Effect of snuff and herpes simplex virus-1 on rat oral mucosa: possible associations with the development of squamous cell carcinoma

Detection of herpes simplex virus in oral tongue squamous cell carcinoma

Introduction: Oral tongue squamous cell carcinoma (OTSCC) is the most common cancer of the oral cavity. Contradictory results have been observed on the involvement of herpes simplex virus 1 (HSV-1) in oral squamous cell carcinomas. Here, we aimed to study the predominance of HSV-1 or HSV-2 in oral HSV infections and to investigate the presence of HSV-1 in OTSCC and its effect on carcinoma cell viability and invasion. Methods: The distribution of HSV types one and two in diagnostic samples taken from suspected oral HSV infections was determined from the Helsinki University Hospital Laboratory database. We then analysed 67 OTSCC samples for HSV-1 infection using immunohistochemical staining. We further tested the effects of HSV-1 using six concentrations (0.00001-1.0 multiplicity of infection [MOI]) on viability and two concentrations (0.001 and 0.1 MOI) on invasion of highly invasive metastatic HSC-3 and less invasive primary SCC-25 OTSCC cell lines using MTT and Myogel-coated Transwell invasion assays. Results: Altogether 321 oropharyngeal samples were diagnosed positive for HSV during the study period. HSV-1 was the predominant (97.8%) HSV type compared with HSV-2 (detected in 2.2% of samples). HSV-1 was also detected in 24% of the OTSCC samples and had no association with patient survival or recurrence. OTSCC cells were viable even after 6 days with low viral load (0.00001, 0.0001, 0.001 MOI) of HSV-1. In both cell lines, 0.001 MOI did not affect cell invasion. However, 0.1 MOI significantly reduced cell invasion in HSC-3 cells. Discussion: HSV-1 infection is predominant compared with HSV-2 in the oral cavity. HSV-1 is detected in OTSCC samples without clinical significance, and OTSCC cell survival or invasion was not affected at low doses of HSV-1.

The interaction between human papillomavirus and other viruses

The etiological role of human papillomavirus (HPV) in anogenital tract and head and neck cancers is well established. However, only a low percentage of HPV-positive women develop cancer, indicating that HPV is necessary but not sufficient in carcinogenesis. Several biological and environmental cofactors have been implicated in the development of HPV-associated carcinoma that include immune status, hormonal changes, parity, dietary habits, tobacco usage, and co-infection with other sexually transmissible agents. Such cofactors likely contribute to HPV persistent infection through diverse mechanisms related to immune control, efficiency of HPV infection, and influences on tumor initiation and progression. Conversely, HPV co-infection with other factors may also harbor anti-tumor effects. Here, we review epidemiological and experimental studies investigating human immunodeficiency virus (HIV), herpes simplex virus (HSV) 1 and 2, human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), BK virus (BKV), JC virus (JCV), and adeno-associated virus (AAV) as viral cofactors in or therapeutic factors against the development of genital and oral HPV-associated carcinomas.

Nested PCR for detection of HSV-1 in oral mucosa

Background

It has been estimated that 15%-20% of human tumours are driven by infection and inflammation, and viral infections play an important role in malignant transformation. The evidence that herpes simplex virus type 1 (HSV-1) could be involved in the aetiology of oral cancer varies from weak to persuasive. This study aimed to investigate by nested PCR (NPCR) the prevalence of HSV-1 in samples from normal oral mucosa, oral leukoplakia, and oral squamous cell carcinoma (OSCC).

Material and Methods

We investigated the prevalence of HSV-1 in biopsies obtained from 26 fresh, normal oral mucosa from healthy volunteers as well as 53 oral leukoplakia and 27 OSCC paraffin-embedded samples. DNA was extracted from the specimens and investigated for the presence of HSV-1 by nested polymerase chain reaction (NPCR) and DNA sequencing.

Results

HSV-1 was detected in 14 (54%) of the healthy samples, in 19 (36%) of the oral leukoplakia samples, and in 14 (52%) of the OSCC samples. The differences were not statistically significant.

Conclusions

We observed a high incidence of HSV-1 in healthy oral mucosa, oral leukoplakia, and OSCC tissues. Thus, no connection between OSCC development and presence of HSV-1 was detected.

Key words:HSV-1, nested PCR, PCR.

Viruses and oral cancer. Is there a link?

