Use of differential display reverse transcription-PCR to reveal cellular changes during stimuli that result in herpes simplex virus type 1 reactivation from latency: upregulation of immediate-early cellular response genes TIS7, interferon, and interferon regulatory factor-1

Vestibular Neuritis Following COVID-19 Vaccination: A Retrospective Study

Objective

To determine if the COVID-19 vaccine can cause vestibular neuritis (VN).

Design

Retrospective study.

Setting

Vertigo outpatient clinic of the Department of Otolaryngology JR Tokyo General Hospital.

Participants:

378 patients who presented at the Vertigo clinic between July 2018 and March 2022

Results

23 out of 378 cases were diagnosed with vestibular neuritis. There was a significant seasonal bias of the onset of VN in 2021-3Q compared to other seasons. All 7 patients diagnosed with VN whose onset was 2021-3Q and 2021-4Q had received the BNT162b2 (Pfizer-BioNTech) vaccine within the previous 3 months and one patient diagnosed with VN whose onset was 2022-1Q had a history of COVID-19 infection six months earlier.

Conclusions

VN should be recognized as one of the side-effects of the BNT162b2 COVID-19 vaccination.

Evidence in the prevention of the recurrence of herpes simplex and herpes zoster keratitis after eye surgery

OBJECTIVE

Herpetic keratitis, either due to herpes simplex keratitis (HSK) or herpes zoster ophthalmicus (HZO), can recur after eye surgery.º Prophylaxis is postulated as necessary to avoid it. The objective of this study was to review the scientific evidence on the preventive methods used in the perioperative period in patients previously affected by HSK/HZO.

METHODS

An exhaustive search was carried out in the PubMed and Web of Science databases to identify relevant articles on prophylaxis and risk of recurrence of HSK/HZO in patients undergoing eye surgery up to 31 December 2019.

RESULTS

There is strong evidence that oral prophylaxis should be recommended after penetrating keratoplasty in patients who have previously had HSK/HZO. For other types of surgery, the evidence is less compelling. However, a latent period of inactivity should be considered between disease and oral prophylaxis.

CONCLUSIONS

Penetrating and lamellar keratoplasty, corneal crosslinking, cataract surgery, and photorefractive and phototherapeutic surgery cause an alteration of the subbasal nerve plexus of the cornea. Due to surgical trauma, as well as the modulation of the ocular immune response caused by steroids applied in the postoperative period, it is possible to induce the reactivation of HSK/HZO, which is common in some cases. Within this article, we discuss the available evidence for HSK/HZO prophylaxis in eye surgery. Further studies are necessary to define the real risk of HSK/HZO recurrence after ocular surgeries, particularly in cataract surgery, and to confirm the efficacy of perioperative prophylaxis with anti-HSK/HZO antivirals.

Ocular surgery after herpes simplex and herpes zoster keratitis

PURPOSE

The recurrence of herpetic stromal keratitis (HSK) and herpes zoster ophthalmicus (HZO) has been reported after a variety of ocular surgeries. The aim of this study was to review the evidence on the preventive methods employed in the perioperative period in patients having undergone HSK/HZO.

METHODS

The PubMed and Web of Science databases were the main resources used to conduct the medical literature search. An extensive search was performed to identify relevant articles concerning the prophylaxis against and risk of HSK/HZO recurrence in patients undergoing ocular surgery up to December 31, 2019.

RESULTS

The disturbance of the corneal nerve plexus occurs during several ocular surgeries including penetrating keratoplasty, lamellar keratoplasty, corneal cross-linking, cataract surgery, as well as photorefractive and phototherapeutic procedures. Such trauma, as well as modulation of the ocular immunological response caused by steroids applied postoperatively, might engender the HSK/HZO reactivation which is not uncommon. There is strong evidence that oral prophylaxis should be recommended just after surgery in patients undergoing penetrating keratoplasty and having suffered from HSK/HZO. For other types of surgeries, the evidence is less compelling; nevertheless, a period of disease quiescence and oral prophylaxis should still be considered.

