Bendamustine--a new approach to the treatment of advanced hepatocellular carcinoma?

AIMS: Therapeutic options for advanced hepatocellular carcinoma (HCC) are limited. Bendamustine, a bifunctional cytostatic agent with mainly alkylating effect may be an alternative. METHODS: Five HCC cell lines were incubated in vitro with five different concentrations of bendamustine. In addition, cell lines Huh-7 and HepG2 were tested in a chimeric mouse model. RESULTS: In vitro treatment with bendamustine resulted in an IC( 50 )<6 microg/mL in two, <12 microg/mL in one, and 12-23 microg/mL in two cell lines. In vivo, bendamustine reduced significantly tumor volume in chimeric mice. CONCLUSION: Bendamustine demonstrated significant tumor growth inhibition both in vitro and in vivo at concentrations that can be reached in the plasma. The potential role of bendamustine therapy for HCC and its tolerability in impaired liver function is currently subject of a phase II study.

Male-killing Wolbachia in a live-bearing arthropod: brood abortion as a constraint on the spread of a selfish microbe.

Maternally inherited, cellular endosymbionts can enhance their fitness by biasing host sex ratio in favor of females. Male killing (MK), an extreme form of sex-ratio manipulation, is selectively advantageous, if the death of males results in increased microbe transmission through female siblings. In live-bearing hosts, females typically produce more embryos than are brought to term, and reproductive compensation through maternal resource reallocation from dead male embryos to female siblings provides a direct, physiological mechanism that could increase the number of daughters born to infected females, thereby promoting MK endosymbiont spread. In this study, a Wolbachia-infected line and an uninfected line of the viviparous pseudoscorpion, Cordylochernes scorpioides were genetically homogenized for nuclear DNA by repeated backcrossing of the infected line with the uninfected, laboratory population. Photomicroscopy of early-stage embryos demonstrated that female C. scorpioides invariably produced an excess of embryos, with Wolbachia-infected females producing as many early-stage embryos as uninfected female controls. However, Wolbachia-infected females that successfully carried broods to term gave birth to significantly fewer offspring, indicating that the extreme female bias characteristic of their broods results from the killing rather than the feminization of male embryos. Infected females that carried broods to term gave birth to significantly larger nymphs and did produce 10% more female offspring than uninfected females. However, the slight transmission advantage that the MK Wolbachia accrued from this reproductive compensation appears to be heavily outweighed by the high rate of spontaneous brood abortion suffered by infected females.

Wolbachia, sex ratio bias and apparent male killing in the harlequin beetle riding pseudoscorpion.

Bacterial endosymbionts that manipulate host reproduction are now known to be widespread in insects and other arthropods. Since they inhabit the cytoplasm and are maternally inherited, these microorganisms can enhance their fitness by biasing host sex ratio in favour of females. At its most extreme, sex ratio manipulation may be achieved by killing male embryos, as occurs in a number of insect species. Here, we provide evidence for the first case of male killing by a tetracycline-sensitive microbe in pseudoscorpions. Using a combination of inheritance studies, antibiotic treatment and molecular assays, we show that a new strain of Wolbachia is associated with extreme female bias in the pseudoscorpion, Cordylochernes scorpioides. In a highly female-biased line, sex ratio distortion was maternally inherited, and occurred in conjunction with a high rate of spontaneous abortion and low reproductive success. Antibiotic treatment cured females of the Wolbachia infection, restored offspring sex ratio to 1:1, and significantly enhanced female reproductive success. The discovery of apparent male-killing in C. scorpioides is of interest because pseudoscorpions are viviparous. Theory predicts that male killing should be favoured, if male death enhances the fitness of infected female siblings. In a live-bearing host, reallocation of maternal resources from dead male embryos to their sisters provides a direct, physiological mechanism through which fitness compensation could favour male killing by cellular endosymbionts. Our results suggest, however, that fitness compensation and the spread of male-killing endosymbionts may be undermined by a high rate of spontaneous abortion in infected females of this viviparous arthropod.

Phylogeography of the harlequin beetle-riding pseudoscorpion and the rise of the Isthmus of Panamá.