Oral squamous cell carcinoma (OSCC) is the most common malignant tumour of the oral cavity. The aetiology of epithelial cancer of the head and neck is considered to be a multifactorial, sequential process. DNA viruses are found in many different cancers and are also capable of transforming cells to a malignant phenotype. Human Papilloma Virus (HPV) has been proposed as risk factors in OSCC development and HPV type 16 is the most important subtype. Other oncogenic virus species i.e., Epstein-Barr Virus and Herpes Simplex Virus Type 1 have been proposed to be involved in oral carcinogenesis. However, no convincing evidence exist that they are an established risk factor in OSCC. Therefore more studies are needed in order to clarify the different aspects of virus involvement. Here, we review the existing literature on viral involvement in oral cancer.

Evidences suggesting involvement of viruses in oral squamous cell carcinoma

Oral cancer is one of the most common cancers and it constitutes a major health problem particularly in developing countries. Oral squamous cell carcinoma (OSCC) represents the most frequent of all oral neoplasms. Several risk factors have been well characterized to be associated with OSCC with substantial evidences. The etiology of OSCC is complex and involves many factors. The most clearly defined potential factors are smoking and alcohol, which substantially increase the risk of OSCC. However, despite this clear association, a substantial proportion of patients develop OSCC without exposure to them, emphasizing the role of other risk factors such as genetic susceptibility and oncogenic viruses. Some viruses are strongly associated with OSCC while the association of others is less frequent and may depend on cofactors for their carcinogenic effects. Therefore, the exact role of viruses must be evaluated with care in order to improve the diagnosis and treatment of OSCC. Although a viral association within a subset of OSCC has been shown, the molecular and histopathological characteristics of these tumors have yet to be clearly defined.

Role of viruses in oral squamous cell carcinoma

The etiology of oral squamous cell carcinoma (OSCC) is complex and involves many factors. The most clearly defined risk factors are smoking and alcohol, which substantially increase the risk of oral SCC. However, despite this clear association, a substantial proportion of patients develop OSCC without exposure to them, emphasizing the role of other risk factors such as genetic susceptibility and oncogenic viruses. Some viruses are strongly associated with OSCC while the association of others is less frequent and may depend on co-factors for their carcinogenic effects. Therefore, the exact role of viruses must be evaluated with care in order to improve the diagnosis and treatment of OSCC.

Adverse effects of Sudanese toombak vs. Swedish snuff on human oral cells

BACKGROUND

The high incidence of oral cancer in Sudan has been associated with the use of toombak, the local type of smokeless tobacco. However, its specific effects on human oral cells are not known. We aimed to investigate the effects of toombak on primary normal human oral keratinocytes, fibroblasts, and a dysplastic oral keratinocytic cell line, and to compare them with the effects induced by Swedish snuff.

METHOD

Aqueous extracts were prepared from moist toombak and Swedish snuff and added in serial dilutions on in vitro monolayer cultured cells. Cell viability, morphology and growth, DNA double-strand breaks (gammaH2AX staining), expression of phosphatidylserine (Annexin V staining), and cell cycle were assessed after various exposure time periods.

RESULTS

Significant decrease in cell number, occurrence of DNA double-strain breaks, morphological and biochemical signs of programmed cell death were detected in all oral cell types exposed to clinically relevant dilutions of toombak extract, although to a lesser extent in normal oral fibroblasts and dysplastic keratinocytes. G2/M-block was also detected in normal oral keratinocytes and fibroblasts exposed to clinically relevant dilutions of toombak extract. Swedish snuff extract had less adverse effects on oral cells, mainly at non-clinically relevant dilutions.

CONCLUSION

This study indicates a potential for toombak, higher than for Swedish snuff, to damage human oral epithelium. Dysplastic oral keratinocytes were less sensitive than their normal counterparts, suggesting that they might have acquired a partially resistant phenotype to toombak-induced cytotoxic effects while still being prone to DNA damage that could lead to further malignant progression.

The role of viruses in squamous cell carcinoma of the oropharyngeal mucosa

The development of squamous cell carcinomas of the oropharyngeal mucosa may involve many factors, including viruses. This review examines the evidence that viruses could be involved in the etiology of oral cancer, and shows that the evidence for a role of different viruses varies from very weak to very persuasive. Papillomaviruses are probably involved in the etiology of some carcinomas, particularly those of the oropharynx, and some herpes viruses may be involved as well. On the other hand some viruses can cause cancer in experimental situations but not in humans. Thus the importance of viruses in oral cancer is not always clear and must be evaluated with care. Those viruses that are associated with the disease provide targets for therapy and for diagnostic assays.

