to HSV-1. We have studied the effect of HSV infection of monocytes and macrophages on production of essential cytokines and related this effect to the reproduction of the virus. Blood-derived MP were cultured in vitro and inoculated with HSV at different stages of differentiation. Replication of the virus was measured by infectivity titration, detection of HSV antigens by immunofluorescence and detection of HSV-specific mRNA. In monocytes, no viral replication and no production of late protein was seen. HSV IE gene was transcribed in monocytes from some donors, but not from others. In macrophages, virus replicated, but less efficiently than in fully permissive fibroblast cells. The production of IL-1 beta, IL-6 and TNF-alpha in both non-permissive monocytes and permissive macrophages was assayed both at the transcriptional level, as mRNA, and as protein released from the cells. Production of cytokines by MP was affected by HSV-1. The level of cytokine mRNA and cytokine protein did not correspond for all cytokines, which may suggest that translational regulation and/or cytokine inhibitors are important in the regulation of the cytokine response. The cytokine modulation, both at the transcriptional level and measured as biological activity, was different in monocytes and macrophages, and varied between different donors. Our results indicate a relation between permissiveness and cytokine response in mononuclear phagocytes infected with HSV-1. Such a relation may be of importance to both intrinsic and extrinsic defence mechanisms of MP against HSV-1. Our study also demonstrates that even the functions of non-permissive cells such as blood-derived monocytes may be affected by viral infections.

Interaction of herpes simplex virus 1 alpha regulatory protein ICP0 with elongation factor 1delta: ICP0 affects translational machinery.

The herpes simplex virus 1 (HSV-1)-infected cell protein 0 (ICP0) is a promiscuous transactivator, and by necessity, its functions must be mediated through cellular gene products. In an attempt to identify cellular factors interacting with ICP0, we used the carboxyl-terminal domain of ICP0 as "bait" in the yeast (Saccharomyces cerevisiae) two-hybrid system. Our results were as follows: (i) All 43 cDNAs in positive yeast colonies were found to encode the same translation factor, elongation factor delta-1 (EF-1delta). (ii) Purified chimeric protein consisting of glutathione S-transferase (GST) fused to EF-1delta specifically formed complexes with ICP0 contained in HSV-1-infected cell lysate. (iii) Fractionation of infected HEp-2 cells and immunofluorescence studies revealed that ICP0 was localized both in the nucleus and in the cytoplasm. In primary human foreskin fibroblasts, ICP0 was localized predominantly in the cytoplasm throughout HSV-1 infection even early in infection. (iv) Addition of the chimeric protein GST-carboxyl-terminal domain of ICP0 to the rabbit reticulocyte lysate in vitro translation system resulted in a dose-dependent decrease in protein synthesis. In contrast, GST alone or GST fused to the amino-terminal domain of ICP0 had no effect on the in vitro translation system. (v) The predominant forms of EF-1delta on electrophoresis in denaturing gels have apparent Mrs of 38,000 and 40,000. The higher-Mr form is a minor species in mock-infected cells, whereas in human fibroblasts and Vero cells infected with HSV-1, this isoform becomes dominant. These results indicate that ICP0 is present and may have a significant role in the cytoplasm of infected cells, possibly by altering the efficiency of translation of viral mRNAs.

Interaction of herpes simplex virus 1 origin-binding protein with DNA polymerase alpha.

The herpes simplex virus 1 (HSV-1) genome encodes seven polypeptides that are required for its replication. These include a heterodimeric DNA polymerase, a single-strand-DNA-binding protein, a heterotrimeric helicase/primase, and a protein (UL9 protein) that binds specifically to an HSV-1 origin of replication (oris). We demonstrate here that UL9 protein interacts specifically with the 180-kDa catalytic subunit of the cellular DNA polymerase alpha-primase. This interaction can be detected by immunoprecipitation with antibodies directed against either of these proteins, by gel mobility shift of an oris-UL9 protein complex, and by stimulation of DNA polymerase activity by the UL9 protein. These findings suggest that enzymes required for cellular DNA replication also participate in HSV-1 DNA replication.