Molecular and geological evidence indicates that the emergence of the Isthmus of Panamá influenced the historical biogeography of the Neotropics in a complex, staggered manner dating back at least 9 Myr bp. To assess the influence of Isthmus formation on the biogeography of the harlequin beetle-riding pseudoscorpion, Cordylochernes scorpioides, we analysed mitochondrial COI sequence data from 71 individuals from 13 locations in Panamá and northern South America. Parsimony and likelihood-based phylogenies identified deep divergence between South American and Panamanian clades. In contrast to low haplotype diversity in South America, the Panamanian Cordylochernes clade is comprised of three highly divergent lineages: one clade consisting predominantly of individuals from central Panamá (PAN A), and two sister clades (PAN B1 and PAN B2) of western Panamanian pseudoscorpions. Breeding experiments demonstrated a strictly maternal mode of inheritance, indicating that our analyses were not confounded by nuclear-mitochondrial pseudogenes. Haplotype diversity is striking in western Atlantic Panamá, where all three Panamanian clades can occur in a single host tree. This sympatry points to the existence of a cryptic species hybrid zone in western Panamá, a conclusion supported by interclade crosses and coalescence-based migration rates. Molecular clock estimates yield a divergence time of approximately 3 Myr between the central and western Panamanian clades. Taken together, these results are consistent with a recent model in which a transitory proto-Isthmus enabled an early wave of colonization out of South America at the close of the Miocene, followed by sea level rise, inundation of the terrestrial corridor and then a second wave of colonization that occurred when the Isthmus was completed approximately 3 Myr bp.

Reproductive mode and speciation: the viviparity-driven conflict hypothesis.

In birds and frogs, species pairs retain the capacity to produce viable hybrids for tens of millions of years, an order of magnitude longer than mammals. What accounts for these differences in relative rates of pre- and postzygotic isolation? We propose that reproductive mode is a critically important but previously overlooked factor in the speciation process. Viviparity creates a post-fertilization arena for genomic conflicts absent in egg-laying species. With viviparity, conflict can arise between: mothers and embryos; sibling embryos in the womb, and maternal and paternal genomes within individual embryos. Such intra- and intergenomic conflicts result in perpetual antagonistic coevolution, thereby accelerating interpopulation postzygotic isolation. In addition, by generating intrapopulation genetic incompatibility, viviparity-driven conflict favors polyandry and limits the potential for precopulatory divergence. Mammalian diversification is characterized by rapid evolution of incompatible feto-maternal interactions, asymmetrical postzygotic isolation, disproportionate effects of genomically-imprinted genes, and "F(2) hybrid enhancement. " The viviparity-driven conflict hypothesis provides a parsimonious explanation for these patterns in mammalian evolution.

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.

Risk factors for HIV-1 shedding in semen.

Semen is the body fluid most commonly associated with sexual transmission of human immunodeficiency virus type-1 (HIV-1). Because the male genitourinary tract is distinct immunologically from blood, compartment-dependent factors may determine HIV-1 shedding in semen. To identify these factors, the authors obtained 411 semen and blood specimens from 149 men seen up to three times. Seminal plasma was assayed for HIV-1 RNA and semen was cocultured for HIV-1 and cytomegalovirus (CMV), which may up-regulate HIV-1 replication. The best multivariate model for predicting a positive semen HIV-1 coculture included two local urogenital factors, increased seminal polymorphonuclear cell count (odds ratio (OR) = 12.6 for each log10 increase/mL, 95% confidence interval (CI) 12.2, 134.5) and a positive CMV coculture (OR = 3.0, 95% CI 1.2, 7.7). The best multivariate model for predicting semen HIV-1 RNA included two systemic host factors, CD4+ cell counts <200/microliter (OR = 3.0, 95 percent CI 1.3, 6.9) and nucleoside antiretroviral therapy (monotherapy: OR = 0.5, 95% CI 0.3, 1.0; combination therapy: OR = 0.4, 95% CI 0.2, 0.9), and a positive CMV coculture (OR = 1.7, 95% CI 1.0, 3.0). Thus, both systemic and local genitourinary tract factors influence the risk of semen HIV-1 shedding. These findings suggest that measures of systemic virus burden alone may not predict semen infectivity reliably.

Genetic benefits enhance the reproductive success of polyandrous females.

