Targeted in situ cross-linking mass spectrometry and integrative modeling reveal the architectures of three proteins from SARS-CoV-2.

Atomic structures of several proteins from the coronavirus family are still partial or unavailable. A possible reason for this gap is the instability of these proteins outside of the cellular context, thereby prompting the use of in-cell approaches. In situ cross-linking and mass spectrometry (in situ CLMS) can provide information on the structures of such proteins as they occur in the intact cell. Here, we applied targeted in situ CLMS to structurally probe Nsp1, Nsp2, and nucleocapsid (N) proteins from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and obtained cross-link sets with an average density of one cross-link per 20 residues. We then employed integrative modeling that computationally combined the cross-linking data with domain structures to determine full-length atomic models. For the Nsp2, the cross-links report on a complex topology with long-range interactions. Integrative modeling with structural prediction of individual domains by the AlphaFold2 system allowed us to generate a single consistent all-atom model of the full-length Nsp2. The model reveals three putative metal binding sites and suggests a role for Nsp2 in zinc regulation within the replication-transcription complex. For the N protein, we identified multiple intra- and interdomain cross-links. Our integrative model of the N dimer demonstrates that it can accommodate three single RNA strands simultaneously, both stereochemically and electrostatically. For the Nsp1, cross-links with the 40S ribosome were highly consistent with recent cryogenic electron microscopy structures. These results highlight the importance of cellular context for the structural probing of recalcitrant proteins and demonstrate the effectiveness of targeted in situ CLMS and integrative modeling.

Kinetics of Maternally Derived Anti-Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Antibodies in Infants in Relation to the Timing of Antenatal Vaccination.

BACKGROUND: SARS-CoV-2 infection during early infancy can result in severe disease. We evaluated the durability of maternally-derived anti-SARS-CoV-2 antibodies in infants and its relation to antenatal vaccination timing. METHODS: Sera were prospectively collected at birth and 3 months after delivery from mother-infant pairs following antenatal BNT162b2 vaccination. SARS-CoV-2 receptor binding domain (RBD)-specific IgG levels and neutralizing activity were evaluated. RESULTS: 56 mother-infant pairs were included: 15 (26.8%) were vaccinated in the first trimester, 16 (28.6%) in the second trimester, and 25 (44.6%) in the third trimester.At the time of delivery, all neonates were positive for anti-RBD-specific IgG with a median concentration of 4046 [IQR 2446-7896] AU/mL, with the highest concentration found after third trimester vaccination (median 6763 [IQR 3857-12561] AU/mL). At 3 months after delivery, anti RBD-specific IgG levels in infants significantly waned with a median concentration of 545 [IQR 344-810] AU/mL (P < .001). The half-life of anti-RBD-specific IgG was 66 days among mothers and 30 days among infants. While at the time of delivery, all neonates had detectable neutralizing activity regardless of gestational age at vaccination, at 3-months of age, a higher proportion of infants born to mothers vaccinated in third trimester had persistent neutralizing activity as compared to those born to mothers vaccinated in second trimester. CONCLUSIONS: Maternal vaccination leads to efficient transplacental antibody transfer, with persistent anti-SARS-CoV-2 antibodies detected at 3 months of age in all infants. The observed effect of antenatal immunization timing on the kinetics of maternally-derived antibodies may have implications for SARS-CoV-2 vaccination strategies.

The human cytomegalovirus protein UL147A downregulates the most prevalent MICA allele: MICA*008, to evade NK cell-mediated killing.

Natural killer (NK) cells are innate immune lymphocytes capable of killing target cells without prior sensitization. One pivotal activating NK receptor is NKG2D, which binds a family of eight ligands, including the major histocompatibility complex (MHC) class I-related chain A (MICA). Human cytomegalovirus (HCMV) is a ubiquitous betaherpesvirus causing morbidity and mortality in immunosuppressed patients and congenitally infected infants. HCMV encodes multiple antagonists of NK cell activation, including many mechanisms targeting MICA. However, only one of these mechanisms, the HCMV protein US9, counters the most prevalent MICA allele, MICA*008. Here, we discover that a hitherto uncharacterized HCMV protein, UL147A, specifically downregulates MICA*008. UL147A primarily induces MICA*008 maturation arrest, and additionally targets it to proteasomal degradation, acting additively with US9 during HCMV infection. Thus, UL147A hinders NKG2D-mediated elimination of HCMV-infected cells by NK cells. Mechanistic analyses disclose that the non-canonical GPI anchoring pathway of immature MICA*008 constitutes the determinant of UL147A specificity for this MICA allele. These findings advance our understanding of the complex and rapidly evolving HCMV immune evasion mechanisms, which may facilitate the development of antiviral drugs and vaccines.

