Attenuated Replication-Competent Herpes Simplex Virus Expressing an ECM-Modifying Transgene Hyaluronan Synthase 2 of Naked Mole Rat in Oncolytic Gene Therapy.

Herpes simplex virus (HSV) has proven successful in treating human cancer. Since the approval of talimogene laherparepvec (T-VEC) in 2015, HSV has been thoroughly researched to discover novel mechanisms to combat cancer and treat other diseases. Another HSV-based drug, beremagene geperpavec (B-VEC), received approval in 2023 to treat the rare genetic disease dystrophic epidermolysis bullosa, and was also the first clinically approved HSV vector carrying an extracellular matrix (ECM)-modifying transgene. The ECM is a network of macromolecules surrounding cells, which provides support and regulates cell growth and differentiation, the disruption of which is common in cancer. The naked mole rat (NMR) has a thick ECM and a unique mutation in the hyaluronan synthase 2 (HAS2) gene, which has been linked to the high cancer resistance of the species. To study the effect of this mutation in human cancer, we have developed an attenuated, replication-competent HSV vector expressing the NMR-HAS2 gene. The viral replication, transgene expression and cytotoxic effect of the novel vector was studied in glioma cells. Our results show that an attenuated, replication-competent HSV vector expressing a foreign ECM-modifying transgene, namely HAS2, provides an effective tool to study and combat cancer in humans.

Swarms of chemically modified antiviral siRNA targeting herpes simplex virus infection in human corneal epithelial cells.

Herpes simplex virus type 1 (HSV-1) is a common virus of mankind and HSV-1 infections are a significant cause of blindness. The current antiviral treatment of herpes infection relies on acyclovir and related compounds. However, acyclovir resistance emerges especially in the long term prophylactic treatment that is required for prevention of recurrent herpes keratitis. Earlier we have established antiviral siRNA swarms, targeting sequences of essential genes of HSV, as effective means of silencing the replication of HSV in vitro or in vivo. In this study, we show the antiviral efficacy of 2´-fluoro modified antiviral siRNA swarms against HSV-1 in human corneal epithelial cells (HCE). We studied HCE for innate immunity responses to HSV-1, to immunostimulatory cytotoxic double stranded RNA, and to the antiviral siRNA swarms, with or without a viral challenge. The panel of studied innate responses included interferon beta, lambda 1, interferon stimulated gene 54, human myxovirus resistance protein A, human myxovirus resistance protein B, toll-like receptor 3 and interferon kappa. Our results demonstrated that HCE cells are a suitable model to study antiviral RNAi efficacy and safety in vitro. In HCE cells, the antiviral siRNA swarms targeting the HSV UL29 gene and harboring 2´-fluoro modifications, were well tolerated, induced only modest innate immunity responses, and were highly antiviral with more than 99% inhibition of viral release. The antiviral effect of the 2'-fluoro modified swarm was more apparent than that of the unmodified antiviral siRNA swarm. Our results encourage further research in vitro and in vivo on antiviral siRNA swarm therapy of corneal HSV infection, especially with modified siRNA swarms.

The In Vitro Replication, Spread, and Oncolytic Potential of Finnish Circulating Strains of Herpes Simplex Virus Type 1.

Herpes simplex virus type 1 (HSV-1) is the only FDA- and EMA- approved oncolytic virus, and accordingly, many potential oncolytic HSVs (oHSV) are in clinical development. The utilized oHSV parental strains are, however, mostly based on laboratory reference strains, which may possess a compromised cytolytic capacity in contrast to circulating strains of HSV-1. Here, we assess the phenotype of thirty-six circulating HSV-1 strains from Finland to uncover their potential as oHSV backbones. First, we determined their capacity for cell-to-cell versus extracellular spread, to find strains with replication profiles favorable for each application. Second, to unfold the differences, we studied the genetic diversity of two relevant viral glycoproteins (gB/UL27, gI/US7). Third, we examined the oncolytic potential of the strains in cells representing glioma, lymphoma, and colorectal adenocarcinoma. Our results suggest that the phenotype of a circulating isolate, including the oncolytic potential, is highly related to the host cell type. Nevertheless, we identified isolates with increased oncolytic potential in comparison with the reference viruses across many or all of the studied cancer cell types. Our research emphasizes the need for careful selection of the backbone virus in early vector design, and it highlights the potential of clinical isolates as backbones in oHSV development.