CONCLUSIONS

Within the article, we discuss the available evidence for HSK/HZO prophylaxis in ocular surgery. Additional studies would be required to define the real risk of HSK/HZO recurrence following eye surgeries, and particularly cataract surgery, and to confirm the utility of perioperative HSK/HZO prophylaxis.

Study of interferon-β antiviral activity against Herpes simplex virus type 1 in neuron-enriched trigeminal ganglia cultures

Herpes simplex virus type 1 (HSV-1) causes a lytic infection in epithelial cells before being captured and moved via retrograde axonal transport to the nuclei of the sensory neurons of the trigeminal ganglion or dorsal root, where it establishes a latent infection. HSV-1 infection induces an antiviral response through the production of Beta Interferon (IFN-β) in infected trigeminal ganglia. The aim of this work was to characterize the response induced by IFN-β in neuron-enriched trigeminal ganglia primary cultures infected with HSV-1. An antiviral effect of IFN-β in these cultures was observed, including reduced viral production and increased cell survival. In contrast, viral infection significantly decreased both double stranded RNA dependent protein kinase (Pkr) transcription and Jak-1 and Stat-1 phosphorylation, suggesting a possible HSV-1 immune evasion mechanism in trigeminal cells. Additionally, HSV-1 infection upregulated Suppressor of Cytokine Signaling-3 (Socs3) mRNA; upregulation of socs3 was inhibited in IFN-β treated cultures. HSV-1 infection increased the number of Socs3 positive cells and modified the intracellular distribution of Socs3 protein, in infected cells. This neuron-enriched trigeminal ganglia culture model could be used to elucidate the HSV-1 viral cycle in sensory neurons and to study cellular antiviral responses and possible viral evasion mechanisms that underlie the choice between viral replication and latency.

[Experience with multiplex nested PCR and fluorescent antibody tests in the diagnosis of acute central nervous system infections with herpes simplex virus type 1 and 2]

The specific diagnosis of herpes simplex virus type 1 and 2 infections has an extreme importance in acute infections of central nervous system due to both availability of specific antiviral therapy and the possible serious consequences of the disease.

AIMS

Evaluation of the relevance and interpretation of the results of PCR and the specific antibody testing.

METHODS

Home made multiplex nested herpes simplex virus PCR and immunofluorescent IgM, IgA, IgG antibody tests were carried out in a total of 474 cerebrospinal fluid and 555 serum samples of 396 patients with acute infection of the central nervous system between 1. January, 2003 and 31. December, 2009.

RESULTS

The herpes simplex virus etiology was verified in 21% of 396 patients (82 patients, mean 12 cases per year): 26 were diagnosed by both methods (32%), 41 by PCR only (50%), 15 by the detection of intrathecal antibody production only (18%) (p<0.0001). HSV type1 or 2 DNA remained detectable in 35% of the samples drawn after the 30th day of the disease. These patients were all younger than two years of age.

CONCLUSIONS

1. PCR increased the ratio of verified herpes simplex virus etiology in acute central nervous infections. 2. Testing the specific antibody response cannot be ceased even in the availability of PCR. 3. Herpes simplex virus type 1 or 2 DNA might persist in central nervous system in spite of the specific antiviral therapy especially in the infants. 4. Herpes simplex virus PCR can be repeated if an early sample is negative or if it is suspected false positive. 5. There is a need for cooperation between clinicians and virologists in the appropriate interpretation of the results and in finding etiology.