SARS-CoV-2 receptor binding domain fusion protein efficiently neutralizes virus infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the COVID-19 pandemic. Currently, as dangerous mutations emerge, there is an increased demand for specific treatments for SARS-CoV-2 infected patients. The spike glycoprotein on the virus envelope binds to the angiotensin converting enzyme 2 (ACE2) on host cells through its receptor binding domain (RBD) to mediate virus entry. Thus, blocking this interaction may inhibit viral entry and consequently stop infection. Here, we generated fusion proteins composed of the extracellular portions of ACE2 and RBD fused to the Fc portion of human IgG1 (ACE2-Ig and RBD-Ig, respectively). We demonstrate that ACE2-Ig is enzymatically active and that it can be recognized by the SARS-CoV-2 RBD, independently of its enzymatic activity. We further show that RBD-Ig efficiently inhibits in-vivo SARS-CoV-2 infection better than ACE2-Ig. Mechanistically, we show that anti-spike antibody generation, ACE2 enzymatic activity, and ACE2 surface expression were not affected by RBD-Ig. Finally, we show that RBD-Ig is more efficient than ACE2-Ig at neutralizing high virus titers. We thus propose that RBD-Ig physically blocks virus infection by binding to ACE2 and that RBD-Ig should be used for the treatment of SARS-CoV-2-infected patients.

Severe Acute Respiratory Syndrome Coronavirus 2 Third Vaccine Immune Response in Multiple Sclerosis Patients Treated with Ocrelizumab.

The introduction of a third-dose vaccination along with new variants of concern raises questions regarding serology and T-cell responses in patients with multiple sclerosis (pwMS) treated with B-cell depletion who develop attenuated humoral response to vaccines. The aim of this study was to longitudinally evaluate humoral and cellular response to SARS-CoV-2 mRNA vaccine in ocrelizumab-treated pwMS before and following a third vaccine dose. Following the third vaccine dose, patients who are low or nonresponders following initial vaccination did not increase antibody titers. In healthy controls and ocrelizumab-treated pwMS, cellular response decreased 6 months after initial vaccination and increased significantly after the third dose. ANN NEUROL 2022;91:796-800.

High rate of adenovirus detection in gastrointestinal biopsies of symptomatic stem cell transplant recipients.

OBJECTIVES: The gastrointestinal (GI) tract is a major human adenovirus (HAdV) replication site in patients undergoing hematopoietic stem cell transplantation (HSCT), yet the prevalence and correlates of HAdV GI infection in this setting have remained poorly recognized, especially among adult HSCT recipients. DESIGN OR METHODS: We retrospectively studied the prevalence and risk factors of HAdV GI-tissue infection in HSCT recipients (73 adults and 15 children) with GI symptoms who underwent GI-tissue biopsy between January-2012 and December-2017. The presence of HAdV in the GI tissues was determined by real-time PCR. RESULTS: HAdV GI-tissue infection was detected in 21 (23.9%) patients, with similar infection rates identified in adults and children. GI-tissue detection was more common at late (>100 days) compared to early times post-transplantation (50% vs. 12.9%, p < .001). The presence of bloody diarrhea, Arab ethnicity (p = .014) and concurrent cytomegalovirus GI-tissue detection (p = .025) were significantly correlated with HAdV GI-tissue infection, while chronic graft versus host disease was of borderline association (p = .055). CONCLUSIONS: Our findings reveal a high rate and new clinical-demographic correlates of HAdV GI-tissue infection in adult and pediatric HSCT recipients with GI symptoms. The findings highlight the need for future prospective studies to assess the relatedness of HAdV infection to the GI symptoms, and the prevalence, impact, and treatment of HAdV GI infection in HSCT recipients.

