Primary Human Cytomegalovirus Infection Research Articles

Antibody Treatment Promotes Compensation for Human Cytomegalovirus-Induced Pathogenesis and a Hypoxia-Like Condition in Placentas with Congenital Infection

Human cytomegalovirus (HCMV) is the major viral cause of birth defects worldwide. Affected infants can have temporary symptoms that resolve soon after birth, such as growth restriction, and permanent disabilities, including neurological impairment. Passive immunization of pregnant women with primary HCMV infection is a promising treatment to prevent congenital disease. To understand the effects of sustained viral replication on the placenta and passive transfer of protective antibodies, we performed immunohistological analysis of placental specimens from women with untreated congenital infection, HCMV-specific hyperimmune globulin treatment, and uninfected controls. In untreated infection, viral replication proteins were found in trophoblasts and endothelial cells of chorionic villi and uterine arteries. Associated damage included extensive fibrinoid deposits, fibrosis, avascular villi, and edema, which could impair placental functions. Vascular endothelial growth factor and its receptor fms-like tyrosine kinase 1 (Flt1) were up-regulated, and amniotic fluid contained elevated levels of soluble Flt1 (sFlt1), an antiangiogenic protein, relative to placental growth factor. With hyperimmune globulin treatment, placentas appeared uninfected, vascular endothelial growth factor and Flt1 expression was reduced, and sFlt1 levels in amniotic fluid were lower. An increase in the number of chorionic villi and blood vessels over that in controls suggested compensatory development for a hypoxia-like condition. Taken together the results indicate that antibody treatment can suppress HCMV replication and prevent placental dysfunction, thus improving fetal outcome.

Comparative evaluation of eight commercial human cytomegalovirus IgG avidity assays

Background The interpretation of a positive IgM antibody result to human cytomegalovirus (HCMV) in a pregnant woman is of major importance for the correct management of the pregnancy. Determination of HCMV-specific IgG avidity is considered an useful approach for distinguishing IgM antibody due to primary HCMV infection from IgM antibody elicited during non-primary infection. Objective Comparative evaluation of eight commercial HCMV IgG avidity assays currently available in Europe. Study design A panel of 198 sequential samples collected from 65 pregnant women at 0–90, 91–180, and >180 days after the onset of primary HCMV infection was retrospectively tested by Abbott, BioMérieux, Bio-Rad, DiaSorin, Diesse, Euroimmun, Radim, and Technogenetics HCMV IgG avidity assays according to the manufacturer's instructions. Results None of the 198 samples tested yielded identical scores by the kits under evaluation. The Euroimmun and Radim assays showed the best correlation with expected results in terms of low (0–90 days), intermediate (90–180 days) and high (>180 days) avidity results, respectively. The best accuracy in diagnosing a recent (<90 days after the onset) or non-recent (>180 days after the onset) primary HCMV infection was shown by Radim followed by Euroimmun and Diesse. The best correlation with a well established in-house developed HCMV IgG avidity assay was shown by Radim. Conclusions HCMV IgG avidity kits need to be improved and standardized. In the meantime, highly specific IgM assays are preferable for screening purposes in pregnant women.

Positive predictive value of anti-HCMV IgM as an index of primary infection

A search for specific IgM antibodies was used for the detection of primary human cytomegalovirus (HCMV) infections, but the significance of the results is limited by the possible persistence of specific IgM over time, the fact that they are also produced during episodes of reactivation or reinfection, and possible cross-reactions with other viruses. Anti-HCMV antibody screening was carried out to assess the positive predictive value of detecting specific IgM antibodies using IgG and IgM enzyme-linked immunosorbent assays (ELISAs) in 6990 patients examined during the period 2005–2007. In comparison with IgG avidity, the positive predictive value of screening by IgM ELISA alone was 49.3%, which increased to 73% when the presence of IgM was confirmed by an enzyme-linked fluorescent assay (ELFA). The predictive values of highly or weakly positive IgM ELISA alone were respectively 68.8% and 16.4%, but increased to 83.1% and 39.1% if IgM was confirmed by ELFA. The positive predictive value of the IgM/IgG ratio ranged from 26.7% for a low ratio and the detection of IgM by ELISA alone, to 90.7% for a high ratio and ELFA-confirmed IgM detection. These findings indicate that a specimen in which highly positive IgM ELISA values are confirmed by ELFA, or which shows a high IgM/IgG ratio, is a good indicator of infection occurring within the previous three months.

