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Purpose: Previously, clinical trials of experimental virotherapy for recurrent glioblastoma multiforme (GBM) demonstrated that inoculation with a conditionally replication-competent Δγ 1 34.5 oncolytic herpes simplex virus (oHSV), G207, was safe. Following the initial safety study, a phase Ib trial enrolled 6 adult patients diagnosed with GBM recurrence from which tumor tissue was banked for future studies., Patients and Methods: Here, we analyzed tumor RNA sequencing (RNA-seq) data obtained from pre- and posttreatment (collected 2 or 5 days after G207 injection) biopsies from the phase Ib study patients., Results: Using a Spearman rank-order correlation analysis, we identified approximately 500 genes whose expression pattern correlated with survival duration. Many of these genes were enriched for the intrinsic IFN-mediated antiviral and adaptive immune functional responses, including immune cell chemotaxis and antigen presentation to T-cells. Furthermore, we show that the expression of several T-cell-related genes was highest in the patient with the longest survival after G207 inoculation., Conclusions: Our data support that the oHSV-induced type I IFN production and the subsequent recruitment of an adaptive immune response differed between enrolled patients and showed association with survival duration in patients with recurrent malignant glioma after treatment with an early generation oHSV., (©2022 The Authors; Published by the American Association for Cancer Research.)

Limited expression and distribution of nectin-1, the major herpes simplex virus (HSV) type-1 entry-receptor, within tumors has been proposed as an impediment to oncolytic HSV (oHSV) therapy. To determine whether resistance to oHSVs in malignant peripheral nerve sheath tumors (MPNSTs) was explained by this hypothesis, nectin-1 expression and oHSV viral yields were assessed in a panel of MPNST cell lines using γ134.5-attenuated (Δγ134.5) oHSVs and a γ134.5 wild-type (wt) virus for comparison. Although there was a correlation between nectin-1 levels and viral yields with the wt virus (R=0.75, P =0.03), there was no correlation for Δγ134.5 viruses (G207, R7020 or C101) and a modest trend for the second-generation oHSV C134 (R=0.62, P=0.10). Nectin-1 overexpression in resistant MPNST cell lines did not improve Δγ134.5 oHSV output. While multistep replication assays showed that nectin-1 overexpression improved Δγ134.5 oHSV cell-to-cell spread, it did not confer a sensitive phenotype to resistant cells. Finally, oHSV yields were not improved with increased nectin-1 in vivo. We conclude that nectin-1 expression is not the primary obstacle of productive infection for Δγ134.5 oHSVs in MPNST cell lines. In contrast, viruses that are competent in their ability to counter the antiviral response may derive benefit with higher nectin-1 expression.

Herpes simplex virus (HSV) evolved an elegant strategy that enables the virus to impact a large fraction of the human population. The virus replicates at the portal of entry (mouth, genitals) and concurrently it is transported retrograde to sensory neurons. In sensory neurons it establishes a silent (latent) infection. A variety of stimuli can reactivate the virus. The reactivated virus is transmitted anterograde to a site at the portal of entry for transmission by physical contact between infected and uninfected tissues to other individuals. The central issue is how a virus that vigorously replicates and successfully blocks the innate immune defenses of the host at the portal of entry into the body remains silent in sensory neurons. The presentation focuses on three key issues: (a) current assessment of the impact of HSV on human health, (b) the mechanisms by which the virus overcomes a key host defense mechanism at the portal of entry into the body and yet is silenced in latently infected neurons, and (c) the mechanisms by which the virus reactivates.

Herpes simplex virus 1 (HSV-1) mutants that lack the γ(1)34.5 gene are unable to replicate in the central nervous system but maintain replication competence in dividing cell populations, such as those found in brain tumors. We have previously demonstrated that a γ(1)34.5-deleted HSV-1 expressing murine interleukin-12 (IL-12; M002) prolonged survival of immunocompetent mice in intracranial models of brain tumors. We hypothesized that M002 would be suitable for use in clinical trials for patients with malignant glioma. To test this hypothesis, we (i) compared the efficacy of M002 to three other HSV-1 mutants, R3659, R8306, and G207, in murine models of brain tumors, (ii) examined the safety and biodistribution of M002 in the HSV-1-sensitive primate Aotus nancymae following intracerebral inoculation, and (iii) determined whether murine IL-12 produced by M002 was capable of activating primate lymphocytes. Results are summarized as follows: (i) M002 demonstrated superior antitumor activity in two different murine brain tumor models compared to three other genetically engineered HSV-1 mutants; (ii) no significant clinical or magnetic resonance imaging evidence of toxicity was observed following direct inoculation of M002 into the right frontal lobes of A. nancymae; (iii) there was no histopathologic evidence of disease in A. nancymae 1 month or 5.5 years following direct inoculation; and (iv) murine IL-12 produced by M002 activates A. nancymae lymphocytes in vitro. We conclude that the safety and preclinical efficacy of M002 warrants the advancement of a Δγ(1)34.5 virus expressing IL-12 to phase I clinical trials for patients with recurrent malignant glioma.

