SARS-CoV-2 (COVID-19) en gestación y placenta: una revisión narrativa sobre el estado del arte / SARS-CoV-2 (COVID-19) in pregnancy and placenta: a narrative review on state of the art

Resumen La crisis sanitaria por la pandemia de COVID-19, enfermedad generada por la infección con el SARS-CoV-2, ha llevado a la pérdida de más de 25,000 vidas en Chile, con más de 370,000 mujeres entre 15 y 44 años con infección confirmada. Se ha reportado una mayor vulnerabilidad de las mujeres gestantes en cuanto a desarrollar cuadros de COVID-19 graves o críticos, con un aumento de la incidencia de resultados obstétricos y perinatales adversos. Es relevante considerar que un alto porcentaje de las gestantes infectadas con SARS-CoV-2 son asintomáticas, lo cual nos pone en alerta en cuanto a que ciertos efectos del virus durante la gestación podrían no ser evidentes para la observación clínica. Se ha demostrado la presencia de SARS-CoV-2 en la placenta, asociándose la infección placentaria con alteraciones vasculares que podrían afectar el flujo útero-placentario. Por otro lado, la transmisión vertical al feto parece que es poco frecuente, pero factible. Se resumen las evidencias disponibles hasta el momento sobre los principales efectos de la COVID-19 en la gestación, con énfasis en los estudios sobre los efectos de la infección por SARS-CoV-2 en la placenta. El objetivo es relevar el tema, destacando que son diversas las preguntas que necesitan ser abordadas, considerando el impacto que esta pandemia podría tener sobre la salud gestacional.

Abstract In Chile, the COVID-19 pandemic, a disease induced by infection with SARS-CoV-2, has caused more than 25,000 deaths. More than 370,000 women between 15 and 44 years have been detected with the infection. The greater vulnerability of pregnant women has been reported, mainly related to a higher risk for severe or critical COVID-19, with an increased incidence of adverse obstetrics and perinatal outcomes. It is relevant to consider that a high percentage of pregnant women infected with SARS-CoV-2 are asymptomatic for COVID-19, which indicates that specific effects of the virus during pregnancy may not be evident from clinical observation. The presence of SARS-CoV-2 in the placenta has been demonstrated, associating placental infection with vascular alterations that could affect utero-placental flow. On the other hand, vertical transmission to the fetus is rare but feasible. This manuscript summarizes the evidence available to date on the main effects of COVID-19 in pregnancy, emphasizing studies about the impact of SARS-CoV-2 in the placenta. This review aims to promote this issue, highlighting that several questions need to be addressed, considering the effect this pandemic could have on gestational health.

SARS-CoV-2 Infection and Placental Pathology Infecção por SARS-CoV-2 e patologia placentária

Abstract Placental pathophysiology in SARS-CoV-2 infection can help researchers understand more about the infection and its impact on thematernal/neonatal outcomes. This brief review provides an overview about some aspects of the placental pathology in SARSCoV- 2 infection. In total, 11 papers were included. The current literature suggests that there are no specific histopathological characteristics in the placenta related to SARSCoV- 2 infection, but placentas frominfected women aremore likely to show findings of maternal and/or fetal malperfusion. The most common findings in placentas from infected women were fibrin deposition and intense recruitment of inflammatory infiltrates. The transplacental transmission of this virus is unlikely to occur, probably due to low expression of the receptor for SARS-CoV-2 in placental cell types. Further studies are needed to improve our knowledge about the interaction between the virus and the mother-fetus dyad and the impact on maternal and neonatal/fetal outcomes.

Resumo A fisiopatologia da placenta na infecção por SARS-CoV-2 pode ajudar os pesquisadores a entender mais sobre a infecção e seu impacto nos resultados maternos/neonatais. Esta revisão breve fornece uma visão geral sobre alguns aspectos da patologia placentária na infecção por SARS-CoV-2. Ao todo, 11 artigos foram incluídos. A literatura atual sugere que não há características histopatológicas específicas nas placentas relacionadas à infecção por SARS-CoV-2, mas as placentas de mulheres infectadas têm maior probabilidade de apresentar achados de má perfusão materna e/ou fetal. Os achados mais comuns em placentas de mulheres infectadas foram deposição de fibrina e intenso recrutamento de infiltrado inflamatório. A transmissão transplacentária deste vírus é improvável, devido à baixa expressão do receptor para SARS-CoV-2 em tipos de células da placenta. Mais estudos são necessários para melhorar nosso conhecimento sobre a interação entre o vírus e a díade mãe-feto e o impacto nos resultados maternos e neonatais/fetais.