Herpes Simplex Virus Infection Presenting as a Piriform Sinus Mass

Evidence is accumulating that herpes simplex virus (HSV) infection is implicated in oncogenesis. HSV antigens have been observed in some oral cancers. We present the case of a 62-year-old man who presented with dysphagia, odynophagia, and dysphonia and who was found on computed tomography (CT) to have a mass in his piriform sinus. We suspected a malignancy, but histopathology of biopsy specimens revealed that the mass exhibited the classic signs of the HSV cytopathic effect, including the presence of intranuclear inclusion bodies, ballooning degeneration of epithelial cells, and a ground-glass appearance of some nuclei. The patient responded well to antiviral therapy, and posttherapy CT revealed that the mass had resolved completely. To the best of our knowledge, this is the first report in the literature of a case of HSV infection presenting as a piriform sinus mass.

Current management of tonsillar cancer

Traditionally, risk factors for the development of tonsil cancer include the use of alcohol and/or tobacco, however a significant proportion of new cases develop in young patients without these risk factors. Recent investigation suggests that human papilloma virus (HPV) may serve as an etiology in such cases and represent a unique risk factor in a sub-set of patients. Irrespective of the etiology, in the majority of cases early carcinoma of the tonsil can effectively be treated using single modality therapy. While local-regional control and survival are similar following surgery or radiotherapy, primary surgery can be accomplished with minimal functional morbidity while reserving radiation for recurrent disease. In contrast, surgical salvage following external beam radiotherapy can be technically challenging and is often associated with a significant increase in surgical complications and functional morbidity. In contrast to early tonsillar disease, advanced tonsil cancer represents a clinical challenge that requires multimodality therapy. While advanced lesions are often treated with a combination of radiation, chemotherapy, and surgical ablation, management of the neck and distant metastases continues to present a therapeutic dilemma.

Oral squamous cell carcinoma; from an hypothesis about a virus, to concern about possible sexual transmission

Nearly two decades ago, we produced the first evidence for the presence of viral nucleic acids in oral squamous cell carcinoma (OSCC) tissues, hypothesising that there may be a viral involvement in at least some OSCC. Subsequently, human papillomaviruses (HPV) in particular have been implicated in OSCC. Antibody responses to HPV are seen and HPV-DNA detected in tumors by us and many others, the virus being mainly HPV-16, the genotype associated with ano-genital cancer. HPV are seen by in situ hybridisation only in tumour and premalignant tissue but not in surrounding normal mucosa suggesting HPV has a causal relationship. HPV may also be integrated in the host genome, further suggesting a causal role. Studies of patients with OSCC have suggested possible sexual transmission of HPV. Recent studies have indicated that HPV may be aetiologically important particularly in some types of oropharyngeal cancer, at least in tonsillar carcinogenesis, and may represent an alternative pathway in carcinogenesis to the established factors of tobacco and alcohol. We have come a very long way in the two decades since our first suggestion of a viral aetiopathogenesis was greeted with incredulity, and data from on-going studies by the International Agency for Research on Cancer, Johns Hopkins Oncology Center and others are eagerly awaited.

Smokeless tobacco and oral cancer: an assessment of evidence derived from laboratory animals

