DNA Damage Kills Bacterial Spores and Cells Exposed to 222-Nanometer UV Radiation.

This study examined the microbicidal activity of 222-nm UV radiation (UV222), which is potentially a safer alternative to the 254-nm UV radiation (UV254) that is often used for surface decontamination. Spores and/or growing and stationary-phase cells of Bacillus cereus, Bacillus subtilis, Bacillus thuringiensis, Staphylococcus aureus, and Clostridioides difficile and a herpesvirus were all killed or inactivated by UV222 and at lower fluences than with UV254B. subtilis spores and cells lacking the major DNA repair protein RecA were more sensitive to UV222, as were spores lacking their DNA-protective proteins, the α/ß-type small, acid-soluble spore proteins. The spore cores' large amount of Ca2+-dipicolinic acid (∼25% of the core dry weight) also protected B. subtilis and C. difficile spores against UV222, while spores' proteinaceous coat may have given some slight protection against UV222 Survivors among B. subtilis spores treated with UV222 acquired a large number of mutations, and this radiation generated known mutagenic photoproducts in spore and cell DNA, primarily cyclobutane-type pyrimidine dimers in growing cells and an α-thyminyl-thymine adduct termed the spore photoproduct (SP) in spores. Notably, the loss of a key SP repair protein markedly decreased spore UV222 resistance. UV222-treated B. subtilis spores germinated relatively normally, and the generation of colonies from these germinated spores was not salt sensitive. The latter two findings suggest that UV222 does not kill spores by general protein damage, and thus, the new results are consistent with the notion that DNA damage is responsible for the killing of spores and cells by UV222IMPORTANCE Spores of a variety of bacteria are resistant to common decontamination agents, and many of them are major causes of food spoilage and some serious human diseases, including anthrax caused by spores of Bacillus anthracis Consequently, there is an ongoing need for efficient methods for spore eradication, in particular methods that have minimal deleterious effects on people or the environment. UV radiation at 254 nm (UV254) is sporicidal and commonly used for surface decontamination but can cause deleterious effects in humans. Recent work, however, suggests that 222-nm UV (UV222) may be less harmful to people than UV254 yet may still kill bacteria and at lower fluences than UV254 The present work has identified the damage by UV222 that leads to the killing of growing cells and spores of some bacteria, many of which are human pathogens, and UV222 also inactivates a herpesvirus.

A case of herpes simplex virus reactivation after fractional ablative carbon dioxide laser to treat a burn scar.

Fractional photothermolysis was initially introduced by Manstein in 2004 .Fractional CO2 laser technology introduced has allowed physicians to obtain good cosmetic results with a lower rate of complications than non-fractionated ablative laser treatment. However, adverse effects may still occur.Reported cases of HSV infection after fractional photothermolysis are rare. A 48-year-old woman with Fitzpatrick skin type III presented with a scar in her perioral area desiring esthetic improvement of her burn scar. She didn't have a history of recurrent herpes simplex virus (HSV) infection periorally. A fractionated resurfacing laser Quadralase (Candela) was used to treat her perioral burn scar. Two sessions were performed with a month interval. Five days after the second session of laser therapy even after she took antiviral prophylaxis based on valacyclovir 500mg twice daily 24 hours before the laser session and 3 days after, she presented with a rash on the perioral area preceded by pain. Correlation of the history and the clinical presentation was consistent with HSV reactivation. Treatment was initiated with acyclovir 10mg/kg/8h administered intravenously for 10 days with a clearing of her vesicular eruption. Fractional CO2 laser is a very safe procedure when used with accepted parameters. Early recognition, close monitoring and careful wound care will prevent long term sequelae when complications occur.

[Investigating the risk of two model virus in the laboratory].

OBJECTIVE: To study the survival time of recombination rival in environment and inactivation ability of different disinfectant and ultraviolet radiation against virus. METHODS: NC membranes absorbed the recombinant adenovirus (rADV) or herpes simplex virus (rHSV) with green fluorescence protein (GFP) were laid, or immersed in various concentration of different disinfectants such as ethanol, sodium hypochlorite, lysol and geramine and then taked out them every 15 min, or exposed under ultraviolet radiation, then the NC membranes were adsorbed 1 h in cell, 37 degrees C 5% CO2 48 h. The results were observed under the fluorescence microscope. RESULTS: (1) the average survival time of rHSV under environment is less than 60 min, rADV is almost up to 2 h. (2) The infection ability of rHSV and rADV was inactived 15 min by both ethanol (100%, 70% and 50%) and sodium hypochlorite (5%, 2.5% and 1.25%). (3) Two virus can be killed by 0.1% bromogeramine. (4) Both 5% and 2.5% lysol, but rADV can not lost the infection on Vero Cell until 75 min by 1.25% Lysol. (5) The rHSV was inactivated under ultraviolet radiation, but rADV was not. CONCLUSION: The survival time of is different from both envelope rival and the no-envelope viral under nature environment and the inactivate ability of disinfectant also is different between two model virus; Disinfectant should be choose according to virus type.

