Herpes genitalis in guinea-pigs. I. Kinetic study in infection with Herpesvirus hominis type 2

Intravaginal administration of herpes simplex virus type 2 to mice leads to infection of several neural and extraneural sites

Female mice have been used extensively to study mucosal immunity against herpes simplex virus type 2 (HSV-2) infection of the vagina, but comparatively little is known about the spread of this virus to other tissues. Here the authors have used immunolabeling to demonstrate that HSV-2 infected the vaginal epithelium; the epithelium covering the vulva, perineum, and anal canal; and perineal hair follicles and sebaceous glands. The kinetics and basal localization of the immunolabeling indicated that the virus spread horizontally within the epithelial layer, starting in the vagina and then proceeding to the distal epithelial sites. HSV-2 also spread from the vagina to multiple neuronal sites including the paracervical ganglia (PCG), which are the major autonomic ganglia of the pelvis. The authors demonstrated both sympathetic and parasympathetic neurons in the PCG by labeling of acetylcholinesterase and tryosine hydroxlyase, and noted that infection was limited mainly or entirely to parasympathetic neurons. Infection of the PCG was correlated with the presence of virus in the autonomic ganglia in the walls of the rectum and urinary bladder, which in turn correlated with distention of these organs and retention of urine and feces. HSV-2 infection was also detected in cell bodies and axons in the lumbosacral sympathetic chain, in lumbosacral dorsal root ganglia, and in the dorsal portions of the lumbar spinal cord. Collectively, the data show that vaginal HSV-2 infection in mice leads to subsequent infection of multiple neural and epithelial sites. This information should be useful for development of a mouse model that can be used to study HSV-2 latency and for development of therapeutic vaccines to prevent recurrent infections.

Pathogenesis of HSV-1/2 induced vaginitis/vulvitis of the mouse: dependence of lesions on genetic properties of the virus and analysis of pathohistology

A scoring system for herpes simplex virus (HSV) induced vaginitis/vulvitis in Balb/c mice was delineated from vaginal infections. Four degrees of vaginitis/vulvitis could be distinguished after infection with suitable strains of HSV despite nearly identical replication rates. The time course of replication, inflammation and pathohistology was compared further. Grade 0 was defined by lack of symptoms despite presence of strong replication, which was detectable at days 3-6. Focal necrotic lesions of the epithelial layer were present containing HSV-specific antigens. DNA could be detected by hybridization only in the outer zone of these areas. At day 6 these zones began to be re-epithelialized. In the vaginal lumen abundant detached epithelial cells and granulocytes were already present by day 2. Grade 1 was macroscopically characterized by a slight inflammation commencing on days 5-6. Replication and antigens in the epithelium were found on days 2-6. HSV-antigens were only detected above the basal membrane, and some infiltration with granulocytes and lymphocytes was observed below the basal membrane at day 4. Grade 2 showed strong redness and inflammation as well as hyperemia. Cellular infiltrates were present in the large antigen containing epithelial lesions and below the basal membrane. From day 4 on, neurons were HSV-antigen and DNA positive and macrophages in the stroma contained antigen. The vulva was also shown to be involved. Grade 3 exhibited prolonged severe hyperemia, and destruction of the epithelium and the stroma with necrosis and infiltration, especially of the vulva. This grading system was shown to depend on certain unknown genetic properties of HSV-strains. Neither thymidine-kinase activity, replication in macrophages, fusion activity of strains nor presence or absence of the Hpa I P-fragment were shown to be of importance for severity of vaginitis/vulvitis. Vaginitis/vulvitis was shown to be an all or none response to HSV independent of the rate of replication. The set of virus genes responsible for neuroinvasiveness after vaginal or i.p. inoculation was found to be different. The time course of replication (mainly days 3-6) and inflammation (days 5-10) indicates that inflammation seems to be a secondary immunological phenomenon induced later by the replication phase of HSV. Our system could be useful for separately testing drugs with antiviral and anti-inflammatory properties.

