HLA-G alleles and their impacts on placental HSV-1 infection in women from southern Brazil.

The Human Leukocyte Antigen G (HLA-G) is an immunoregulatory molecule with a critical role in pregnancy success. HLA-G alleles are associated with differential susceptibility to multiple conditions, including gestational problems, infectious diseases, and viral persistence. Of note, both herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) can impair HLA-G expression, interfering with HLA-G-associated immunoregulation. On the other hand, the impacts of HLA-G alleles on susceptibility to Herpesviridae infection is a neglected issue. Therefore, this study evaluated HLA-G allele frequencies and their associations with placental Herpesviridae infection in women from southern Brazil. Placenta samples were collected soon after delivery, and detection of viral DNA of HSV-1, HSV-2 and human cytomegalovirus (HCMV) was performed by polymerase chain reaction (PCR). A fragment of HLA-G (exons 2-4) was amplified by PCR, sequenced, and analyzed to allele determination. One hundred and seventy women had their alleles determined. Overall, 25 HLA-G alleles were found, distributed into 56 different genotypes. The most frequent alleles were G* 01:01:01 and G* 01:01:02, found in 37.9 % and 16.5 % of samples, respectively. Among the 170 women, 89 (52.4 %) tested positive for Herpesviridae DNA in the placenta, 55 (32.3 %) tested negative, 3 (1.8 %) were negative for HSV-1 and HSV-2 (with absent HCMV data), and 23 (13.5 %) were undetermined. The G* 01:01:01 allele was significantly associated with an increased risk of placental HSV-1 infection (p = 0.0151; OR=1.837; IC=1.108-3.045). This study describes new information concerning placental HLA-G alleles in women from southern Brazil and helps explain how genetic background can modify susceptibility to placental infections.

Impact of TLR7 and TLR9 polymorphisms on susceptibility to placental infections and pregnancy complications.

This study evaluated the impact of the TLR7 Gln11Leu (rs179008) and TLR9 -1237 T/C (rs5743836) single nucleotide polymorphisms (SNPs) on susceptibility to placental infections and pregnancy complications in 455 Brazilian women. Demographic, socioeconomic, gynecological, and clinical characteristics of the women were collected. Placental tissues were sampled from pregnant women and human and viral DNA was extracted. Human alphaherpesvirus 1 (Herpes simplex virus type 1, HSV-1), Human alphaherpesvirus 2 (Herpes simplex virus type 2, HSV-2) and Human betaherpesvirus 5 (Human cytomegalovirus, HCMV) were detected by nested PCR. TLR9 and TLR7 SNPs were genotyped by PCR amplification of bi-directional specific alleles (Bi-PASA) and restriction fragment length polymorphism (RFLP), respectively. Infections at the time of birth were detected in 45.71 % of women. The presence of the TT genotype (recessive model) of the TLR7 SNP was associated with increased susceptibility to HSV-1 infection (O.R. = 2.23, p = 0.05). The presence of the C allele of the TLR9 SNP, in heterozygosis or homozygosis (dominant model), decreased the infection risk by HCMV (O.R. = 0.31, p-mod<0.05). The TT genotype (recessive model) of the TLR7 SNP was significantly associated (p < 0.05) with increased occurrence of pre-treated hypertension. The codominant model of the TLR9 SNP was significantly associated (p < 0.05) with reduced risk of hospitalization during pregnancy. In combination, the AA/CT (TLR7-TLR9) genotypes significantly decreased the risk of placental infection by HSV-1 and/or HSV-2 (O.R. = 0.47, p = 0.02), the susceptibility to all infectious agents considered in combination (O.R. = 0.4, p = 0.00), and the need of hospitalization (O.R. = 0.48, p = 0.02). In conclusion, TLR7 and TLR9 SNPs are potential modulating factors for the risk of placental infections and pregnancy complications.

High Incidence of Herpes Simplex Virus-1 in Cord Blood and Placenta Infection of Women in Southern Brazil.

