Pathogenesis of genital herpes simplex virus infection in mice

Experiments in the mouse model of herpes simplex virus (HSV) infection involving the intact genital mucous membranes as inoculation site yielded the following results. In untreated mice the extent of latency was correlated with the degree of peripheral virus replication. This correlation could not be observed when the course of infection was interrupted by chemotherapy, interferon, or passive immunization. Acyclovir had little effect on peripheral virus multiplication, but markedly reduced latent ganglionic infection. As acute ganglionic infection and virus concentration in the spinal nerves were already reduced, acyclovir is assumed to inhibit either virus penetration into the nerve endings or virus replication in the ganglia. Interferon apparently has an active role in the elimination of virus infected cells from the ganglia, as its effect was restricted to a reduced rate of latency and of lethality. Passive immunization with antiserum led to similar results as ACV-treatment. While lacking a pronounced effect on virus replication in the mucous membranes, specific antibody was found to influence both virus elimination from the ganglia, and conversion from productive to latent ganglionic infection. Immune lymphocytes proved to be the only agent capable of suppressing peripheral infection, thereby inhibiting the neural spread of the virus. These results suggest that the decrease in latency may result from modulations occurring at different stages in the course of infection.Supported by Deutsche Forschungsgemeinschaft Schn 174/6-2     

Pathogenesis of genital herpes simplex virus infection in mice

This study was undertaken to establish the role of virulence of various herpes simplex virus (HSV) strains in the course of infection when applying the virus to the non-injured mucous membranes of mice.Wild-type HSV-type 1 (HSV-1) strains with marked differences in their neurovirulence following intracerebral inoculation showed minor differences in virulence after vaginal inoculation, but essentially their neurovirulence in cerebral infection corresponded to their virulence on the mucous membranes.In comparison with the wild-types, however, there were pronounced differences among syn- and TK^–-mutants of HSV-1 and HSV-2 in the degree of virulence at different sites in the course of virus infection. Whereas syn-mutants proved avirulent on the mucous membranes but not in neural tissues, TK^–-mutants were avirulent both on mucous membranes and in neural tissues.Ts-mutants of HSV-2 were not found to establish themselves when administered to the non-injured mucous membranes, nor did they induce neutralizing antibodies, but a later challenge with the wild-type virus at the same site lead only to an attenuated course of infection.Supported by the Deutsche Forschungsgemeinschaft Schn 174/6-2     

Inapparent genital herpes simplex virus infection in college women

During a six-month period, 600 gynecological samples were collected from 585 women with typical herpes lesions, women with non-herpes symptoms (ie, vaginitis, moniliasis, trichomoniasis, etc), and normal women seen at the student health center gynecological clinic and processed for herpes simplex virus (HSV) isolation. From these specimens, 29 samples from 25 of the 585 women (4.3%) were positive for HSV. When these isolates were typed using plaque diameter in chick cells, heat stability of viral thymidine kinase (T.K.), and restriction endonuclease patterns it was found that 18 samples (15 patients or 60%) were HSV-2 and 11 samples (10 patients or 40%) were HSV-1. Inapparent HSV infections constituted 20.0% of the virologically confirmed samples (5 of 25 patients) and represented 0.9% of the total patients studied (5 of 585). The inapparent infections were about equally divided between the two HSV types (2 were HSV-2 and 3 were HSV-1), and 4 of 5 occurred in the presence of clinically diagnosed monilia.     

Cellular immune response in genital herpes simplex virus infection.

