Failure to induce cervical cancer in mice by long-term frequent vaginal exposure to live or inactivated herpes simplex viruses.

C57 mice aged 8-10 weeks in groups of 50 each received vaginal cotton pellets soaked in lysates of HEp-2 cells, either mock-infected or infected with herpes simplex virus I, herpes simplex virus 2, and highly attenuated recombinant viruses 5 times a week for 89 to 114 weeks. An untreated group was also included. The mock-infected and some of the infected cell lysates were exposed to ultraviolet light at a dose sufficient to inactivate virus. Smears of exfoliated vaginal cells collected once a month and histopathologic sections of genital organs removed at autopsy were coded and examined blind for the presence of abnormal cells indicative of malignant changes and cervical cancer, respectively. Sera collected before termination of the study were tested blind for the presence of antibody to infected cell lysates and to purified herpes simplex virus glycoprotein B. The results were as follows: Over 74% of 826 mice examined at autopsy contained tumors at non-genital sites. The tumors were randomly distributed among the various groups. Gross genital abnormalities were less common in untreated animals than in mice receiving vaginal implants. The fraction of mice which developed cervical cancer diagnosed by histopathologic examination was small (7.2%) and not significantly different among various groups. There was no correlation between the presence of abnormal exfoliated cells indicative of early invasive or invasive cancer lesions and the histopathologically proven diagnosis of micro-invasive or invasive cervical cancer. The incidence and levels of antibody were highest in animals exposed to live virus; some mice exposed to inactivated virus also developed weak or moderately high antibody levels. The presence of antibodies did not correlate with the presence of histopathologically proven cervical cancer. The results do not support the ability of herpes simplex viruses to cause genital neoplasia in mice.

Analyses of transplanted murine tumors for HSV DNA sequences.

Meignier et al. (1986) report the results of exposure of C57BL/6NCr mice to vaginal plugs containing live or inactivated herpes simplex virus 1 or 2 (HSV-1 or HSV-2) or recombinant viruses 5 times a week for up to 114 weeks. Genital organs showing abnormalities were transplanted into nude mice. Of 33 transplants, 13 produced subcutaneous tumors in nude mice and 12 were subsequently transplanted into C57BL/6NCr mice. We report that the DNA extracted from coded tumor tissues of nude mice and from normal viscera of the same rodents did not hybridize with HSV-1 and HSV-2 DNA probes representing the viral genomic regions shown previously to be capable of morphologically transforming cells in culture. The sensitivity of the assays was such that we could detect 0.5 copies of the HSV sequences of complexity equal to or greater than 1 Kbp per cell DNA equivalent. To control for the sensitivity of the assays in the actual hybridizations, the tumor-cell DNA was also hybridized with a beta-globin mouse DNA probe. A striking feature of these control hybridizations was the detection of beta-globin polymorphism in some nude mouse tumors. The beta-globin polymorphism allowed us to conclude that the analyzed tissues contained significant amounts of the tumor cells occurring in the C57BL/6NCr mice.

Mechanisms of the synergistic effect of oral dimethyl sulfoxide on antineoplastic therapy.

The purpose of this study was to determine whether dimethyl sulfoxide (DMSO) when administered in conjunction with antitumor drugs would potentiate their activity against a rodent tumor. Twelve compounds of diverse modes of action were examined using standard protocols of the National Cancer Institute. Median survival time and median tumor diameter were the parameters used for determining any synergistic effects of DMSO when it was ingested in the drinking water and the drug administered parenterally. The continuous ingestion of DMSO alone mixed in drinking water at concentrations between 0.25-32% was not toxic and had no effect on the tumor. Although the intraperitoneal inoculation of drugs into animals ingesting DMSO did not enhance drug effectiveness, when both DMSO and drug were added to the drinking water, it did increase antineoplastic potency. DMSO ingestion also inhibited the tumor growth rate of several parenterally administered drugs even though these same compounds failed to prolong the survival time of tumor-bearing rats. The toxicity of 12 compounds when combined with DMSO was only moderately increased in four instances. Orally ingested DMSO was found to cause a twofold increase in the concentration of labeled CPA in plasma, brain, and liver tissues. This elevation persisted for approximately two to three hours but subsequently returned to the same level as that observed in water-fed rodents. The DMSO-enhancement of tissue levels coupled with a more rapid drug rate clearance offers one explanation for the therapeutic benefit noted when oral DMSO was administered concomitantly with CPA.

Application of molecular genetics to the design of live herpes simplex virus vaccines.

In principle, several avenues for attenuation of herpes simplex viruses (HSV) are now available. These include intermixing of HSV-1 and HSV-2 genes by recombination, altering the regulation of gene expression and the deletion of viral genes not required for replication of the virus in permissive cells in culture. Results of analyses of HSV-1 x HSV-2 recombinants and of mutants containing a deletion in a gene expressed early in infection showed a loss of virulence when infected by intracerebral route into adult Balb/c mice. In addition, immunization of the mice by intracerebral route with relatively low doses of virus protected the mice from challenge with high doses (3000 LD50) of virulent virus. The application of genetic engineering to the construction of live vaccines is discussed.

Synergistic effect of combined hyperthermia and a nitrosourea in treatment of a murine ependymoblastoma.

The effectiveness of heat therapy in combination with 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea on a murine ependymoblastoma was investigated. Based on survival time and the number of survivors, whole-body hyperthermia (40 degrees) increased the therapeutic effectiveness of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea. Heat alone did not modify the course of the tumor. Microscopic evidence of accelerated tumor destruction in hyperthermic mice was apparent within 24 hr of drug administration. A temporary drop in animal weight was observed with hyperthermia at the higher dose levels of drug. Mechanisms which may be involved in this synergism are discussed.

Therapeutic effect of prolonged hyperbaric oxygen in adjuvant arthritis of the rat.

Development of adjuvant disease in the rat is suppressed if hyperbaric oxygen is administered within one day after the inoculation of an oil suspension of Mycobacterium tuberculosis and continued for 16 to 17 days. Although 10 to 40% of the rodents developed mild arthritis after discontinuance of therapy, most remained symptom-free for at least 50 days. Oxygen administered after arthritis is advanced still exerted a significant curative effect. Possible mechanisms underlying the therapeutic action of oxygen are discussed.

Oxygen immunosuppression: modification of experimental allergic encephalomyelitis in rodents.

Using protocols that incorporated double blind examination of animals sensitized to CNS antigen, we confirmed and amplified earlier findings of the complete suppression of EAE in rodents by hyperbaric oxygen. The effects of O2 were related to the gas pressure and duration of treatment. The development of paralytic disease was prevented for 34 days after sensitization (the longest interval studied). Compressed air or normobaric O2 administered under similar conditions did not modify the course of illness. Within 7 to 10 days after the discontinuance of oxygen therapy the majority of treated guinea pigs developed typical signs of EAE with characteristic lesions in the CNS. The relapses occurred sooner in the Lewis rat. The development of the delayed hypersensitivity reaction to myelin basic protein and to tuberculin is also suppressed by O2 therapy indicating that its effects upon autoimmune encephalomyelitis involves fundamental alterations of the cellular components of the immune response, some or all of which are reversible.