Platelet count and risk of severe illness in hospitalised children with Influenza-Like illness.

AIM: To examine the clinical significance of thrombocytosis (platelets > 500 × 109 /L) in admitted children with an influenza-like illness. METHODS: We performed a database analysis consisting of patients evaluated at our medical centers with an influenza-like illness between 2009 and 2013. We included paediatric patients and examined the association between platelet count, respiratory viral infections, and admission outcomes (hospital length of stay and admission to the paediatric intensive care unit) using regression models adjusting for multiple variables. RESULTS: A total of 5171 children were included in the study cohort (median age 0.8 years; interquartile range, 0.2-1.8; 58% male). Younger age, and not the type of viral infection, was associated with a high platelet count (p < 0.001). Elevated platelet count independently predicted admission outcomes (p ≤ 0.05). The presence of thrombocytosis was associated with an increased risk for a prolonged length of stay (odds ratio = 1.2; 95% Confidence interval = 1.1 to 1.4; p = 0.003) and admission to the paediatric intensive care unit (odds ratio = 1.5; 95% Confidence interval = 1.1 to 2.0; p = 0.002). CONCLUSION: In children admitted with an influenza-like illness, a high platelet count is an independent predictor of admission outcomes. Platelet count may be used to improve risk assessment and management decisions in these paediatric patients.

A mutation in POLR3E impairs antiviral immune response and RNA polymerase III.

RNA polymerase (Pol) III has a noncanonical role of viral DNA sensing in the innate immune system. This polymerase transcribes viral genomes to produce RNAs that lead to induction of type I interferons (IFNs). However, the genetic and functional links of Pol III to innate immunity in humans remain largely unknown. Here, we describe a rare homozygous mutation (D40H) in the POLR3E gene, coding for a protein subunit of Pol III, in a child with recurrent and systemic viral infections and Langerhans cell histiocytosis. Fibroblasts derived from the patient exhibit impaired induction of type I IFN and increased susceptibility to human cytomegalovirus (HCMV) infection. Cultured cell lines infected with HCMV show induction of POLR3E expression. However, induction is not restricted to DNA virus, as sindbis virus, an RNA virus, enhances the expression of this protein. Likewise, foreign nonviral DNA elevates the steady-state level of POLR3E and elicits promoter-dependent and -independent transcription by Pol III. Remarkably, the molecular mechanism underlying the D40H mutation of POLR3E involves the assembly of defective initiation complexes of Pol III. Our study links mutated POLR3E and Pol III to an innate immune deficiency state in humans.

Severe Acute Respiratory Syndrome Coronavirus 2 in Infants Younger Than 90 Days Presenting to the Pediatric Emergency Department: Clinical Characteristics and Risk of Serious Bacterial Infection.

OBJECTIVES: There are scant data on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in infants younger than 90 days. This study was designed to characterize COVID-19 presentation and clinical course in this age group and evaluate the risk of serious bacterial infection. METHODS: Data on all SARS-CoV-2-polymerase chain reaction-positive infants presenting to the pediatric emergency department (PED) were retrospectively collected, followed by a case-control study comparing those infants presenting with fever (COVID group) to febrile infants presenting to the PED and found to be SARS-CoV-2 negative (control group). RESULTS: Of the 96 PCR-positive SARS-CoV-2 infants who met the inclusion criteria, the most common presenting symptom was fever (74/96, 77.1%) followed by upper respiratory tract infection symptoms (42/96, 43.8%). Four (4.2%) presented with symptoms consistent with brief resolved unexplained event (4.2%).Among the febrile infants, the presenting symptoms and vital signs were similar in the COVID and control groups, with the exception of irritability, which was more common in the control group (8% and 26%; P < 0.01). The SARS-CoV-2-positive infants had decreased inflammatory markers including: C-reactive protein (0.6 ± 1 mg/dL vs 2.1 ± 2.7 mg/dL; P < 0.0001), white blood cell count (9.3 ± 3.4 × 10 9 /L vs 11.8 ± 5.1 × 10 9 /L; P < 0.001), and absolute neutrophils count (3.4 ± 2.4 × 10 9 /L vs 5.1 ± 3.7 × 10 9 /L; P < 0.001). The rate of invasive bacterial infection was similar between groups (1.4% and 0%; P = 0.31). No mortality was recorded. Although not significantly different, urinary tract infections were less common in the COVID group (7% and 16%; P = 0.07). CONCLUSIONS: The SARS-CoV-2 infection in infants aged 0 to 90 days who present to the PED seems to be mostly mild and self-limiting, with no increased risk of serious bacterial infection.