Ocular HSV-1 latency, reactivation and recurrent disease

Ocular infection with HSV-1 continues to be a serious clinical problem despite the availability of effective antivirals. Primary infection with HSV-1 can involve ocular and adenaxial sites and can manifest as blepharitis, conjunctivitis, or corneal epithelial keratitis. After initial ocular infection, HSV-1 can establish latent infection in the trigeminal ganglia for the lifetime of the host. During latency, the viral genome is retained in the neuron without producing viral proteins. However, abundant transcription occurs at the region encoding the latency-associated transcript, which may play significant roles in the maintenance of latency as well as neuronal reactivation. Many host and viral factors are involved in HSV-1 reactivation from latency. HSV-1 DNA is shed into tears and saliva of most adults, but in most cases this does not result in lesions. Recurrent disease occurs as HSV-1 is carried by anterograde transport to the original site of infection, or any other site innervated by the latently infected ganglia, and can reinfect the ocular tissues. Recurrent corneal disease can lead to corneal scarring, thinning, stromal opacity and neovascularization and, eventually, blindness. In spite of intensive antiviral and anti-inflammatory therapy, a significant percentage of patients do not respond to chemotherapy for herpetic necrotizing stromal keratitis. Therefore, the development of therapies that would reduce asymptomatic viral shedding and lower the risks of recurrent disease and transmission of the virus is key to decreasing the morbidity of ocular herpetic disease. This review will highlight basic HSV-1 virology, and will compare the animal models of latency, reactivation, and recurrent ocular disease to the current clinical data.

Role of TIS7 family of transcriptional regulators in differentiation and regeneration

The regulation of gene expression plays an important role not only during embryonic development but also in the course of cell differentiation and regeneration processes of various tissues, e.g. skeletal muscles, intestines, or nerves. Tightly regulated gene expression in particular cell types requires a sophisticated interplay between the basic transcriptional machinery and specific transcriptional regulators--activators, repressors, co-activators, and co-repressors. The last category includes the TPA Induced Sequence 7 (TIS7) protein family, recently characterized as transcriptional co-repressors. The expression of these proteins is regulated on the mRNA level and directly correlates with the processes of cell and tissue differentiation not only during embryonic development but mainly throughout the regeneration events in adult organisms. The expression of TIS7 and its homologue SKMc15 is ubiquitous and according to current knowledge, as summarized in this review, TIS7 plays a role in the differentiation of various cell types, e.g. epithelial cells, myoblasts, hematopoietic cells, or neurons. Here, we not only focus on the description of TIS7 expression in various systems (species, organs) but also try to provide current state of knowledge of the regulatory mechanisms in which TIS7 is involved. The clarification of biochemical mechanisms directed by the TIS7 family members during regeneration events, e.g. following injury, will additionally provide us with the opportunity to intervene therapeutically.

A Gene Similar to the Human Hyaluronan-mediated Motility Receptor (RHAMM) Gene is Upregulated During Porcine Circovirus Type 2 Infection

Little is known on the cellular events triggered by the Porcine Circovirus type 2 (PCV2) in Porcine Multisystemic Wasting Syndrome (PMWS). The differential display reverse-transcription PCR (DDRT-PCR) was used to identify cellular target molecules in lymph node tissue that were regulated in PMWS. Comparative profile analysis of a pool of lymph node tissues from PMWS and healthy animals showed that some transcripts were up-regulated in PMWS. Bacterial recombinant clones containing up-regulated transcripts were analyzed by reverse dot blot. Clones showing enhanced hybridization when probed with cDNAs from PMWS animals were sequenced and compared to existing databases. Two of the differentially regulated transcripts displayed homology with human genes such as an RNA splicing factor and hyaluronan-mediated motility receptor (RHAMM). Clones encoding theses genes were subsequently used as probes to analyze their expression pattern in PK15 cells persistently infected with PCV2. Northern blot analyzes indicated that these transcripts were up-regulated in these cells as observed in infected lymph node tissue from PMWS cases. A role for the up-regulation of the RHAMM gene is proposed.