We have previously demonstrated safety of G207, a doubly mutated (deletion of both gamma(1)34.5 loci, insertional inactivation of U(L)39) herpes simplex virus (HSV) for patients stereotactically inoculated in enhancing portions of recurrent malignant gliomas. We have now determined safety of two inoculations of G207, before and after tumor resection. Inclusion criteria were histologically proven recurrent malignant glioma, Karnofsky score >or=70, and ability to resect the tumor without ventricular system breach. Patients received two doses of G207 totaling 1.15 x 10(9) plaque-forming units with 13% of this total injected via a catheter placed stereotactically in the tumor. Two or five days later, tumor was resected en bloc with catheter in place. The balance of G207 dose was injected into brain surrounding the resection cavity. Six patients with recurrent glioblastoma multiforme were enrolled. Two days after the second G207 inoculation, one patient experienced transient fever, delirium, and hemiparesis, which entirely resolved on high-dose dexamethasone. No patient developed HSV encephalitis or required treatment with acyclovir. Radiographic and neuropathologic evidence suggestive of antitumor activity is reported. Evidence of viral replication was demonstrated. G207 appears safe for multiple dose delivery, including direct inoculation into the brain surrounding tumor resection cavity.

Disseminated herpes simplex virus (HSV) infection may lead to acute liver failure (ALF) and the need for emergency liver transplantation (LT). The primary aim of this study was to determine the utility of HSV serological testing and HSV DNA testing by polymerase chain reaction (PCR) in the diagnosis and management of indeterminate, pregnancy-related, and known HSV-related ALF. Stored sera obtained on study day 1 or 2 from patients enrolled in the United States ALF Study Group with indeterminate (n = 51), pregnancy-related (n = 12), and HSV-related (n = 4) ALF were screened for HSV DNA by PCR and serology. While 7 of the indeterminate and pregnant patients had positive anti-HSV immunoglobulin M, none had detectable HSV DNA. The 4 known HSV cases all had high-titer HSV DNA on presentation (range: 3.5 to 36 x 10(8) copies/mL). Two HSV patients underwent LT but developed posttransplant extrahepatic HSV infection despite suppression of HSV DNA with acyclovir treatment, and one of them eventually died. The 2 other fulminant HSV patients died within 48 hours of presentation. In conclusion, serum HSV DNA indicative of occult HSV infection was not detected in 51 indeterminate and 12 pregnancy-related ALF patients. The 4 patients with known HSV-related ALF all had high HSV DNA levels at presentation, and despite the rapid use of antiviral therapy and emergency LT, substantial morbidity and mortality were encountered, highlighting the poor prognosis with severe disseminated HSV infection., ((c) 2008 AASLD.)

Antiviral management options for recurrent herpes simplex virus (HSV) infection include daily suppressive and episodic therapy. New data on patient-initiated, short-course, high-dose antiviral therapy provide a new, more convenient option for patients who choose episodic therapy. A head-to-head comparison of suppressive valaciclovir versus famciclovir treatment indicates that both drugs have comparable clinical benefits, but that valaciclovir may have a greater impact on virological end-points. However, a more recent study shows that famciclovir effectively reduces the frequency of total and subclinical HSV shedding compared with placebo, as well as the percentage of days with genital lesions for subjects with or without a history of genital herpes. This article reports on presentations given at the IHMF Annual Meeting and International Congress of Antimicrobial Agents and Chemotherapy, both of which took place in late 2006.

Lack of effective therapy of primary brain tumors has promoted the development of novel experimental approaches utilizing oncolytic viruses combined with gene therapy. Towards this end, we have assessed a conditionally replication-competent, gamma(1)34.5-deleted herpes simplex virus type 1 (HSV-1) expressing cytosine deaminase (CD) for treatment of malignant brain tumors. Our results are summarized as follows: (i) a recombinant HSV (M012) was constructed in which both copies of the gamma(1)34.5 gene were replaced with the bacterial CD gene, under the control of the cellular promoter Egr-1; (ii) M012-infected cells in vitro efficiently convert 5-fluorocytosine (5-FC) to 5-fluorouracil, thereby enhancing cytotoxicity of neighboring, uninfected cells; (iii) both direct and bystander cytotoxicity of murine neuroblastoma and human glioma cell lines after infection with M012 were demonstrated; (iv) direct intracerebral inoculation of A/J mice demonstrated lack of neurotoxicity at doses similar to G207, a gamma(1)34.5-deleted HSV with demonstrated safety in human patient trials and (v) intratumoral injection of M012 into Neuro-2a flank tumors in combination with 5-FC administration significantly reduced tumor growth versus tumors treated with R3659 combined with 5-FC, or treated with M012 alone. Thus, M012 is a promising new oncolytic HSV vector with an enhanced prodrug-mediated, antineoplastic effect that is safe for intracranial administration.