OBJECTIVE: Estimate the prevalence of human herpesvirus type 1 HSV-1 DNA in placental samples, its incidence in umbilical cord blood of newborns and the associated risk factors. METHODS: Placental biopsies and umbilical cord blood were analyzed, totaling 480 samples, from asymptomatic parturients and their newborns at a University Hospital. Nested polymerase chain reaction (PCR) and gene sequencing were used to identify the virus; odds ratio (OR) and relative risk (RR) were performed to compare risk factors associated with this condition. RESULTS: The prevalence of HSV-1 DNA in placental samples was 37.5%, and the incidence in cord blood was 27.5%. Hematogenous transplacental route was identified in 61.4% from HSV-1+ samples of umbilical cord blood paired with the placental tissue. No evidence of the virus was observed in the remaining 38.6% of placental tissues, suggesting an ascendant infection from the genital tract, without replication in the placental tissue, resulting in intra-amniotic infection and vertical transmission, seen by the virus in the cord blood. The lack of condom use increased the risk of finding HSV-1 in the placenta and umbilical cord blood. CONCLUSION: The occurrence of HSV-1 DNA in the placenta and in cord blood found suggests vertical transmission from asymptomatic pregnant women to the fetus.

OBJETIVO: Estimar a prevalência do DNA do vírus herpes humano 1 (HSV-1) em amostras de placenta, sua incidência no sangue do cordão umbilical de recém-nascidos e fatores de risco associados. MéTODOS: Biópsias de placenta e de sangue de cordão umbilical foram analisadas, totalizando 480 amostras de parturientes assintomáticas e seus recém-nascidos em um hospital universitário. Reação de cadeia de polimerase (RCP) nested e sequenciamento gênico foram usados para identificar o vírus; odds ratio (OR) e risco relativo (RR) foram realizados para comparar os fatores de risco associados à essa condição. RESULTADOS: A prevalência do DNA do HSV-1 em amostras de placenta foi de 37,5%, e a incidência no sangue do cordão foi de 27,5%. A via transplacentária hematogênica foi identificada em 61,4% das amostras de HSV-1 + do sangue do cordão umbilical, pareadas com o tecido placentário. Nenhuma evidência do vírus foi observada nos restantes 38,6% dos tecidos placentários, sugerindo uma infecção ascendente do trato genital. A falta de uso do preservativo aumentou o risco de encontrar o HSV-1 na placenta e no sangue do cordão umbilical. CONCLUSãO: A ocorrência de DNA do HSV-1 na placenta e no sangue do cordão umbilical sugere uma transmissão vertical de gestantes assintomáticas para o feto.

High incidence of herpes simplex virus-1 in cord blood and placenta infection of women in southern Brazil / Alta incidência do vírus herpes simplex 1 em sangue de cordão e infecção na placenta de mulheres no sul do Brasil

Abstract Objective Estimate the prevalence of human herpesvirus type 1 HSV-1 DNA in placental samples, its incidence in umbilical cord blood of newborns and the associated risk factors. Methods Placental biopsies and umbilical cord blood were analyzed, totaling 480 samples, from asymptomatic parturients and their newborns at a University Hospital. Nested polymerase chain reaction (PCR) and gene sequencingwere used to identify the virus; odds ratio (OR) and relative risk (RR) were performed to compare risk factors associated with this condition. Results The prevalence of HSV-1 DNA in placental samples was 37.5%, and the incidence in cord blood was 27.5%. Hematogenous transplacental route was identified in 61.4% from HSV-1+ samples of umbilical cord blood paired with the placental tissue. No evidence of the virus was observed in the remaining 38.6% of placental tissues, suggesting an ascendant infection from the genital tract, without replication in the placental tissue, resulting in intra-amniotic infection and vertical transmission, seen by the virus in the cord blood. The lack of condom use increased the risk of finding HSV-1 in the placenta and umbilical cord blood. Conclusion The occurrence of HSV-1 DNA in the placenta and in cord blood found suggests vertical transmission from asymptomatic pregnant women to the fetus.

Resumo Objetivo Estimar a prevalência do DNA do vírus herpes humano 1 (HSV-1) em amostras de placenta, sua incidência no sangue do cordão umbilical de recém-nascidos e fatores de risco associados. Métodos Biópsias de placenta e de sangue de cordão umbilical foram analisadas, totalizando 480 amostras de parturientes assintomáticas e seus recém-nascidos emum hospital universitário. Reação de cadeia de polimerase (RCP) nested e sequenciamento gênico foram usados para identificar o vírus; odds ratio (OR) e risco relativo (RR) foram realizados para comparar os fatores de risco associados à essa condição. Resultados A prevalência do DNA do HSV-1 em amostras de placenta foi de 37,5%, e a incidência no sangue do cordão foi de 27,5%. A via transplacentária hematogênica foi identificada em 61,4% das amostras de HSV-1+do sangue do cordão umbilical, pareadas com o tecido placentário. Nenhuma evidência do vírus foi observada nos restantes 38,6% dos tecidos placentários, sugerindo uma infecção ascendente do trato genital. A falta de uso do preservativo aumentou o risco de encontrar o HSV-1 na placenta e no sangue do cordão umbilical. Conclusão A ocorrência de DNA do HSV-1 na placenta e no sangue do cordão umbilical sugere uma transmissão vertical de gestantes assintomáticas para o feto.