The cellular response to herpes simplex virus type 1 (HSV-1) during latency and reactivation

In order to learn more about the cellular response to viral gene activity during latency and reactivation of herpes simplex virus type 1 (HSV-1), the authors have employed microarray analysis. On an array of about 1200 cellular genes, approximately 56 genes were found to be differentially regulated in infected trigeminal ganglia of mice, compared to uninfected mice, during latency and reactivation. Of these genes, 10 were examined more closely using quantitative real-time polymerase chain reaction (PCR) to confirm the microarray results. Genes involved in interferon and other signaling pathways appeared to predominate in response to a latent or reactivating HSV infection. Interestingly, some genes found to be differentially regulated in latently infected ganglia are neuronal-specific genes (pro-opiomelanocortinin; zinc finger proteins of the cerebellum 1 and 2). During reactivation, the involvement of several cell signaling molecules that may be important for the initiation of an HSV infection was observed, including various receptors and molecules involved in cell-cell spread.

Microarray analysis in the HSV-1 latently infected mouse trigeminal ganglion

PURPOSE

To review our previous studies regarding alterations in gene expression in HSV-1 latently infected mouse trigeminal ganglia (TGs) following treatment with immunosuppressants and hyperthermia.

METHODS

Uninfected and HSV-1 latently infected mice were treated with immunosuppressants or heat stressed (43 degrees C for 10 minutes). In the immunosuppressant study, 4 groups of animals were examined: (1) uninfected, not treated; (2) uninfected, drug-treated; (3) latently infected, not treated; and (4) latently infected, drug-treated. In the hyperthermia study, TG from 6 groups of mice were studied: (1) uninfected, not stressed; (2) uninfected, heat-stressed; killed at 6 hours after hyperthermia; (3) uninfected, heat-stressed, killed at 24 hours after hyperthermia; (4) latently infected, not stressed; (5) latently infected, heat-stressed, killed at 6 hours after hyperthermia; and (6) latently infected, heat-stressed, killed at 24 hours after hyperthermia. PolyA mRNA from the TGs of each group was reverse-transcribed, labeled with P, incubated on a gene array membrane, and analyzed by phosphorimaging. As a comparison and to confirm microarray results, semiquantitative RT-PCR for selected genes was also performed.

RESULTS

The immunosuppressive drugs significantly increased expression of two genes--calpactin 1 light chain and guanine nucleotide-binding protein alpha stimulating activity polypeptide (GNAS)--in the ganglia of uninfected mice compared with untreated, uninfected mice. Ten genes were shown to be significantly increased in the latent TGs from mice treated with the immunosuppressants compared with latently infected untreated mice. These genes were prostaglandin E2 receptor EP4 subtype (PTGER4), insulin promoter factor 1 (IPF1), glutathione S-transferase mu2, cyclin D2, peripherin, plasma glutathione peroxidase, methyl CpG-binding protein 2, retinal S-antigen, ErbB2 protooncogene, and GNAS. Eight genes were shown to be significantly decreased in the HSV-1 latent TGs treated with the drugs compared with untreated latent mice. These genes were peripheral myelin protein 22, decorin, transcription factor AP-1, dystroglycan 1, myelin protein zero, mitogen-activated protein kinase 3, prothymosin beta4, and brain lipid-binding protein. The results obtained by semiquantitative RT-PCR results were similar to those obtained by microarray analysis. Six hours after heat stress, the genes whose expression was altered included the FK506-binding protein gene (decreased), the T-complex protein 1alpha subunit gene (increased), and the 94-kDa glucose-regulated protein gene (increased in uninfected TG, decreased in infected TG). Heat stress increased expression of the DNA excision repair protein ERCC5 gene 24 hours after the treatment. Genes previously reported to exhibit increased transcription 1 hour after heat stress did not continue to show significant transcriptional activation at 6 or 24 hours.

CONCLUSIONS

Those genes whose expression is altered by immunosuppressive drug treatment may play an important role in ocular HSV-1 recurrence. Changes in gene expression in the prostaglandin pathway, a transcription factor, and an enzyme in the cell cycle are considered of special importance for HSV-1 reactivation by immunosuppression. Altered gene expression at 6 and 24 hours after heat stress was different from previously reported changes in gene expression 1 hour after hyperthermia in HSV-1 latently infected mice.