No carcinogenic activity was observed when snuff was inserted into the cheek pouch of the hamster or spread over the oral mucosa. This negative result was obtained in a number of experiments whether snuff was applied once only and left in place for several months or inserted repeatedly for up to 2 years. In the rat, a few tumours were observed when snuff was inserted into the artificial lip canal. The insertion appeared to cause a considerable reaction in the surrounding tissue so it is plausible to assume that trauma plays an important role in the development of these tumours. An extract of snuff applied to the oral mucosa of the rat did not produce any tumours, but an extract enriched by the addition of 10 times the naturally-occurring amounts of NNN and NNK produced a few benign tumours at the site of application. A higher incidence of tumours was produced when an equivalent amount of an aqueous solution of these two nitrosamines was applied directly to the oral mucosa, suggesting, according to the authors, that snuff inhibits the carcinogenic activity of TSNAs. Initiation/promotion studies were carried out on snuff in the rat in order to explore further its carcinogenic potential. The results were consistent with the conclusion that snuff does not possess any promotional activity. No increase in tumour incidence was observed in mice when snuff was given in the diet at concentrations of 25% gradually decreasing to 5% in a 14 month study. A negative result was also obtained in the rat given snuff at a concentration of 5% for 18 months. In hamsters given snuff at a concentration of 20% for 2 years, forestomach tumours occurred. A comparable incidence of this type of tumour occurred in animals given 20% cellulose. The result of this study does not provide valid evidence of carcinogenicity. HSV and snuff applied orally in the hamster produced a high incidence of squamous cell carcinomas. The sustained high level of squamous cell hyperplasia generated by the experimental design could account for the development of these tumours. Despite the defects in some of the earlier studies, the sum total of this experimental work suggests that snuff is not carcinogenic to the oral mucosa of the hamster or the rat. It is also unlikely to cause tumours in other tissues in these species. These results give some degree of reassurance that snuff is not likely to be carcinogenic to the human oral mucosa. The interaction of snuff and HSV viruses is, at the moment, questionable and requires further investigation.

Immunotoxic effects of smokeless tobacco on the accessory cell function of rat oral epithelium

Smokeless tobacco (ST) is known to adversely effect the oral mucosa, but knowledge about the influence on immune defence is limited. Few studies have investigated the effect of ST on the local immune response. In the present study, we have assessed the effect of a crude Swedish moist snuff (SS) extract, alkaloids, and nitrosamines on T-cell mitogenic response to Con A using epithelial cells, including Langerhans cells, of the rat oral mucosa as accessory cells. SS extract at a concentration of 4% reduced the T-cell proliferation by 50% (IC50 = 4%). Pretreatment of either oral epithelial cells or T-cells with SS extract also gave a significant inhibition of T-cell proliferation. This effect was not obtained following preincubation with SS components as alkaloids and different tobacco-specific nitrosamines (TSNA). None of the tested compounds were found to possess any mitogenic properties. This in vitro study showed that SS extract can evoke an immunosuppressive effect on mitogen-driven T-cell proliferation using cells from oral epithelium as accessory cells. This effect was more pronounced when SS extract was employed compared to when the single SS components were used alone.

The effect of N-nitrosonornicotine on the buccal mucosa of Syrian hamsters

PURPOSE

The carcinogens in smokeless tobacco have been identified as the tobacco-specific nitrosamines and the effect of one of these, N-Nitrosonornicotine (NNN), on the buccal mucosa of the Syrian hamster was studied.

MATERIALS AND METHODS

Buccal pouches of 36 Syrian hamsters were painted five times per week for 24 weeks with 10 mg/mL 98% pure NNN in suspension with mineral oil. Animals were killed at 6, 8, 12, and 24 weeks.

RESULTS

At 6 weeks, the buccal pouch mucosa of the experimental animals appeared clinically more hyperemic than those of the controls. From 12 weeks onward, all experimental animals showed epithelial hyperplasia and inflammation on histologic examination. Three animals killed at 24 weeks showed mild epithelial dysplasia.

CONCLUSIONS

Exposure of Syrian hamster buccal mucosa to NNN, five times per week for 24 weeks, did not result in clinical or histologic cancerous changes. NNN may require other factors for cancer production, such as a cocarcinogen, a higher concentration, or a longer period of application.

Oncogenes, tumor suppressors and viruses in oral squamous carcinoma

The pathogenesis of oral squamous cell carcinoma involves recognised carcinogens in tobacco and/or alcohol but other factors, including viruses, may also have a role. This paper reviews the gene changes revealed in oral carcinoma, the evidence implicating viruses, and mechanisms whereby viruses may affect gene function.