Although it is generally accepted that females can gain material benefits by mating with more than one male, the proposal that polyandry provides genetic benefits remains controversial, largely because direct experimental support is lacking. Here, we report the results of a study testing for genetic benefits to polyandry in the pseudoscorpion Cordylochernes scorpioides. In an experiment that controlled for male mating experience and the number of spermatophores accepted by a female, twice-mated females received either one sperm-packet from each of two different males (the "DM" treatment) or two sperm-packets from a single male (the same male or "SM" treatment). Over their lifetime, DM females gave birth to 32% more offspring than did SM females, primarily because of a significantly reduced rate of spontaneous abortion. This result could not be attributed to male infertility nor to lack of sexual receptivity in males paired with previous mates. Spermatophore and sperm numbers did not differ between males presented with a previous mate and males paired with a new female. Because SM and DM females received the same quantity of ejaculate, it was possible to eliminate material benefits as a contributor to the enhanced reproductive success of DM females. The reduction in embryo failure rate achieved by DM females is most consistent with the genetic incompatibility avoidance hypothesis, i.e., that polyandry enables females to exploit postcopulatory mechanisms for reducing the risk and/or cost of fertilization by genetically incompatible sperm. This study, which rigorously controlled for material benefits and excluded inbreeding effects, demonstrates that polyandry provides genetic benefits that significantly enhance female lifetime reproductive success.

Clinical reactivation of genital herpes simplex virus infection decreases in frequency over time.

BACKGROUND: Visits to physicians for genital herpes simplex virus (HSV) infection continue to increase. Most patients with symptomatic infections have recurrences, but no studies of the long-term clinical course of genital herpes are available. OBJECTIVE: To determine whether the frequency of HSV recurrences decreases over time. DESIGN: Observational cohort study. SETTING: University-based research clinic. PATIENTS: 664 persons with genital herpes followed for at least 14 months. MEASUREMENTS: Patients were classified as having initial or recurrent HSV-1 or HSV-2 infection. Patient-reported recurrences and observed recurrences were recorded in a database; more than 12,000 recurrences were analyzed. RESULTS: Median recurrence rates in the first year of follow-up were one and five per year in patients with newly acquired HSV-1 and HSV-2 infection, respectively; second-year rates were significantly lower in both groups. Patients presenting with recurrent HSV-2 infection had higher rates of recurrence in the first and second years and no significant decrease; significant decreases were detected with longer follow-up. One third of all patients experienced a decrease of two or more recurrences per year between years 1 and 2. Patients infected with HSV-2 who were followed for more than 4 years had a median decrease of two recurrences between years 1 and 5. However, 25% of these patients had an increase of at least one recurrence in year 5, illustrating the variability among HSV-infected persons. Decreases over time among patients who never received suppressive therapy were similar to decreases during untreated periods in patients who received suppressive therapy. CONCLUSIONS: Herpes simplex virus type 2 infection continues to be a chronic remitting illness. Over time, however, clinically significant reductions occur in a majority of patients. Physicians may wish to periodically assess the need for continued treatment with daily suppressive antiviral chemotherapy.

Human herpesvirus 6 infections after bone marrow transplantation: clinical and virologic manifestations.

Human herpesvirus 6 (HHV-6) DNA levels in peripheral blood mononuclear cells were prospectively evaluated in 20 cytomegalovirus-seronegative allogeneic marrow transplant patients and in 10 healthy control subjects. Blood and saliva specimens obtained weekly for 3 months after transplant were evaluated by quantitative HHV-6 polymerase chain reaction. One of 20 patients experienced primary HHV-6 infection after marrow transplant (seroconversion, HHV-6 viremia, skin rash); 18 of 20 had increased peripheral blood mononuclear cell HHV-6 DNA levels consistent with asymptomatic reactivations, and 1 patient experienced a reactivation-associated skin rash. Genotyping revealed HHV-6 variant B DNA in all cases. Therapy with acyclovir or intravenous immunoglobulin was not correlated with lower HHV-6 DNA levels. Thus, asymptomatic HHV-6 reactivations appear to be common following allogeneic marrow transplantation. Among HHV-6-seronegative and viral DNA-negative patients, primary HHV-6 infection can ensue in association with self-limited clinical symptoms, including diffuse maculopapular rash.

Frequency of symptomatic and asymptomatic herpes simplex virus type 2 reactivations among human immunodeficiency virus-infected men.

Herpes simplex virus (HSV) infection is common in persons coinfected with human immunodeficiency virus (HIV). In a prospective study, daily viral cultures of the mouth, genitals, and rectum were collected from 68 HIV-positive and 13 HIV-negative men who have sex with men. Subjects completed a median of 57 days of follow-up. Anogenital HSV-2 cultures were positive on 405 (9.7%) of 4167 days for HIV-positive men and on 24 (3.1%) of 766 days for HIV-negative men. Most reactivations were perirectal and subclinical. Risk factors for increased HSV-2 shedding among HIV-positive men were low CD4 cell count (odds ratio, 2.5; 95% confidence interval, 1.2-5.4) and antibodies to both HSV-1 and HSV-2 versus HSV-2 only (odds ratio, 1.9; 95% confidence interval, 1.0-3.7). Three isolates obtained from 3 separate subjects were resistant to acyclovir. Thus, subclinical HSV-2 reactivation is an important opportunistic infection in persons with HIV infection. Further studies are necessaryto determine the impact of subclinical HSV-2 reactivation on the natural history of HIV infection.