Maternal and Neonatal Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Variant Neutralization After Antenatal Messenger RNA Vaccination.

We evaluated the neutralization efficiency against SARS-CoV-2 Omicron variant in maternal and cord blood sera after antenatal BNT162b2 vaccination. Neutralizing antibodies against Omicron were lacking at the time of delivery after 2-dose vaccination. A third booster dose was essential in building neutralizing antibody capacity against Omicron among mothers and neonates.

The Effect of Gestational Age at BNT162b2 mRNA Vaccination on Maternal and Neonatal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Antibody Levels.

BACKGROUND: Coronavirus disease 2019 (COVID-19) during pregnancy and early infancy can result in severe disease. Evaluating the effect of gestational age at the time of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination on maternal antibody levels and transplacental antibody transfer has important implications for maternal care and vaccination strategies. METHODS: Maternal and cord blood sera were collected from mother-newborn dyads (n = 402), following term delivery after antenatal 2-dose SARS-CoV-2 BNT162b2 mRNA vaccination. SARS-CoV-2 spike protein (S) and receptor binding domain (RBD)-specific IgG levels were evaluated in the samples collected. RESULTS: Median anti-S and anti-RBD-specific IgG levels in maternal sera at the time of delivery were lowest following first-trimester vaccination (n = 90; anti-S IgG: 76 AU/mL; anti-RBD-specific IgG: 478 AU/mL), intermediate in those vaccinated in the second trimester (n = 124; anti-S IgG: 126 AU/mL; anti-RBD-specific IgG: 1263 AU/mL), and highest after third-trimester vaccination (n = 188; anti-S IgG: 240 AU/mL; anti-RBD-specific IgG: 5855 AU/mL). Antibody levels in neonatal sera followed a similar pattern and were lowest following antenatal vaccination in the first trimester (anti-S IgG: 126 AU/mL; anti-RBD-specific IgG: 1140 AU/mL). In a subgroup of parturients vaccinated in the first trimester (n = 30), a third booster dose was associated with significantly higher maternal and neonatal antibody levels. CONCLUSIONS: These results suggest a considerable antibody waning throughout pregnancy in those vaccinated at early gestation. The observed boosting effect of a third vaccine dose hints at its potential benefit in those who completed the 2-dose vaccine series at early pregnancy or before conception. The impact of antenatal immunization timing on SARS-CoV-2 transplacental antibody transfer may influence neonatal seroprotection.

External Quality Assessment of SARS-CoV-2 Sequencing: an ESGMD-SSM Pilot Trial across 15 European Laboratories.

This first pilot trial on external quality assessment (EQA) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) whole-genome sequencing, initiated by the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Genomic and Molecular Diagnostics (ESGMD) and the Swiss Society for Microbiology (SSM), aims to build a framework between laboratories in order to improve pathogen surveillance sequencing. Ten samples with various viral loads were sent out to 15 clinical laboratories that had free choice of sequencing methods and bioinformatic analyses. The key aspects on which the individual centers were compared were the identification of (i) single nucleotide polymorphisms (SNPs) and indels, (ii) Pango lineages, and (iii) clusters between samples. The participating laboratories used a wide array of methods and analysis pipelines. Most were able to generate whole genomes for all samples. Genomes were sequenced to various depths (up to a 100-fold difference across centers). There was a very good consensus regarding the majority of reporting criteria, but there were a few discrepancies in lineage and cluster assignments. Additionally, there were inconsistencies in variant calling. The main reasons for discrepancies were missing data, bioinformatic choices, and interpretation of data. The pilot EQA was overall a success. It was able to show the high quality of participating laboratories and provide valuable feedback in cases where problems occurred, thereby improving the sequencing setup of laboratories. A larger follow-up EQA should, however, improve on defining the variables and format of the report. Additionally, contamination and/or minority variants should be a further aspect of assessment.