Inhibition of herpes simplex virus replication and protein synthesis by non-smoked tobacco, tobacco alkaloids and nitrosamines

Inhibitory effects of snuff extract and the tobacco chemicals nicotine, anabasine, diethyl-N-nitrosamine (DEN), and the tobacco-specific nitrosamines (TSNA), N-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) on herpes simplex virus type 1 (HSV-1) replication in vitro and on HSV-1 protein synthesis in infected cells were analysed. Snuff extract and nicotine caused a significant reduction of HSV-1 attachment to cell membranes whereas anabasine, DEN, NNN and NNK did not affect adsorption of HSV-1. Virus production assays in the presence of snuff added after virus adsorption resulted in a significantly reduced production of virus at low multiplicities of infection (MOI), but at high MOI the inhibitory effect of snuff extract was less pronounced. DEN, NNN and NNK only affected virus production at toxic concentrations. Nicotine and anabasine reduced virus production in non-toxic doses but not at the concentrations present in snuff extract. In HSV-infected cells exposed to snuff extract, the immediate early (alpha-) infected cell proteins (ICPs) 4 and 27 (as well as the early (beta-) ICPs 6 and 8) were markedly increased, whereas the late (gamma-) ICPs 5, 11 and 29 were reduced. Nicotine had a less pronounced stimulating effect on the production of alpha-proteins but no detectable effect on production of beta- or gamma-proteins. Anabasine, DEN, NNN and NNK did not affect HSV protein synthesis at non-toxic concentrations. Synthesis of thymidine kinase and DNA polymerase was significantly reduced by snuff extract. Also nicotine and anabasine affected thymidine kinase and DNA polymerase but only at toxic concentrations. The production of the cellular protein actin, which almost disappears a few hours after HSV-1 infection, remained at a significant level in HSV-infected cells exposed to snuff. Thus snuff extract blocks the replicative cycle of HSV at an early stage, which results in an increased production of alpha-proteins in the infected cells and in prolonged maintenance of cellular functions. This may be of importance for HSV-induced transformation and the development of HSV-associated tumours.

Association between malignancies of the upper aerodigestive tract and uterine cervix

Cancers of the cervix and buccal cavity share histologic, epidemiologic, and exposure characteristics. In particular, cigarette smoking and human papillomavirus (HPV) have been cited as etiologic cofactors of both malignancies. Using incidence data from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute for the years 1973 through 1984, we evaluated the incidence of second cancers of the buccal cavity following an initial cervical cancer. Standardized incidence ratios (SIR) were uniformly elevated for both white (SIR = 2.0), and black (SIR = 3.5) women. There were also elevated risks for the development of cervical cancer following an initial buccal cavity cancer (SIRs = 3.3 and 2.5, respectively). A similar pattern was evident for laryngeal cancer among white women. HPV transmission could account in part for the paired occurrence of these two anatomically distinct cancer sites. Cigarette smoking could act as a synergistic cofactor in the malignant transformation of viral genome-harboring tissue.

Pathogenesis of oral submucous fibrosis. Relationship to risk factors associated with oral cancer

Oral submucous fibrosis (OSF) is a chronic disease of the oral mucosa characterized by inflammation and a progressive fibrosis of the lamina propria and deeper connective tissues. It is a condition predominantly seen among people of Indian origin, and an epidemiologic survey done a decade ago showed no less than 250,000 cases in India, a figure that must have increased sharply. OSF is a condition with a high risk of malignant transformation; to date, no conclusive etiologic agent has been identified, although plenty of data have been generated on various aspects of the disease. These include genetic, carcinogenic, immunologic, viral, nutritional, and autoimmune possibilities, all of which also have been implicated in the development of oral cancer. This article reviews existing evidence on the pathogenesis of OSF and its relation to oral cancer and suggests a possible multifactorial model to explain the disease process.

Viruses in the aetiology of oral carcinoma? Examination of the evidence

This paper examines the evidence for an aetiological role for viruses in the development of oral carcinoma. Several viruses have been sought in oral cancer and evidence found for some, particularly herpes simplex and human papillomavirus. However, the evidence also suggests that these viruses are ubiquitous agents and a number of criteria must be met before these potentially oncogenic agents can reliably be implicated in human carcinogenesis. In contrast, there is no evidence that viruses such as adenovirus, Epstein-Barr virus, and retroviruses play any role in oral carcinogenesis.

Viruses and chronic disorders involving the human oral mucosa

Viruses have been implicated in the etiology of several chronic disorders of the oral mucosa. Most of these associations have been with DNA viruses, particularly certain herpesviruses, which are associated, for example, with some cases of erythema multiforme and with hairy leukoplakia. Papillomaviruses are associated with various papillomatous lesions, focal epithelial hyperplasia, and possibly with some carcinomas. Viruses may possibly be associated with recurrent aphthae, Behçet's syndrome, and some dermatoses. The literature concerning these possible associations is reviewed. However, much more research needs to be done before the full story of viral associations with oral mucosal disorders can be written.