Enzymatically synthesized 2'-fluoro-modified Dicer-substrate siRNA swarms against herpes simplex virus demonstrate enhanced antiviral efficacy and low cytotoxicity.

Chemical modifications of small interfering (si)RNAs are used to enhance their stability and potency, and to reduce possible off-target effects, including immunogenicity. We have earlier introduced highly effective antiviral siRNA swarms against herpes simplex virus (HSV), targeting 653 bp of the essential UL29 viral gene. Here, we report a method for enzymatic production and antiviral use of 2'-fluoro-modified siRNA swarms. Utilizing the RNA-dependent RNA polymerase from bacteriophage phi6, we produced 2'-F-siRNA swarms containing either all or a fraction of modified adenosine, cytidine or uridine residues in the antisense strand of the UL29 target. The siRNA containing modified pyrimidines demonstrated high resistance to RNase A and the antiviral potency of all the UL29-specific 2'-F-siRNA swarms was 100-fold in comparison with the unmodified counterpart, without additional cytotoxicity. Modest stimulation of innate immunity signaling, including induced expression of both type I and type III interferons, as well as interferon-stimulated gene 54, by 2'-F-cytidine and 2'-F-uridine modified siRNA swarms occurred at early time points after transfection while the 2'-F-adenosine-containing siRNA was similar to the unmodified antiviral siRNA swarm in this respect. The antiviral efficacy of the 2'-F-siRNA swarms and the elicited cellular innate responses did not correlate suggesting that innate immunity pathways do not significantly contribute to the observed enhanced antiviral activity of the modified siRNAs. The results support further applications of enzymatically produced siRNA molecules with incorporated adenosine nucleotides, carrying fluoro-modification on ribose C2' position, for further antiviral studies in vitro and in vivo.

HERQ-9 Is a New Multiplex PCR for Differentiation and Quantification of All Nine Human Herpesviruses.

Infections with the nine human herpesviruses (HHVs) are globally prevalent and characterized by lifelong persistence. Reactivations can potentially manifest as life-threatening conditions for which the demonstration of viral DNA is essential. In the present study, we developed HERQ-9, a pan-HHV quantitative PCR designed in triplex reactions to differentiate and quantify each of the HHV-DNAs: (i) herpes simplex viruses 1 and 2 and varicella-zoster virus; (ii) Epstein-Barr virus, human cytomegalovirus, and Kaposi's sarcoma-associated herpesvirus; and (iii) HHV-6A, -6B, and -7. The method was validated with prequantified reference standards as well as with mucocutaneous swabs and cerebrospinal fluid, plasma, and tonsillar tissue samples. Our findings highlight the value of multiplexing in the diagnosis of many unsuspected, yet clinically relevant, herpesviruses. In addition, we report here frequent HHV-DNA co-occurrences in clinical samples, including some previously unknown. HERQ-9 exhibited high specificity and sensitivity (LOD95s of ∼10 to ∼17 copies/reaction), with a dynamic range of 101 to 106 copies/µl. Moreover, it performed accurately in the coamplification of both high- and low-abundance targets in the same reaction. In conclusion, we demonstrated that HERQ-9 is suitable for the diagnosis of a plethora of herpesvirus-related diseases. Besides its significance to clinical management, the method is valuable for the assessment of hitherto-unexplored synergistic effects of herpesvirus coinfections. Furthermore, its high sensitivity enables studies on the human virome, often dealing with minute quantities of persisting HHVs.IMPORTANCE By adulthood, almost all humans become infected by at least one herpesvirus (HHV). The maladies inflicted by these microbes extend beyond the initial infection, as they remain inside our cells for life and can reactivate, causing severe diseases. The diagnosis of active infection by these ubiquitous pathogens includes the detection of DNA with sensitive and specific assays. We developed the first quantitative PCR assay (HERQ-9) designed to identify and quantify each of the nine human herpesviruses. The simultaneous detection of HHVs in the same sample is important since they may act together to induce life-threatening conditions. Moreover, the high sensitivity of our method is of extreme value for assessment of the effects of these viruses persisting in our body and their long-term consequences on our health.