Differential display RT-PCR analysis of enterovirus-71-infected rhabdomyosarcoma cells reveals mRNA expression responses of multiple human genes with known and novel functions

In order to better understand cellular responses to viral infection at the transcriptional level, we employed differential display RT-PCR to analyze mRNAs from RD rhabdomyosarcoma cells following infection with a neurovirulent enterovirus 71 (EV71) strain, compared with mRNAs from uninfected cells. Of 250 expressed sequence tags (ESTs) isolated, sequenced, and identified, all were of cellular origin except 1 that was of viral origin. Of these, 156 were individual distinctive clones, comprising 45 mRNAs showing unaltered expression and 111 mRNAs exhibiting upregulation or downregulation. Of the 45 uniformly expressed mRNAs, 14 represented unknown genes. Of the 111 differentially expressed mRNAs, 63 did not match any known genes. Forty-eight of the 111 mRNAs modified by EV71 infection matched known genes, including those encoding components of cell cycle, cytoskeleton, and cell death mediators; protein degradation mediators; mitochondrial-related proteins; components of protein translation and modification; and cellular transport proteins. The altered expression profiles of representative genes were authenticated by semiquantitative RT-PCR and real-time RT-PCR. We also identified a novel alternatively spliced transcript of TRIP7 thyroid receptor interactor protein; the putative human homolog of murine mc7 mRNA predominantly expressed in the brain; and a novel mRNA similar to that encoding vacuolar protein 8 involved in protein targeting. These results underscore the applicability of the mRNA differential display technique for elucidating the expression profiles of known and even novel genes in response to cellular infection with pathogenic viruses.

Gene array analysis reveals changes in peripheral nervous system gene expression following stimuli that result in reactivation of latent herpes simplex virus type 1: induction of transcription factor Bcl-3

The earliest events within the peripheral mammalian nervous system that cause herpes simplex virus type 1 (HSV-1) to reactivate from latency are unknown but are highly likely to include altered regulation of cellular transcription factors. Using gene array analysis, we have examined the changes that occur in cellular mRNA levels in mouse trigeminal ganglia following explantation, a stimulus that results in HSV-1 reactivation from latency. We have detected both increased and decreased expression levels of particular cellular transcripts, which include RNAs encoding neuronal factors, transcription factors, and factors involved in the cell cycle. Among the transcription factors that are upregulated is Bcl-3, a coactivator for NFkappaB. We have confirmed these increases in Bcl-3 transcription levels using reverse transcription-PCR and S1 nuclease protection assays. In addition, we have shown Bcl-3 upregulation at the protein level. Importantly, Bcl-3 RNA levels were found to increase specifically in neuronal cells within the trigeminal ganglia. We discuss a potential role for this factor in upregulating ICP0 transcription, which is an important viral event for initiation of HSV-1 reactivation.

Analysis of individual human trigeminal ganglia for latent herpes simplex virus type 1 and varicella-zoster virus nucleic acids using real-time PCR

Herpes simplex virus type 1 (HSV-1) and varicella-zoster virus (VZV) establish latent infections in the peripheral nervous system following primary infection. During latency both virus genomes exhibit limited transcription, with the HSV-1 LATs and at least four VZV transcripts consistently detected in latently infected human ganglia. In this study we used real-time PCR quantitation to determine the viral DNA copy number in individual trigeminal ganglia (TG) from 17 subjects. The number of HSV-1 genomes was not significantly different between the left and right TG from the same individual and varied per subject from 42.9 to 677.9 copies per 100 ng of DNA. The number of VZV genomes was also not significantly different between left and right TG from the same individual and varied per subject from 37.0 to 3,560.5 copies per 100 ng of DNA. HSV-1 LAT transcripts were consistently detected in ganglia containing latent HSV-1 and varied in relative expression by >500-fold. Of the three VZV transcripts analyzed, only transcripts mapping to gene 63 were consistently detected in latently infected ganglia and varied in relative expression by >2,000-fold. Thus, it appears that, similar to LAT transcription in HSV-1 latently infected ganglia, VZV gene 63 transcription is a hallmark of VZV latency.