Herpes simplex encephalitis (HSE) remains one of the most devastating infections of the central nervous system despite available antiviral therapy. Children and adolescents account for approximately one third of all cases of HSE. Clinical diagnosis is suggested in the encephalopathic, febrile patient with focal neurologic signs. However, these clinical findings are not pathognomonic because numerous other diseases in the central nervous system can mimic HSE. Neurodiagnostic evaluation can provide support for the diagnosis by the demonstration of temporal lobe edema/hemorrhage by magnetic resonance image scan and spike and slow-wave activity on electroencephalogram. In the current era, the diagnostic gold standard is the detection of herpes simplex virus (HSV) DNA in the cerebrospinal fluid by polymerase chain reaction (PCR). Although PCR is an excellent test and preferable to brain biopsy, false negatives can occur early after disease onset. Acyclovir is the treatment of choice and is administered at 10 mg/kg every 8 h for 21 days. Even with early administration of therapy after the disease onset, nearly two thirds of survivors have significant residual neurologic deficits. Current investigative efforts are assessing the prognostic value of quantitative PCR detection of viral DNA at the onset of therapy as well as at the completion of therapy and the contribution of prolonged antiviral therapy to improved neurologic outcome.

We are using genetically modified, conditionally replicating herpes simplex virus (HSV) that express either interleukin (IL)-12 or granulocyte macrophage-colony stimulating factor (GM-CSF) as live, attenuated vaccine candidates for protection against HSV infection and/or disease. We report the following: (1) animals previously vaccinated with these candidate vaccines exhibited dose-dependent protection after intranasal, intraperitoneal or intracranial challenge with the highly virulent E377-MB wild-type HSV-1; (2) the IL-12 expressing virus (M002) consistently conferred protection at lower immunization doses than GM-CSF expressing virus (M004); (3) between 80 and 100% protection from E377-MB challenge was conferred after intramuscular immunization of mice with any of the three Deltagamma1 34.5 HSV, as opposed to 50% protection elicited after immunization with wild-type HSV-1 (F); and (4) latent virus was not detected at a higher rate in animals immunized and subsequently challenged with E377-MB than in immunized animals alone. These data suggest that conditionally replicating, cytokine-expressing HSV are able to elicit protective immune responses while retaining safety in an experimental murine model.

Long-term survivors of glioblastoma multiforme, the most common form of primary intracranial malignancy in adults, are extremely rare. Experimental animal models that more closely resemble human disease are essential for the identification of effective novel therapies. We report here an extensive analysis of the 4C8 glioma model to assess its suitability for evaluating novel type 1 herpes simplex virus (HSV-1) therapies of malignant glioma. We first determined that expression of major histocompatibility complex I and II and of alphavbeta3 in the 4C8 model was comparable to that seen in human glioma cells. Next, using a panel of Delta(gamma1)34.5 HSVs, we demonstrated that, in vitro, 4C8 cells were as sensitive as human glioma cells to both infection and lysis and that the 4C8 cells supported the production of foreign gene products. Replication competence of HSV was demonstrated in vitro. Finally, 4C8 intracranial gliomas were established in immunologically competent syngeneic B6D2F1 mice, treated by intratumoral injection of selected engineered HSVs, including the interleukin-12-expressing virus, M002. Survival data from these studies demonstrated that 4C8 cells in vivo are sensitive to both direct oncolysis and HSV-mediated interleukin-12 expression. Fluorescence-activated cell sorting analyses of immune-related infiltrating cells supported the concept that survival was prolonged in part because of antitumor actions of these cells. We conclude that the 4C8/B6D2F1 syngeneic glioma model is suitable for preclinical evaluation of HSV-based therapies and that M002 is a superior virus for the treatment of murine glioma in this model.

Viral shedding of HSV occurs frequently in infected individuals. HSV is shed asymptomatically from multiple anatomical sites and shedding, like exposure, is a significant risk for transmission. However, the relationship between shedding frequency, viral titer and transmission is unknown. HSV-2 shedding is affected by the site and time since acquisition of infection. The advent of sensitive PCR techniques has shown that the magnitude and frequency of viral shedding is higher than shown previously with viral culture techniques. It has also clearly demonstrated that suppressive (daily) antiviral therapy reduces clinical and subclinical reactivation rates, and has been successfully used in the prevention of recurrent oral and genital HSV infections. A recent study has demonstrated that daily antiviral therapy with valaciclovir can significantly reduce transmission of HSV-2 between discordant heterosexual couples in monogamous relationships.