Comparison of Clinically Relevant Oncolytic Virus Platforms for Enhancing T Cell Therapy of Solid Tumors.

Despite some promising results, the majority of patients do not benefit from T cell therapies, as tumors prevent T cells from entering the tumor, shut down their activity, or downregulate key antigens. Due to their nature and mechanism of action, oncolytic viruses have features that can help overcome many of the barriers currently facing T cell therapies of solid tumors. This study aims to understand how four different oncolytic viruses (adenovirus, vaccinia virus, herpes simplex virus, and reovirus) perform in that task. For that purpose, an immunocompetent in vivo tumor model featuring adoptive tumor-infiltrating lymphocyte (TIL) therapy was used. Tumor growth control (p < 0.001) and survival analyses suggest that adenovirus was most effective in enabling T cell therapy. The complete response rate was 62% for TILs + adenovirus versus 17.5% for TILs + PBS. Of note, TIL biodistribution did not explain efficacy differences between viruses. Instead, immunostimulatory shifts in the tumor microenvironment mirrored efficacy results. Overall, the use of oncolytic viruses can improve the utility of T cell therapies, and additional virus engineering by arming with transgenes can provide further antitumor effects. This phenomenon was seen when an unarmed oncolytic adenovirus was compared to Ad5/3-E2F-d24-hTNFa-IRES-hIL2 (TILT-123). A clinical trial is ongoing, where patients receiving TIL treatment also receive TILT-123 (ClinicalTrials.gov: NCT04217473).

Personalized Cancer Vaccine Platform for Clinically Relevant Oncolytic Enveloped Viruses.

The approval of the first oncolytic virus for the treatment of metastatic melanoma and the compiling evidence that the use of oncolytic viruses can enhance cancer immunotherapies targeted against various immune checkpoint proteins has attracted great interest in the field of cancer virotherapy. We have developed a novel platform for clinically relevant enveloped viruses that can direct the virus-induced immune response against tumor antigens. By physically attaching tumor-specific peptides onto the viral envelope of vaccinia virus and herpes simplex virus 1 (HSV-1), we were able to induce a strong T cell-specific immune response toward these tumor antigens. These therapeutic peptides could be attached onto the viral envelope by using a cell-penetrating peptide sequence derived from human immunodeficiency virus Tat N-terminally fused to the tumor-specific peptides or, alternatively, therapeutic peptides could be conjugated with cholesterol for the attachment of the peptides onto the viral envelope. We used two mouse models of melanoma termed B16.OVA and B16-F10 for testing the efficacy of OVA SIINFEKL-peptide-coated viruses and gp100-Trp2-peptide-coated viruses, respectively, and show that by coating the viral envelope with therapeutic peptides, the anti-tumor immunity and the number of tumor-specific CD8+ T cells in the tumor microenvironment can be significantly enhanced.

Herpes simplex and human papilloma virus coinfections in oral mucosa of men-A 6-year follow-up study.

Herpes simplex virus (HSV) establishes latency in neurons and recurrent infections in oral mucosa. This prospective study analyzes HSV prevalence in oral mucosal brush samples from men with known human papillomavirus (HPV) status. We hypothesized that HSV-1-infection could facilitate HPV persistence as a cofactor. This study was a part of the Finnish Family HPV study accomplished at the University of Turku/Turku University Hospital, Finland. A total of 139 men (mean age 28.6 ± 4.9 years) were enrolled at 36+-weeks of their partner's pregnancy and thereafter followed-up for 6 years. Altogether, 722 samples, extracted from oral brush samples collected at the enrollment timepoint (baseline) and at 2-, 6-, 12-, 24-, 36-month, and 6 years, were available. HSV DNA was analyzed with quantitative PCR. HSV-1 results were compared with the known HPV data. The prevalence of oral HSV-1 shedding varied between 0-7.2% (mean 2.8%) among the men. Mean copy numbers varied between 4 and 550 genome copies/sample. A total of 18 (12.9%) men were found HSV-1-positive at least once, two of them twice. Neither smoking nor oral sex was associated with the oral HSV-1-DNA finding. HPV/HSV-1 co-infection was found in 6 (4.3%) men, all of them having persistent HPV-infection. In conclusion, HSV-1 and its coinfection with HPV in oral mucosa was rare.