The prevalence of herpes simplex virus shedding and infection in the oral cavity of seropositive patients undergoing head and neck radiation therapy.

OBJECTIVE: Herpes viruses are characterized by their ability to establish and maintain a latent infection that can reactivate. Only 2 preliminary studies have examined herpes simplex virus (HSV) reactivation in patients receiving head and neck radiotherapy. The role of radiation therapy in the reactivation of a latent virus has not been established. The purpose of the present study was to evaluate the incidence of HSV reactivation in patients receiving radiation treatment for head and neck malignancies. METHODS: Twenty patients, 19 of whom were HSV seropositive, undergoing head and neck radiation therapy were assessed weekly before and during radiation therapy, and HSV cultures were completed during cancer treatment. RESULTS: Only 3.6% of the cultures were positive for HSV during radiation therapy. HSV was cultured in 4 men receiving a mean of 6,000 cGy to the head and neck area. Recovery from HSV was seen in patients nearing completion of radiation therapy. CONCLUSIONS: The results of this study suggest that HSV reactivation is not common during radiation therapy. Therefore, this study does not support prophylaxis of HSV in patients undergoing head and neck irradiation.

The IL-12 response to herpes simplex virus is mainly a paracrine response of reactive inflammatory cells.

Herpes simplex virus (HSV) infection results in rapid and sustained up-regulation of interleukin (IL)-12, but the primary cellular source of IL-12 after HSV infection is unknown. We demonstrate that this cytokine largely derives from inflammatory cells rather than from productively infected epithelial cells. For optimal IL-12 induction, epithelial cells needed to be infected with replication-competent virus, and cells needed to be able to synthesize proteins. Our results also indicate that HSV-infected cells generate intermediary products that signal recruited inflammatory cells, which themselves were not HSV-infected, to generate IL-12. Possible mechanisms by which infected cells communicate with inflammatory cells to cause IL-12 production are discussed.

Herpes simplex virus proteins are damaged following photodynamic inactivation with phthalocyanines.

The photodynamic inactivation of herpes simplex virus type 1 (HSV-1) by two phthalocyanines (Pcs), the cationic dye HOSi-PcOSi(CH3)2(CH2)3N+(CH3)3I-(Pc5) and the amphiphilic dye aluminum dibenzodisulfophthalocyanine hydroxide (AlN2SB2POH), has been compared with that by the anionic dye, Merocyanine 540 (Mc540). Both Pc derivatives demonstrate a remarkable virucidal activity upon light activation even 3 h after the onset of HSV-1 adsorption, while Mc540 is effective for only 30 min after adsorption. Since fusion and virus penetration are promoted by membrane glycoproteins, we have studied the damage to viral proteins following photodynamic treatment (PDT) of HSV-1 and its relation to inactivation. The effect of AlN2SB2POH PDT is assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Major changes are found in the protein profile of PDT-treated HSV-1. A reduced ability of specific antibodies to react with HSV-1 major envelope proteins is detected by employing the Western blot assay. In particular, we demonstrate the related changes of glycoprotein D (gD), a structural protein of the HSV envelope. Since the envelope proteins participate in viral entry into the host cell, these alterations to viral envelope proteins may impair their ability to participate in early events of viral entry, leading to reduced infectivity of HSV-1. In contrast, no significant changes in the proteins' electrophoretic mobility could be seen after PDT with Mc540 or with Pc5. When HSV-1 purified proteins are subjected to combined electrophoretic and electro osmotic forces on cellulose acetate, there is a shift in their cathode mobility, which may indicate changes in the protein mass and protein net charges following AlN2SB2POH photosensitization. There are only minor changes in the virus proteins, assayed as above, when HSV-1 is treated with Pc5.

