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

Abstract

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.

Mixed vaginal infections of Balb/c mice with low virulent herpes simplex type 1 strains result in restoration of virulence properties: vaginitis/vulvitis and neuroinvasiveness

“…These complementation and recombination events need to be borne in mind when constructing vaccines with avirulent strains of HSV and gene delivery vectors. These results also strengthen our earlier observation about the existence of strains of HSV with different degrees of potency in inducing vaginal inflammation (Fleck et al 1993).…”

“…Individual mice were marked with black ink and were examined daily for symptoms of vaginitis/vulvitis and neurological disease. The scoring system of Fleck et al (1993) was used to assess the severity of vaginitis/vulvitis: no alteration (grade zero); redness or loss of hair (grade 1); strong redness and swelling as well as loss of hair in the area around the vulva (grade 2); persisting symptoms of grade 2 (grade 3).…”

“…Vaginal infections of mice with different laboratory strains of HSV produce vaginitis of different severity. Infection ranges from the absence of clinical signs to severe inflammation with necrosis of the skin and loss of hair around the vulva region (Fleck et al 1993). Unlike human genital infections, mice developing vaginitis often die due to myeloencephalitis.…”

Correlation of virus replication, cytokine (TNF-? and IL-1) producing cells, neuronal necrosis and inflammation after intranasal infection of mice with herpes simplex virus strains of different virulence

“…The TK-virus 1301 does not replicate, but produces few lymphocytic infiltrates at days 5, 7 and 9; taken together the latter virus and strain HFEM exhibit a low inflammation induction capacity. After vaginal infection, we detected strains without any local inflammation but with strong replication [2] in the epithelial layer. In contrast to these observations, without detectable replication, the TK-virus 1301, interestingly, induced lymphocytic infiltrations at days 5, 7 and 9.…”

Decreased T Cell Stimulatory Capacity of Monocyte‐Derived Human Macrophages following Herpes simplex Virus Type 1 Infection

“…Infectious HSV was determined by a plaque assay using confluent monolayers of Vero cells. The plaque assay was carried out as described previously [20]. To assure infection of the vast majority of the cells, a multiplicity of infection (MOI) of 4 was used throughout the experiments.…”