Polyandrous females discriminate against previous mates.

In most animal species, particularly those in which females engage in polyandry, mate choice is a sequential process in which a female must choose to mate or not to mate with each male encountered. Although a number of theoretical and empirical investigations have examined the effects of sequential mate choice on the operation of sexual selection, how females respond to solicitation by previous mates has received little attention. Here, we report the results of a study carried out on the polyandrous pseudoscorpion, Cordylochernes scorpioides, that assessed the sexual receptivity of once-mated females presented after a lapse of 1.5 hr or 48 hr with either their first mate or a different male. Females exhibited a high level of receptivity to new males, irrespective of intermating interval. By contrast, time between matings exerted a strong effect on female receptivity to previous mates. After a lapse of 48 hr, females did not differ significantly in their receptivity toward previous mates and different males, whereas at 1.5 hr after first mating, females were almost invariably unreceptive to males from whom they had previously accepted sperm. This result could not be attributed to male size or mating experience or to male sexual receptivity. Indeed, males were as willing to transfer sperm to a previous mate as they were to a new female. This difference between males and females in their propensity to remate with the same individual may reflect a conflict between the sexes, with males seeking to minimize postcopulatory sexual selection and females actively keeping open the opportunity for sperm competition and female choice of sperm by discriminating against previous mates.

Unintegrated circular HIV-1 DNA in the peripheral mononuclear cells of HIV-1-infected subjects: association with high levels of plasma HIV-1 RNA, rapid decline in CD4 count, and clinical progression to AIDS.

We observed 36 HIV-infected patients to evaluate whether the presence of tandem 2-long terminal repeat circular unintegrated HIV-1 DNA (2-LTR) in peripheral blood mononuclear cells (PBMC) at baseline was associated with acceleration of HIV disease. Detection of 2-LTR at baseline correlated with high plasma HIV-1 RNA levels (p < .01), recovery of culturable HIV-1 from plasma (p = .02), and progression to AIDS during follow-up (p = .01). More patients with 2-LTR (68%) than without 2-LTR (31%) had a decline in CD4 levels of >50 cells/mm3 over the first 18 months of follow-up (p = .04), and the average annual CD4 decline was 35% in patients with 2-LTR compared with 16% in those without 2-LTR (p = 0.06). Detection of 2-LTR in PBMC at baseline was an independent predictor of high plasma HIV-1 RNA levels and subsequent CD4 cell decline in this cohort of patients with predominantly nonsyncytium-inducing (NSI) isolates at baseline. The presence of 2-LTR in PBMC appears to be reflective of ongoing HIV-1 replication, as measured by plasma HIV-1 RNA levels, and identifies persons at risk for immunologic and clinical decline.

Famciclovir for the suppression of symptomatic and asymptomatic herpes simplex virus reactivation in HIV-infected persons. A double-blind, placebo-controlled trial.

BACKGROUND: Herpes simplex virus (HSV) infection is one of the most common opportunistic infections in HIV-infected persons. However, most documentation of the effectiveness of antiviral therapy in reducing HSV reactivation is anecdotal. OBJECTIVE: To evaluate the quantitative effect of antiviral therapy on the frequency of HSV reactivation in HIV-infected persons. DESIGN: Double-blind, placebo-controlled, crossover trial. SETTING: Research clinic at a university hospital. PATIENTS: 48 persons (45 men and 3 women) who were HIV positive and HSV seropositive. INTERVENTION: Patients were randomly assigned to receive famciclovir, 500 mg orally twice daily, or placebo for 8 weeks. They then crossed over to receive the other regimen after a 1-week washout period. MEASUREMENTS: Patients obtained daily cultures of their perirectal, urethral, oral, and genital areas and kept dairy records of signs and symptoms of genital and oral-labial herpes. RESULTS: The median CD4 cell count at study entry was 384 cells/mm3. In the intention-to-treat analysis of the first study period, HSV was isolated on 122 of 1114 (11%) placebo days compared with 9 of 1071 (1%) famciclovir days (relative risk, 0.15; P < 0.001). For patients who completed the crossover, the median difference in days with symptoms between placebo and famciclovir was 13.8% of days and the median difference in days on which HSV was isolated was 5.4% of days (P < 0.001 for both). Percentage of days with HSV-2 shedding was reduced from 9.7% to 1.3%. Breakthrough reactivations that occurred while patients were receiving famciclovir were infrequent, short, and often asymptomatic, HSV-2 isolates from these reactivations were susceptible to penciclovir in vitro. CONCLUSIONS: Antiviral chemotherapy with famciclovir results in clinically and statistically significant reductions in the symptoms associated with HSV infection and the symptomatic and asymptomatic shedding of HSV among HIV-positive persons.