Vesicular stomatitis virus and pseudorabies virus induce a vig1/cig5 homologue in mouse dendritic cells via different pathways

The homologous genes vig1 and cig5 were identified by differential display PCR as virus-induced genes in rainbow trout and humans, respectively. These genes are significantly related to sequences required for the biosynthesis of metal cofactors, but their function remains unknown. In this study, it is shown that the mouse homologue of vig1/cig5 was induced by vesicular stomatitis virus (VSV) and pseudorabies virus (PrV) in mouse spleen cells. Among a collection of cell lines from dendritic, myeloid, lymphoid or fibroblast lineages, only the dendritic cell line, D2SC1, showed expression of mvig after virus infection. This dendritic restriction was confirmed by our finding that mvig was also induced by both VSV and PrV in CD11c(++) spleen cells, separated by magnetic purification or derived from bone marrow precursor cells. Similar to the fish rhabdovirus viral haemorrhagic septicaemia virus in trout cells, VSV directly induced mvig in the dendritic cell line D2SC1, but the PrV-mediated induction required the integrity of the interferon pathway. This result indicates that mvig is interferon-inducible like its fish and human homologues. Furthermore, mvig was also induced by LPS in bone marrow-derived cells. Thus, mvig expression seems to correlate with an activated state of dendritic cells subjected to different pathogen-associated stimuli.

An RNA helicase, RHIV -1, induced by porcine reproductive and respiratory syndrome virus (PRRSV) is mapped on porcine chromosome 10q13

The impact of porcine reproductive and respiratory syndrome virus (PRRSV) infection on porcine alveolar macrophages (Mo) was examined by differential display reverse transcription PCR (DDRT-PCR). A PRRSV-induced expressed gene tag (EST) was used to isolate and identify a single cDNA clone from a library prepared from porcine peripheral blood. Rapid amplification of cDNA ends (RACE) was employed to clone a 1.5 kb fragment at the 5' end of the mRNA. DNA sequencing identified an open reading frame (ORF) of 2820 bp. Deduced amino acid sequence revealed the eight conserved domains characteristic of the DEAD/H box protein superfamily. The putative porcine RNA helicase induced by virus (RHIV -1) showed 84% amino acid similarity to human retinoic acid-induced gene (RIG-I). Porcine RHIV -1 transcripts were ubiquitously expressed in various pig tissues, while in PRRSV-infected pigs, higher expression was observed in several tissues persistent for PRRSV. These data indicate the association of PRRSV genome replication with enhaced host cell RNA helicase gene expression. Finally, the RHIV -1 gene was localized on porcine chromosome 10q13 between markers SSC25A02 and SWR334 via somatic cell panel and radiation hybrid (RH) mapping strategies.

A gE-negative bovine herpesvirus 1 vaccine strain is not re-excreted nor transmitted in an experimental cattle population after corticosteroid treatments

To study possible reactivation and to quantify subsequent transmission of a live gE-negative bovine herpesvirus 1 (BHV1) vaccine strain in cattle populations, four experiments were performed. Two groups of cattle were each tested twice for the possibility of reactivation. Inoculation with a gE-negative BHV1 vaccine was done either intramuscularly or intranasally and treatment with corticosteroids in an attempt to reactivate vaccine virus, was done after 6 or 11 weeks, and again after 6 months. To quantify transmission of vaccine virus following possible reactivation, each cattle was housed together with one susceptible contact-cattle. Contact-infections were monitored using virus shedding and antibody responses. After corticosteroid treatments, re-excretion of virus was never detected in cattle that had been inoculated with the gE-negative BHV1 vaccine strain. Contact cattle did not shed gE-negative BHV1, nor mounted any antibody response against BHV1. In contrast, positive control cattle, inoculated intranasally with wild-type BHV1, re-excreted virus in high titers in nasal fluids and transmitted the virus to contact cattle. Based on these results, the transmission ratio R(0) of the vaccine strain was zero. We concluded that it is highly unlikely that the live gE-negative BHV1 vaccine strain will be re-excreted after possible reactivation, and consequently, it is even less likely that reactivated vaccine virus will spread in the cattle population.