We studied the relations between the cellular immune response, pre-existing complement-fixing antibody and virus type with duration of virus excretion in genital herpes simplex virus (HSV) infection. Thirty-six patients (seven with HSV-1 and 29 with HSV-2) with genital herpes underwent serologic testing, sequential viral cultures and weekly determination of lymphocyte-transformation stimulation index with inactivated HSV antic n. The duration of virus excretion was shortest in those with pre-existing complement-fixing antibody, was unrelated to virus type, and was inversely correlated with the magnitude of the mean peak stimulation index (r = -0.69, P less than 0.001). Prolonged virus excretion occurred in patients with a delayed and diminished peak index. Recurrent episodes had a higher peak index (29.4 compared to 14.5) (P less than 0.02), an earlier development of the peak during recurrences (9.1 vs. 25.8 days) (P less than 0.01) and a briefer duration of viral shedding than initial episodes. Thus, the temporal course and magnitude of the stimulation index correlate with and may determine the duration of genital HSV infection.     

Epidemiology of herpes simplex virus type 2 infection in the developing world

Herpes simplex virus type 2 (HSV-2) is a common infection in many countries, with prevalence in some regions, such as sub-Saharan Africa, higher than in the USA. Prevalence in adult general populations in sub-Saharan Africa ranges from 30% to 80% in women, and from 10% to 50% in men. Most data from Central and South America are from women, in whom HSV-2 prevalence ranges from about 20% to 40%. Prevalence in the general population in developing Asian countries appears to be lower (10-30%). In common with the developed world, HSV-2 seropositivity is uniformly higher in women than in men and increases with age. In general, HSV-2 seroprevalence is high in populations whose behaviour leads to a high risk of acquiring other sexually transmitted infections (STIs), such as STI clinic attendees and sex workers (SWs), with some African studies reporting greater than 80% HSV seropositivity in SWs. New infections are most common among young adults, a fact that should be considered when proposing and implementing measures to reduce HSV, and possibly HIV, transmission. Currently, comparison between studies is hampered by the lack of a validated type-specific serological assay that has a similar performance across a range of populations. HSV-2 is a major cause of genital ulcer disease (GUD) in the developing world. Genital herpes is a cause of morbidity and increases the risk of HIV acquisition, due to disruption of mucosal membranes. Where possible, the aetiology of GUD should be evaluated using polymerase chain reaction (PCR), while recognizing that co-pathogens can exist in a lesion. GUD management should incorporate HIV testing and antiherpetic treatment.     

Reactivation of genital herpes simplex virus type 2 infection in asymptomatic seropositive persons

BACKGROUND: Most persons who have serologic evidence of infection with herpes simplex virus (HSV) type 2 (HSV-2) are asymptomatic. Historically, it has been assumed that these persons have less frequent viral reactivation than those with symptomatic infection. METHODS: We conducted a prospective study to investigate genital shedding of HSV among 53 subjects who had antibodies to HSV-2 but who reported having no history of genital herpes, and we compared their patterns of viral shedding with those in a similar cohort of 90 subjects with symptomatic HSV-2 infection. Genital secretions of the subjects in both groups were sampled daily and cultured for HSV for a median of 94 days. RESULTS: HSV was isolated from the genital mucosa in 38 of the 53 HSV-2-seropositive subjects (72 percent) who reported no history of genital herpes, and HSV DNA was detected by the polymerase-chain-reaction assay in cultures prepared from genital mucosal swabs in 6 additional subjects. The rate of subclinical shedding of HSV in the subjects with no reported history of genital herpes was similar to that in the subjects with such a history (3.0 percent vs. 2.7 percent). Of the 53 subjects who had no reported history of genital herpes, 33 (62 percent) subsequently reported having typical herpetic lesions; the duration of their recurrences in these subjects was shorter (median, three days vs. five days; P<0.001) and the frequency lower (median, 3.0 per year vs. 8.2 per year; P<0.001) than in the 90 subjects with previously diagnosed symptomatic infection. Only 1 of these 53 subjects had no clinical or virologic evidence of HSV infection. CONCLUSIONS: Seropositivity for HSV-2 is associated with viral shedding in the genital tract, even in subjects with no reported history of genital herpes.     

Virus-specific antibodies in sera from patients with genital herpes simplex virus infection.