Placental Sampling for Understanding Viral Infections - A Simplified Protocol for the COVID-19 Pandemic / Coleta placentária para entender infecções virais - Um protocolo simplificado para a pandemia de COVID-19

Abstract Objective The coronavirus disease 2019 (COVID-19) is a pandemic viral disease, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The impact of the disease among the obstetric population remains unclear, and the study of the placenta can provide valuable information. Adequate sampling of the placental tissue can help characterize the pathways of viral infections. Methods A protocol of placental sampling is proposed, aiming at guaranteeing representativity of the placenta and describing the adequate conservation of samples and their integrity for future analysis. The protocol is presented in its complete and simplified versions, allowing its implementation in different complexity settings. Results Sampling with the minimum possible interval from childbirth is the key for adequate sampling and storage. This protocol has already been implemented during the Zika virus outbreak. Conclusion A protocol for adequate sampling and storage of placental tissue is fundamental for adequate evaluation of viral infections on the placenta. During the COVID-19 pandemic, implementation of this protocol may help to elucidate critical aspects of the SARS-CoV-2 infection.

Resumo Objetivo A doença do novo coronavírus (COVID-19) é uma doença viral pandêmica causada pelo coronavírus da síndrome respiratória aguda 2 (SARS-CoV-2). O impacto da doença entre a população obstétrica ainda é incerto, e o estudo da placenta pode fornecer informações valiosas. Assim, a coleta adequada do tecido placentário pode ajudar a caracterizar algumas propriedades das infecções virais. Métodos Um protocolo de coleta placentária é proposto, objetivando a garantia de representatividade da placenta, descrevendo a maneira de conservação adequada das amostras, e visando garantir sua integridade para análises futuras. O protocolo é apresentado em suas versões completa e simplificada, permitindo sua implementação em diferentes configurações de infraestrutura. Resultados A amostragem com o intervalo mínimo possível do parto é essencial para coleta e armazenamento adequados. Esse protocolo já foi implementado durante a epidemia de vírus Zika. Conclusão Um protocolo para coleta e armazenamento adequados de tecido placentário é fundamental para a avaliação adequada de infecções virais na placenta. Durante a pandemia de COVID-19, a implementação deste protocolo pode ajudar a elucidar aspectos críticos da infecção por SARS-CoV-2.

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.

Zika virus damages the human placental barrier and presents marked fetal neurotropism

An unusually high incidence of microcephaly in newborns has recently been observed in Brazil. There is a temporal association between the increase in cases of microcephaly and the Zika virus (ZIKV) epidemic. Viral RNA has been detected in amniotic fluid samples, placental tissues and newborn and fetal brain tissues. However, much remains to be determined concerning the association between ZIKV infection and fetal malformations. In this study, we provide evidence of the transplacental transmission of ZIKV through the detection of viral proteins and viral RNA in placental tissue samples from expectant mothers infected at different stages of gestation. We observed chronic placentitis (TORCH type) with viral protein detection by immunohistochemistry in Hofbauer cells and some histiocytes in the intervillous spaces. We also demonstrated the neurotropism of the virus via the detection of viral proteins in glial cells and in some endothelial cells and the observation of scattered foci of microcalcifications in the brain tissues. Lesions were mainly located in the white matter. ZIKV RNA was also detected in these tissues by real-time-polymerase chain reaction. We believe that these findings will contribute to the body of knowledge of the mechanisms of ZIKV transmission, interactions between the virus and host cells and viral tropism.

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. .

Coxsackievirus B Infection Is Highly Related with Missed Abortion in Korea

PURPOSE: This study investigated the possible relationship between viral infection and first trimester pregnancy loss. MATERIALS AND METHODS: A prospective study was performed on 51 gravidas with missed abortion, fetal anomaly, pre-term delivery, and full-tem delivery at Hanyang University Hospital. Enteroviruses were detected by semi-nested reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry in abortive tissues and placentas. Enterovirus serotypes were confirmed by genome sequencing. Herpesviruses were detected by PCR. RESULTS: Coxsackievirus B3 (CVB3) was detected in 8 of 14 missed abortion cases, 1 of 27 full-term cases, and none of the 9 pre-term cases. Coxsackievirus B1 (CVB1) was detected in an encephalocele case. Herpes simplex virus type 1 was found in 4 full-term cases, 3 pre-term cases, and none of the missed abortion cases. CONCLUSION: The prevalence of CVB3 was significantly higher in missed abortion cases compared to full-term or pre-term delivery cases. CVB infection may therefore be an important etiological agent of missed abortion.

Antiviral activity of bovine uterus and placenta induced by Newcastle disease virus

The antiviral activity profile of the uterus and fetal membranes from bovine placenta, induced by the Newcastle disease virus (NDV) throughout gestation, was investigated. Explants of the endometrium and caruncles were collected from the uterus, and amniochorion, allantochorion and cotyledons, from fetal placenta. Tissue cultures were induced with ~6.0 hemagglutinating units (HU) of NDV. Supernatants were concentrated 20 fold, filtered in 100kDa cut-off membranes and antiviral activity was titrated in MDBK x VSV system. Tissues of the uterus did not exhibit antiviral activity, while allantochorion and amniochorion produced antiviral factors throughout gestation. Antiviral factors were not related with IFN-alpha, gamma, tau or TNF-alpha. The antiviral activity pattern observed showed to be related with the development of fetal membranes and increased at the end of pregnancy. Such data suggest that IFN genes inducible by virus are present in fetal membranes of the cow placenta and their expression is dependent on the age of gestation.