IFN-alpha1 plasmid construct affords protection against HSV-1 infection in transfected L929 fibroblasts

The purpose of the present study was to evaluate the resistance against herpes simplex virus type 1 (HSV-1) using an interferon-alpha1 (IFN-alpha1) transgene in specifically targeted cells in vitro. Transfection of mouse fibroblast L929 cells with an IFN-alpha1 plasmid construct reduced viral load and viral gene expression in a time-dependent fashion. Supernatants from IFN-alpha1-transfected cells augmented natural killer (NK) cell activity, and such an effect was antagonized with neutralizing antibody to IFN-alpha/beta. In addition, transfected cells displayed an increase in the IFN inducible genes (2',5'-oligoadenylate synthetase [2',5'-OAS], T cell-specific guanine nucleotide triphosphate-binding protein, IFN regulatory factor 1 [IRF-1], and major histocompatibility complex [MHC] class I) compared with plasmid vector-treated controls. Collectively, these results show that IFN-alpha1 transfection of cells in vitro induces or upregulates a spectrum of IFN-regulated genes involved in the direct or indirect antiviral action of this cytokine. In addition, the transgene significantly increases the resistance of transfected cells in vitro to HSV-1 infection.

HSV-1-based vectors for gene therapy of neurological diseases and brain tumors: part I. HSV-1 structure, replication and pathogenesis

The design of effective gene therapy strategies for brain tumors and other neurological disorders relies on the understanding of genetic and pathophysiological alterations associated with the disease, on the biological characteristics of the target tissue, and on the development of safe vectors and expression systems to achieve efficient, targeted and regulated, therapeutic gene expression. The herpes simplex virus type 1 (HSV-1) virion is one of the most efficient of all current gene transfer vehicles with regard to nuclear gene delivery in central nervous system-derived cells including brain tumors. HSV-1-related research over the past decades has provided excellent insight into the structure and function of this virus, which, in turn, facilitated the design of innovative vector systems. Here, we review aspects of HSV-1 structure, replication and pathogenesis, which are relevant for the engineering of HSV-1-based vectors.

Molecular responses of macrophages to porcine reproductive and respiratory syndrome virus infection

The detailed mechanism(s) by which porcine reproductive and respiratory syndrome virus (PRRSV) impairs alveolar Mo homeostasis and function remains to be elucidated. We used differential display reverse-transcription PCR (DDRT-PCR) to identify molecular genetic changes within PRRSV-infected Mo over a 24 h post infection period. From over 4000 DDRT-PCR amplicons examined, 19 porcine-derived DDRT-PCR products induced by PRRSV were identified and cloned. Northern blot analysis confirmed that four gene transcripts were induced during PRRSV infection. PRRSV attachment and penetration alone did not induce these gene transcripts. DNA sequence revealed that one PRRSV-induced expressed sequence tag (EST) encoded porcine Mx1, while the remaining 3 clones represented novel ESTs. A full-length cDNA clone for EST G3V16 was obtained from a porcine blood cDNA library. Sequence data suggests that it encodes an ubiquitin-specific protease (UBP) that regulates protein trafficking and degradation. In pigs infected in vivo, upregulated transcript levels were observed for Mx1 and Ubp in lung and tonsils, and for Mx1 in tracheobronchial lymph node (TBLN). These tissues correspond to sites for PRRSV persistence, suggesting that the Mx1 and Ubp genes may play important roles in clinical disease during PRRSV infection.