Human Nasal and Lung Tissues Infected Ex Vivo with SARS-CoV-2 Provide Insights into Differential Tissue-Specific and Virus-Specific Innate Immune Responses in the Upper and Lower Respiratory Tract.

The nasal mucosa constitutes the primary entry site for respiratory viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). While the imbalanced innate immune response of end-stage coronavirus disease 2019 (COVID-19) has been extensively studied, the earliest stages of SARS-CoV-2 infection at the mucosal entry site have remained unexplored. Here, we employed SARS-CoV-2 and influenza virus infection in native multi-cell-type human nasal turbinate and lung tissues ex vivo, coupled with genome-wide transcriptional analysis, to investigate viral susceptibility and early patterns of local mucosal innate immune response in the authentic milieu of the human respiratory tract. SARS-CoV-2 productively infected the nasal turbinate tissues, predominantly targeting respiratory epithelial cells, with a rapid increase in tissue-associated viral subgenomic mRNA and secretion of infectious viral progeny. Importantly, SARS-CoV-2 infection triggered robust antiviral and inflammatory innate immune responses in the nasal mucosa. The upregulation of interferon-stimulated genes, cytokines, and chemokines, related to interferon signaling and immune-cell activation pathways, was broader than that triggered by influenza virus infection. Conversely, lung tissues exhibited a restricted innate immune response to SARS-CoV-2, with a conspicuous lack of type I and III interferon upregulation, contrasting with their vigorous innate immune response to influenza virus. Our findings reveal differential tissue-specific innate immune responses in the upper and lower respiratory tracts that are specific to SARS-CoV-2. The studies shed light on the role of the nasal mucosa in active viral transmission and immune defense, implying a window of opportunity for early interventions, whereas the restricted innate immune response in early-SARS-CoV-2-infected lung tissues could underlie the unique uncontrolled late-phase lung damage of advanced COVID-19. IMPORTANCE In order to reduce the late-phase morbidity and mortality of COVID-19, there is a need to better understand and target the earliest stages of SARS-CoV-2 infection in the human respiratory tract. Here, we have studied the initial steps of SARS-CoV-2 infection and the consequent innate immune responses within the natural multicellular complexity of human nasal mucosal and lung tissues. Comparing the global innate response patterns of nasal and lung tissues infected in parallel with SARS-CoV-2 and influenza virus, we found distinct virus-host interactions in the upper and lower respiratory tract, which could determine the outcome and unique pathogenesis of SARS-CoV-2 infection. Studies in the nasal mucosal infection model can be employed to assess the impact of viral evolutionary changes and evaluate new therapeutic and preventive measures against SARS-CoV-2 and other human respiratory pathogens.

Drivers of within-host genetic diversity in acute infections of viruses.

Genetic diversity is the fuel of evolution and facilitates adaptation to novel environments. However, our understanding of what drives differences in the genetic diversity during the early stages of viral infection is somewhat limited. Here, we use ultra-deep sequencing to interrogate 43 clinical samples taken from early infections of the human-infecting viruses HIV, RSV and CMV. Hundreds to thousands of virus templates were sequenced per sample, allowing us to reveal dramatic differences in within-host genetic diversity among virus populations. We found that increased diversity was mostly driven by presence of multiple divergent genotypes in HIV and CMV samples, which we suggest reflect multiple transmitted/founder viruses. Conversely, we detected an abundance of low frequency hyper-edited genomes in RSV samples, presumably reflecting defective virus genomes (DVGs). We suggest that RSV is characterized by higher levels of cellular co-infection, which allow for complementation and hence elevated levels of DVGs.

The human cytomegalovirus microRNA miR-UL112 acts synergistically with a cellular microRNA to escape immune elimination.