Reactivation of oral herpes simplex virus: implications for clinical management of herpes simplex virus recurrence during radiotherapy.

Herpes viruses are characterized by their ability to establish and maintain latent infections that can be reactivated. Several stimuli can trigger the reactivation of herpes viruses, which are perhaps best recognized in the recurrent blisters and ulcers associated with herpes simplex virus. We present two clinical cases of reactivation of herpes simplex virus during radiation therapy for management of cancers of the head and neck. Although the role of ionizing radiation in the reactivation of herpes simplex virus has not been established, we review the viral and host events associated with the establishment of orofacial herpes simplex virus infection, latency, and reactivation of the virus. We discuss current models of viral reactivation and suggest directions for further clinical research into the reactivation of orolabial herpes simplex virus during radiotherapy.

Herpes simplex virus induces appearance of interferon-alpha/beta-producing cells and partially interferon-alpha/beta-dependent accumulation of leukocytes in murine regional lymph nodes.

As in vivo experimental system involving the local induction of interferon-alpha/beta (IFN-alpha/beta) responses was established in mice by injecting s.c. ultraviolet (UV)-inactivated herpes simplex virus (HSV) in the right ears, the left ears receiving phosphate-buffered saline (PBS) as a control. Circulating IFN-alpha/beta was present in blood as early as 6 h postinjection, and little or none was found 24 h postinjection. Identification of IFN-alpha/beta-producing cells, carried out by immunohistochemistry and in situ hybridization, demonstrated that the IFN response occurred mainly in the lymph node draining the HSV-injected ear and not in the contralateral lymph node. Occasionally, IFN-alpha/beta-producing cells were found in the spleen and in the skin. The injected HSV caused an inflammatory reaction in the skin and an almost threefold enlargement of the draining lymph node within 6 h. The latter was characterized by a general accumulation of all major lymphocyte subsets and a striking infiltration of neutrophils. Injection s.c. of neutralizing anti-IFN-alpha/beta antibodies before HSV injection reduced the increase in size of the draining lymph node by approximately 50% at 6 h, and no significant effects were seen at 24 h. The localization of cells producing IFN-alpha/beta in the lymph node and the capacity of such IFN-alpha/beta to at least partially mediate an early accumulation of cells suggest that the local IFN-alpha/beta response may have an important role in the initiation of early antiviral immune responses.

UV radiation and mouse models of herpes simplex virus infection.

Orolabial human infections with herpes simplex virus type 1 (HSV-1) are very common; following the primary epidermal infection, the virus is retained in a latent form in the trigeminal ganglia from where it can reactivate and cause a recrudescent lesion. Recrudescences are triggered by various stimuli including exposure to sunlight. In this review three categories of mouse models are used to examine the effects of UV irradiation on HSV infections: these are UV exposure prior to primary infection, UV exposure as a triggering event for recrudescence and UV exposure prior to challenge with virus in mice already immunized to HSV. In each of these models immunosuppression occurs, which is manifest, in some instances, in increased morbidity or an increased rate of recrudescence. Where known, the immunological mechanisms involved in the models are summarized and their relevance to human infections considered.

Activation of the radiosensitive EGR-1 promoter induces expression of the herpes simplex virus thymidine kinase gene and sensitivity of human glioma cells to ganciclovir.

Herein we describe experiments showing that the early growth response gene 1 (EGR-1) promoter is sufficient to confer selective expression of the luciferase gene (Luc) in glioma cell lines exposed to ionizing radiation. Activity of the EGR-1 promoter was investigated in human glioblastoma cells using the plasmid vector, pEGR-Luc. The EGR-1 promoter gene directed radiosensitive expression of luciferase. This promoter showed high levels of activity (10-fold) in irradiated glioma cell lines as compared to basal levels of activity in nonirradiated cell lines. Maximum activation was detectable at 1-3 hr after stimulation with 20 Gy. The results also demonstrate that cells modified to contain the herpes simplex virus-thymidine kinase (HSV-tk) gene under control of the EGR-1 promoter become sensitive to treatment with the antiviral agent ganciclovir (GCV), whereas nonirradiated cells and nontransfected cells were unaffected by this agent. This results suggest that therapeutic genes can be expressed selectively in irradiated glioma cells. The results also indicate that the EGR-1 promoter can be used to induce exogenous genes selectively in radiation fields used for the treatment of malignant brain tumors.