Virus-specific antibodies against a number of herpes simplex virus type 2 antigens were determined by radioimmunoprecipitation assays in sequential serum samples obtained from 12 patients with initial genital herpes simplex virus infection. The progressive appearance of antibodies to virus-specific antigens was observed; antibodies against a 130,000-molecular-weight glycoprotein complex appeared first, followed by antibodies against the major nucleocapsid polypeptide and then antibodies against a number of other viral antigens, including a polypeptide with a molecular weight of 62,000. Patients who developed a wide variety of antibodies to viral polypeptides shortly after resolution of their initial episode seemed to experience more severe initial infections and more recurrences than did those who reacted poorly with these virus-specific antigens. This was most apparent with respect to antibodies to virus-specific polypeptides with molecular weights between 30,000 and 43,000. Antibody specificity did not change during the course of follow-up regardless of whether serum samples were taken shortly before, during, or after recurrent episodes. Glycoprotein-specific antibodies were quantitated with the purified 130,000-molecular-weight glycoprotein material. No significant fluctuations in these antibody titers were observed before or after recurrences of the disease.     

Autonomic nervous system involvement in experimental genital infection by herpes simplex virus type 2

Summary Peroxidase-antiperoxidase technique and histology were employed to elucidate the peripheral routes involved in HSV-2 progression from vagina towards the central nervous system in mice. 12 week-old female Balb/c mice were intravaginally infected with 5 × 10⁵LD₅₀ of HSV-2. Sixty per cent of animals developed vulvovaginitis, perigenital alopecia and hind-limb paresia. Death occurred at 9–11 days post-infection. Colon dilatation and urinary bladder distention were observed in all cases. Complete transversal sections from vulva to kidneys were obtained of each animal, including the spinal cord in situ. Herpes antigen were regularly detected in vulvovaginal epithelium, intramural, perigenital and perivesical small nerves. Besides, their invariable presence in Auerbach's plexus and sympathetic ganglia, strongly suggests preferential autonomic nervous system involvement in the progression of HSV-2 intravaginal infection towards the spinal cord.With 7 Figures     

Evaluation of biotin-streptavidin enzyme-linked immunosorbent assay for detection of genital herpes simplex virus infection

A biotin-streptavidin enzyme-linked immunosorbent assay (B-SA ELISA) was evaluated for detection of herpes simplex virus (HSV) in clinical specimens which were cervico-vaginal swabs from 205 asymptomatic women and swabs from the genital lesions of 163 suspected patients. All specimens were also subjected to a conventional virus isolation in cell culture. A blocking B-SA ELISA had 100% specificity and 98% sensitivity compared with viral isolation from patients, but had only 40% sensitivity using specimens from asymptomatics. The conventional B-SA ELISA might also be used; it gave results corresponding to B-SA ELISA blocking test except for a single specimen which was considered a false positive.     

Hepatitis E virus infection in developed countries

Hepatitis E was considered to be endemic infectious disease in developing countries in tropical or subtropical regions with poor sanitary conditions. Large, previously reported outbreaks were mainly due to contaminated water or heavy flooding. Prototype hepatitis E viruses of genotypes I and II were obtained from such endemic cases. In developed countries, in contrast, hepatitis E was rare and diagnosed only in travelers or imported cases. However, the development of accurate diagnostic tests, mainly PCR detection elucidated that autochthonous hepatitis E in developed countries is far more common than previously thought. Although the main route of transmission is food-borne, other routes including blood-borne have been suggested. Recent developments of gene-based diagnostic assays and molecular epidemiology have disclosed the significance of hepatitis E virus infection in developed countries.     