Although approximately 200 viral microRNAs are known, only very few share similar targets with their host's microRNAs. A notable example of this is the stress-induced ligand MICB, which is targeted by several distinct viral and cellular microRNAs. Through the investigation of the microRNA-mediated immune-evasion strategies of herpesviruses, we initially identified two new cellular microRNAs that targeted MICB and were expressed differently both in healthy tissues and during melanocyte transformation. We show that coexpression of various pairs of cellular microRNAs interfered with the downregulation of MICB, whereas the viral microRNAs optimized their targeting ability to efficiently downregulate MICB. Moreover, we demonstrate that through site proximity and possibly inhibition of translation, a human cytomegalovirus (HCMV) microRNA acts synergistically with a cellular microRNA to suppress MICB expression during HCMV infection.

Boosting maternal and neonatal humoral immunity following SARS-CoV-2 infection using a single messenger RNA vaccine dose.

BACKGROUND: Post-COVID-19 vaccine boosting is a potent tool in the ongoing pandemic. Relevant data regarding this approach during pregnancy are lacking, which affects vaccination policy guidance, public acceptance, and vaccine uptake during pregnancy. We aimed to investigate the dynamics of anti-SARS-CoV-2 antibody levels following SARS-CoV-2 infection during pregnancy and to characterize the effect of a single postinfection vaccine booster dose on the anti-SARS-CoV-2 antibody levels in parturients in comparison with the levels in naïve vaccinated and convalescent, nonboosted parturients. STUDY DESIGN: Serum samples prospectively collected from parturients and umbilical cords at delivery at our university-affiliated urban medical center in Jerusalem, Israel, from May to October 2021, were selected and analyzed in a case-control manner. Study groups comprised the following participants: a consecutive sample of parturients with a polymerase chain reaction-confirmed history of COVID-19 during any stage of pregnancy; and comparison groups selected according to time of exposure comprising (1) convalescent, nonboosted parturients with polymerase chain reaction-confirmed COVID-19; (2) convalescent parturients with polymerase chain reaction-confirmed COVID-19 who received a single booster dose of the BNT162b2 messenger RNA vaccine; and (3) infection-naïve, fully vaccinated parturients who received 2 doses of the BNT162b2 messenger RNA vaccine. Outcomes that were determined included maternal and umbilical cord blood anti-SARS-CoV-2 antibody levels detected at delivery, the reported side effects, and pregnancy outcomes. RESULTS: A total of 228 parturients aged 18 to 45 years were included. Of those, samples from 64 were studied to characterize the titer dynamics following COVID-19 at all stages of pregnancy. The boosting effect was determined by comparing (1) convalescent (n=54), (2) boosted convalescent (n=60), and (3) naïve, fully vaccinated (n=114) parturients. Anti-SARS-CoV-2 antibody levels detected on delivery showed a gradual and significant decline over time from infection to delivery (r=0.4371; P=.0003). Of the gravidae infected during the first trimester, 34.6% (9/26) tested negative at delivery, compared with 9.1% (3/33) of those infected during the second trimester (P=.023). Significantly higher anti-SARS-CoV-2 antibody levels were observed among boosted convalescent than among nonboosted convalescent (17.6-fold; P<.001) and naïve vaccinated parturients (3.2-fold; P<.001). Similar patterns were observed in umbilical cord blood. Side effects in convalescent gravidae resembled those in previous reports of mild symptoms following COVID-19 vaccination during pregnancy. CONCLUSION: Postinfection maternal humoral immunity wanes during pregnancy, leading to low or undetectable protective titers for a marked proportion of patients. A single boosting dose of the BNT162b2 messenger RNA vaccine induced a robust increase in protective titers for both the mother and newborn with moderate reported side effects.

Cytomegalovirus in the transplant setting: Where are we now and what happens next? A report from the International CMV Symposium 2021.

The CMV Symposium in September 2021 was an international conference dedicated to cytomegalovirus (CMV) infection after solid organ or hematopoietic stem cell transplantation. This review provides an overview of the presentations given by the expert faculty, supplemented with educational clinical cases. Topics discussed include CMV epidemiology and diagnosis, the burden of CMV infection and disease, CMV-specific immunity and management of CMV in transplant settings. Major advances in the prevention and treatment of CMV in the past decade and increased understanding of CMV immunity have led to improved patient outcomes. In the future, management algorithms may be individualized based on the transplant recipient's immune profile, which will mark the start of a new era for patients with CMV.

