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.

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.