Evidence for an Interaction of Herpes Simplex Virus with Chondroitin Sulfate Proteoglycans during Infection

In a previous study, a mouse L cell mutant was isolated which is 90% resistant to HSV-1 infection (S. Gruenheid, L. Gatzke, H. Meadows, and F. Tufaro. J. Virol. 67, 93-100, 1993). This cell line, termed gro2C, failed to express heparan sulfate (HS) glycosaminoglycans on the cell surface, which normally act as initial receptors for HSV-1 attachment to cultured cells. In this report, we extended the characterization of gro2C cells to explore the possibility that cell-surface chondroitin sulfate (CS) facilitates virus attachment to gro2C cells in the absence of HS. We found that soluble CS types A, B, and C strongly interfere with adsorption of HSV-1 to the surface of gro2C cells in a dose-dependent manner, and CS type B (dermatan sulfate) inhibited adsorption to parental (control) L cells by up to 10%. Moreover, gro2C cell infection was hypersensitive to inhibition by HS in comparison to control L cell infection. In all cases, a decrease in adsorption resulted in a decrease in infection. By contrast, the highly-sulfated glycosaminoglycan analog dextran sulfate was a relatively poor inhibitor of gro2C cell infection, indicating that the inhibitory effects of CS were related to its carbohydrate structure and not solely to its strong negative charge. By using a mutant virus strain which does not express the heparin-binding glycoprorein gC, we show that gC was not required for infection of gro2C cells, and was not required for the inhibition by HS or CS. Thus, the characterization of gro2C cell infection has revealed that one or more components of the HSV-1 particle can interact with cell-surface CS as well as HS to mediate infection of susceptible cells.

Glycoprotein C-independent binding of herpes simplex virus to cells requires cell surface heparan sulphate and glycoprotein B.

Previous studies have shown that the initial interaction of herpes simplex virus (HSV) with cells is binding to heparan sulphate and that HSV-1 glycoprotein C (gC) is principally responsible for this binding. Although gC-negative viral mutants are impaired for binding and entry, they retain significant infectivity. The purpose of the studies reported here was to explore the requirements for infectivity of gC-negative HSV-1 mutants. We found that absence or alteration of cell surface heparan sulphate significantly reduced the binding of gC-negative mutant virus and rendered cells resistant to infection, as shown previously for the wild-type virus. We isolated a recombinant double-mutated HSV strain that produces virions devoid of both of the known heparin-binding glycoproteins, gB and gC. The drastically impaired binding of these mutant virions to cells, relative to gC-negative and wild-type virions, indicates that gB mediates the binding of gC-negative virions to cells. Thus at least two HSV glycoproteins can independently mediate the binding of HSV to cell surface heparan sulphate to start the process of viral entry into cells.

Factors influencing the interaction of herpes simplex virus glycoprotein C with the third component of complement.

The factors influencing the interaction of herpes simplex virus (HSV) glycoprotein C (gC) with the third component of complement (C3) were investigated in this study. The ability of gC of HSV type 1 (gC-1) to bind to the C3b fragment of C3 was found to be influenced by cell specific processing of gC-1 in a different manner, binding being remarkably enhanced in some cell lines following removal of sialic acid residues. Testing several intertypic recombinants of HSV we found that only strains expressing gC-1 exhibited binding to C3b, even though their genome consisted mainly of HSV-2 sequences in some recombinants. Expression of type-2 glycoproteins gB, gD, gE, gG, gH, and gI did not alter the ability of gC-1 to bind to C3b. Rosetting of HSV-1 infected Vero cells with C3b-coated red blood cells (EAC) was found to be temperature dependent and could be inhibited with purified C3b and anti-C3 antibodies. Polyanions like heparin or dextran sulfate were also inhibitory in a dose dependent manner, whereas C3d, neomycin and other aminoglycoside antibiotics failed to block. As the tested polyanions are also known to inhibit the infectivity of HSV, it could be speculated, that the complement binding function and the heparin-binding/attachment function of gC might be related.

Activation of the cellular transcription factor AP-1 in herpes simplex virus infected cells is dependent on the viral immediate-early protein ICPO.

Lytic infection with herpes simplex virus (HSV) results in the repression of most host cell protein synthesis but produces an increased activity of the cellular AP-1 transcription factor. This increase is paralleled by an increase in the transcription rate of the proto-oncogene encoding the AP-1 component, c-Jun resulting in an increase in c-Jun protein in infected cells. The increased AP-1 activity in infected cells is dependent upon the HSV immediate-early protein ICPO. Thus a mutant lacking the gene encoding this protein fails to increase AP-1 activity whilst an ICPO expression plasmid can specifically increase the activity of an AP-1 dependent promoter in co-transfection experiments. The implications of these effects in the interaction of HSV with cultured cells are discussed.