Efficient Maternofetal Transplacental Transfer of Anti- Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Spike Antibodies After Antenatal SARS-CoV-2 BNT162b2 Messenger RNA Vaccination.

Maternal and cord blood sera were collected from 20 parturients who received the BNT162b2 vaccine. All women and infants were positive for anti S- and anti-receptor binding domain antibody-specific immunoglobulin G. Cord blood antibody concentrations were correlated to maternal levels and to time since vaccination. Antenatal severe acute respiratory syndrome coronavirus 2 vaccination may provide maternal and neonatal protection.

Human Nasal Turbinate Tissues in Organ Culture as a Model for Human Cytomegalovirus Infection at the Mucosal Entry Site.

The initial events of viral infection at the primary mucosal entry site following horizontal person-to-person transmission have remained ill defined. Our limited understanding is further underscored by the absence of animal models in the case of human-restricted viruses, such as human cytomegalovirus (HCMV), a leading cause of congenital infection and a major pathogen in immunocompromised individuals. Here, we established a novel ex vivo model of HCMV infection in native human nasal turbinate tissues. Nasal turbinate tissue viability and physiological functionality were preserved for at least 7 days in culture. We found that nasal mucosal tissues were susceptible to HCMV infection, with predominant infection of ciliated respiratory epithelial cells. A limited viral spread was demonstrated, involving mainly stromal and vascular endothelial cells within the tissue. Importantly, functional antiviral and proleukocyte chemotactic signaling pathways were significantly upregulated in the nasal mucosa in response to infection. Conversely, HCMV downregulated the expression of nasal epithelial cell-related genes. We further revealed tissue-specific innate immune response patterns to HCMV, comparing infected human nasal mucosal and placental tissues, representing the viral entry and the maternal-to-fetal transmission sites, respectively. Taken together, our studies provide insights into the earliest stages of HCMV infection. Studies in this model could help evaluate new interventions against the horizontal transmission of HCMV.IMPORTANCE HCMV is a ubiquitous human pathogen causing neurodevelopmental disabilities in congenitally infected children and severe disease in immunocompromised patients. The earliest stages of HCMV infection in the human host have remained elusive in the absence of a model for the viral entry site. Here, we describe the establishment and use of a novel nasal turbinate organ culture to study the initial steps of viral infection and the consequent innate immune responses within the natural complexity and the full cellular repertoire of human nasal mucosal tissues. This model can be applied to examine new antiviral interventions against the horizontal transmission of HCMV and potentially that of other viruses.

Saliva Real-Time Polymerase Chain Reaction for Targeted Screening of Congenital Cytomegalovirus Infection.

BACKGROUND: Saliva real-time polymerase chain reaction (PCR) was shown to be sensitive and specific for the detection of congenital cytomegalovirus (cCMV) in universal screening studies. In the current study, we assessed the performance of saliva real-time PCR in newborns undergoing targeted cCMV screening. METHODS: Saliva real-time PCR results were prospectively correlated with reference-standard urine detection in newborns undergoing targeted cCMV screening over a 3-year period, in successive validation (concurrent testing of all saliva and urine specimens) and routine-screening (confirmatory urine testing of positive saliva results) implementation phases. RESULTS: The sensitivity, specificity, and positive and negative predictive values of saliva real-time PCR were 98.3% (95% confidence interval, 90.8%-99.9%), 91.5% (89.3%-93.3%), 45.6% (36.7%-54.7%), and 99.9% (99.2%-99.9%), respectively, in 856 concurrently tested newborns. True-positive saliva real-time PCR detection (defined in relation to urine detection) was associated with earlier saliva sampling (P = .002) and a higher saliva viral load (P < .001). We further identified a saliva viral load cutoff value that reliably distinguished between true-positive and false-positive saliva results. CONCLUSIONS: In newborns undergoing targeted screening for cCMV, saliva real-time PCR is highly sensitive yet has a low positive predictive value, necessitating confirmatory testing. Early sampling and application of a validated viral load cutoff could improve the assay performance and support its large-scale implementation in this growing clinical setting.