Reactivity against herpes simplex virus in patients with head and neck cancer

The relation between herpes simplex virus (HSV) and head and neck cancer was examined. A total of ninety patients were analyzed for IgG antibodies against HSV. Antibody titers were established with an enzyme-linked immunosorbent assay and antibodies against specific HSV-antigens were analyzed by Western blot. These patients' seroreactivity was compared to that of an age-matched control group of patients with arteriosclerotic disease in their lower limbs, a disease also closely related to heavy tobacco consumption. Prevalence of antibodies against HSV was around 90% and did not differ significantly between cancer patients and controls, but antibody titers against HSV were significantly higher in the cancer patients. The cancer patients also reacted more constantly (80%) in Western blot analysis against the early immediate protein, ICP-4, than controls (50%). This suggests a different course of an earlier herpetic infection in these patients with a prolonged exposure to early immediate HSV-proteins which may be related to an increased risk of developing head and neck cancer. We propose that heavy smoking may contribute to this phenomenon.

Viruses and oral cancer

Oral cancer is a disease with a complex etiology. There is evidence for important roles of smoking, drinking, and genetic susceptibility, as well as strong indications that DNA viruses could be involved. The herpes simplex virus type 1 has been associated with oral cancer by serological studies, and animal models and in vitro systems have demonstrated that it is capable of inducing oral cancer. Papillomaviruses are found in many oral cancers and are also capable of transforming cells to a malignant phenotype. However, both virus groups depend on co-factors for their carcinogenic effects. Future research on viruses and oral cancer is expected to clarify the role of these viruses, and this will lead to improvements in diagnosis and treatment of the disease.

Synergism of herpes simplex virus and tobacco-specific N'-nitrosamines in cell transformation

Previous studies indicate that herpes simplex virus (HSV) enhances the carcinogenic activity of smokeless tobacco and tobacco-related chemical carcinogens in animals. Since tobacco-specific N'-nitrosamines (TSNAs) such as N'-nitrosonornicotine (NNN) and 4-(N-methyl-N'-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are major chemical carcinogens of smokeless tobacco and are known to be responsible for the development of oral cancers in smokeless tobacco users, the combined effects of TSNAs and HSV in cell transformation were investigated. Exposure of cells to NNN or NNK followed by virus infection resulted in a significant enhancement of transformation frequency when compared with that observed with chemical carcinogens or virus alone. This study suggests that TSNAs and HSV can interact together and show synergism in cell transformation.

Forward mutation of S. typhimurium by smokeless tobacco extracts

Mutagenicity of 4 popular brands of smokeless tobaccos was studied using a S. typhimurium forward mutation assay. Aqueous extracts of 4 brands and dichloromethane and methanol extracts of 1 of the 4 brands of smokeless tobacco's did not induce significant mutagenicity either in the presence or absence of metabolic activation. Aqueous and organic extracts were however mutagenic when treated with physiological levels of sodium nitrite (0.25 mM) at acidic pH and without metabolic activation. The results indicate that smokeless tobacco contain polar and non-polar chemicals which become mutagenic to S. typhimurium under nitrosation conditions.

Effect of repeated oral administration of tobacco snuff on natural killer-cell activity in the rat

The possible immune effect of oral snuff was investigated. In male adult rats, oral snuff given for 15 weeks significantly decreased NK-cell activity in peripheral blood against murine NK cell-sensitive target cells (YAC-1 lymphoma).

Primary herpes simplex virus (type 1) infection delays healing of oral excisional and extraction wounds in the rat

The effect of acute herpes simplex virus type 1 (HSV-1) infection on the healing process of intraoral wounds and tooth extraction sockets in the rat was studied. A standardized size of the buccal mucosa was excised and molars were extracted and a HSV-1 suspension was topically applied. The virus infected wounds were clinically characterized by erythema and swelling and histologically by heavy inflammation cell infiltrate and abscesses during the first week. The acute HSV-1 infection was found to significantly delay healing of both types of wounds by 3 days. Antiviral treatment with acyclovir (ACV) decreased the degree of inflammation and improved healing of the infected wounds. The present results indicate a delayed and disturbed healing of wounds in the oral cavity in the presence of HSV-1. The findings may have a clinical significance for primary or latent HSV-1 infections in conjunction with surgical intervention in the oral cavity.