Herpes simplex virus-1 (HSV-1) is a relatively large double-stranded DNA virus encoding at least 89 proteins with well characterized disease pathology. An understanding of the functions of viral proteins together with the ability to genetically engineer specific viral mutants has led to the development of attenuated HSV-1 for gene therapy. This review highlights the progress in creating attenuated genetically engineered HSV-1 mutants that are either replication competent (viral non-essential gene deleted) or replication defective (viral essential gene deleted). The choice between a replication-competent or -defective virus is based on the end-goal of the therapeutic intervention. Replication-competent HSV-1 mutants have primarily been employed as antitumor oncolytic viruses, with the lytic nature of the virus harnessed to destroy tumor cells selectively. In replacement gene therapy, replication-defective viruses have been utilized as delivery vectors. The advantages of HSV-1 vectors are that they infect quiescent and dividing cells efficiently and can encode for relatively large transgenes.

Herpes simplex virus (HSV) infections are among the infections most frequently encountered by humans. Two types of HSV infections have been identified-HSV-1, which usually causes orolabial disease, and HSV-2, which is associated more frequently with genital and newborn infections. Usually, HSV causes mild and self-limited disease of the mouth and lips or at genital sites. However, on occasion, the disease can be life-threatening. Such is the case with neonatal HSV infection and HSV infections of the central nervous system. Furthermore, in the immunocompromised host, severe infection has been encountered and is a source of morbidity. Even in the immunocompetent host, frequent recurrences, particularly those of the genital tract, can be debilitating. Because HSV does cause genital ulcerative disease, it is associated with an increased risk of acquiring a human immunodeficiency virus infection. During the past 2 decades, selective and specific inhibitors of HSV replication have been developed. These agents, acyclovir, valaciclovir, and famciclovir, all accelerate the events of healing and decrease the probability of excreting the virus when they are taken in a suppressive fashion. The long-term safety of acyclovir has been unequivocally established. Its prodrug, valaciclovir, and the prodrug of penciclovir, famciclovir, have not been used in practice as long and, therefore, less is known about these agents; however, neither is available as a pediatric formulation.

Central nervous system malignancies--particularly glioblastoma multiforme--pose significant problems for the development of novel therapeutics. In the absence of advances with standard surgical and chemotherapeutic approaches, the utilization of genetically engineered viruses--both as direct oncolytic agents (virus therapy) and for the delivery of foreign proteins (gene therapy)--represents a significant advance in the experimental approach to the management of patients with incurable tumours. Among other viruses, herpes simplex virus (HSV) offers an opportunity to influence the replication of tumour cells directly within the central nervous system. The propensity for HSV to replicate in tumour cells, and its large coding capacity, provide an experimental model for the development of novel therapeutics. The status of these experimental approaches and Phase I studies are summarized.

Hippocrates was the first to describe lesions that could have been caused by herpes simplex virus (HSV), but the clinical conditions caused by this virus have only been described in more detail over the past 3 centuries. Most of the key findings relating to HSV infection and treatment have been made since the early 20th Century. These range from discovering some of the mechanisms behind virus latency and reactivation, to the development of the drug aciclovir, which was the first selective inhibitor of HSV replication. This review provides an evolutionary understanding of HSV, but HSV research is still in its golden age. New facts continue to emerge about HSV, and manipulation of the virus is providing much information. Genetic engineering of this virus is likely to have a most significant impact on future medical therapies, which could extend to specialties beyond virology.

Central nervous system malignancies, particularly glioblastoma multiforme, pose significant problems for the development of novel therapeutics. In the absence of advances with standard surgical and chemotherapeutic approaches, the utilisation of genetically engineered viruses, both as direct oncolytic agents as well as for the delivery of foreign proteins, represents a significant advance in the experimental approach to management of patients with these incurable tumours. Among other viruses, HSV offers an opportunity to directly influence the replication of tumour cells within the central nervous system. Because of its propensity to replicate in neuronal tissue as well as its large coding capacity, it provides an experimental model for the development of novel therapeutics. The status of these experimental approaches will be summarised in this review., (Copyright 2000 John Wiley & Sons, Ltd.)

A genetically engineered, nonneurotropic herpes simplex virus (R7020) with a proven safety profile in both animals and humans was found effective in the treatment of large xenotransplanted tumors arising from a radiation- and chemotherapy-resistant human epidermoid carcinoma and a hormone-refractory prostate adenocarcinoma. R7020 replicated to high titer and caused rapid regression of the human tumor xenografts. Tumor destruction was accelerated in animals given both R7020 and fractionated ionizing radiation. Tumors arising from cells surviving one treatment with R7020 were fully susceptible to a second dose of virus. We conclude R7020 is an effective antitumor agent for non-central nervous system tumor xenografts with an excellent safety profile.