Photoinactivation (365 nm) of vaccinia and herpes simplex viruses induced by a new built-in DNA photosensitizer: 4-thiothymidine.

The thymidine analogue 4-thiothymidine (s4T) strongly absorbs light at wavelengths in the UVA range (lambda max 335 nm) and we have examined the photoinactivation of vaccinia and herpes simplex viruses grown in the presence of this nucleoside. The cells used in this study (Vero, mouse 1D-TK+) were able to grow at the same rate when cultured in the presence of 2 mM s4T or 2 mM thymidine, albeit at a slower rate than control cells. Consistent with this finding, viruses grown in the presence of 1-4 mM s4T were obtained in reduced yield but retained full infectivity. Both viruses were specifically inactivated by irradiation with 365 nm light and their photosensitivity, as measured by the initial slope of the inactivation curve, increased in parallel with the concentration of s4T added to the culture medium. More than 90% of vaccinia virus grown in the presence of 4 mM s4T was inactivated. Organomercurial agarose chromatography of sheared DNA isolated from vaccinia virus grown in the presence of 2 mM s4T showed that approximately 2.5% of DNA fragments were specifically retained, as compared to 0.2% for control DNA. This value corresponds to at least one s4T residue incorporated per 30,000 nucleotides of vaccinia virus DNA. In fact, it is likely that this ratio is actually approximately 10 times higher because of the incomplete retention of control thiolated oligodeoxynucleotides.(ABSTRACT TRUNCATED AT 250 WORDS)

Herpes virus infection and repair in cells pretreated with gilvocarcin V or merocyanine 540 and radiation.

Pretreatment of mammalian cells with certain genotoxic agents decreases the ability of the cell monolayers to support virus plaque formation but enhances repair of UV-irradiated virus. This study was made to determine whether these phenomena extend to pretreatments with light and photosensitizers, including one dye that primarily affects cell membranes. Confluent CV-1 monkey kidney fibroblast monolayers were pretreated with either gilvocarcin V (GV) or merocyanine 540 (MC540) and light of appropriate wavelengths and infected with control or UV-irradiated herpes simplex virus (HSV). GV phototreatment is known to affect cells at the DNA level, and MC540 at the membrane level. UV radiation served as a positive control pretreatment. Phototoxic concentrations of GV and MC540 were determined via the capacity of pretreated cell monolayers to support plaque formation by unirradiated HSV. Parallel monolayer pretreatment and subsequent infection by UV-irradiated HSV demonstrated that both types of phototreatments enhanced virus survival, but the dose responses and time courses were different. The DNA-damaging GV phototreatment mimicked the effect of UV-irradiating the cells and produced delayed enhanced repair of UV-irradiated virus. However, the MC540-phototreatment produced enhancement of virus survival with a bimodal dose response pattern for immediate infection, suggesting a different route for affecting repair of damaged virus.

Human cell clones, RSa and UVr-1, differing in their capability for UV-induced virus reactivation and phenotypic mutation.

UVr-1 is a human cell clone established as a variant with increased resistance to cell killing by ultraviolet light (UV, principally 254 nm wavelength) from a UV-sensitive cell clone, RSa. Both cells have been characterized to have much the same capacity of UV-induced DNA repair synthesis in whole cells, and the parent RSa cells were recently found to be hypermutable. In the present study UVr-1 cells were characterized in comparison RSa cells with respect to UV-induced virus reactivation and phenotypic mutation. Survival levels of UV-irradiated vaccinia virus and herpes simplex virus type 1 (HSV-1) were much the same in logarithmically proliferating UVr-1 and RSa cells. Correlated with these host cell reactivation levels, the same extent of UV-induced DNA repair replication synthesis was observed in isolated nuclei of the two cell clones. Enhancement of survival levels of UV-irradiated HSV-1 was detected when proliferating RSa cells were irradiated with UV prior to the virus infection. In contrast, this enhanced virus reactivation (EVR) was not detected in similarly irradiated and infected UVr-1 cells. As for phenotypic mutation frequencies assessed by the cloning efficiency of cells with increased resistance to ouabain cell killing (OuaR), OuaR mutants were not obtained from UVr-1 cells either with or without UV irradiation. When the proliferation of cells was synchronized, both EVR and OuaR mutations were detected in RSa cells irradiated with UV at any cell cycle phase, being greatest in the later half of the G1 phase. However, there was no detectable EVR or mutation in any phase of synchronous UVr-1 cells. The hypomutability of UVr-1 cells and hypermutability of RSa cells in a G1 cell cycle phase was also found even if 4-nitroquinoline 1-oxide was used as a mutagen or mutant cells with increased resistance to 6-thioguanine cell killing were estimated.