Molecular and Clinical Profiles of Human Pegivirus Type 1 Infection in Individuals Living with HIV-1 in the Extreme South of Brazil.

Human pegivirus type 1 (HPgV-1) infection has been associated with a beneficial effect on the prognosis of human immunodeficiency virus type 1 (HIV-1)-coinfected individuals. However, the mechanisms involved in this protection are not yet fully elucidated. To date, circulating HPgV-1 genotypes in HIV-1-infected individuals have not yet been identified in the extreme south of Brazil. The present study aimed to determine the genotypic circulation of HPgV-1 and the influence of HPgV-1 status and persistence time on the evolution of HIV-1 infection. A retrospective cohort of 110 coinfected individuals was analyzed. Samples were subjected to viral RNA extraction, cDNA synthesis, nested PCR, and genotyping. Genotypes 1 (2.8%), 2 (47.9% of subtype 2a and 42.3% of subtype 2b), and 3 (7%) were identified. In antiretroviral treatment-naïve subjects HPgV-1 subtype 2b was associated with lower HIV-1 viral load (VL) rates (p = 0.04) and higher CD4+ T-cell counts (p = 0.03) than was subtype 2a, and the positivity for HPgV-1 was associated with higher CD4+ T-cell counts (p = 0.02). However, there was no significant difference in HIV-1 VL between HPgV-1-positive and HPgV-1-negative subjects (p = 0.08). There was no significant association between the different groups in HPgV-1 persistence and median HIV-1 VL (p = 0.66) or CD4+ T-cell counts (p = 0.15). HPgV-1 subtype 2b is associated with better prognosis of HIV-1 infection. Although HPgV-1 infection is persistent, our data suggest that the time of infection does not influence HIV-1 VL or CD4+ T-cell counts in coinfected subjects.

High prevalence and autochtonous transmission of human pegivirus (HPgV-1) in blood donors in the extreme southern of Brazil.

Recent studies have suggested that human pegivirus 1 (HPgV-1) may have some pathogenic potential. In the southernmost region of Brazil, studies on HPgV-1 are scarce, and circulating genotypes have not yet been identified. The current study aimed to evaluate the prevalence of HPgV-1 among blood donors from the southernmost region of Brazil and identify the genotypes involved with associated factors. A cross-sectional study was conducted with 281 blood donors, who had their plasma subjected to RNA extraction, complementary DNA synthesis, HPgV-1 detection by nested polymerase chain reaction, and subsequent genotyping. The observed prevalence of HPgV-1-RNA was 21.7%. The only variable that was significantly associated with virus infection was the relationship status of the donor. Single or no fixed partner blood donors were twice as likely to have HPgV-1 (95% CI, 1.12 to 4.56; P = 0.02). Genotype 2-subtypes 2b (69%) and 2a (29%)-was the most prevalent. In the absence of risk factors for parenteral transmission, it is likely that sexual transmission was the route of infection in the individuals studied. Further work will be needed to determine whether this virus is inert in the population, or if there are potential deleterious effects in infected individuals.

Herpes simplex virus type 2 IgG antibodies in sera of umbilical cord as a proxy for placental infection in asymptomatic pregnant women.

PROBLEM: Herpes simplex virus type 2 (HSV-2) infection is one of the most prevalent diseases worldwide and is mainly sexually transmitted. When infecting pregnant women, HSV-2 is able to infect the placenta, can reach the fetus, and may affect the fetal development. We sought to determine the prevalence of HSV-2 infection and reactivation in asymptomatic pregnant women, the correlation between IgG in the maternal circulation and cord blood, and the correlation between circulating IgG, placental, and newborn infection (blood cord). METHOD OF STUDY: Serum samples and placental tissues from pregnant women and umbilical cord blood samples from their newborns were collected. Anti-HSV-2 antibodies were identified by ELISA, and HSV-2 DNA was detected by nested PCR. RESULTS: The seropositivity of IgG in pregnant women was 29.7% and IgM was detected in 1 woman (0.5%). In the umbilical cord of newborns, 33.1% were IgG-positive and IgM was detected in 2 samples (1.5%). A positive correlation between HSV-2 IgG titers in serum from pregnant women and cord blood samples was found (r = .36, P = .001). A difference between the positive and negative placental groups (maternal side) was found in titers of IgG in sera of umbilical cord, which were significantly higher in the positive placental group (P = .004). CONCLUSION: We describe for the first time that newborns from mothers with HSV-2 placental infection have higher IgG titers in sera of umbilical cord, suggesting IgGs antibodies can be indicative of placental viral infection in asymptomatic women.