This report describes a test of the hypothesis that the oncolytic effect of genetically engineered, replication competent herpes simplex viruses (HSV) depends both on cell destruction by the virus and an immune response to the tumor cells induced in an immunocompetent animal system. The oncolytic vector was a HSV recombinant virus in which both copies of the gamma 1 34.5 gene were replaced with the murine genes encoding the cytokine interleukin-4 (IL-4) or interleukin-10 (IL-10). The hypothesis predicted that if an immune response plays a role in survival following intratumoral treatment of tumor-bearing animals with HSV, expression of IL-4 should prolong survival whereas expression of IL-10 should reduce it. The results are that (1) these cytokines can be expressed by HSV in productively infected cells both in vitro and in vivo; (2) HSV-expressing IL-4 or IL-10 genes were able to infect and destroy glioma cells in vitro; (3) intracerebral inoculation of HSV expressing either IL-4 or IL-10 into syngeneic murine glioma GL-261 cells implanted in the brains of immunocompetent C57BL/6 mice produced dramatically opposite physiologic responses. The IL-4 HSV significantly prolonged survival of tumor bearers, whereas tumor-bearing mice that received the IL-10 HSV had a median survival that was identical to that of saline treated controls; (4) immunohistochemical analyses of mouse brains at 3 and 7 days after virus inoculation showed marked accumulation of inflammatory cells composed primarily of macrophages/microglia, with various proportions of CD8+ and CD4+ T cells, but few B lymphocytes. We conclude that the cytokines expressed from genes encoded in the viral genome influence HSV therapy of tumors and this is probably due to the host immune response. Thus, cytokine expression may be an important adjunct to tumor therapy utilizing genetically engineered HSV.

Cerebrospinal fluid (CSF) specimens from 77 neonates with herpes simplex virus (HSV) disease were evaluated retrospectively by polymerase chain reaction (PCR). Samples were collected from 202 infants enrolled in a National Institute of Allergy and Infectious Diseases Collaborative Antiviral Study Group trial that compared vidarabine with acyclovir for the treatment of neonatal HSV infection. HSV DNA was detected in the CSF of 26 (76%) of 34 infants with CNS disease, in 13 (93%) of 14 infants with disseminated infection, and in 7 (24%) of 29 with skin, eye, or mouth (SEM) involvement. One of the 7 PCR-positive SEM patients subsequently developed severe neurologic impairment. Eighteen (95%) of 19 infants with positive CSF PCR results after the completion of 10 days of antiviral therapy experienced significant morbidity or mortality. Application of PCR to neonatal HSV disease may provide additional information on which clinical decisions may be based, although its diagnostic utility outside the research setting is unproven.

Due to lack of effective therapy, primary brain tumors are the focus of intense investigation of novel experimental approaches that use vectors and recombinant viruses. Therapeutic approaches have been both indirect, whereby vectors are used, or direct to allow for direct cell killing by the introduced virus. Genetically engineered herpes simplex viruses are currently being evaluated as an experimental approach to eradicate malignant human gliomas. Initial studies with gamma (1)34.5 mutants, R3616 (from which both copies of the gamma (1)34.5 gene have been deleted) and R4009 (a construct with two stop codons inserted into the gamma (1)34.5 gene), have been assessed. In a syngeneic scid mouse intracranial tumor model, recombinant herpes simplex virus can be experimentally used for the treatment of brain tumors. These viruses and additional engineered viruses were subsequently tested in human glioma cells both in vitro and in vivo. Using a xenogeneic scid mouse intracranial glioma model, R4009 therapy of established tumors significantly prolonged survival. Most importantly, long-term survival was achieved, with histologic evidence that R4009 eradicated intracranial tumors in this model. Furthermore, the opportunity to evaluate gamma (1)34.5 mutants that have enhanced oncolytic activity, e.g., R8309 where the carboxyl terminus of the gamma (1)34.5 gene has been replaced by the murine homologue, MyD116, are considered.

Isolation of herpes simplex virus (HSV) from brain tissue after biopsy has been considered the reference standard for the diagnosis of herpes simplex encephalitis (HSE). During the evaluation of antiviral treatment of HSE, cerebrospinal fluid (CSF) was obtained from patients with clinical disease indicative of HSE who underwent diagnostic brain biopsy. HSV DNA was detected by polymerase chain reaction (PCR) in CSF of 53 (98%) of 54 patients with biopsy-proven HSE and was detected in all 18 CSF specimens obtained before brain biopsy from patients with proven HSE. Four of 19 CSF specimens were positive after 2 weeks of antiviral therapy. Positive results were found in 3 (6%) of 47 patients whose brain tissue was culture-negative. Detection of HSV DNA in the CSF correlated significantly with age and focal radiographic findings. Thus, PCR detection of HSV DNA should be the standard for diagnosis of HSE.

Genetically engineered viruses and viral genes inserted into retroviral vectors are increasingly being considered for experimental therapy of brain tumors. A primary target of these viruses and vectors is human gliomas, the most frequently occurring primary human brain tumor. To investigate the potential of genetically engineered herpes simplex viruses (HSVs) in the therapy of these tumors, we compared the attributes of two viruses, a recombinant from which the gamma 1(34.5) gene had been deleted (R3616) and a recombinant in which the gamma 1(34.5) gene had been interrupted by a stop codon (R4009). Previous studies have shown that these recombinants were completely devoid of the ability to multiply in the central nervous system of rodents. To pursue these studies, we developed a scid mouse glioma model. Tumor cell response (survival) for 10(3), 10(4), and 10(5) implanted MT539MG glioma cells was 38, 23, and 15 days, respectively. The results were as follows: (i) both R3616 and R4009 replicate and cause cytolysis in diverse glioma cell lines of murine and human origin in vitro, and (ii) Winn-type assays 10(5) MT539MG cells coinoculated with R3616 or R4009 as compared to saline significantly prolonged survival in a dose-dependent fashion. Mice that received only tumor cells or the wild-type parent strain of the recombinants, HSV-1(F), died within 15 days. Survival was greatest with R4009. These experiments define both a model for screening oncolytic viruses and a genetically engineered virus of significant potential use as an oncolytic agent.