The acquisition of herpes simplex virus during pregnancy.

BACKGROUND: The acquisition of genital herpes during pregnancy has been associated with spontaneous abortion, prematurity, and congenital and neonatal herpes. The frequency of seroconversion, maternal symptoms of the disease, and the timing of its greatest effect on the outcome of pregnancy have not been systematically studied. METHODS: We studied 7046 pregnant women whom serologic tests showed to be at risk for herpes simplex virus (HSV) infection. Serum samples obtained at the first prenatal visit, at approximately 16 and 24 weeks, and during labor were tested for antibodies to HSV types 1 and 2 (HSV-1 and HSV-2) by the Western blot assay, and the results were correlated with the occurrence of antenatal genital infections. RESULTS: Ninety-four of the women became seropositive for HSV; 34 of the 94 women (36 percent) had symptoms consistent with herpes infection. Women who were initially seronegative for both HSV-1 and HSV-2 had an estimated chance of seroconversion for either virus of 3.7 percent; those who were initially seropositive only for HSV-1 had an estimated chance of HSV-2 seroconversion of 1.7 percent; and those who were initially HSV-2-seropositive had an estimated chance of zero for acquiring HSV-1 infection. Among the 60 of the 94 pregnancies for which the time of acquisition of HSV infection was known, 30 percent of the infections occurred in the first trimester, 30 percent in the second, and 40 percent in the third. HSV seroconversion completed by the time of labor was not associated with an increase in neonatal morbidity or with any cases of congenital herpes infection. However, among the infants born to nine women who acquired genital HSV infection shortly before labor, neonatal HSV infection occurred in four infants, of whom one died. CONCLUSIONS: Two percent or more of susceptible women acquire HSV infection during pregnancy. Acquisition of infection with seroconversion completed before labor does not appear to affect the outcome of pregnancy, but infection acquired near the time of labor is associated with neonatal herpes and perinatal morbidity.

Mitochondrial DNA sequencing reveals extreme genetic differentiation in a cryptic species complex of neotropical pseudoscorpions.

The neotropical pseudoscorpion Cordylochernes scorpioides (Chernetidae: Lamprochernetinae) is currently described as a single species ranging from Central America to northern Argentina. However, interpopulation crosses have recently demonstrated that C. scorpioides actually represents a complex of cryptic species. Here we present mitochondrial COI gene sequence data from C. scorpioides individuals from Panama, Trinidad, and French Guiana which demonstrate little or no intrapopulation variability but divergence ranging from 2.6 to 13.8% between geographic populations. Phylogenetic analysis provides evidence of a major split between C. scorpioides lineages from Central and South America. Levels of interpopulation mtDNA divergence correspond well with previously established patterns of postzygotic reproductive incompatibility between geographically distinct units within the C. scorpioides complex. By contrast, multivariate morphometric analysis demonstrates that extensive sequence divergence has occurred in the absence of appreciable morphological differentiation between the populations. To provide a framework for assessing the scale of geographic divergence in C. scorpioides, Cordylochernes sequences were compared with homologous sequence from its presumed sister taxon, Lustrochernes, and from Parachernes and Semeiochernes, representatives of the second chernetid subfamily, the Chernetinae. Our preliminary, generic-level analysis suggests that COI sequence data may prove useful in resolving relationships within this problematic family.

Frequent genital herpes simplex virus 2 shedding in immunocompetent women. Effect of acyclovir treatment.