Antiviral Properties of Chemical Inhibitors of Cellular Anti-Apoptotic Bcl-2 Proteins.

Viral diseases remain serious threats to public health because of the shortage of effective means of control. To combat the surge of viral diseases, new treatments are urgently needed. Here we show that small-molecules, which inhibit cellular anti-apoptotic Bcl-2 proteins (Bcl-2i), induced the premature death of cells infected with different RNA or DNA viruses, whereas, at the same concentrations, no toxicity was observed in mock-infected cells. Moreover, these compounds limited viral replication and spread. Surprisingly, Bcl-2i also induced the premature apoptosis of cells transfected with viral RNA or plasmid DNA but not of mock-transfected cells. These results suggest that Bcl-2i sensitizes cells containing foreign RNA or DNA to apoptosis. A comparison of the toxicity, antiviral activity, and side effects of six Bcl-2i allowed us to select A-1155463 as an antiviral lead candidate. Thus, our results pave the way for the further development of Bcl-2i for the prevention and treatment of viral diseases.

Regulation of kynurenine biosynthesis during influenza virus infection.

Influenza A viruses (IAVs) remain serious threats to public health because of the shortage of effective means of control. Developing more effective virus control modalities requires better understanding of virus-host interactions. It has previously been shown that IAV induces the production of kynurenine, which suppresses T-cell responses, enhances pain hypersensitivity and disturbs behaviour in infected animals. However, the regulation of kynurenine biosynthesis during IAV infection remains elusive. Here we showed that IAV infection induced expression of interferons (IFNs), which upregulated production of indoleamine-2,3-dioxygenase (IDO1), which catalysed the kynurenine biosynthesis. Furthermore, IAV attenuated the IDO1 expression and the production of kynurenine through its NS1 protein. Interestingly, inhibition of viral replication prior to IFN induction limited IDO1 expression, while inhibition after did not. Finally, we showed that kynurenine biosynthesis was activated in macrophages in response to other stimuli, such as influenza B virus, herpes simplex virus 1 and 2 as well as bacterial lipopolysaccharides. Thus, the tight regulation of the kynurenine biosynthesis by host cell and, perhaps, pathogen might be a basic signature of a wide range of host-pathogen interactions, which should be taken into account during development of novel antiviral and antibacterial drugs.

Interleukin-27 Inhibits Herpes Simplex Virus Type 1 Infection by Activating STAT1 and 3, Interleukin-6, and Chemokines IP-10 and MIG.

Interleukin-27 (IL-27) inhibits the replication of many viruses, but the mechanism differs according to virus and cell type. In this study, we observed that IL-27 expression was upregulated in herpes simplex virus type 1 (HSV-1)-infected SJL/J mice, which led us to further investigate the role of IL-27 in HSV-1 infection using epithelial, glioma, and immunological cells as cell models. We showed that in all studied cell lines, the IL-27 messenger RNA (mRNA) level was upregulated due to the HSV-1 infection. When the cells were primed with IL-27 before the virus infection, the virus release was prevented, indicating an antiviral role of IL-27 in HSV-1 infection. Furthermore, we observed that IL-27 secretion to the culture medium was reduced in infected epithelial and immunological cells, but not in glioma cells. Not surprisingly, HSV-1 induced type I, II, and III interferons regardless of cell line, but IL-27 itself caused varying interferon responses dependent on cell type. However, common to all cell types was the IL-27-stimulated secretion of IL-6 and chemokines IP-10 and MIG. In addition, IL-27 stimulation activated STAT1 and STAT3 in HeLa and T98G cells, suggesting that IL-27 engages the STAT1/3 pathway, which then leads to the upregulation of IL-6, IP-10, and MIG.