Previous studies have shown that a gene mapping in the inverted repeats of the L component of herpes simplex virus, type 1 DNA, designated as gamma (1) 34.5, was dispensable for growth in cells in culture but that the deletion mutant (R3616) and a mutant containing a stop codon (R4009) in each copy of the gene were incapable of replicating in the central nervous systems (CNS) of mice. Restoration of the deleted sequences restored the wild type virus phenotype. We report here that the gamma (1) 34.5 mutant viruses (R3616 and R4009) replicated in the vaginal tract of two different strains of mice and guinea pig, although both viruses were shed at lower titer and for fewer days than the wild type and restored viruses. Both R3616 and R4009 failed to replicate or cause significant pathology in the cornea of Balb/C mice or following intranasal inoculation of Swiss Webster mice. Analyses of sensory trigeminal and dorsal root ganglia innervating the site of inoculation indicated that the incidence of establishment of latency or reactivation from latency by R3616 and R4009 viruses was significantly lower than that determined for mice infected with wild type or restored virus. Thus, selective deletion of gamma (1) 34.5 gene abolished the capacity of the virus to spread from peripheral mucosal sites to the CNS or replicate in the CNS, and diminished the capacity of the virus to replicate at mucosal sites and, subsequently, establish latency, or be able to be reactivated ex vivo. The results of our studies may have direct implications for the development of genetically engineered herpes simplex virus vaccines.

An extract of culture medium of Lentinus edodes mycelia, JLS-S001, significantly blocked the release of infectious herpes simplex virus type 1 (HSV-1) from African green monkey kidney cells. The block in replication was not due to the effect of JLS-S001 on the adsorption and penetration of HSV-1 to the monkey kidney cells. This observation was supported by the fact that JLS-S001 had no significant effect on the expression of virus-specific nucleocapsid proteins in the treated cells. Furthermore, electron microscopy demonstrated the presence of nucleocapsids within the nuclei of the infected and JLS-S001-treated cells. However, the expression of glycoproteins B, C, D, E and I was reduced in the JLS-S001-treated cells. These results suggested that JLS-S001 blocked HSV-1 replication at a late stage in virus replication cycle probably in the assembly and budding of nucleocapsids and subsequent egress from the treated cells.

Neonatal herpes simplex virus (HSV) infections are of increasing incidence in North America, now occurring at a rate of approximately one in 3,500 to one in 5,000 deliveries per year. Disease manifests as one of three forms; namely, infection: localized to the skin, eye and mouth (SEM), encephalitis (CNS), or disseminated disease. With the advent of antiviral therapy, it has become possible to decrease mortality and improve morbidity for babies suffering from infection. Advances in antiviral therapy have allowed for prevention of disease progression beyond states of SEM involvement. Furthermore, life threatening infections of the CNS or of multiple organs, have mortality with either acyclovir or vidarabine therapy. Now approximately 15% (CNS) and 50% (disseminated disease) of babies die from neonatal HSV disease. The results of ongoing studies in the United States will summarize the pathogenesis and treatment of neonatal HSV infection.

Treatment of African green monkey kidney cells with 1 microgram/ml of (S)-1-[(3-hydroxy-2-phosphonyl methoxy) propyl] cytosine (HPMPC) inhibited the release of infectious herpes simplex virus type 1 (HSV-1) by more than 90%. Electron microscopic observations of HPMPC-treated monkey kidney cells demonstrated few intracellular or extracellular viral particles. The viral particles seen were without dense cores. In addition, HPMPC blocked cell fusion induced by HSV-1 in monkey kidney cells. Immunoblot analysis showed that HPMPC significantly blocked the expression of HSV-1-specific proteins. Furthermore, HPMPC inhibited the synthesis of viral DNA as determined by in situ hybridization. These results indicate that HPMPC inhibits the replication of HSV by blocking one of the events involved in DNA synthesis.

The expression of herpes simplex virus type 2 (HSV-2) glycoproteins on the surface of human neuroblastoma cells has been investigated using Millipore Millicell culture plate inserts. Utilizing a modified radioimmunoassay, we learned that glycoproteins B, C, D, E, and I were expressed predominantly on the apical membrane domain of the infected neuroblastoma cells. The unidirectional transport of HSV-2 glycoproteins was substantiated by the analysis of extracellular glycoproteins released from neuroblastoma cells. The results suggest that the evaluated HSV-2 glycoproteins were transported primarily to the apical plasma membrane domain of human neuroblastoma cells.