Reactivation of herpes simplex virus type 2 (HSV-2) occurs intermittently as perceived clinically and by viral culture. We performed a series of studies to evaluate the frequency and pattern of HSV-2 reactivation using both viral isolation and HSV PCR assay. Daily samples of genital secretions were obtained from 27 HSV-2 seropositive women; a subset of subjects obtained samples while receiving oral acyclovir 400 mg PO twice a day. HSV DNA was detected in genital swab specimens on 28% of 1,410 d compared with 8.1% of days by viral isolation. 11 of 20 women had HSV DNA detected on > 20% of days, 4 on > 50%, and 2 on > 75% of days; in contrast, none of the women shed on > 21% of days by viral isolation. The daily administration of oral acyclovir promptly reduced the frequency of HSV DNA detection by a median of 80%. Within 3-4 d of discontinuing daily acyclovir, HSV DNA again appeared in the genital area. HSV-2 shedding in the genital mucosa occurs much more frequently than previously appreciated. This frequent reactivation likely plays a role in the epidemic spread of genital herpes worldwide.

Suppression of subclinical shedding of herpes simplex virus type 2 with acyclovir.

OBJECTIVE: To assess the effect of the antiviral drug acyclovir on the frequency of subclinical shedding of herpes simplex virus (HSV) in the genital tract. DESIGN: A double-blind, placebo-controlled, crossover clinical trial. SETTING: A university-based virology research clinic. PATIENTS: 34 women with herpes simplex virus type 2 (HSV-2) antibody only and genital herpes of less than 2 years' duration. INTERVENTION: Participants were randomly assigned to receive either acyclovir, 400 mg twice daily for 70 days, followed by a 14-day washout period, and then placebo for 70 days, or the study medications in the reverse order. MEASUREMENTS: Women collected daily genital swabs of the vulvar, cervicovaginal, and perianal areas for HSV culture, maintained a diary of genital lesions, and were examined at the time of recurrences. RESULTS: In an intent-to-treat analysis of the initial treatment period, 15 of the 17 women who received placebo and 3 of the 17 women who received acyclovir had at least 1 day of subclinical shedding (P < 0.001). Among the participants who received placebo, subclinical shedding occurred on 64 of 928 (6.9%) days compared with 3 of 1057 (0.3%) days among the participants who received acyclovir (P < 0.001). The relative risk for subclinical shedding was 0.09 (95% CI, 0.03 to 0.35) for the women who received acyclovir compared with the women who received placebo. In a paired analysis of 26 women who completed both arms of the study, acyclovir therapy was associated with a decrease in the frequency of subclinical shedding; subclinical shedding occurred on 83 of 1439 (5.8%) days with placebo, and on 6 of 1611 (0.37%) days with acyclovir (P < 0.001)--a 94% reduction. The frequency of subclinical shedding was reduced at all anatomic sites and in all patients. CONCLUSIONS: Daily therapy with oral acyclovir suppresses subclinical shedding of HSV-2 in the genital tract, suggesting that studies to evaluate the use of acyclovir in preventing HSV-2 transmission are warranted.

Virologic characteristics of subclinical and symptomatic genital herpes infections.

BACKGROUND: The frequency, pattern, and anatomical sites of subclinical shedding of herpes simplex virus (HSV) in the genital tract, along with factors that predict such shedding, have not been well characterized. METHODS: We studied prospectively the clinical and virologic course of genital herpes in 110 women. The women kept symptom diaries and provided daily samples from the vulva, cervix, and rectum for viral culture. RESULTS: During a median follow-up of 105 days, subclinical shedding of virus was identified in 36 of 65 women (55 percent) with HSV type 2 (HSV-2), in 16 of 31 women (52 percent) with HSV type 1 (HSV-1) and HSV-2, and in 4 of 14 women (29 percent) with only HSV-1. Among women with genital HSV-2 infection, subclinical shedding occurred on a mean of 2 percent of the days. The mean duration of viral shedding during subclinical episodes was 1.5 days, as compared with 1.8 days during symptomatic episodes. HSV was isolated from several sites in the genital tract and rectum in 17 percent of subclinical episodes and 22 percent of symptomatic episodes. Half the episodes of subclinical shedding of HSV occurred within seven days of a symptomatic recurrence. The risk of subclinical shedding increased with the frequency of symptomatic recurrences. Subclinical shedding was more frequent among women with more than 12 recurrences per year than among those with no symptomatic recurrences (odds ratio, 3.3; 95 percent confidence interval, 1.4 to 7.9); it was also more frequent among women who had recently acquired genital herpes (odds ratio for women with HSV acquired in the past year as compared with those who had had the infection for a year or more, 1.85; 95 percent confidence interval, 1.1 to 3.1). CONCLUSIONS: Among women with a history of genital herpes infection, subclinical shedding of HSV is common and accounts for nearly one third of the total days of reactivation of HSV infection in the genital tract. Women with frequent symptomatic recurrences also have frequent subclinical shedding and may be at high risk for transmitting HSV.