Human cytomegalovirus (HCMV) genotype populations in immunocompetent individuals during primary HCMV infection

Background Immunocompetent individuals can harbor multiple human cytomegalovirus (HCMV) genotypes. However, little is known about the genotype populations acquired during primary HCMV infection. Objective The aim of this study was to assess the HCMV genotype populations present in the blood of non-immunocompromised patients experiencing primary HCMV infection. Study design HCMV glycoprotein B (gB), glycoprotein H (gH), and UL10 genotyping was performed on HCMV-positive serum samples of 36 immunocompetent patients during primary infection by sensitive gB- and gH-genotype-specific real-time-PCR assays and by UL10 sequencing. Results In all cases only one gB–gH–UL10 genotype was detected. In contrast, mixed-genotype infections were found in 4 of 14 immunocompetent patients experiencing HCMV reactivation/reinfection ( P = 0.004). Conclusion Thus, the data support the presumption that multiple HCMV genotypes in immunocompetent individuals are often a result of serial reinfection rather than primary coinfection with different strains.

Human cytomegalovirus tropism for endothelial/epithelial cells: scientific background and clinical implications

Human cytomegalovirus (HCMV) has been routinely isolated from and propagated in vitro in human embryonic lung fibroblast (HELF) cell cultures, while in vivo it is known to infect predominantly endothelial and epithelial cells. In recent years, genetic determinants of the HCMV tropism for endothelial/epithelial cells were identified in the UL131A/UL130/UL128 locus of HCMV genome of wild-type strains. UL131A-UL128 gene products form a complex with glycoprotein H (gH) and L (gL) resulting in a gH/gL/UL131A-UL128 complex that is required for HCMV entry into endothelial/epithelial cells. In contrast, virus entry into fibroblasts has its genetic determinants in the complex gH/gL/gO (or gH/gL). During primary HCMV infection, the neutralising antibody response measured in endothelial cells (EC) is potent, occurs very early and is directed mostly against combinations of two or three gene products of the UL131A-128 locus. On the contrary, neutralising antibodies measured in fibroblasts appear late, are relatively weak in potency and are directed against gH and gB. The T-cell immune response to UL131A-UL128 gene products remains to be investigated. Recently, a role has been proposed for neutralising antibody in conferring prevention/protection against HCMV infection/disease in pregnant women with primary HCMV infection. However, the level of cooperation between humoral immunity and the well-established T-cell protection remains to be defined.

Serologic Screening of Pregnant Korean Women for Primary Human Cytomegalovirus Infection Using IgG Avidity Test

Primary human cytomegalovirus (CMV) infection during pregnancy is a major cause of congenital malformation. We detected primary CMV infection in pregnant Korean women by using an algorithm that comprises CMV IgG, IgM, and IgG avidity tests. During a 2-month period, 744 pregnant women who were at 10-19 weeks of gestation were consecutively enrolled in this study. Human anti-CMV IgG and IgM levels in their sera were determined by chemiluminescence immunoassays. Serum samples from the women who were positive for CMV IgG and IgM were assayed by the ARCHITECT CMV IgG avidity test in order to distinguish primary from non-primary CMV infection. Gross examination of the neonates of the women who were positive for CMV IgM was conducted. The seroprevalence of CMV IgG and IgM was estimated to be 98.1% and 1.7%, respectively. The samples from all the women who were positive for CMV IgM or with grey zone results contained high avidity CMV IgG. Seven women with positive CMV IgG and IgM results who completed follow-up up to delivery showed no gross evidence of in utero CMV transmission. Maternal primary CMV infection was not detected in any of the pregnant women included in this study cohort. CMV IgG avidity test enabled the identification of women who were at a low risk of transmitting CMV infection and provided informative for subsequent pregnancy outcomes. Compared to previous studies, the seroprevalence of CMV IgG antibody across pregnant Korean women remained unchanged.

