Prevention of herpes genitalis by the 'Bulgarian' vaccine F.HSV-2V(PRK): preliminary clinical evidence

AIM

To examine the antigenic properties of the formalin-inactivated herpes simplex virus type 2 (HSV-2) virus-particle vaccine F. HSV-2V(PRK), which has been used therapeutically in Bulgaria for 30 years, and to make preliminary assessment of its potential protective efficacy by a follow-up of vaccinated patients with herpes genitalis.

METHODS

Properties of the vaccine were examined by standard immunological laboratory tests. Fifty-five patients at risk of herpes genitalis received 2-4 vaccinations and were monitored during a 6-year follow-up.

RESULTS

The vaccine was antigenic in laboratory tests and absorbed neutralizing antibody from hyperimmune rabbit serum against herpes simplex virus type 1 (HSV-1). In vaccinated patients, there was an overall contraction rate of herpes genitalis of 5.4%. There was no evidence of significant local or generalized adverse effects from vaccination.

CONCLUSION

Bulgarian vaccine F.HSV-2V(PRK) may have protective efficacy, which, in association with its apparent safety from our findings and from its clinical use for over 30 years in Bulgaria, suggests that it should be scrutinized by a formal clinical trial.

Balm mint extract (Lo-701) for topical treatment of recurring herpes labialis

A double-blind, placebo-controlled, randomized trial was carried out with the aim of proving efficacy of standardized balm mint cream [active ingredient: 1% Lo-701--dried extract from Melissa officinalis L. leaves (70:1)] for the therapy of herpes simplex labialis. Sixty six patients with a history of recurrent herpes labialis (at least four episodes per year) in one center were treated topically; 34 of them with verum and 32 with placebo. The cream had to be smeared on the affected area four times daily over five days. A combined symptom score of the values for complaints, size of affected area and blisters at day 2 of therapy was formed as the primary target parameter. There was a significant difference in the values of the primary target parameter between both treatment groups: verum 4.03 +/- 0.33 (3.0); placebo 4.94 +/- 0.40 (5.0); values given are mean +/- SEM (median) of the symptoms score on day 2 of therapy. The tested formulation is effective for the treatment of herpes simplex labialis. The significant difference in the combined symptom score on the second day of treatment is of particular importance having in mind that the complaints in patients suffering from herpes labialis are usually most intensive at that time. In addition to the shortening of the healing period, the prevention of a spreading of the infection and the rapid effect on typical symptoms of herpes like itching, tingling, burning, stabbing, swelling, tautness and erythema, the balm mint cream has a further advantage. The different mechanism of action of the balm mint extract rules out the development of resistance of the herpes virus. Some indication exists that the intervals between the periods with herpes might be prolonged with balm mint cream treatment.

Seventeen years of application of herpes vaccines in Bulgaria

This study reports on our experience with whole herpes simplex vaccines in Bulgaria for a period of 17 years. More than 1,500 immunized patients with herpes ophtalmicus showed a reduction of the recovery period, reduced number of the recurrences and reduced risk of visual damage. More than 14,000 patients suffering from other forms of herpes diseases for a longer period showed reduced recovery period and recurrence frequency in over 95% of the cases. Whole vaccines were well tolerable with no side effects. This report emphasizes the usefulness of whole herpes vaccines.

Preparation and efficacy of antiherpes type 1 and 2 subunit vaccines

DNA free antiherpes subunit vaccines were prepared from diploid human embryonic lung cells infected either with type 1 or type 2 herpes simplex viruses (HSV). Virion and membrane-bound virus-specific glycoproteins were solubilized with Nonidet P-40 and separated by ultracentrifugation. The antigenic properties of the vaccine were tested in guinea pigs. Antibody response was followed by virus neutralization and complement fixation. The vaccine itself was low-immunogenic, however its immunogenicity has considerably increased by usage of suitable adjuvants. In virus neutralization test higher antibody titre was found against homologous virus. The antibody response was related to protein content and to the frequency of vaccination.

Induction of chromosomal aberrations in human cells by a temperature-sensitive mutant of herpes simplex virus type 2 and its revertants

The induction of chromosomal aberrations by a temperature-sensitive (ts) mutant of herpes simplex virus type 2 (HSV-2) strain Hg52 (ts 13), its revertants 4-8 and 5-8 and by etalon strains HSV-1 17 syn+ and HSV-2 Hg52 was studied in human fibroblast and lymphocyte cultures. The effect on chromosomes of the revertants was tested at permissive (31 degrees C) and non-permissive (38 degrees C) temperatures. At 38 degrees C the revertants could not induce DNase activity. The present results contribute to the possible role of a herpes-coded nuclease in induction of chromosomal aberrations.