HSV-1 Infection Modulates the Radioresponse of a HPV16-positive Head and Neck Cancer Cell Line.

BACKGROUND: The combined effects of Human papillomavirus (HPV) and Herpes simplex type 1 (HSV-1) infections and their effects on cancer cell radioresistance are unexplored. MATERIALS AND METHODS: An HPV16-positive hypopharyngeal carcinoma cell line (UD-SCC-2) was infected with wt-HSV-1 at low multiplicity of infection (MOI) and irradiated with 2 Gy at 24 h postinfection. Viability assays and quantitative reverse-transcriptase PCR for HPV16 E6, E7, nuclear factor kappa B1, B-cell CLL/lymphoma 2 (BCL2), and caspases 3, 8 and 9 at 24, and 72 h, as well as immunocytochemistry for BCL2, caspase 3, cyclin E, mouse double minute 2 homolog (MDM2), HSV-1 and Ki-67 were performed at 144 h postirradiation. RESULTS: At 144 h, cell viability was significantly lowered by irradiation only in uninfected cells. Infection combined with irradiation resulted in increased expression of E6, E7, BCL2 and NF-κB1 at 144 h. Simultaneously, E6 and E7 were down-regulated in non-irradiated infected cells. Irradiation and infection with 0.00001 MOI separately up-regulated caspase 3 but infection with 0.0001 MOI halved its expression in irradiated cells. CONCLUSION: HSV-1 infection modulates radioresistance of HPV16-positive hypopharyngeal carcinoma cells.

Carriage of herpes simplex virus and human papillomavirus in oral mucosa is rare in young women: A long-term prospective follow-up.

BACKGROUND: Following the primary oral infection, herpes simplex virus (HSV) establishes latency in the ganglia of sensory neurons. Episodically induced by stress, HSV is able to cause recurrent infection at the primary infection site, accompanied by virus shedding. The oral shedding of HSV contributes to mother-child-transmission of HSV. Human papillomavirus (HPV) is associated with oral malignancies, and its interaction with oral HSV should be studied further. OBJECTIVES: To analyze the prevalence of HSV-1 and HSV-2-infection in oral mucosal scrapings of women during and after pregnancy and to elucidate the prevalence of HPV and HSV-co-carriage in oral mucosa. STUDY DESIGN: A longitudinal cohort study of 304 mothers in the Finnish Family HPV study followed-up for 6 years after pregnancy, with 7 serial samplings. Mothers' oral brush samples were analyzed with quantitative PCR for HSV-1 and -2 DNA and the findings were compared with their HPV DNA status. RESULTS: Altogether, 2.2% of all 1873 collected epithelial brush samples were HSV-1 DNA positive, while none tested HSV-2 DNA positive. Of the 304 mothers, 11.8% were HSV-1 DNA positive at least once. Most of the women who tested HSV-1 DNA positive before delivery remained HSV-1 DNA positive also after pregnancy. HSV-1 positive women were almost invariably HPV-negative; only four (0.2%) samples were detected with HSV-HPV co-carriage. CONCLUSIONS: This is the first prospective follow-up study on oral HSV shedding and its association with coexistent HPV, analyzed in the same oral mucosal scrapings. HSV and HPV co-carriage is rare in oral mucosa of healthy young mothers.

Innate responses to small interfering RNA pools inhibiting herpes simplex virus infection in astrocytoid and epithelial cells.