CMV infection in pregnancy: Prevention of vertical transmission by means of specific immunoglobulin therapy (CMV-IgG)

Human Cytomegalovirus (HCMV) is the main cause of congenital infections in industrialized countries, with incidence ranging between 0.3 and 2.4%. Complications of congenital HCMV infection may include deafness and mental retardation. Primary HCMV infection during pregnancy carries a high risk of vertical transmission. An uncontrolled, non-randomized study published in 2005 reported that the intravenous administration of anti-CMV immunoglobulin (Ig) reduced the maternal–fetal transmission of the virus from 40 to 16%. This is an experimental non-randomized spontaneous monocentric study — Phase 2. Between 2003 and 2007: 26 pregnant women with primary CMV infection documented serologically and/or virologically between the 6th and 22nd weeks of pregnancy were enrolled to receive anti-CMV IgG (Cytotect) monthly from the moment of diagnosis until birth. Children born to 15 mothers (57.96%) were uninfected, while the newborns of 8 mothers (30.76%) presented CMV infection; 2 of these were symptomatic (1 with hearing impairment, 1 with encephalopathy), while the third, although asymptomatic, showed neuroradiological alterations. The remaining 3 pregnancies were interrupted by miscarriage in 1 case and voluntary abortion in 2 cases because of signs of CMV infection-induced alterations on ultrasonography. Overall, 42.3% of newborns/fetuses were infected. None of the expecting mothers presented side effects. Our study revealed no advantage in the use of anti-CMV IgG. Nevertheless, controlled, and ideally, randomized trials are warranted to better clarify the usefulness of this therapeutic approach.

Quantitative detection of HCMV‐DNA in saliva from infants and breast milk on real‐time polymerase chain reaction

The role of breast milk in viral transmission has not been fully studied. To determine the effect of breast milk on the establishment of primary human cytomegalovirus (HCMV) infection in term infants, HCMV-DNA was measured in breast milk and infant saliva. The study population consisted of 48 healthy term infants and their mothers. The copy number of HCMV-DNA in the infants' saliva and mothers' milk was measured on quantitative real-time polymerase chain reaction (PCR). HCMV-DNA was detected in both saliva and breast milk from 21 infant-mother pairs, in milk only from four pairs, in saliva only from 12 pairs, and in neither from 11 pairs. HCMV-DNA was first detected in the saliva of 10 infants at age 4 months, seven infants at 7 months, 13 infants at 10 months, and three infants at 12 months. The viral loads peaked 4-10 months after birth, and thereafter decreased or became negative. The peak copy number and rate of HCMV-DNA detection in saliva were significantly related to peak copy number and rate of detection in the corresponding breast milk. Thus, HCMV passed through breast milk 1-7 months after delivery affects the persistence and level of HCMV-DNA in infant saliva and is the most important route of primary infection.

Dynamics of the Emergence of a Human Cytomegalovirus UL97 Mutant Strain Conferring Ganciclovir Resistance in a Pediatric Stem-Cell Transplant Recipient

Stem-cell transplant recipients are at risk of developing ganciclovir-resistant human cytomegalovirus (HCMV) infection caused by mutations in the viral UL97 gene. Knowledge of the relative proportions of coexisting HCMV wild-type and mutant strains may contribute to a better understanding of the dynamics of in vivo mutant strain selection under ganciclovir. Currently, genotype resistance screening for UL97 is routinely performed by restriction fragment length polymorphism detection and sequencing. We present here the longitudinal course of a pediatric recipient of an allogeneic stem-cell transplant infected with a ganciclovir-resistant HCMV strain. EDTA-treated blood samples were analyzed longitudinally. The patient acquired a primary HCMV infection shortly before transplantation and reactivated the virus following allogeneic hematopoietic stem cell transplantation, thus receiving an intensive antiviral treatment schedule. Three different methods for UL97 mutation analysis, restriction fragment length polymorphism detection, sequencing, and a new, real-time PCR approach were performed. In conclusion, for our pediatric patient, during peak viral load, the UL97 wild-type strain predominates, while during clinical deterioration with low viral load, the predominant mutant strain persists.

Human cytomegalovirus-specific CD4+ and CD8+ T cell responses in primary infection of the immunocompetent and the immunocompromised host

The kinetics of primary human cytomegalovirus (HCMV) infection and specific T-cell responses were investigated in 16 immunocompetent pregnant women and 8 solid-organ transplant recipients (SOTR). T-cell responses to whole HCMV and to pp65 and IE-1 peptides were determined by flow cytometry evaluation of IFNgamma production. HCMV-specific CD4(+) and CD8(+) T-cells appeared earlier and simultaneously in immunocompetent subjects, whereas specific CD8(+) T-cells preceded CD4(+) T-cells in half of the SOTR examined. The magnitude of the HCMV-specific T-cell pool was comparable. HCMV load reached peak levels 100-1000 times higher in SOTR than in immunocompetent women, while the virus persisted for months in blood of both groups. T-cells directed to pp65 and IE-1 were only detected in a portion of subjects developing a full T-cell response to the whole virus. Thus, the development of cell-mediated immune response in primary HCMV infection may be missed when looking at pp65 and IE-1 peptide-stimulated T-cells only.