Molecular epidemiology of herpes simplex virus type 1 genital infection in association with clinical manifestations

Summary.  The antigenic types of herpes simplex virus (HSV), HSV-1 and HSV-2 are considered to be the etiology of genital herpes. Symptoms of primary HSV-1 and HSV-2 genital infections are similar, however, recurrence of the infection is less frequent after the HSV-1-related genital infection. We determined genotypes of 79 HSV-1 strains isolated from genital lesions in women (43 from primary and 36 from recurrent infections), by analyzing restriction fragment length polymorphism of the HSV-1 strains. Each proportion of genotypes of F1, F12, and F41 in strains isolated from recurrent genital lesions was higher than the corresponding proportion in strains from primary genital lesions. Genotypes of HSV-1 strains isolated two or more times from recurrent genital lesions of each of three subjects were genotye F1, thereby supporting the hypothesis that the F1 genotype is closely associated with recurrence. While the possibility of a genotype preference at the site of infection was not ruled out, genotypes of more than half the number of HSV-1 strains from genital lesions were the same as those from non-genital (mainly oral-facial) lesions analyzed in our foregoing studies, thus indicating that most HSV-1 genotypes are apparently shared by genital and non-genital lesions. Accepted October 1, 1999     

Cytokines in experimental herpes simplex virus infection

Herpes simplex virus (HSV) causes productive and latent forms of infection in humans and experimental animals. The primary infection and reactivation of the latent infection evoke an immune response in the host organism, involving activities of macrophages, CD4+ and CD8+ lymphocytes, and B lymphocytes. Strong cytokine responses are associated with the acute and recurrent phases of HSV infection. Also, during the latent phase of HSV infection in the sensory ganglia, expression of certain cytokines can be detected. The cytokine response to HSV infection is dominated by proinflammatory and Th1 type cytokines; however, Th2 type cytokines such as interleukin-4 also are expressed in the infected tissue. The use of novel HSV-derived, cytokine-expressing gene therapy vectors necessitates studies on the possible modulation of the host responses by the virus-encoded cytokine transgenes. This review focuses on the roles of certain Th1 and Th2 type cytokines in different phases of the experimental HSV infections.     

Critical involvement of CD40 in protection against herpes simplex virus infection in a murine model of genital herpes

Summary.  We studied the requirement for CD40⁺ cells in the resolution of vaginal infection with avirulent herpes simplex virus type I (HSV-1) in vivo using CD40-deficient mice, which were susceptible to infection with avirulent HSV-1. Compared with wild-type mice, CD40-deficient mice could not eliminate HSV-1 virus effectively from the vaginal mucosa and produced lower amounts of interleukin-12 and interferon-γ. These results show that the induction and activation of CD40⁺ cells are important for HSV prevention, facilitating the activation of T cells to induce an efficient HSV clearance from the vaginal mucosa and to prevent lethal illness due to HSV infection. June 14, 2001 September 10, 2001     

A trial of topical acyclovir in genital herpes simplex virus infections

Seventy-seven patients with first episodes of genital herpes and 111 with recurrent episodes were enrolled in a double-blind trial comparing topical acyclovir with a placebo (polyethylene glycol ointment). Among acyclovir-treated patients with first-episode primary genital herpes, the mean duration of viral shedding (4.1 days) and the time to complete crusting of lesions present at the initiation of therapy (7.1 days) were shorter than among placebo recipients (7.0 and 10.5 days, respectively) (P less than 0.05). Acyclovir-treated patients with recurrent herpes had a shorter duration of viral shedding than placebo recipients (0.95 vs. 1.90 days) (P = 0.03). Among the patients with recurrent herpes, acyclovir reduced the time to crusting of lesions in men but had no effect on the symptoms or healing times in women. Topical acyclovir shortens the duration of viral shedding and accelerates healing of some genital herpes simplex virus infections.     