Herpes simplex virus (HSV) is a human pathogen that can cause severe diseases such as encephalitis, keratitis and neonatal herpes. Control of HSV infection may be achieved by using small interfering (si)RNAs. We have designed and enzymatically produced pools of siRNAs targeting HSV. In addition to the target-specific effects, such siRNAs may induce innate immunity responses that may contribute to antiviral effects. HSV has versatile ways of modulating innate immunity, and it remains unclear whether HSV-specific antiviral treatment would benefit from the potential immunostimulatory effects of siRNAs. To address this, cell lines derived from epithelium and nervous system were studied for innate immunity reactions to HSV infection, to siRNA treatment, and to a combination of treatment and infection. In addition, the outcome of HSV infection was quantitated. We show that innate immunity reactions vary drastically between the cell lines. Moreover, our findings indicate only a minimal relation between the antiviral effect and the treatment-induced innate immunity responses. Thus, the antiviral effect is mainly sequence specific and the inhibition of HSV infection is not ascribed to the slight innate immunity induction.

The combined effects of irradiation and herpes simplex virus type 1 infection on an immortal gingival cell line.

BACKGROUND: Oral mucosa is frequently exposed to Herpes simplex virus type 1 (HSV-1) infection and irradiation due to dental radiography. During radiotherapy for oral cancer, the surrounding clinically normal tissues are also irradiated. This prompted us to study the effects of HSV-1 infection and irradiation on viability and apoptosis of oral epithelial cells. METHODS: Immortal gingival keratinocyte (HMK) cells were infected with HSV-1 at a low multiplicity of infection (MOI) and irradiated with 2 Gy 24 hours post infection. The cells were then harvested at 24, 72 and 144 hours post irradiation for viability assays and qRT-PCR analyses for the apoptosis-related genes caspases 3, 8, and 9, bcl-2, NFκB1, and viral gene VP16. Mann-Whitney U-test was used for statistical calculations. RESULTS: Irradiation improved the cell viability at 144 hours post irradiation (P = 0.05), which was further improved by HSV-1 infection at MOI of 0.00001 (P = 0.05). Simultaneously, the combined effects of infection at MOI of 0.0001 and irradiation resulted in upregulation in NFκB1 (P = 0.05). The combined effects of irradiation and HSV infection also significantly downregulated the expression of caspases 3, 8, and 9 at 144 hours (P = 0.05) whereas caspase 3 and 8 significantly upregulated in non-irradiated, HSV-infected cells as compared to uninfected controls (P = 0.05). Infection with 0.0001 MOI downregulated bcl-2 in non-irradiated cells but was upregulated by 27% after irradiation when compared to non-irradiated infected cells (P = 0.05). Irradiation had no effect on HSV-1 shedding or HSV gene expression at 144 hours. CONCLUSIONS: HSV-1 infection may improve the viability of immortal cells after irradiation. The effect might be related to inhibition of apoptosis.

A herpes simplex virus-derived replicative vector expressing LIF limits experimental demyelinating disease and modulates autoimmunity.

Herpes simplex virus type 1 (HSV-1) has properties that can be exploited for the development of gene therapy vectors. The neurotropism of HSV enables delivery of therapeutic genes to the nervous system. Using a bacterial artificial chromosome (BAC), we constructed an HSV-1(17(+))-based replicative vector deleted of the neurovirulence gene γ134.5, and expressing leukemia inhibitory factor (LIF) as a transgene for treatment of experimental autoimmune encephalomyelitis (EAE). EAE is an inducible T-cell mediated autoimmune disease of the central nervous system (CNS) and is used as an animal model for multiple sclerosis. Demyelination and inflammation are hallmarks of both diseases. LIF is a cytokine that has the potential to limit demyelination and oligodendrocyte loss in CNS autoimmune diseases and to affect the T-cell mediated autoimmune response. In this study SJL/J mice, induced for EAE, were treated with a HSV-LIF vector intracranially and the subsequent changes in disease parameters and immune responses during the acute disease were investigated. Replicating HSV-LIF and its DNA were detected in the CNS during the acute infection, and the vector spread to the spinal cord but was non-virulent. The HSV-LIF significantly ameliorated the EAE and contributed to a higher number of oligodendrocytes in the brains when compared to untreated mice. The HSV-LIF therapy also induced favorable changes in the expression of immunoregulatory cytokines and T-cell population markers in the CNS during the acute disease. These data suggest that BAC-derived HSV vectors are suitable for gene therapy of CNS disease and can be used to test the therapeutic potential of immunomodulatory factors for treatment of EAE.