Identification of a stress-induced protein during human trophoblast differentiation by differential display analysis

Differentiation of human placental trophoblast is characterized by a process during which mononuclear villous cytotrophoblasts fuse to form a multinucleate syncytium. This event is associated with dramatic changes in gene expression. In the present study, we have applied a sensitive approach-differential display analysis-to evaluate changes in gene expression during in vitro forskolin-induced differentiation of a model of human trophoblast, the choriocarcinoma BeWo. We identified seven genes that were up-regulated; their expression and function have not previously been reported in trophoblast. Four up-regulated genes were novel upon comparison of their sequences to the GenBank database. The other three genes encode human cytochrome p450 IIC, inosine monophosphate dehydrogenase type II, and reducing agent and tunicamycin-responsive protein (RTP). Northern blot analysis revealed that RTP mRNA expression was induced to 3-fold in BeWo after 24-h incubation with forskolin and increased up to 11-fold by 72 h of forskolin treatment. The expression pattern of RTP was further investigated by in situ hybridization on second trimester and term placenta tissues. RTP mRNA was predominantly expressed in syncytiotrophoblasts in both second trimester and term placentae. The expression of RTP gene in BeWo cells was protein kinase C dependent. This is the first description of RTP gene expression in placenta and the first study elucidating the signaling pathway involved in the regulation of RTP gene expression. These results suggest that RTP may play a role in trophoblast cell proliferation and differentiation.

Reactivation of herpes simplex virus: the role of cytokines and intracellular factors

Considerable progress has been achieved in relating environmental stimuli and viral genetics to herpes simplex virus reactivation. The cytokines IL-1, IL-6, nerve growth factor NGF, and interferons have been implicated in herpes simplex virus reactivation. These molecules may act as signals which convey important information about the environment to the latent viral genome. Herpes simplex virus latency associated transcript expression is important for viral reactivation. The function of these unique viral RNA's is not completely understood, but they appear to be necessary for the efficient establishment of a latent infection in the ganglion. A better understanding of the mechanisms underlying the herpes simplex virus reactivation can be expected to lead to novel effective treatments for herpes simplex diseases.

Molecular aspects of herpes simplex virus I latency, reactivation, and recurrence

The application of molecular biology in the study of the pathogenesis of herpes simplex virus type 1 (HSV-1) has led to significant advances in our understanding of mechanisms that regulate virus behavior in sensory neurons and epithelial tissue. Such study has provided insight into the relationship of host and viral factors that regulate latency, reactivation, and recurrent disease. This review attempts to distill decades of information involving human, animal, and cell culture studies of HSV-1 with the goal of correlating molecular events with the clinical and laboratory behavior of the virus during latency, reactivation, and recurrent disease. The purpose of such an attempt is to acquaint the clinician/scientist with the current thinking in the field, and to provide key references upon which current opinions rest.

Adenovirus induction of an interferon-regulatory factor during entry into the late phase of infection

Virus infection of animal cells can induce intracellular antiviral responses mediated by the induction of interferon-regulatory transcription factors (IRFs), which bind to and control genes directed by the interferon-stimulated response element (ISRE). The purpose of this study was to determine whether adenovirus (Ad) induces IRFs during infection, because they might play a role in promoting viral pathogenesis. Here we show that after the late phase of infection, Ad induces a transcription factor related to the IRF family of factors. The IRF is induced shortly after Ad entry into late phase and is shown to stimulate ISRE-directed transcription, to require activation by protein tyrosine kinase signalling, and to be induced several hours prior to the inhibition of cell protein synthesis. Inhibition of tyrosine kinase activity blocks Ad induction and activation of the IRF. Attempts to identify the Ad-induced factor immunologically and by photo-UV cross-linking indicate that it is likely a novel member of the IRF family. Finally, several independent lines of evidence also suggest that Ad induction of the IRF might correlate with the ability of the virus to block host cell protein synthesis later during infection.