Initial interaction of herpes simplex virus with cells is binding to heparan sulfate

We have shown that cell surface heparan sulfate serves as the initial receptor for both serotypes of herpes simplex virus (HSV). We found that virions could bind to heparin, a related glycosaminoglycan, and that heparin blocked virus adsorption. Agents known to bind to cell surface heparan sulfate blocked viral adsorption and infection. Enzymatic digestion of cell surface heparan sulfate but not of dermatan sulfate or chondroitin sulfate concomitantly reduced the binding of virus to the cells and rendered the cells resistant to infection. Although cell surface heparan sulfate was required for infection by HSV types 1 and 2, the two serotypes may bind to heparan sulfate with different affinities or may recognize different structural features of heparan sulfate. Consistent with their broad host ranges, the two HSV serotypes use as primary receptors ubiquitous cell surface components known to participate in interactions with the extracellular matrix and with other cell surfaces.

Early interactions of herpes simplex virus with mouse peritoneal macrophages.

Adsorption of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) to resident peritoneal macrophages (PM) of 4-week-old Swiss albino (SA) and GR/AFib mice was studied. A significantly (P less than 0.05) higher HSV-2 adsorption rate was found with PM of SA mice than with PM of GR/AFib mice. Of added HSV-2 65% bound to the cells of SA mice over a 120-min period versus 15% to PM of GR/AFib mice. Only 15 to 20% of added HSV-1 bound to PM regardless of the mouse strain. These patterns of adsorption were found with all four HSV-1 and four HSV-2 strains tested. Pretreatment of PM with an HSV-2 mutant blocked the adsorption of added HSV-2. Thus, the receptors for HSV attachment seemed to be virus type selective. To avoid masking of adsorption by phagocytotic activity, the adsorption studies had to be performed at 4 degrees C. Transport of attached HSV-1 and HSV-2 to the nuclei of SA PM was studied with purified virus labeled with 32Pi and [3H]thymidine. In double-isotope experiments, only transport of HSV-2 was detected. The possible importance of differences in density or avidity of virus-binding receptors on the plasma membrane of PM is discussed in relation to macrophage-dependent focal liver necrosis, which was only demonstrable after intraperitoneal inoculation of HSV-2, not HSV-1, only in SA, not GR/AFib, mice.

Interaction of Herpes simplex virus with human cell lines at various stages of lymphoid differentiation.

The growth of herpes simplex virus (HSV) type 1 in human lymphoid cell lines, arrested at various stages of differentiation, was studied. The synthesis of viral DNA and antigens and the production of infectious virus were followed in null, B and T leukemia-lymphoma cell lines. It was found that while "nondifferentiated" null cells and cells differentiating along the B pathway, even at very early stages of differentiation, supported HSV growth, cell lines of T origin at all stages of differentiation were generally nonpermissive. The failure of T cells to support the growth of HSV did not result from inefficient adsorption to the host cells. However, viral DNA synthesis was not detected, and a significant reduction in the ability of synthesize HSV antigens was observed. It is suggested that the block in the growth cycle of the virus occurs at a stage after adsorption of the virion to the cells, but prior to synthesis of its DNA and proteins.

The interaction of Herpes Simplex Virus with murine lymphocytes. I. Mitogenic properties of herpes simplex virus.

Herpes simplex virus (HSV) stimulates DNA synthesis in mouse spleen cultures prepared from normal, macrophage-depleted, and T-cell-depleted spleen cells, but not from thymocytes. In addition, a polyclonal antibody response is observed in HSV-infected spleen cultures. These findings indicate that the cells stimulated to undergo DNA synthesis after HSV infection appear to be the bone marrow-derived lymphocytes. The newly synthesized DNA is host cell and not of viral origin. Heat treatment and ultraviolet irradiation of HSV before addition to spleen cultures prevents the induction of DNA synthesis. We consider the use of this system as assay for the study of cell transformation by HSV and also for the study of host cell control of the expression of the viral genome.

Interaction of herpes simplex virus and rhinovirus in cell culture. Brief report.

Interaction of herpes simplex virus and rhinovirus in cell culture. Brief report.