The effectiveness of a u-v toothbrush sanitizing device in reducing the number of bacteria, yeasts and viruses on toothbrushes.

Sixty-six sterile toothbrushes were exposed to one of the following microorganisms: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Bacillis subtilis, Serratia marcescens and Baker's yeast. The Pollenex DS60 Daily Dental Sanitizer was found to be effective in substantially reducing the number of retained bacteria and yeasts as compared to contaminated toothbrushes not treated with such a device. Different toothbrush types had different response rates. Seventy-two sterile toothbrushes were exposed to Herpes Simplex Virus, Type I and seventy-two sterile toothbrushes were exposed to Parainfluenza Virus, Type III. The Pollenex DS60 Daily Dental Sanitizer consistently killed both viruses on all of the toothbrushes treated. Both viruses were consistently retained on non-treated toothbrushes for at least 24 hours.

Antiviral activity of gilvocarcin V plus UVA radiation.

Gilvocarcin V (GV), a coumarin, is a nucleic acid photosensitizer that is phototoxic to bacteria and mammalian cells at picomolar levels in the presence of near-UV radiation (UVA). We evaluated the effectiveness of GV plus UVA for inactivation of several viruses, including herpes simplex virus, type 1 (HSV) and the bacterial viruses phi X174, T7, PRD1 and phi 6. Some inactivation of the bacterial viruses was observed with UVA radiation alone (4-50% survival at 26 kJ/m2). Additional photosensitized inactivation was observed only with T7 and phi 6 at 2.0 microM GV. On the other hand, HSV was photoinactivated with concentrations of GV three orders of magnitude lower (1.0 nM). Similar to the case with UV (254 nm) inactivation, the GV-UVA survival curve for HSV indicated multicomponent inactivation kinetics, which could not be explained by photobleaching of GV. The wide range of photosensitivities of these viruses to GV cannot be adequately explained by models based only on viral nucleic acid content or presence of lipid envelopes.

Effect of indomethacin on ultraviolet radiation-induced recurrent herpes simplex virus disease in guinea-pigs.

Exposure to u.v. radiation increases the local level of prostaglandins which may play a role in u.v. radiation-induced herpes simplex virus (HSV) recurrences. We used the guinea-pig model of u.v. radiation-induced recurrent genital HSV-2 disease for examining the effects of indomethacin, a prostaglandin inhibitor, on u.v.-induced recurrences. In the first experiment, performed 100 days after HSV-2 inoculation, treatment with indomethacin for 5 days begun 24 h before u.v.-irradiation decreased the proportion of animals developing HSV disease recurrences from 11/13 (84.6%) to 2/13 (15.4%) (P < 0.001). In the second experiment, performed 135 days after HSV-2 inoculation, treatment with indomethacin for 5 days begun 24 h before u.v.-irradiation decreased the number of animals developing recurrences from 12/21 (57.1%) to 5/21 (23.8%) (P < 0.05). Five days of indomethacin treatment begun 4 h after u.v.-irradiation, however, did not reduce the percentage of animals developing disease recurrences but did decrease the mean number of days with recurrent lesions in animals that developed recurrences. Our data suggest that indomethacin may modify u.v. radiation-induced recurrent lesions by decreasing viral reactivation when given before u.v. radiation exposure or by reducing prostaglandin-induced immunosuppression when given before or after exposure. Future studies are needed for evaluating indomethacin prophylaxis for recurrent HSV disease when prolonged u.v. radiation exposure is anticipated.

Herpes simplex virus type 1 and pseudorabies virus bind to a common saturable receptor on Vero cells that is not heparan sulfate.

