Transformation of mammalian cells by DNA-containing viruses following photodynamic inactivation

Trends and targets in antiviral phototherapy

Photodynamic therapy (PDT) is a well-established treatment option in the treatment of certain cancerous and pre-cancerous lesions. Though best-known for its application in tumor therapy, historically the photodynamic effect was first demonstrated against bacteria at the beginning of the 20^th century. Today, in light of spreading antibiotic resistance and the rise of new infections, this photodynamic inactivation (PDI) of microbes, such as bacteria, fungi, and viruses, is gaining considerable attention. This review focuses on the PDI of viruses as an alternative treatment in antiviral therapy, but also as a means of viral decontamination, covering mainly the literature of the last decade. The PDI of viruses shares the general action mechanism of photodynamic applications: the irradiation of a dye with light and the subsequent generation of reactive oxygen species (ROS) which are the effective phototoxic agents damaging virus targets by reacting with viral nucleic acids, lipids and proteins. Interestingly, a light-independent antiviral activity has also been found for some of these dyes. This review covers the compound classes employed in the PDI of viruses and their various areas of use. In the medical area, currently two fields stand out in which the PDI of viruses has found broader application: the purification of blood products and the treatment of human papilloma virus manifestations. However, the PDI of viruses has also found interest in such diverse areas as water and surface decontamination, and biosafety.

Local clinical phototreatment of herpes infection in São Paulo

The clinical use of topical photodynamic therapy in herpes simplex lesions in São Paulo is presented and discussed. Although previous attempts utilising this type of approach in the USA were discontinued in the early 1970s due to several presentations of post-treatment Bowen's disease, none of the cases from the clinic presented here have displayed any complications on follow-up. In addition, lesion recrudescence periods are generally much longer than with conventional approaches. This is thought to be due to improvements in the treatment protocol, viz. use of the non-toxic photosensitisers methylene blue and Hypericum perforatum extract in place of proflavine and neutral red in the original trials, differences in photosensitisation pathway and illumination of the treatment site with red rather than fluorescent/UV light. Post-treatment cosmesis is also excellent.

Photosensitizers as virucidal agents

The photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA) has been studied regarding its ability to destroy enveloped viruses in blood and blood products when activated by light. Its maximum wavelength of absorption (690 nm) has proven useful in terms of activation of the photosensitizer in materials containing red blood cells. Experiments conducted on whole blood of patients infected with the human immunodeficiency virus (HIV) demonstrated that BPD-MA and light could effectively eliminate the virus when treated materials were placed in culture and tested for viral p24, but did not appear to damage blood cells or blood components. Since HIV is largely intracellular in infected individuals, these results were investigated further. We have shown, using flow cytometry, that in HIV-infected blood, BPD-MA and light appear to selectively destroy white cells that bear the interleukin 2 receptor and the DR antigen. These markers are prevalent on activated lymphocytes, and since HIV replicates only in CD4+ T cells which are activated, this finding provides an explanation for the selective killing of HIV.

Phototherapy, photochemotherapy, and bone marrow transplantation

Recent preclinical and clinical investigations indicate that phototherapy and photochemotherapy may have applications that go far beyond their "traditional" roles in the treatment of skin disorders, selected solid tumors, and neonatal hyperbilirubinemia. Bone marrow transplantation is one area that may benefit substantially from these new developments. This review focuses on new applications of phototherapy and photochemotherapy that pertain to the inactivation of tumor cells in autologous bone marrow grafts, the prevention and treatment of acute and chronic graft-versus-host disease, the prevention of transfusion-induced allosensitization and graft rejection, and the inactivation of pathogenic viruses and parasites in bone marrow grafts and blood products.

Alterations in the cellular phenotype induced by herpes simplex viruses

Numerous studies have shown that herpes simplex virus types 1 and 2 (HSV-1, HSV-2) are able to transform the morphological phenotype of rodent cells. Unlike other DNA tumor viruses the transformed cells did not consistently retain or express a given set of viral genes. In fact, transformation could be obtained using fragments of viral DNA that did not wholly encode viral proteins. Of interest within the transforming fragments were sequences which could assume a secondary structure like that of insertion elements. The failure to detect viral DNA in transformed cells led to the hit-and-run hypothesis of HSV transformation. The mechanism by which HSV induces transformation is not understood. Various lines of investigation have shown that HSV is able to cause mutations--both point mutations and gene rearrangements. HSV is also able to induce gene amplification, particularly of sequences harboring an origin of replication such as SV40 or papillomaviruses. Other experiments have shown that HSV can activate the expression of endogenous type C retroviruses. More broadly, HSV has been shown to activate cellular transcription or to switch on the synthesis of host cell proteins not normally expressed in untransformed cells. The failure to detect viral DNA in a high proportion of human anogenital tumors made it difficult to implicate HSV in the etiology of those neoplasias, but it is consistent, however, with the observations on the mode of HSV transformation in vitro, and suggests that HSV could be involved in a multistage process of oncogenic transformation.