Germline V-genes sculpt the binding site of a family of antibodies neutralizing human cytomegalovirus

Immunoglobulin genes are generated somatically through specialized mechanisms resulting in a vast repertoire of antigen-binding sites. Despite the stochastic nature of these processes, the V-genes that encode most of the antigen-combining site are under positive evolutionary selection, raising the possibility that V-genes have been selected to encode key structural features of binding sites of protective antibodies against certain pathogens. Human, neutralizing antibodies to human cytomegalovirus that bind the AD-2S1 epitope on its gB envelope protein repeatedly use a pair of well-conserved, germline V-genes IGHV3-30 and IGKV3-11. Here, we present crystallographic, kinetic and thermodynamic analyses of the binding site of such an antibody and that of its primary immunoglobulin ancestor. These show that these germline V-genes encode key side chain contacts with the viral antigen and thereby dictate key structural features of the hypermutated, high-affinity neutralizing antibody. V-genes may thus encode an innate, protective immunological memory that targets vulnerable, invariant sites on multiple pathogens.

Molecular epidemiology of primary human cytomegalovirus infection in pregnant women and their families

The source of human cytomegalovirus (HCMV) infection was investigated in 29 pregnant women with primary HCMV infection by comparing DNA sequences of UL146, UL144 and a portion of UL55 gene of HCMV strains circulating within each family. Thirteen families were identified in which the pregnant woman, the husband and/or a child were shedding HCMV. In three of these families, both the woman and the husband suffered from a concomitant primary HCMV infection. Phylogenetic analysis of UL146, UL144, and UL55 genes indicated that strains circulating within each family were identical, whereas strains from different families appeared to be distinct. However, identical UL146, UL144, and UL55 DNA sequences were observed sporadically among unrelated strains. A child rather than the husband was the virus source for the great majority of pregnant women. No association was observed between UL144 polymorphisms and intrauterine transmission.

The effect of the human cytomegalovirus pp65 IgG-avidity index for the human cytomegalovirus primary infection in mice model

Objective To investigate the significance of human cyomeg Movirus(HCMV)pp65 IgG antibody avidity index(AI)for the clinical diagnosis of HCMV primary infection through the experimental model of HCMV primaly infection in BALB/c mice.Methods 6～8 weeks,female,specific-pathogen-free BALB/c mice were divided into 5 groups.6 mice in each group. And he mice were injected with 2×106 PFU/m1,2×105 PFU/mi,2×104 PFU/ml,2×103 PFU/ml and 2×102 PFU/ml of HCMV intraperitoneally respectively. Another 6 mice were injected intraperitoneally with the maximum dose of HCMV kept at 56℃ for 30 min as inactivated virus group.And HF negative control group was established at same time. All the mice ere sacrificed to obtain brain and lung tissues for the following experiments after 1 montll.(1)Tissue samples obtained from mice were inoculated in human embryo fibroblasts(HF)monolayers after routine treatment for virus isolation.HCMV specific eytopathie effect(CPE) was observed bv inverted phase-contrast microscopy.HCMV UL83 DNA in the ultures as tested by PCR and pp65 antigen was detected by indirect immunofluorescence.(2)Extracted mRNA from tissue samples and HCMV pp67 mRNA were analyzed by reverse transcriptase PCR(RT-PcR).(3)Immunoglobulin M(IgM)antibody and immunoglobulin G(1gG)antibody avidity Was investigated for their usefulness in distinguishing primary genital HCMV infections rom nonprimary infections with ELISA kit using truncated pp65 protein.ResultsHCMV can be isolated in the tissues from the mice injected with 2×106 PFU/ml and 2×105 PFU/m1.RT- PCR and ELISA showed positive results in the same groups.The infective rates were 100%.The analysis of the low doses groups,inactivated group and HF negative ontrol group all showed negative results.Conclusions BALB/c mice can be infected with HCMV and appeared as primary infection after1 month.Determination of HCMV pp65 IgM and HCMV p065 IgG-AI by ELISA incorporated with virus isolation and RT-PCR are helpful for distinguishing primary infections from nonpfimary infections.The detection of HCMV p65 IgM and HCMV pp65 IgG-AI by ELISA utilizing recombinant protein pp5 as antigens can be used for preliminary screening. Key words: Cytomegalovirus infections; Disease models,animal; PhosphoproteinsImmunoglobuli G; Antibody affinity; Enzyme-linked immunosorbent assay