Characterisation of complete high- and low-risk human papillomavirus genomes isolated from cervical specimens in southern Brazil

The classification of human papillomavirus (HPV) intratypic lineages by complete genome sequencing is a determinant in understanding biological differences in association with this disease. In this work, we have characterised complete HPV genomes from southern Brazil. Fifteen cervicovaginal Pap smear negative samples previously categorised as HPV-positive were sequenced using ultradeep sequencing, and 18 complete genomes from 13 different HPV types were assembled. Phylogenetic and genetic distance analyses were performed to classify the HPV genomes into lineages and sublineages. This is the first report describing the distribution of HPV intratype lineages of high and low oncogenic risk in asymptomatic women from southern Brazil.

Characterisation of complete high- and low-risk human papillomavirus genomes isolated from cervical specimens in southern Brazil.

The classification of human papillomavirus (HPV) intratypic lineages by complete genome sequencing is a determinant in understanding biological differences in association with this disease. In this work, we have characterised complete HPV genomes from southern Brazil. Fifteen cervicovaginal Pap smear negative samples previously categorised as HPV-positive were sequenced using ultradeep sequencing, and 18 complete genomes from 13 different HPV types were assembled. Phylogenetic and genetic distance analyses were performed to classify the HPV genomes into lineages and sublineages. This is the first report describing the distribution of HPV intratype lineages of high and low oncogenic risk in asymptomatic women from southern Brazil.

Human papillomavirus type distribution and HPV16 intratype diversity in southern Brazil in women with and without cervical lesions

BACKGROUND Increasing evidence suggests that human papillomavirus (HPV) intratype variants (specific lineages and sublineages) are associated with pathogenesis and progression from HPV infection to persistence and the development of cervical cancer. OBJECTIVES This study aimed to verify the prevalence of HPV infection and distribution of HPV types and HPV16 variants in southern Brazil in women with normal cytology or intraepithelial lesions. METHODS HPV typing was determined by L1 gene sequencing. To identify HPV16 variants, the LCR and E6 regions were sequenced, and characteristic single nucleotide variants were identified. FINDINGS A total of 445 samples were studied, with 355 from cervical scrapes and 90 from cervical biopsies. HPV was detected in 24% and 91% of these samples, respectively. The most prevalent HPV types observed were 16 (cervical, 24%; biopsies, 57%) and 58 (cervical, 12%; biopsies, 12%). Seventy-five percent of the HPV16-positive samples were classified into lineages, with 88% defined as lineage A, 10% as lineage D, and 2% as lineage B. MAIN CONCLUSIONS This study identified a high frequency of European and North American HPV16 lineages, consistent with the genetic background of the human population in southern Brazil.

Human papillomavirus type distribution and HPV16 intratype diversity in southern Brazil in women with and without cervical lesions.

BACKGROUND: Increasing evidence suggests that human papillomavirus (HPV) intratype variants (specific lineages and sublineages) are associated with pathogenesis and progression from HPV infection to persistence and the development of cervical cancer. OBJECTIVES: This study aimed to verify the prevalence of HPV infection and distribution of HPV types and HPV16 variants in southern Brazil in women with normal cytology or intraepithelial lesions. METHODS: HPV typing was determined by L1 gene sequencing. To identify HPV16 variants, the LCR and E6 regions were sequenced, and characteristic single nucleotide variants were identified. FINDINGS: A total of 445 samples were studied, with 355 from cervical scrapes and 90 from cervical biopsies. HPV was detected in 24% and 91% of these samples, respectively. The most prevalent HPV types observed were 16 (cervical, 24%; biopsies, 57%) and 58 (cervical, 12%; biopsies, 12%). Seventy-five percent of the HPV16-positive samples were classified into lineages, with 88% defined as lineage A, 10% as lineage D, and 2% as lineage B. MAIN CONCLUSIONS: This study identified a high frequency of European and North American HPV16 lineages, consistent with the genetic background of the human population in southern Brazil.