Effect of snuff extract on the replication and synthesis of viral DNA and proteins in cells infected with herpes simplex virus

The water-extractable component of snuff (snuff extract) inhibits the replication of herpes simplex virus (HSV) by suppressing the synthesis of viral DNA. This process probably causes HSV to be oncogenic. To further understand the mechanism of inhibitory action of snuff extract on HSV replication, the effect of snuff extract on the synthesis of viral DNA and proteins in type 1 HSV (HSV-1) infected cells was investigated. Snuff extract inhibited the synthesis of viral DNA and altered the production of certain classes of viral proteins. The syntheses of ICP4, a viral alpha-protein, and ICP8, a beta-protein, were not generally reduced by noncytotoxic concentrations of snuff extract (where ICP = infected cell polypeptide). However, snuff extracts significantly inhibited the production of ICP gC (glycoprotein C), a gamma 2-protein, and the inhibition was in a concentration-dependent fashion: the higher the concentration of snuff extracts, the greater the inhibition. Based on the fact that the production of alpha- and beta-proteins is absolutely necessary for and precedes the viral DNA synthesis and that viral gamma 2-proteins are mostly produced by the newly synthesized viral DNA, it is concluded that snuff extract inhibits HSV-1 DNA replication directly rather than indirectly via the alteration of viral protein synthesis.

Occurrence of recurrent herpes labialis in an adult Swedish population

In a general adult Swedish population recurrent herpes labialis (RHL) was found in 3.1% of 20,333 people aged 15 years and more. When a 2-year history of RHL was considered, the total prevalence was 17.4%. There was a slight predominance among women. Only slight differences were found between various age groups. In a fraction of the population studied, constituting 2771 people, interviews concerning cases of RHL were carried out. Thus, for example, most individuals referred to only one herpes episode a year; the most prevalent site of eruption was an area comprising both the vermilion border and the skin, and most of the lesions showed healing times of 5-8 days. The prevalence of RHL was influenced by some tobacco habits. Thus, the prevalence was significantly lower among smokers, and especially among pipe smokers, than among people with no tobacco habit at all. Snuff dipping did not seem to influence the prevalence values.

Snuff tumorigenesis: effects of long-term snuff administration after initiation with 4-nitroquinoline-N-oxide and herpes simplex virus type 1

The tumor promoting effects of snuff was studied in Lewis rats initiated with 4-nitroquinoline-N-oxide (4-NQO) and Sprague Dawley rats repeatedly inoculated with herpes simplex virus type 1 (HSV-1). The test substances were administered in a surgically created canal in the lower lips of the rats. There were 15 rats in each test group and 10 rats in the control group. In the groups treated with 4-NQO and 4-NQO + snuff, 8 and 12 tumors (5 and 9 malignant) were found, respectively. In the group subjected to HSV-1 only, 3 tumors were found (2 malignant), in the group subjected to snuff only, 4 tumors were found (3 malignant) and in the group subjected to the combination of HSV-1 and snuff, 13 tumors were found (7 malignant). In the control group only one malignancy was found. The study did not show any promoting effects of snuff in the oral cavity after initiation with 4-NQO. Neither was there any increase in the number of oral tumors in rats treated with HSV-1 and snuff. However, there was a marked increase in the number of malignant tumors outside the oral cavity in the group treated with HSV-1 and snuff, underlining the importance of interactions between these two agents in the development of malignant lesions.

Monoclonal antibodies to HSV-infection-related antigens cross-react with tumor cell lines and tumor tissue sections

The purpose of our study was to evaluate a possible association between herpes simplex virus (HSV) and various tumors, including oral squamous cell carcinoma (SCC). To this end, we tested the binding of appropriate monoclonal antibodies to a panel of cell lines and tumor sections. The 25 monoclonal antibodies were reactive with HSV-infected cells but not with uninfected cells. Of these antibodies, three bound to several SCC cell lines and to one non-SCC cell line (K562). One of these three antibodies also reacted with sections of oral SCC tumors, the adjacent mucosa, and normal esophageal epithelium. In contrast, it did not bind to sections of kidney, spleen, esophageal smooth muscle, and skin. To evaluate whether the observed antibody binding could reflect an actual infection by HSV, hybridization experiments between K562 DNA and HSV DNA were performed. HSV DNA sequences were found in K562 DNA at a ratio of 0.1 genome-equivalents/cell. Although these data do not characterize the nature of the relationship, they clearly confirm the postulated association of HSV with some tumors (in particular oral SCC).