Cancer chemoprevention by supplemental carotenoids in animals and humans

Experiments were carried out in mice demonstrating that dietary carotenoids (beta-carotene or canthaxanthin), starting before cancer initiation and continuing throughout the experiment, have a protective effect against indirect skin carcinogenesis induced by benzo[a]pyrene +/- UVA and breast cancer induced by 8-methoxypsoralen + UVA. Experiments in rats demonstrated that carotenoids also prevent the direct gastric carcinogenesis induced by N-methyl-N'-nitro-nitroso-guanidine. Recently, prevention by beta-carotene against colon cancer induced in mice by dimethylhydrazine, another indirect carcinogen, was confirmed by others. The prospects for carotenoid intervention with humans were based on their antitumorigenic effect, which is quite independent of pro-vitamin A activity, their lack of toxicity even after prolonged administration, and their immunostimulating activity. These facts helped to build up a rationale predicting that any epithelial cancer, after radical surgery, can be chemoprevented with supplemental carotenoids. Thus, it is expected that the remaining initiated epithelial tissue will be protected by quenching oxygen radical formation, against the onset of a second primary malignancy. This type of prevention can be envisaged in organs like the lung, urinary bladder, breast, stomach, and colon-rectum. At present, human intervention protocols with a randomized drug/placebo method are underway under the supervision of the Centro Tumori of Pavia to chemoprevent with beta-carotene second primary lung or bladder cancer after radical surgery. Preliminary observations regarding findings in humans without randomization (1980-1988) in Pavia are also reported here. This consisted of chemoprevention with beta-carotene plus canthaxanthin against recurrence of different epithelial malignancies after radical treatment (surgery +/- chemoradiotherapy). None of the 11 cases recruited, on the basis of radical nature of treatment and patient adherence, have shown any recurrence beyond their expected disease-free intervals.

Immunotherapeutic studies of different clonal lines of herpesvirus-induced fibrosarcoma in a syngeneic rat

Transformation of White Buffalo rat embryonic cells by dye-light-inactivated herpesvirus type 2 resulted in the development of two clones of transformed cells (G2 and rat fibrosarcoma) with significantly different tumorigenic capabilities. The G2 cell line was initially nontumorigenic, while the rat fibrosarcoma line was very highly tumorigenic in rats. These significant differences in transformed cell clones from the same initial culture offered an opportunity to study aspects of the immunobiology of oncogenicity. The development of fibrosarcomas in immunoincompetent nude mice with the same early passages of the G2 cell line which were nontumorigenic in the immunocompetent rat suggested that immunologic resistance developed more effectively in the competent host against the G2 line than against rat fibrosarcoma cells. Syngeneic rats which were first exposed to the early passage nontumorigenic G2 cells were completely protected against tumor development by the rat fibrosarcoma cell lines. In subsequent in vitro passages of the G2 cell line, it lost its ability to protect against rat fibrosarcoma challenge and gradually became oncogenic in rats. Modification of antigenic exposure, accomplished by treating the G2 cells with cholesteryl hemisuccinate, resulted in an increase in the protection by these cells and a delay in tumor development.

Combined effect of herpes simplex virus and tobacco on the histopathologic changes in lips of mice

In the present study we have examined the combined effect of HSV-1 inoculation and tobacco application (snuff water extract or smoking tar condensate) on the histopathologic changes of mouse labial mucosa. Two months' exposure to tobacco or HSV-1 inoculation alone did not induce dysplasia in the epithelium of labial mucosa, while HSV-1 inoculation combined with snuff water extract or smoking tar condensate produced epithelial dysplasia and other histomorphologic changes (that is, hyperkeratosis, increased granular cell layer thickness, acanthosis, and increased inflammatory cell infiltration in a significant number of animals). This result indicates that HSV-1 and tobacco could possibly act synergistically in the development of precancerous oral lesions and oral cancer.

Blocked herpes simplex virus type 2-specific DNA synthesis in simian virus 40-transformed hamster cells permissive for herpes simplex virus type 1

Simian virus 40-transformed hamster cells (LL-1) permissive to herpes simplex virus type 1 (HSV-1) were shown to be relatively nonpermissive to HSV-2. When LL-1 cells were infected with HSV-2, there was a 3- to 4-log reduction in infectious viral progeny at 24 h postinfection as compared with HSV-1 under identical cultured conditions. HSV-2 could be carried in the LL-1 cell line for up to 12 passages without any appreciable cytopathology. Various early functions of the replicative cycle of HSV-2 appeared to be normal. Experiments demonstrated that early enzyme activity, HSV-2 thymidine kinase, and DNA polymerase appeared at permissive levels in extracts of HSV-2-infected LL-1 cells. However, DNA analysis of HSV-2 infected LL-1 cells demonstrated a block in HSV-2-specific DNA synthesis, although HSV-2 was capable of inhibiting DNA synthesis in LL-1 cells. Furthermore, indirect immunofluorescence studies indicate that late HSV-2 structural protein synthesis was inhibited in infected LL-1 cells. Thus, the inability of HSV-2 to replicate in LL-1 cells is due to a block at or before HSV-specific DNA synthesis, resulting in a reduction of the structural protein synthesis required for viral maturation.