Prevalence of herpes simplex virus types 1 and 2 at maternal and fetal sides of the placenta in asymptomatic pregnant women.

PROBLEM: Herpes simplex virus 1 (HSV-1) commonly causes orolabial infection, but can also infect the genital mucosa. In contrast, HSV-2 is usually genital. Genital herpes can transmit the virus vertically to the fetus during pregnancy. We sought to estimate the prevalence of HSV-1/2 on the maternal and fetal sides of the placenta. METHOD OF STUDY: Placental tissues were collected from pregnant women seen at the Rio Grande University Hospital. HSV-1 and HSV-2 were detected by nested PCR. RESULTS: The prevalence of HSV-1 and HSV-2 was, respectively, 28% and 12.6% (maternal side) and 29.9% and 8.3% (fetal side). All HSV-positive women were asymptomatic. Sexual behavior, vaginal delivery, and presence of HSVs on one side of the placenta were risk factors associated with HSV infection. CONCLUSION: The occurrence of HSVs in placental tissue was high, especially for HSV-1. Novel strategies need to be implemented for the management of asymptomatic women who might transmit HSV to their newborns.

Prevalence of human pegivirus (HPgV) infection in patients carrying HIV-1C or non-C in southern Brazil.

Previous studies have demonstrated that coinfection with HPgV is a protective factor for human immunodeficiency virus (HIV)-infected patients, leading to slower disease progression, and longer survival after established disease. The present study sought to estimate the prevalence of HPgV infection and associated risk factors in patients harboring C or non-C HIV-1 subtypes followed-up at HU-FURG, southern Brazil. Samples from 347 HIV-1-infected subjects were subjected to plasma RNA extraction, cDNA synthesis, HPgV RNA detection, and HIV-1 genotyping. The overall prevalence of HPgV RNA was 34%. Individuals aged 18-30 years had higher chances of infection compared with those 50 years or older (95%CI 1.18-52.36, P = 0.03). The number of sexual partner between one and three was a risk factor for HPgV infection (95%CI 1.54-10.23; P < 0.01), as well as the time since diagnosis of HIV-1 ≥ 11 years (95%CI 1.01-2.89; P = 0.04). Patients infected with HIV non-C subtypes had six times more chance of being HPgV-infected when compared to subtype C-infected subjects (95%CI 2.28-14.78; P < 0.01). This was the first study conducted in southern Brazil to find the circulation of HPgV. HIV/HPgV coinfection was associated with a longer survival among HIV+ patients. Of novelty, individuals infected by HIV non-C subtypes were more susceptible to HPgV infection. However, additional studies are needed to correlate the HIV-1 subtypes with HPgV infection and to clarify cellular and molecular pathways through which such associations are ruled. J. Med. Virol 88:2106-2114, 2016. © 2016 Wiley Periodicals, Inc.

[Frequency of Human Papillomavirus in the placenta, in the colostrum and in the umbilical cord blood]. / Frequência do Papilomavírus Humano na placenta, no colostro e no sangue do cordão umbilical.

PURPOSE: To determine the frequency of Human Papillomavirus (HPV) in the placenta, in the colostrum and in the umbilical cord blood of parturient women and their newborns assisted at the Clinic of Gynecology and Obstetrics of the University Hospital of Rio Grande (RS), Brazil. METHODS: Biopsies were collected from 150 placentas on the maternal side, 150 on the fetal side, 138 samples of umbilical cord blood and 118 of the colostrum. The placenta biopsies were collected from the central and peripheral portions. DNA was extracted according to the manufacturer's protocol and to a reference found in the literature. HPV was detected by the nested polymerase chain reaction (PCR-Nested) using primers MY09/11 and GP5/GP6. Genotyping was performed by direct sequencing. The participants responded to a self-applied questionnaire with demographic and clinical data, in order to characterize the sample. RESULTS: HPV was detected in 4% (6/150) of cases on the mother's side of the placentas, in 3.3% (5/150) on the fetal side, in 2.2% (3/138) in umbilical cord blood and in 0.84% (1/118) in colostrum samples. The vertical transmission rate was 50%. HPV-6 was the low-risk genotype found (60%) and the high-risk genotypes were HPV-16 and HPV-18 (20% each). CONCLUSIONS: These results suggest that HPV can infect the placenta, the colostrum and the umbilical cord blood.