Virus spread and initial pathological changes in the nervous system in genital herpes simplex virus type 2 infection in mice. A correlative immunohistochemical, light and electron microscopic study

Mice were infected by the vaginal route with the MS strain of herpes simplex virus type 2 (HSV-2). Serial vaginal cultures were used to confirm infection and to select mice for this study. Two mice were killed by perfusion on days 2-6 post infection (p.i.) and lumbar and sacral cord with cauda were fixed and embedded for electron microscopy. Semithin Epon-sections were stained for viral antigen using a rabbit anti-HSV-2 antiserum and the Avidin-Biotin (ABC) method. Thin sections from antigen-positive blocks were examined by electron microscopy, and the number and types of infected cells detected by these two methods were compared. A good correlation was found between detection of infected cells by these methods. Infected cells included neurons of dorsal root ganglia and spinal cord, satellite cells of dorsal root ganglia, non-myelinating Schwann cells, astrocytes, oligodendrocytes and arachnoidal cells. Infected cells were first detected in the cauda on day 3 p.i. and in the spinal cord on day 5 p.i. The temporal and spatial distribution of infected cells was consistent with neural spread to and within the CNS. The pathological lesions showed a good correlation with the distribution and number of infected cells and are probably due to a direct virus effect. The similar sensitivity of the Epon-ABC method to electron microscopy in detecting infected cells indicates that this method may have useful applications in both experimental and diagnostic work.

Antiviral activity of 5-ethyl-2'-deoxyuridine against herpes simplex viruses in cell culture, mice, and guinea pigs

The susceptibility of 3 laboratory strains and 24 clinical isolates of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) to 5-ethyl-2'-deoxyuridine was determined in plaque reduction assays in Vero cells. The median effective doses were 8.6 and 7.8 microM, respectively. The drug was less potent than acyclovir and other related antiviral drugs, but it had a high therapeutic index against both HSV-1 and HSV-2. Drug-resistant viruses were readily produced in cell culture. These variants were cross-resistant to acyclovir, 2'-fluoro-5-iodoaracytosine, and 2'-fluoro-5-methylarauracil but were susceptible to vidarabine or phosphonoformate. These findings confirm that the selective antiviral activity of 5-ethyl-2'-deoxyuridine is mediated by the virus-induced thymidine kinase. Oral or intraperitoneal administration of the drug at nontoxic doses was ineffective in protecting mice against intracerebral challenge with virus. Using implanted osmotic minipumps or coadministering the drug with dimethyl sulfoxide failed to decrease the mortality rate. In guinea pigs infected genitally with HSV-2, topical drug treatment was more effective than placebo in reducing lesion severity and other clinical and virological variables. These effects were noted whether the drug treatment was initiated 3 or 24 h after infection (ascertained serologically). Drug-treated animals had a significantly lower herpes antibody titer than did placebo-treated guinea pigs, suggesting that the drug can also reduce the viral antigen load. In this model, the drug appeared to be as effective as topical phosphonoformate or acyclovir.

Protection from genital herpes simplex virus type 2 infection by vaccination with cloned type 1 glycoprotein D

Guinea pigs were vaccinated with truncated herpes simplex virus type-1 (HSV-1) glycoprotein D produced in the genetically engineered mammalian cell line gD10.2. Vaccinated animals formed antibodies that neutralized both HSV-1 and herpes simplex virus type 2 (HSV-2) in an in vitro neutralization assay. Vaccinated animals were challenged with HSV-2 by intravaginal infection. Animals that received the immunogen in Freund's complete adjuvant were completely protected from the clinical manifestations of genital HSV-2 infection. Animals that received the immunogen incorporated in alum adjuvants were partly protected from clinical disease; the infections that did develop were significantly less severe than those that occurred in control animals injected with adjuvant alone. The results demonstrate that immunization with a purified viral protein can provide significant protection against primary genital infection by HSV-2 in guinea pigs.

Effect of trisodium phosphonoformate in genital infection of female guinea pigs with herpes simplex virus type 2

A genital herpesvirus type 2 infection in guinea pigs has been used to evaluate the inhibitory effect of phosphonoformate on the infection. An early topical treatment prevented the appearance of vesicles and histopathological changes and no virus could be recovered. When treatment, either topical or both systemic and topical, was delayed to 24 hours post infection no therapeutic effect was observed.

Recurrent genital Herpes simplex virus (HSV) infection of guinea pigs

Intravaginal infection of guinea pigs with HSV type 2 induced lesions resembling genital herpes in humans. Chronic latent infection with spontaneously recurring genital lesions developed in animals surviving the primary disease. Clinical observations and virological studies during the acute and chronic infection are reported.