Herpes simplex virus type 1 (HSV-1) and pseudorabies virus (PRV) infect different natural hosts but are very similar in structure, replicative cycle, and entry into cultured cells. We determined whether HSV-1 and PRV use the same cellular components during entry into Vero cells, which are highly susceptible to each virus but are not from native hosts for either. UV-inactivated virions of either HSV-1 or PRV could saturate cell surfaces to block infection of challenge HSV-1 or PRV. In the presence of saturating levels for infection of either virus, radiolabeled virus bound well and in a heparin-sensitive manner. This result shows that heparan sulfate proteoglycans on Vero cells are not the limiting cellular component. To identify the virus component required for blocking, we used an HSV-1 null mutant virus lacking gB, gD, or gH as blocking virus. Virions lacking gB were able to block infection of challenge virus to the same level as did virus containing gB. In contrast, virions lacking gD lost all and most of the ability to block infection of HSV-1 and PRV, respectively. HSV-1 lacking gH and PRV lacking gp50 also were less competent in blocking infection of challenge virus. We conclude that HSV-1 and PRV bind to a common receptor for infection of Vero cells. Although both viruses bind a heparin-like cell component on many cells, including Vero cells, they also attach to a different and limited cell surface component that is bound at least by HSV-1 gD and possibly gH and to some degree by PRV gp50 but not gB. These results clearly demonstrate binding of both HSV-1 and PRV to a common cell receptor that is not heparan sulfate and demonstrate that several types of attachment occur for both viruses during infectious entry.

The effect of UV therapy on immune function in patients with psoriasis.

Ultraviolet radiation (UVR) is known to suppress some cell-mediated immune responses to antigens encountered during or soon after exposure. Phototherapy is widely used in psoriasis, and this study was undertaken to monitor changes in a range of immunological parameters during standard courses of treatment, with the aim of ascertaining whether such modulations contribute to the effectiveness of therapy. The responses of 17 patients with psoriasis undergoing UVB therapy, and four receiving PUVA therapy, were compared with 15 patients receiving coal tar treatment and four normal subjects undergoing UVB irradiation. In each case, samples were taken before starting therapy, after 4 weeks of therapy, and 4 weeks after completion of treatment. Serum immunoglobulin isotypes and complement components were within normal ranges in most of the psoriasis patients, and remained unchanged throughout therapy. Similarly, percentages of subsets of peripheral blood mononuclear cells (PBMC) were normal, and were unaltered by treatment. Patients who were already infected with herpes simplex virus (HSV), as demonstrated by a positive lymphoproliferation test in vitro, were monitored for asymptomatic HSV shedding and HSV recrudescences during therapy. There was little evidence that phototherapy caused reactivation of the virus. No significant alteration in lymphoproliferative response to HSV and to the mitogen concanavalin A was observed during therapy. Epidermal cells and blood adherent cells were used to present HSV to PBMC, depleted of adherent cells and enriched for T cells, in a lymphoproliferative assay. The functional antigen-presenting ability of adherent cells remained unchanged throughout therapy, whereas that of epidermal cells was suppressed during UVB irradiation and recovered, in most instances, after UVB therapy had been completed. The epidermis of patients with psoriasis contained about three times the quantity of urocanic acid (UCA) of normal subjects, whereas the UCA concentration in suction blister fluid did not differ between the two groups. During UVB irradiation, the percentage of cis-UCA rose in both the epidermis and suction blister fluid of all subjects, and it remained elevated in the blister fluid after therapy had finished. Tumour necrosis factor-alpha was measured in suction blister fluid, and its concentration did not alter consistently as a result of therapy. Whether any of the immunological parameters measured, and the changes noted, contribute to the effectiveness of phototherapy in the treatment of psoriasis remains uncertain.

Corneal Langerhans cell dynamics after herpes simplex virus reactivation.

PURPOSE: The authors investigated the progressive changes in the distribution of corneal Langerhans cells (LC) after reactivation of latent herpes simplex virus type 1 (HSV-1) in mice. METHODS: After corneal inoculation of National Institutes of Health inbred mice with HSV-1 and the establishment of latency, viral reactivation was induced by irradiating the ocular surface with 250 mJ/cm2 of ultraviolet B (UV-B) light. RESULTS: Subsequent viral replication in the cornea was followed by the migration of the LC toward the paracentral and central corneal epithelium. These areas are normally devoid of LC. The number of LC in the paracentral and central regions of the eye reached a peak at day 14 post-UV-B irradiation. After UV-B irradiation of mice latently infected with HSV-1, the development of corneal stromal opacification and neovascularization closely followed the migration of LC toward the central cornea and paralleled the influx of T-cells into the corneal stroma. This pattern was not observed in irradiated uninfected mice. CONCLUSIONS: LC migrate centrally in the corneal epithelium after viral reactivation. There is a direct correlation between the number of LC in the cornea and the degree of persistent stromal opacification.