An interpretative review of smokeless tobacco research in the United States: Part I

The first part of a two-part series reviewing the published literature of smokeless tobacco in the United States and concomitant health effects associated with its use. This article delineates the current status of its prevalence, behavioral psychosocial factors associated with use, and review of the negative health effects associated with regular use.

Oncogenic potential of sexually transmitted viruses with special reference to oral cancer

Recent changes in social mores have been accompanied by a noted increase in the frequency of sexually transmitted diseases. Viruses that have been identified as causative agents for a large proportion of these diseases have also been associated with various malignant states. Concomitantly, the number of cases of oral cancer (considered to occur usually around or after the fifth decade of life) reportedly has been increasing among young adults. The oncogenic potential of several sexually transmitted viruses (HSV, HPV, CMV, and LAV/HTLV III) and their possible role in the development of malignant conditions, in particular oral cancer, are discussed in this review.

Effect of smokeless tobacco on the replication of herpes simplex virus in vitro and on production of viral lesions in hamster cheek pouch

Previous experiments have shown that combination of herpes simplex virus (HSV) infection and simulated snuff-dipping in hamster buccal pouches enhances the development of micro-invasive squamous cell carcinoma in cheek pouch epithelium. The effect has now been determined of water-extractable components of snuff (snuff-extract) on the growth and the cell-lysing activity of HSV. Various dilutions of snuff-extract in tissue culture medium significantly inhibited the growth of HSV in Vero cell monolayers by inhibiting the viral DNA replication. Moreover, HSV was inactivated and its cell-lysing activity lost when it was incubated with snuff-extract in cell-free condition. Snuff also had a similar anti-herpetic effect in vivo; HSV infection of pouch tissues followed by simulated snuff-dipping resulted in significant inhibition of viral growth. Thus snuff interferes with the DNA synthesis and cytolytic activity of HSV in vitro and in vivo, and this in turn, may increase its oncogenic capacity.

The reversibility of the snuff-induced lesion: an experimental study in the rat

Snuff lesions were induced in 30 rats. Ten of the snuff-exposed rats were killed immediately after 13 months snuff exposure, as were the 10 control animals. Ten rats were killed 1 month and 10 rats 4 months after the snuff administration had ceased. The rats exposed to snuff for 13 months exhibited hyperplastic, hyperorthokeratotic epithelium with focal mild atypia, focal ulcerations and marked subepithelial fibrosis. These changes were markedly reduced or absent in rats exposed to snuff and killed after a snuff-free interval of 1 or 4 months. Similar differences between the test-groups were seen in the epithelium lining the gingival sulcus of the lower incisors. This area seems to be more sensitive to chemical exposure than the oral mucosa proper as more severe microscopical changes were seen here. Snuff exposure results in the development of a hyperplastic, reactive, reversible lesion of the oral mucosa, suggesting that snuff predominantly has promoting activity when administered for a relatively short interval of time.

The reemergence of smokeless tobacco

Smokeless tobacco (snuff and chewing tobacco) is reemerging as a popular form of tobacco, particularly among male adolescents. In different regions of the United States, from 8 to 36 percent of male high-school students are regular users. The use of smokeless tobacco has been shown to cause oral-pharyngeal cancer. The strongest link is with cancers of the cheek and gum. White mucosal lesions (leukoplakia) are found in 18 to 64 percent of users, often at the site where the tobacco was held. Other associations have been suggested for cancers of the esophagus, larynx, and pancreas. Nitrosamines, found in high concentrations in smokeless tobacco, most likely have a role in its carcinogenicity. Other health problems include periodontal disease, acute elevations of blood pressure, and dependence. In early 1986, after action at the state level, Congress enacted a federal law requiring health-warning labels on packages of smokeless tobacco and a ban on electronic advertising. Other regulatory measures under consideration include raising state and federal excise taxes, tightening controls on advertising, and prohibiting sales to minors. In view of the recent growth of this problem, policy makers are taking the opportunity to intervene with preventive measures to protect a new generation of tobacco users.