Dynamics of T cell memory in human cytomegalovirus infection

Primary human cytomegalovirus (HCMV) infection of an immunocompetent individual leads to the generation of a robust CD4+ and CD8+ T cell response which subsequently controls viral replication. HCMV is never cleared from the host and enters into latency with periodic reactivation and viral replication, which is controlled by reactivation of the memory T cells. In this article, we discuss the magnitude, phenotype and clonality of the T cell response following primary HCMV infection, the selection of responding T cells into the long-term memory pool and maintenance of this memory T cell population in the face of a latent/persistent infection. The article also considers the effect that this long-term surveillance of HCMV has on the T cell memory phenotype, their differentiation, function and the associated concepts of T cell memory inflation and immunosenescence.

Human Cytomegalovirus (HCMV) DNAemia in the Mother at Amniocentesis as a Risk Factor for Iatrogenic HCMV Infection of the Fetus

To investigate whether invasive procedures performed in the presence of human cytomegalovirus (HCMV) DNA in maternal peripheral blood (HCMV DNAemia) represent a risk for iatrogenic transmission of HCMV infection to the fetus, 194 pregnant women undergoing prenatal diagnosis because of a primary HCMV infection and their 199 fetuses were investigated. Overall, 27 (37%) of 73 mothers of uninfected fetuses and 22 (37%) of 59 mothers of infected fetuses were HCMV DNAemia-positive at amniocentesis. Of the 8 mothers of the 8 fetuses with false-negative amniocentesis results, 4 were DNAemia-positive and 4 were DNAemia-negative at amniocentesis. Therefore, maternal HCMV DNAemia is not a significant risk factor for iatrogenic HCMV transmission to the fetus during amniocentesis.

Generation of potent neutralizing human monoclonal antibodies against cytomegalovirus infection from immune B cells

BackgroundHuman monoclonal antibodies (mAbs) generated as a result of the immune response are likely to be the most effective therapeutic antibodies, particularly in the case of infectious diseases against which the immune response is protective.Human cytomegalovirus (HCMV) is an ubiquitous opportunistic virus that is the most serious pathogenic agent in transplant patients. The available therapeutic armamentarium (e.g. HCMV hyperimmune globulins or antivirals) is associated with severe side effects and the emergence of drug-resistant strains; therefore, neutralizing human mAb may be a decisive alternative in the prevention of primary and re-activated HCMV infections in these patients.ResultsThe purpose of this study was to generate neutralizing mAb against HCMV from the immunological repertoire of immune donors. To this aim, we designed an efficient technology relying on two discrete and sequential steps: first, human B-lymphocytes are stimulated with TLR9-agonists and IL-2; second, after both additives are removed, the cells are infected with EBV. Using this strategy we obtained 29 clones secreting IgG neutralizing the HCMV infectivity; four among these were further characterized. All of the mAbs neutralize the infection in different combinations of HCMV strains and target cells, with a potency ~20 fold higher than that of the HCMV hyperimmune globulins, currently used in transplant recipients. Recombinant human monoclonal IgG1 suitable as a prophylactic or therapeutic tool in clinical applications has been generated.ConclusionThe technology described has proven to be more reproducible, efficient and rapid than previously reported techniques, and can be adopted at low overall costs by any cell biology laboratory for the development of fully human mAbs for immunotherapeutic uses.