Obatoclax, saliphenylhalamide, and gemcitabine inhibit influenza a virus infection.

Influenza A viruses (IAVs) infect humans and cause significant morbidity and mortality. Different treatment options have been developed; however, these were insufficient during recent IAV outbreaks. Here, we conducted a targeted chemical screen in human nonmalignant cells to validate known and search for novel host-directed antivirals. The screen validated saliphenylhalamide (SaliPhe) and identified two novel anti-IAV agents, obatoclax and gemcitabine. Further experiments demonstrated that Mcl-1 (target of obatoclax) provides a novel host target for IAV treatment. Moreover, we showed that obatoclax and SaliPhe inhibited IAV uptake and gemcitabine suppressed viral RNA transcription and replication. These compounds possess broad spectrum antiviral activity, although their antiviral efficacies were virus-, cell type-, and species-specific. Altogether, our results suggest that phase II obatoclax, investigational SaliPhe, and FDA/EMEA-approved gemcitabine represent potent antiviral agents.

Human lactoferrin but not lysozyme neutralizes HSV-1 and inhibits HSV-1 replication and cell-to-cell spread.

The frequent oral shedding of herpes simplex virus type 1 (HSV-1) in the absence of clinical disease suggests that symptomatic HSV-1 recurrences may be inhibited by the mucosal environment. Indeed, saliva has been shown to contain substances with anti-HSV activity. In the current study, we investigated the anti-HSV-1 activity of human lactoferrin (hLf) and lysozyme (hLz), two highly cationic polypeptides of the mucosal innate defence system. HLf blocked HSV-1 infection at multiple steps of the viral replication cycle, whereas lysozyme displayed no anti-HSV-1 activity. Preincubation of HSV-1 virions and presence of hLf during or after viral absorption period or for the entire HSV-1 infection cycle inhibited HSV-1 infection by reducing both the plaque count and plaque size in a dose- and virus strain-dependent manner. Cell-to-cell spread of wild-type HSV-1 and the strain gC-39, deleted of glycoprotein C, was dramatically reduced, but the cell-to-cell spread of HSV-1 Rid1, harboring a mutated gD and thus unable to react with the cellular HVEM receptor, remained unchanged. This suggests that the inhibition of cell-to-cell spread is mediated by effects on gD or its cellular counterparts. Our results show that the cationic nature is not a major determinant in the anti-HSV action of mucosal innate cationic polypeptides, since whereas hLf inhibited HSV-1 infection efficiently, hLz had no HSV-1 inhibiting activity. Our results show that in addition to inhibiting the adsorption and post-attachment events of HSV-1 infection, hLf is also able to neutralize HSV-1 and that the inhibition of cell-to-cell spread involves viral gD. These results suggest that Lf may have a significant role in the modulation of HSV-1 infection in the oral cavity as well as in the genital mucosa, the major sites of HSV-1 infection.

The cysteine protease inhibitors cystatins inhibit herpes simplex virus type 1-induced apoptosis and virus yield in HEp-2 cells.

The role of cystatins in herpes simplex virus (HSV)-induced apoptosis and viral replication has been studied. Human epithelial (HEp-2) cells infected with wild-type HSV-1 (F), with a deletion virus lacking the anti-apoptotic gene Us3 (R7041) or with a deletion virus lacking the anti-apoptotic genes Us3 and ICP4 (d120) were treated with cystatin A, C or D. Cells and culture media were studied at different time points for replicating HSV-1 and for apoptosis. Cystatins C and D inhibited the yield of replicative HSV-1 significantly in HEp-2 cells. In addition, cystatin D inhibited R7041 and d120 virus-induced apoptosis. Moreover, cystatin A inhibited R7041-induced apoptosis. These inhibitory effects of cystatins on virus replication and apoptosis are likely to be separate functions. Cystatin D treatment decreased cellular cathepsin B activity in HSV-1 infection, suggesting that cathepsin B is involved in virus-induced apoptosis.