Effects of herpes simplex virus strains on human fibroblast and lymphocyte chromosomes and the localization of chromosomal aberrations

The effects on human chromosomes of types 1, 2 and of intermediate serotype of herpes simplex virus (HSV) was compared in fibroblast and lymphocyte cultures. The karyological changes due to HSV were shown to depend on the serotype used as well as on the kind of cells examined (agent-specificity and cell-reaction specificity). Differences were noted among the strains in relation to the degree and character of the aberrations induced. Conventional Giemsa staining and the trypsin G-banding techniques were used to localize aberrations in the length of human fibroblast and lymphocyte chromosomes after HSV infection. A non-random damage of chromosomes 1 and 3 displaying the same pattern in either cell type was established. The distribution of chromosomal abnormalities was independent of the chromosome length. The topographic banding analysis of lesions induced by strains of HSV-1, HSV-2 and intermediate serotypes showed that the most frequent aberrations were localized in bands p32, p34, q21 and q32 of chromosome 1 and in the band q21 of chromosome 3. The localization of the most frequently occurring aberrations in the chromosomes belonging to other groups was also determined.

Infections of susceptible and resistant mouse strains with herpes simplex virus type 1 and 2

The spread of HSV of type 1 and 2 was investigated after intraperitoneal, intraplantar and intracerebral infections of resistant (C57/bl) and susceptible (NMRI) mice. The virus spreads after i.p. infection to the spleen and the liver to the same extent in both strains of mice. However, virus is eliminated earlier in resistant mice. Intracerebral infections revealed a peculiar type of resistance of C57/bl mice especially for type 2 of HSV. HSV multiplies in the thymus at the early stage of infection and can be detected in this organ in sick mice of NMRI strain. HSV-1 and 2 can be detected in the spinal cord of C57/bl mice without sickness or death of these animals.

Characterization of herpes simplex virus strains isolated from patients with various diseases

Herpes simplex virus strains (HSV) were isolated from various herpetic diseases. These HSV-strains isolated in Bulgaria (687) and in other countries (13) were studied by the neutralization test using standard type specific rabbit antisera and human gamma globulin. The serotype distribution of all strains showed: HSV-1 = 323 strains, HSV-2 = 372 strains, 5 strains behaved antigenically intermediate. A close correlation between the serotype of the strains and the localization of the lesions was established. All but four strains (1.24 per cent) isolated from the head belong to HSV-1, and only six HSV-strains (1.9 per cent) from lesions with other localizations were not HSV-2. Within six months to 8 years 2 to 4 herpes strains were isolated repeatedly from 30 patients. In 23 of these cases they were identical and in the other they showed different biological (3) or antigenical (4) properties. The results suggest, that under natural conditions some HSV-intermediate strains may exist.

[Design of inactivated polyvalent antiherpes vaccines]

The variants of inactivated vaccine against herpes simplex virus have been developed: 1, 2 and 1 + 2. The first two variants consist of 5 different strains of herpes virus of the appropriate type, and the third variant of their mixture. The strains differ in their antigenic and biological characteristics. Complete inactivation of the virus suspension was achieved by treatment of the vaccine with formalin. Herpes vaccines were used for immunization of 477 patients with frequently relapsing forms of herpes of different localizations. The therapeutic-prophylactic effect of these vaccines indicates their relatively high efficacy: by the end of 9 months favourable results exceeded 95%. Better results were obtained with HSV-1 vaccine. A second cycle of immunization given to some patients resulted in markedly positive effect.

Induction capacity and influence of dThdMP on thymidine kinase activity of type 1 and 2 strains of herpes simplex virus

The thymidine kinase inducing ability of 104 strains of herpes simplex virus was studied comparatively. A pronounced relationship was established between induction of the enzyme and the serotype of the strains. As a rule, the strains of serotype 2 are weaker inducer of dThd- and dCyd-kinase activity than serotype 1 strains. A certain parallelism exists between induction of both enzymes, however the activity of the thymidine kinase increases after infection with herpes simplex virus 4--5 times more than that of the dCyd-kinase. Adaptation of the strains to cell cultures only slightly modifies the inducing ability of the herpes simplex virus strains. The thymidine kinase activity induced by HSV-1 and HSV-2 differ from each other and are different from the cell enzyme with respect to their thermal stability at 40 degrees C. These differences are expressed more clearly in the presence of 480 muM dThdMP during inactivation. dThdMP stabilizes the type 1 but not the type 2 enzyme.