An immunoblot assay for discrimination of antibodies to herpes simplex virus (HSV) types 1 and 2 was devised using extracts of recombinant-baculovirus-infected insect cells expressing HSV-1 or -2 glycoprotein G (gG1 or gG2). The assay was evaluated by comparing its results with those obtained by using an immunodot assay based on gG immunopurified from HSV-1- and HSV-2-infected cells. Each of 110 human serum specimens was tested blindly and independently three times. At a serum dilution of 1:20, the maximum specificities were 96% and 100% and the maximum sensitivities were 100% and 92% for gG1 and gG2, respectively. Reproducibility was 99% among readers and 95% among individually tested samples of each specimen. Results obtained in two laboratories from a different set of 15 serum specimens were in complete agreement, indicating the assay is accurate and reproducible. The ease of antigen production should allow the test to become widely available.

The gene designated gamma 134.5 maps in the inverted repeats flanking the long unique sequence of herpes simplex virus-1 (HSV-1) DNA, and therefore it is present in two copies per genome. This gene is not essential for viral growth in cell culture. Four recombinant viruses were genetically engineered to test the function of this gene. These were (i) a virus from which both copies of the gene were deleted, (ii) a virus containing a stop codon in both copies of the gene, (iii) a virus containing after the first codon an insert encoding a 16-amino acid epitope known to react with a specific monoclonal antibody, and (iv) a virus in which the deleted sequences were restored. The viruses from which the gene was deleted or which carried stop codons were avirulent on intracerebral inoculation of mice. The virus with the gene tagged by the sequence encoding the epitope was moderately virulent, whereas the restored virus reacquired the phenotype of the parent virus. Significant amounts of virus were recovered only from brains of animals inoculated with virulent viruses. Inasmuch as the product of the gamma 134.5 gene extended the host range of the virus by enabling it to replicate and destroy brain cells, it is a viral neurovirulence factor.

The target specificity of natural killer (NK) cells for either tumor cells or virus-infected cells has been investigated. Lymphocyte clones with the surface phenotype of NK cells (CD3-, CD16+) were obtained by limiting dilution of peripheral blood mononuclear cells stimulated with PHA, Herpes simplex virus type 1 (HSV-1), or Varicella-Zoster antigens. Clones were maintained in media with recombinant interleukin 2 (IL-2). Both NK-sensitive (K562 cells) and NK-resistant (Raji cells) targets were lysed by three cloned lines of NK cells. The ability to lyse NK-resistant target cells was largely lost when the cloned lymphocytes were cultured overnight in the absence of IL-2. Effector cells from all three clones were also capable of specifically lysing HSV-1 infected human fibroblasts in comparison with uninfected fibroblasts. We also showed that lysis of HSV-1 infected targets by NK cloned cells was independent of interferons in the culture system.

The genetically engineered herpes simplex virus strains R7017 and R7020 were tested in owl monkeys (Aotus trivirgatus) previously shown to model herpetic diseases of immunocompromised patients and neonates. In contrast to the lethal disease seen in monkeys receiving 100-1,000 plaque-forming units (pfu) of wild-type virus, inoculation of greater than or equal to 10(6) pfu of recombinant viruses produced local lesions and viral shedding but not disseminated disease. Latent recombinant viruses were recovered from some ganglia innervating the sites of inoculation. Monkeys protected from lethal infection with wild-type virus exhibit recurrent lesions that increase in frequency and severity after total lymphoid gamma irradiation (TLI). In contrast, monkeys immunosuppressed by TLI and inoculated with R7020 could not be differentiated from irradiated controls with respect to morbidity or mortality. Moreover, the virus was not transmitted from immunosuppressed infected females to normal male cage mates.

The role of glycosylation in transport and expression of HSV-1 glycoproteins on the surface of HSV-1-infected African green monkey kidney cells was investigated by using tunicamycin (TM). A concentration of 0.05 microgram/ml of TM inhibited the replication of HSV-1 by greater than 99%. Immunoblot analysis of TM-treated and virus-infected cells indicated that 0.05 microgram/ml of TM blocked the addition of N-linked oligosaccharides into glycoproteins B, C and D. An immunofluorescence assay of TM-treated (0.05 and 0.1 microgram/ml) and virus-infected cells demonstrated the presence of nonglycosylated gC, gD and a reduced amount of gB on the surface of infected cells. The results suggest that the addition of N-linked oligosaccharides on the studied HSV-1 glycoproteins was not necessary for their transport and expression on the virus-infected cell surface.

Herpes-simplex-virus (HSV) DNA in cerebrospinal fluid was amplified by use of the polymerase chain reaction and identified by hybridisation to a specific oligonucleotide probe. Specimens of cerebrospinal fluid (CSF) from 4 of 4 patients with herpes simplex encephalitis were positive for HSV DNA, whereas CSF specimens from 6 patients with other central-nervous-system infections were negative. This technique may expedite diagnosis of herpes simplex encephalitis.