Investigou-se a atividade antiviral do útero e da placenta bovina, ao longo da gestação, induzidos pelo vírus da doença de Newcastle (NDV). Explantes do endométrio e carúnculas foram colhidos do útero. Os tecidos corioamniótico, corioalantóide e cotilédones foram dissecados da placenta fetal. Os cultivos celulares foram induzidos com aproximadamente 6,0 unidades hemaglutinantes do NDV. Os sobrenadantes foram concentrados 20 vezes, filtrados em dispositivos com superfície de separação de 100kDa e a atividade antiviral foi titulada em células MDBK e vírus da estomatite vesicular (VSV). Endométrio, carúnculas e cotilédones não apresentaram atividade antiviral. Corioamniótico e corioalantóide produziram fatores antivirais ao longo da gestação. Estes fatores não foram relacionados aos IFN - alfa, gama ou tau e nem ao TNF - alfa. O padrão de produção de fatores antivirais acompanhou o desenvolvimento dos tecidos fetais e títulos mais altos foram observados no final da gestação. Estes dados sugerem que os genes de IFNs induzidos por vírus localizam-se nas membranas fetais da placenta e a expressão desses genes é dependente do estádio da gestação.

Detection of parvovirus B19 infection in formalin-fixed and paraffin-embedded placenta and fetal tissues

Parvovirus B19 infection was first discovered in 1975 and it is implicated in fetal death from hydrops fetalis the world over. Diagnosis is usually made through histological identification of the intranuclear inclusion in placenta and fetal organs. However, these cells may be scarce or uncharacteristic, making definitive diagnosis difficult. We analyzed histologically placentas and fetal organs from 34 cases of non-immune hydrops fetalis, stained with Hematoxylin and Eosin (HE) and submitted to immunohistochemistry and polymerase chain reaction (PCR). Of 34 tissue samples, two (5.9 percent) presented typical intranuclear inclusion in circulating normoblasts seen in Hematoxylin and Eosin stained sections, confirmed by immunohistochemistry and PCR. However, PCR of fetal organs was negative in one case in which the placenta PCR was positive. We concluded that parvovirus B19 infection frequency is similar to the literature and that immunohistochemistry was the best detection method. It is highly specific and sensitive, preserves the morphology and reveals a larger number of positive cells than does HE with the advantage of showing cytoplasmic and nuclear positivity, making it more reliable. Although PCR is more specific and sensitive in fresh or ideally fixed material it is not so in formalin-fixed paraffin-embedded tissues, frequently the only one available in such cases.

O parvovírus B19 foi detectado em 1975 e desde sua descoberta tem se mostrado um agente infeccioso importante em seres humanos, cujo diagnóstico pode ser feito pelo exame histológico através do encontro de inclusão nuclear em tecidos fetais ou placentários. No entanto, estas células podem ser escassas ou não apresentarem características típicas, dificultando o diagnóstico. Analisamos placentas e órgãos fetais de 34 casos de hidropisia fetal não-imune corados com Hematoxilina e Eosina (HE) e submetidos à reação em cadeia da polimerase (PCR) e imuno-histoquímica (IH). Em dois casos (5,9 por cento) houve positividade na placenta pelo HE, IH e PCR. No entanto, PCR dos órgãos fetais foi negativa em um destes casos enquanto que a identificação pôde ser feita por IH e histologia. Concluímos que a freqüência do parvovírus B19 é similar à literatura e a reação IH foi o melhor método de detecção, com identificação mais específica e segura, permitindo identificação citoplasmática, o que não é possível pelo exame histopatológico. A PCR pode apresentar falsa negatividade, provavelmente pela fixação, não identifica as células e é mais dispendiosa. Embora mais específica e sensível em material a fresco ou idealmente fixado isto não ocorre com tecidos fixados em formalina e embebidos em parafina, freqüentemente os únicos disponíveis.

Detection of human parvovirus B19 nonstrutural protein DNA by nested-polymerase chain reaction in gravida serum and pregnant tissues / 华中科技大学学报（医学）（英德文版）

A new nested-polymerase chain reaction (nested-PCR) assay was developed to detect human parvovirus B19 DNA corresponding to the nonstructural protein in clinical specimens in a routine diagnostic laboratory. The sensitivity of this highly specific assay was up to 0.005 fg of B19 DNA. Parvovirus B19 was identified in sera of 20 pregnant women with abnormal pregnant outcome. Among these 20 cases, intrauterine parvovirus infection did exist in 7 pregnant women because parvovirus B19 DNA was detected in the pregnant tissues of them such as placenta tissues, chorionic villi, amniotic fluid, fetal spleen, liver and abdominal fluids.