Asymptomatic genital excretion of herpes simplex virus during early labor

Asymptomatic human CD4+ cytotoxic T-cell epitopes identified from herpes simplex virus glycoprotein B

The identification of "asymptomatic" (i.e., protective) epitopes recognized by T cells from herpes simplex virus (HSV)-seropositive healthy individuals is a prerequisite for an effective vaccine. Using the PepScan epitope mapping strategy, a library of 179 potential peptide epitopes (15-mers overlapping by 10 amino acids) was identified from HSV type 1 (HSV-1) glycoprotein B (gB), an antigen that induces protective immunity in both animal models and humans. Eighteen groups (G1 to G18) of 10 adjacent peptides each were first screened for T-cell antigenicity in 38 HSV-1-seropositive but HSV-2-seronegative individuals. Individual peptides within the two immunodominant groups (i.e., G4 and G14) were further screened with T cells from HLA-DR-genotyped and clinically defined symptomatic (n = 10) and asymptomatic (n = 10) HSV-1-seropositive healthy individuals. Peptides gB(161-175) and gB(166-180) within G4 and gB(661-675) within G14 recalled the strongest HLA-DR-dependent CD4(+) T-cell proliferation and gamma interferon production. gB(166-180), gB(661-675), and gB(666-680) elicited ex vivo CD4(+) cytotoxic T cells (CTLs) that lysed autologous HSV-1- and vaccinia virus (expressing gB)-infected lymphoblastoid cell lines. Interestingly, gB(166-180) and gB(666-680) peptide epitopes were strongly recognized by CD4(+) T cells from 10 of 10 asymptomatic patients but not by CD4(+) T cells from 10 of 10 symptomatic patients (P < 0.0001; analysis of variance posttest). Inversely, CD4(+) T cells from symptomatic patients preferentially recognized gB(661-675) (P < 0.0001). Thus, we identified three previously unrecognized CD4(+) CTL peptide epitopes in HSV-1 gB. Among these, gB(166-180) and gB(666-680) appear to be "asymptomatic" peptide epitopes and therefore should be considered in the design of future herpes vaccines.

Acyclovir suppression to prevent recurrent genital herpes at delivery

OBJECTIVE

To determine if suppressive acyclovir near term decreased the frequency of clinical recurrences at delivery in women with recurrent genital herpes simplex virus (HSV) infection.

METHODS

We conducted a prospective, double-blind, randomized trial in 234 women with recurrent genital herpes. Women with genital infection of any frequency were enrolled. Patients received either suppressive oral acyclovir 400 mg three times daily or an identical placebo after 36 weeks' gestation. Clinical lesions were identified, and HSV cultures were obtained at delivery. The frequencies of clinical and subclinical HSV recurrences at delivery were evaluated.

RESULTS

Six percent of patients treated with acyclovir, and 14% of patients treated with placebo had clinical HSV at delivery (p = 0.046). No patients in the acyclovir group had positive HSV cultures, compared with 6% of placebo-treated patients (p = 0.029). There was no significant difference in subclinical HSV shedding in the acyclovir group (0%) compared with the placebo-treated group (3%) (p = 0.102).

CONCLUSIONS

Suppressive acyclovir therapy significantly decreased the incidence of clinical genital herpes and the overall incidence of HSV excretion at delivery in patients with previous herpes infection.

Acyclovir suppression to prevent clinical recurrences at delivery after first episode genital herpes in pregnancy: an open-label trial

OBJECTIVE

To continue evaluation of the use of acyclovir suppression in late pregnancy after first episode genital herpes simplex virus (HSV) infection, using an open-label study design.

METHODS

Ninety-six women diagnosed with genital herpes for the first time in the index pregnancy were prescribed suppressive acyclovir 400 mg orally three times daily from 36 weeks until delivery in an open-label fashion. Herpes cultures were obtained when patients presented for delivery. Vaginal delivery was permitted if no clinical recurrence was present; otherwise a Cesarean delivery was performed. Neonatal HSV cultures were obtained and infants were followed clinically. Rates of clinical and asymptomatic genital herpes recurrences and Cesarean delivery for genital herpes were measured, and 95% confidence intervals were calculated.