The role of herpes simplex virus type 1 (HSV-1) glycoprotein E (gE) in the induction of multinucleate cell (syncytium) formation was investigated using monoclonal antibodies and a gE deletion mutant, R7023. We found that monoclonal antibodies directed against gE blocked HSV-1-induced syncytium formation in human cells. R7023 also failed to induce syncytium formation in tissue culture cells. The results indicate that gE, in addition to glycoproteins B, D, H and the gene sequence located between 0.732 and 0.745 map units, is involved in cell fusion. Thus, this important biological property appears to be regulated by several HSV-1 gene products.

Human recombinant alpha interferon, A/D, significantly reduced the replication and cell fusion induced by herpes simplex virus type 1 in monkey cells. Thin-section electron microscopy of interferon-treated monkey cells showed distinct assembly of nucleocapsids within the nucleus. Analysis of virus-specific proteins by the immunoblot technique confirmed that A/D interferon had no significant effect on the expression of major nucleocapsid proteins, although the expression of glycoproteins B and D was reduced in interferon-treated cells. The possibility of an interferon-induced block at a late stage in virus morphogenesis is discussed.

Laboratory procedures were compared with brain biopsy findings in 113 biopsy-proven patients with herpes simplex virus (HSV) encephalitis and 93 biopsy-negative individuals. Examinations of brain tissue by histopathology, immunofluorescence, and electron microscopy demonstrated evidence of HSV infection in 56%, 70%, and 45% of proven cases and apparently false-positive results in 14%, 9% and 2% of those biopsy-negative. Serologic assessments revealed that HSV encephalitis occurred as both a primary (30%) and recurrent (70%) infection. Among patients with HSV encephalitis, 28% failed to seroconvert or seroboost within one month of the onset of disease. Titers of passive hemagglutinating and IgG immunofluorescent antibodies increased fourfold in the cerebrospinal fluid in 74% and 94%, respectively, of patients with proven disease. Similar percentages of patients had antibody ratios in serum and cerebrospinal fluid of less than 20 over the same interval. These data indicate the need for development of noninvasive diagnostic procedures.

In this paper we describe the ability of monoclonal antibodies to prevent herpetic stromal or interstitial keratitis following corneal infection in an outbred mouse model. Monoclonal antibodies recognizing antigenic determinants on glycoproteins B, C, D, and E of herpes simplex virus type 1 were injected intraperitoneally into CF-1 outbred mice 24 or 48 h following inoculation of the cornea with the RE strain of herpes simplex virus type 1. Passive, postexposure immunization with monoclonal antibodies had little effect on the severity of the initial corneal infection or the frequency of latent viral infections in the trigeminal ganglia, except for virus-neutralizing antibodies specific for glycoproteins B and D. A significant correlation was found between the severity of epithelial keratitis and the frequency of latent ganglionic infections. However, immunization with monoclonal antibodies protected the mice against encephalitis and prevented the development of necrotizing stromal keratitis that leads to permanent corneal scarring and blindness. This form of herpetic ocular disease does not respond to antiviral chemotherapy. Since nonneutralizing monoclonal antibodies were just as effective in prevention of encephalitis and stromal keratitis as ones that neutralized the virus in vitro, and antibodies were not administered until 24 or 48 h after corneal inoculation, we suggest that inactivation of infectious virus is not the only protective mechanism in this model.

Monoclonal antibodies against herpes simplex virus type 1 glycoproteins were isolated and utilized to study the synthesis and processing of glycoproteins B, C, and D (gB, gC, gD, respectively). Monoclonal antibodies against both gB and gD had higher virus-neutralizing activity when compared to that of gC. Differences among these glycoproteins were observed in their time of appearance in the virus-infected cells. The presence of gD was detected at a very early stage of infection when compared to gB and gC. The localization of these glycoproteins during their synthesis and processing was studied.

Cerebrospinal fluid (CSF) specimens were obtained from patients with presumed herpes simplex encephalitis who underwent brain biopsy for diagnostic confirmation. Coded CSF specimens were fixed on nitrocellulose filter paper and probed with a pool of monoclonal antibodies directed against four herpes simplex virus glycoproteins (gB, gC, gD, and gE). Herpes simplex virus antigen was detected in 35 of 40 specimens obtained from 26 biopsy-positive patients. In contrast, only three of 25 specimens from 17 biopsy-negative patients gave positive results by this assay. An additional 30 CSF specimens from patients with proven bacterial and fungal infections were all negative by this assay. For all specimens tested, the sensitivity and specificity of the assay were both 88%. However, when results were evaluated by patient, the sensitivity was 92% (24 of 26) with a specificity of 82% (14 of 17). Among specimens collected one week or later after disease onset, the sensitivity was 100%, with a specificity of 93%.