Recurrences after oral and genital herpes simplex virus infection. Influence of site of infection and viral type

We prospectively followed 39 adults with concurrent primary herpes simplex virus (HSV) infection (12 with HSV type 1 and 27 with HSV type 2) of the oropharynx and genitalia, caused by the same virus in each person, to evaluate the influence of viral type (HSV-1 vs. HSV-2) and site of infection (oropharyngeal vs. genital) on the frequency of recurrence. The subsequent recurrence patterns of HSV infection differed markedly according to viral type and anatomical site. Oral-labial recurrences developed in 5 of 12 patients with HSV-1 and 1 of 27 patients with HSV-2 (P less than 0.001). Conversely, genital recurrences developed in 24 of 27 patients with HSV-2 and 3 of 12 patients with HSV-1 (P less than 0.01). The mean rate of subsequent genital recurrences (due to HSV-1 and HSV-2) was 0.23 per month, whereas the mean rate of oral-labial recurrences was only 0.04 per month (P less than 0.001). The mean monthly frequencies of recurrence were, in order, genital HSV-2 infections, 0.33 per month; oral-labial HSV-1 infections, 0.12 per month; genital HSV-1 infections, 0.020 per month; and oral HSV-2 infections, 0.001 per month (P less than 0.01 for each comparison). We conclude that the likelihood of reactivation of HSV infection differs between HSV-1 and HSV-2 infections and between the sacral and trigeminal anatomical sites. The sixfold more frequent clinical recurrence rate of genital HSV infections as compared with oral-labial HSV infections may account for the relatively rapid increase in the prevalence of clinically recognized genital herpes in recent years.     

Ethnic variation in type of genital herpes simplex virus infection in a South London genitourinary medicine clinic

The aims of this study were to investigate the prevalence of herpes simplex virus (HSV) types 1 and 2 in the study population and correlate the results with clinical and demographic details. Consecutive HSV isolates from 334 clinic attendees were typed by immunofluorescence. Patient information was collected from the case notes. Overall, HSV-1 was isolated from 48 and HSV-2 from 287 samples, respectively. There was no significant difference in isolation rates according to gender. However, 33% of white patients' isolates typed as HSV-1, while only 6% of the isolates from the black population were HSV-1 (P < 0.001). Initial infections were seen in 81% of HSV-1 infections and 48% of HSV-2 infections, respectively. A wide discrepancy was observed in the prevalence of HSV-1 and HSV-2 infections between the ethnic groups in this population, which was not explained in terms of gender or age. This may reflect different exposure to HSV-1 in childhood or different sexual practices. The increased prevalence in genital HSV-1 reported in recent studies was not seen in this population. However, the differing proportions of primary and first episode infections may reflect a changing epidemiology.     

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

Summary 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.With 5 Figures     

A double-blind study of oral acyclovir for suppression of recurrences of genital herpes simplex virus infection

Patients with frequently recurring genital herpes were enrolled in a double-blind placebo-controlled trial comparing 200-mg acyclovir capsules, given five or two times daily, with placebo. Of 47 placebo recipients, 44 (94 per cent) had recurrences during the 120-day treatment period, compared with 13 (29 per cent) of 45 patients treated with acyclovir five times daily and 18 of 51 (35 per cent) treated with acyclovir twice daily (P less than 0.001 for each regimen compared with placebo). The median time to the first clinical recurrence was 18 days in placebo recipients, compared with over 120 days in both acyclovir-treated groups (P less than 0.001 for both groups compared with placebo). The mean monthly recurrence rate during the medication period was 0.86 in placebo recipients, compared with 0.13 in patients treated with acyclovir five times daily and 0.14 in patients treated with acyclovir twice daily (P less than 0.001 for both groups compared with placebo). While receiving therapy, 86 of 96 acyclovir-treated patients had over a 50 per cent reduction in their pretreatment recurrence rate. Breakthrough recurrences in acyclovir recipients were of shorter duration and associated with a lower frequency of viral shedding than recurrences in placebo recipients. After medication was discontinued, the subsequent recurrence rate returned to pretreatment frequencies. Daily oral acyclovir was well tolerated. We conclude that oral acyclovir given for four months markedly reduces but does not completely prevent recurrences of genital herpes and does not influence the long-term natural history of the disease.