Genital herpes simplex--concepts and treatment

Genital herpes simplex is an increasingly common venereal disease caused by either herpes simplex virus type 1 or 2. The disease can be manifested in a primary and/or recurrent form, the clinical features and complications of which are reviewed. Potential problems include psychosocial difficulties, neonatal herpes simplex infections, and the possibility of an oncogenic role in cervical cancer. Diagnostic modalities, prophylactic measures, and management technics are discussed.

Transformation of rodent cells by a cloned DNA fragment of herpes simplex virus type 2

Transformation of rodent cells with isolated restriction endonuclease fragments of herpes simplex virus type 2 DNA identified a region of the genome located between map positions 0.58 and 0.62. These sequences were cloned into pBR322, and the recombinant plasmid was used to transform primary rat embryo cells and NIH 3T3 cells. The transformants were selected for their ability to form dense foci on a monolayer or to form colonies in semisolid medium. In contrast to the parental rat or mouse cells, cell lines transformed with the cloned herpes simplex virus type 2 fragment grow to high saturation densities, replicate in medium containing 1% serum, form colonies in dilute methylcellulose, show reduced levels of fibronectin, and are tumorigenic in nude mice and in their syngeneic hosts. Southern blot hybridizations have detected sequences homologous to the viral fragment in high-molecular-weight DNA from the transformed cell lines that are not present in DNA from normal rodents. In all cases, the plasmid DNA was present in less than one copy per cell, and the patterns of viral sequences changed with passage of the cell line in vivo.

Early events in herpes simplex virus type 1 infection: photosensitivity of fluorescein isothiocyanate-treated virions

Herpes simplex virus type 1 is photosensitized by treatment with fluorescein isothiocyante (FITC). The inactivation of FITC-treated virions upon subsequent exposure to light is inhibited by the presence of sodium azide, suggesting the involvement of singlet oxygen in the process. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis revealed that treatment with FITC plus light induces crosslinks in viral envelope glycoproteins. Treatment of virions with high concentrations of FITC (50 micrograms/ml) plus light causes a reduction in the adsorption of the virus to monolayers of human embryonic lung cells. For lower concentrations of FITC (10 micrograms/ml) plus light, treated virions adsorb to the host cells, but remain sensitive to light until entry occurs. The loss of light sensitivity coincides with the development of resistance to antibodies. These results are most consistent with a mechanism of entry for herpes simplex virus involving fusion of the viral membrane with the plasma membrane of the host cell.

Herpes virus inactivation by chemical carcinogens: differential inactivation of herpes simplex viruses by 4-nitroquinoline 1-oxide and related compounds

Treatment of stocks of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) with the chemical carcinogen 4-nitroquinoline 1-oxide (NQO) resulted in inactivation of virus infectivity at rates which were directly dependent on the concentration of NQO and interval of exposure to NQO. HSV-1 strains were more sensitive than HSV-2 strains to inactivation by NQO, although survival curves of both HSV types were multicomponent. Exposure of HSV-2 to a related group of chemicals suggested that the structural specificity required for inactivation of this virus was similar to that established by previous in vivo carcinogenicity tests.

Benzo[a]pyrene metabolism in cells productively infected with simian virus 40

The metabolism of benzo[a]pyrene (BP) by cell cultures and cell-free extracts of the monkey kidney cell line CV-1 was studied in uninfected and Simian virus 40 (SV40) infected cells. Metabolites formed were separated by high-pressure liquid chromatography (HPLC) and quantified by liquid scintillation techniques. The profiles metabolites formed by uninfected and SV40 infected cells were similar except that SV40 infected cell cultures metabolized BP at an increased rate relative to uninfected cells. In addition, SV40 infected cell cultures and cell-free extracts produced an unknown compound which eluted between the 3-hydroxybenzo[a]pyrene and BP fractions. This material does not have a retention time characteristic of any of the known metabolites of BP. Labelled BP and/or its metabolites were bound to the viral DNA and histone components of intracellular viral minichromosomes as well as the viral DNA and proteins of mature virions.