Development of Human Cytomegalovirus–Specific T Cell Immunity during Primary Infection of Pregnant Women and Its Correlation with Virus Transmission to the Fetus

We sought to study the development of human cytomegalovirus (HCMV)-specific T cell-mediated immune responses during primary HCMV infection in pregnancy. The HCMV-specific lymphoproliferative response (LPR) and intracellular cytokine (interferon [IFN]- gamma and interleukin [IL]-2) production were investigated during the first year after primary infection in 49 pregnant women and 9 nonpregnant control subjects. An HCMV-specific CD4(+) and CD8(+) T cell LPR was detected by the 5,6-carboxyfluorescein diacetate succinimidyl ester dilution method, and a cell-division index was calculated. The CD4(+) T cell LPR developed slightly earlier than the CD8(+) T cell LPR. However, CDI values for both T cell subpopulations were lower than those of seropositive control subjects in both pregnant and nonpregnant individuals. During the first month after infection, IFN- gamma -producing CD4(+) and CD8(+) T cells were consistently observed, whereas IL-2-producing T cells were very rarely detected in blood. A correlation between the development of HCMV-specific LPR and virus clearance from blood was observed. A significantly delayed development of the CD4(+) T cell LPR was observed in infected mothers who transmitted virus to the fetus, compared with those who did not. The development of adaptive T cell immunity after primary HCMV infection appears to be a complex and slow process until a memory T cell response develops. The T cell immune response appears to influence vertical HCMV transmission.

Adoptive immunotherapy of HCMV infection

Human cytomegalovirus (HCMV) infection or reactivation is a frequent cause of morbidity and mortality in immunocompromised individuals such as transplant recipients. Primary HCMV infection or reactivation of HCMV from latency is mostly asymptomatic in immunocompetent individuals and is controlled by the host's cell-mediated immune response. Healthy HCMV seropositive individuals develop high frequencies of HCMV-specific cytotoxic T lymphocytes (CTL) in the peripheral blood. Furthermore, a direct correlation between the recovery of HCMV-specific CTL responses and an improved outcome of HCMV disease could be demonstrated in immunocompromised patients. Deriving from these observations, the strategy of an adoptive transfer of HCMV-specific T cells has been developed. Protective immunity can be transferred successfully by the infusion of donor-derived HCMV-specific CD8+ cytotoxic T-cell clones or cell lines. In addition, several studies have supported the importance of antiviral effector functions of Th cells in maintaining CTL responses after adoptive transfer and their capacity to produce antiviral cytokines. Until today, a broad variety of clinical protocols for HCMV-specific immunotherapy has been published. These protocols vary regarding the isolation procedure, composition of cellular product, number of transferred cells and thus treatment efficacy. In this review, we aim to provide a comprehensive synopsis of the current standard of knowledge concerning cellular HCMV-specific immunotherapeutic approaches.

Strong selection of virus-specific cytotoxic CD4+ T-cell clones during primary human cytomegalovirus infection

AbstractTo obtain insight into human CD4+ T cell differentiation and selection in vivo, we longitudinally studied cytomegalovirus (CMV)–specific CD4+ T cells after primary infection. Early in infection, CMV-specific CD4+ T cells have the appearance of interferon γ (IFNγ)–producing T-helper 1 (TH1) type cells, whereas during latency a large population of CMV-specific CD4+CD28– T cells emerges with immediate cytotoxic capacity. We demonstrate that CD4+CD28– T cells could lyse CMV antigen–expressing target cells in a class II–dependent manner. To clarify the clonal relationship between early and late CMV-specific CD4+ T cells, we determined their Vβ usage and CDR3 sequences. The T-cell receptor β (TCRβ) diversity in the early CMV-specific CD4+ T-cell population was high in contrast to the use of a very restricted set of TCRβ sequences in latent infection. T-cell clones found in the late CMV-specific CD4+ T-cell population could not be retrieved from the early CD4+ T-cell population, or were present only at a low frequency. The observation that dominant CMV-specific CD4+ clones during latency were only poorly represented in the acute phase suggests that after the initial control of the virus strong selection and/or priming of novel clones takes place in persistent infections in humans.

Preconceptional Primary Human Cytomegalovirus Infection and Risk of Congenital Infection

The risk of vertical transmission of human cytomegalovirus (HCMV) was investigated in 14 women who had primary HCMV infection 2-18 weeks before their last menstrual period during 2001-2004. One (8.3%) of 12 newborns examined at birth was found to be subclinically infected. Preconceptional primary HCMV infection has a transmission rate that is significantly higher than that observed in an unselected newborn population but significantly lower than that associated with maternal infection during pregnancy. Although a safe time interval between primary infection and initiation of pregnancy still needs to be defined, documented information can now be provided during counseling.