Frequência do Papilomavírus Humano na placenta, no colostro e no sangue do cordão umbilical / Frequency of Human Papillomavirus in the placenta, in the colostrum and in the umbilical cord blood

OBJETIVO: Determinar a frequência do Papilomavírus Humano (HPV) na placenta, no colostro e no sangue do cordão umbilical de parturientes e seus neonatos atendidos no Ambulatório de Ginecologia e Obstetrícia do Hospital Universitário de Rio Grande (RS), Brasil. MÉTODOS: Foram coletadas biópsias de 150 placentas do lado materno, 150 do lado fetal, 138 amostras do sangue do cordão umbilical e 118 amostras de colostro. As biópsias de placenta foram coletadas da porção central e periférica. O DNA foi extraído segundo protocolo do fabricante e conforme referência encontrada na literatura. O HPV foi detectado pela técnica da reação em cadeia da polimerase aninhada (PCR-Nested) com os primers MY09/11 e GP5/GP6. A genotipagem foi por sequenciamento direto. As participantes responderam a um questionário autoaplicado com dados demográficos e clínicos, a fim de caracterizar a amostra. RESULTADOS: O HPV foi detectado em 4% (6/150) do lado materno das placentas, 3,3% (5/150) do lado fetal; 2,2% (3/138) no sangue do cordão e 0,8% (1/118) no colostro. A taxa de transmissão vertical foi de 50%. O genótipo de baixo risco oncogênico encontrado foi o HPV-6 (60%) e de alto risco, os HPV-16 e HPV-18 (20% cada). CONCLUSÕES: Esses resultados sugerem que o HPV pode infectar a placenta, o colostro e o sangue do cordão umbilical. .

PURPOSE: To determine the frequency of Human Papillomavirus (HPV) in the placenta, in the colostrum and in the umbilical cord blood of parturient women and their newborns assisted at the Clinic of Gynecology and Obstetrics of the University Hospital of Rio Grande (RS), Brazil. METHODS: Biopsies were collected from 150 placentas on the maternal side, 150 on the fetal side, 138 samples of umbilical cord blood and 118 of the colostrum. The placenta biopsies were collected from the central and peripheral portions. DNA was extracted according to the manufacturer's protocol and to a reference found in the literature. HPV was detected by the nested polymerase chain reaction (PCR-Nested) using primers MY09/11 and GP5/GP6. Genotyping was performed by direct sequencing. The participants responded to a self-applied questionnaire with demographic and clinical data, in order to characterize the sample. RESULTS: HPV was detected in 4% (6/150) of cases on the mother's side of the placentas, in 3.3% (5/150) on the fetal side, in 2.2% (3/138) in umbilical cord blood and in 0.84% (1/118) in colostrum samples. The vertical transmission rate was 50%. HPV-6 was the low-risk genotype found (60%) and the high-risk genotypes were HPV-16 and HPV-18 (20% each). CONCLUSIONS: These results suggest that HPV can infect the placenta, the colostrum and the umbilical cord blood. .

Herpes simplex virus: prevalence in placental tissue and incidence in neonatal cord blood samples.

Herpes simplex virus (HSV) infection is one of the most prevalent infectious diseases worldwide, with HSV-2 being primarily associated with genital infections. HSV-2 is believed to account for the majority of cases of neonatal herpes, which may cause diverse of complications in infected newborns. The present study sought to estimate the prevalence of HSV-2 in placental tissue samples and the incidence of HSV-2 in the umbilical cord blood of newborn infants. Placental tissue samples from 201 women (maternal-side and fetal-side = 402 specimens) and 184 neonatal cord blood samples, all collected at the obstetric ward of a University hospital were studied. HSV-2 was detected by means of nested PCR. The prevalence of HSV-2 in placental samples was 9.0% (n = 18), and the incidence of neonatal HSV-2 infection was 1.1% (n = 2). All HSV-2-positive patients were asymptomatic at the time of delivery and none reported genital herpes. Women with a time between rupture of membranes and delivery of ≥360 min had an approximately fourfold risk of HSV-2 infection in the placental tissue (95% CI 0.93-5.66, P = 0.01). These results suggest that HSV-2 is present in the placenta of asymptomatic women and that a risk of transmission to the neonate exists. New strategies must be implemented for the management of asymptomatic patients who are capable of transmitting the virus to the newborn.