RESULTS

In 82 patients (85%) compliant with therapy, only 1% had clinical HSV recurrences at delivery. In an intent to treat analysis of the entire cohort, 4% had clinical recurrences (compared with 18-37% in historical controls). Asymptomatic shedding occurred in 1% of women without lesions at delivery. Two of the four clinical recurrences were HSV-culture positive. No significant maternal or fetal side-effects were observed.

CONCLUSIONS

In clinical practice the majority of patients are compliant with acyclovir suppression at term. The therapy appears to be effective at reducing clinical recurrences after a first episode of genital herpes complicating a pregnancy.

Neonatal herpes simplex virus infection in relation to asymptomatic maternal infection at the time of labor

BACKGROUND AND METHODS

To define the risk factors associated with neonatal acquisition of herpes simplex virus (HSV) infection, we prospectively obtained HSV cultures from the cervix and external genitalia of 15,923 pregnant women in early labor who were without symptoms or signs of genital HSV infection. Follow-up of the women with positive cultures for HSV and their HSV-exposed infants included serologic tests and serial cultures for HSV.

RESULTS

HSV was isolated from 56 of the women (0.35 percent), 18 of whom (35 percent) had serologic evidence of a recently acquired, subclinical first episode of genital HSV infection, and 34 of whom (65 percent) had reactivation of HSV. Neonatal HSV developed in 6 of 18 infants (33 percent) born to the women with a first episode of genital HSV, and in 1 of 34 infants (3 percent) born to the women with reactivation of HSV (P less than 0.01); neonatal HSV also occurred in three of the infants born to the 15,867 women with negative cultures. Neonatal HSV-2 occurred in 1 of 4 infants born to mothers seronegative at delivery for both HSV-1 and HSV-2, in 4 of 12 infants exposed to HSV-2 whose mothers had only HSV-1 antibodies at delivery, and in none of the infants born to 31 women who were HSV-2-seropositive. An increased risk of neonatal HSV was associated with exposure to viral shedding from the cervix and the use of fetal-scalp electrodes.

CONCLUSIONS

Of the asymptomatic women who shed HSV in early labor, about a third have recently acquired genital HSV, and their infants are 10 times more likely to have neonatal HSV than those of women with asymptomatic reactivation of HSV. The presence of maternal antibodies specific to HSV-2 but not HSV-1 appears to reduce the neonatal transmission of HSV-2. Further studies are necessary to determine whether screening and prophylactic treatment are warranted for infants of HSV-2-seronegative mothers who shed HSV-1 or HSV-2 in early labor.

Asymptomatic shedding of herpesvirus during labor

Cervical cultures of 2013 consecutive obstetric patients with no history of genital herpes simplex virus infection were used to determine the frequency of asymptomatic herpes simplex virus shedding in labor. Four (0.20%) of these patients had positive cultures. None of the exposed neonates developed clinical evidence of herpetic infection.

Antiviral treatment of herpes simplex infection in neonates and pregnant women

Herpes simplex infections in neonates include (1) infections beginning in skin or mucous membranes, (2) infections of the central nervous system, and (3) disseminated herpes of the newborn. Early recognition of infections beginning in skin or mucous membranes is essential because 75% will disseminate internally if untreated. Skin lesions provide important diagnostic clues in herpes of the nervous system and disseminated herpes, but they often appear late and in only about 60% of infected neonates. Acyclovir and vidarabine are effective therapies but they must be administered early to prevent serious damage or death. Herpetic skin lesions in neonates may be confused with pyodermas. Direct immunofluorescence and cultures are reliable diagnostic tests. Congenital herpes may cause widespread skin involvement and multiple eye and nervous system diseases. The mother is the source of neonatal herpes in about two thirds of cases. Asymptomatic genital shedding of virus late in pregnancy does not accurately predict whether maternal cultures will be positive at the time of delivery. The risk of the infant acquiring neonatal herpes from a mother with recurrent herpes at birth is about 5%, but the risk is much higher if the mother has true primary genital infection.