Mechanisms of photodynamic inactivation of herpes simplex viruses: comparison between methylene blue, light plus electricity, and hematoporhyrin plus light

Herpes simplex virus (HSV) types 1 and 2 have been inactivated in vitro using low concentrations of methylene blue (MB), light (lambda) plus electricity (E), or hematoporphyrin derivative (HPD) plus lambda. Both techniques introduce single strand interruptions into viral DNA, but do not make double strand ruptions into viral DNA, but do not make double strand breaks. MB, lambda plus E-treated virions adsorb normally to and penetrate susceptible cells, whereas HSV inactivated with HPC and light does not. This difference is emphasized by the induction of new viral and cell DNA synthesis after infection with MB, lambda plus E-treated virions, whereas only cell, DNA but no HSV DNA, is made subsequent to HPD and lambda exposure. These observations reflect disparate mechanisms of viral inactivation. A block(s) in viral maturation, subsequent to viral DNA synthesis, occurs as a result of treatment with MB, lambda and E, whereas HPD plus lambda-treated particles fail to enter a susceptible cell, and therefore do not initiate an infection.

Enhancement of host cell reactivation of ultraviolet-irradiated Herpes simplex virus by caffeine, hydroxyurea and 5-bromodeoxyuridine

Enhancement of host cell reactivation (HCR) of ultraviolet (UV)-irradiated herpes simplex virus (HSV) was demonstrated in cell cultures pretreated with caffeine, hydroxyurea, or 5-bromodeoxyuridine (BrdUrd). The effect of caffeine on HCR was shown to depend on the time of drug treatment with respect to infection. In cultures treated with caffeine during the course of virus replication, the infectivity of irradiated HSV was reduced about nine-fold, while cultures pretreated with the drug before infection showed an increase in infectivity. The extent of HCR enhancement depended on the time interval between treatment with caffeine and infection, drug concentration, and the UV irradiation dose to which HSV was exposed. Magnitude of enhancement of HCR by caffeine differed in various cell species. The results suggest that enhanced HCR of UV-irradiated HSV by DNA antimetabolities is associated with DNA repair activated in consequence of cell DNA damage.

Treatment of genital herpes simplex virus infection with photodynamic inactivation

A double-blind randomized study to evaluate the effect of proflavine in the treatment of genital herpesvirus infection was conducted. One hundred fifty-seven women were studied, of whom 75 were treated with proflavine (treated women) and 82 were treated with placebo (control group). There were 62 women with primary disease and 95 with recurrent infection. Under the conditions by which this study was conducted, there was no apparent difference in the time of healing of lesions, development of recurrences, or virus isolation following treatment in the proflavine-treated and control groups.

Bowenoid papulosis of the penis

During the past 18 months we have studied 36 biopsy specimens taken from 11 young men ranging in age from 21 to 36, each of whom had multiple, reddish to violaceous papules, some distinctly verrucoid or velvety on either or both the shaft and glans of the penis. The clinical diagnoses accompanying the biopsy specimens were lichen planus, psoriasis and condyloma acuminatum. In no instance was carcinomia in situ suggested in the differential diagnosis. Histologically, however, all specimens submitted showed indubitable changes of squamous cell carcinoma in situ.

Biochemical Transformation of mouse cells by herpes simplex virus types 1 and 2: comparison of different methods for inactivation of viruses

Comparison of methods to inactivate lytic properties of herpes simplex viruses revealed that ultraviolet irradiation, photodynamic procedures, and heat all destroyed infectivity effectively. Ability to biochemically transform thymidine kinase deficient cells to an enzyme positive phenotype was retained after limited exposure to heat or ultraviolet light but appeared to be destroyed by photodynamic methods employing neutral red. Exposure to 56 degrees C quickly and effectively destroyed transforming activity with lower temperatures being less effective. The most reproducible transforming assays were obtained following inactivation by ultraviolet light. Cell cultures developed by this procedure were virus-free but retained ability to synthesize virus-specific antigens.

A nonlytic transforming mutant of herpes simplex virus type 2

A small-plaque mutant (NO.69) of herpes simplex virus type 2 (HSV-2) strain 333 has been previously isolated and characterized in this laboratory. This mutant was shown to produce a high ratio of noninfectious to infectious particles when grown at the nonpermissive temperature in hamster embryo fibroblasts [Westmoreland D. and Rapp F. (1976). Journal of Virology [8:92--102]. In this study, we have demonstrated that it is possible to obtain noninfectious stocks of this virus which retain transforming ability in a biochemical transformation assay specific for detection of the HSV gene for thymidine kinase. This mutant contains a DNA genome that has a density identical to the DNA of wild-type virus. Virus and cell DNA synthesis after infection with the mutant at both the permissive and nonpermissive temperature are similar to that observed in cultures infected with the parental virus. Clones of mouse cells biochemically transformed by this virus contain HSV antigens and are presently being examined for oncogenicity.