Anti-SARS-CoV-2-specific antibodies in human breast milk following SARS-CoV-2 infection during pregnancy: a prospective cohort study.

BACKGROUND: While the presence of SARS-CoV-2 in human breast milk is contentious, anti-SARS-CoV-2 antibodies have been consistently detected in human breast milk. However, it is uncertain when and how long the antibodies are present. METHODS: This was a prospective cohort study including all consecutive pregnant women with confirmed SARS-CoV-2 infection during pregnancy, recruited at six maternity units in Spain and Hong Kong from March 2020 to March 2021. Colostrum (day of birth until day 4 postpartum) and mature milk (day 7 postpartum until 6 weeks postpartum) were prospectively collected, and paired maternal blood samples were also collected. Colostrum samples were tested with rRT-PCR-SARS-CoV-2, and skimmed acellular milk and maternal sera were tested against SARS-CoV-2 specific immunoglobulin M, A, and G reactive to receptor binding domain of SARS-CoV-2 spike protein 1 to determine the presence of immunoglobulins. Then, we examined how each immunoglobulin type in the colostrum was related to the time of infection by logistic regression analysis, the concordance between these immunoglobulins in the colostrum, maternal serum, and mature milk by Cohen's kappa statistic, and the relationship between immunoglobulin levels in mature milk and colostrum with McNemar. RESULTS: One hundred eighty-seven pregnant women with confirmed SARS-CoV-2 infection during pregnancy or childbirth were recruited and donated the milk and blood samples. No SARS-CoV-2 was found in the human breast milk. Immunoglobulin A, G, and M were present in 129/162 (79·6%), 5/163 (3·1%), and 15/76 (19·7%) colostrum samples and in 17/62 (27·42%), 2/62 (3·23%) and 2/62 (3·23%) mature milk samples, respectively. Immunoglobulin A was the predominant immunoglobulin found in breast milk, and its levels were significantly higher in the colostrum than in the mature milk (p-value < 0.001). We did not find that the presence of immunoglobulins in the colostrum was associated with their presence in maternal, the severity of the disease, or the time when the infection had occurred. CONCLUSIONS: Since anti-SARS-CoV-2 antibodies are found in the colostrum irrespective of the time of infection during pregnancy, but the virus itself is not detected in human breast milk, our study found no indications to withhold breastfeeding, taking contact precautions when there is active disease.

Single-cell analysis reveals transcriptomic and epigenomic impacts on the maternal-fetal interface following SARS-CoV-2 infection.

During pregnancy the maternal-fetal interface plays vital roles in fetal development. Its disruption is frequently found in pregnancy complications. Recent studies show increased incidences of adverse pregnancy outcomes in patients with COVID-19; however, the mechanism remains unclear. Here we analysed the molecular impacts of SARS-CoV-2 infection on the maternal-fetal interface. Generating bulk and single-nucleus transcriptomic and epigenomic profiles from patients with COVID-19 and control samples, we discovered aberrant immune activation and angiogenesis patterns in distinct cells from patients. Surprisingly, retrotransposons were also dysregulated in specific cell types. Notably, reduced enhancer activities of LTR8B elements were functionally linked to the downregulation of pregnancy-specific glycoprotein genes in syncytiotrophoblasts. Our findings revealed that SARS-CoV-2 infection induced substantial changes to the epigenome and transcriptome at the maternal-fetal interface, which may be associated with pregnancy complications.

Biomarkers at 6 weeks' gestation in the prediction of early miscarriage in pregnancy following assisted reproductive technology.

INTRODUCTION: Miscarriage is a major concern in early pregnancy among women having conceived with assisted reproductive treatments. This study aimed to examine potential miscarriage-related biophysical and biochemical markers at 6 weeks' gestation among women with confirmed clinical pregnancy following in vitro fertilization (IVF)/embryo transfer (ET) and evaluate the performance of a model combining maternal factors, biophysical and biochemical markers at 6 weeks' gestation in the prediction of first trimester miscarriage among singleton pregnancies following IVF/ET. MATERIAL AND METHODS: A prospective cohort study was conducted in a teaching hospital between December 2017 and January 2020 including women who conceived through IVF/ET. Maternal mean arterial pressure, ultrasound markers including mean gestational sac diameter, fetal heart activity, crown rump length and mean uterine artery pulsatility index (mUTPI) and biochemical biomarkers including maternal serum soluble fms-like tyrosine kinase-1 (sFlt-1), placental growth factor (PlGF), kisspeptin and glycodelin-A were measured at 6 weeks' gestation. Logistic regression analysis was carried out to determine significant predictors of miscarriage prior to 13 weeks' gestation and performance of screening was estimated by receiver-operating characteristics curve analysis. RESULTS: Among 169 included pregnancies, 145 (85.8%) pregnancies progressed to beyond 13 weeks' gestation and had live births whereas 24 (14.2%) pregnancies resulted in a miscarriage during the first trimester. In the miscarriage group, compared to the live birth group, maternal age, body mass index, and mean arterial pressure were significantly increased; mean gestational sac diameter, crown rump length, mUTPI, serum sFlt-1, glycodelin-A, and the rate of positive fetal heart activity were significantly decreased, while no significant differences were detected in PlGF and kisspeptin. Significant prediction for miscarriage before 13 weeks' gestation was provided by maternal age, fetal heart activity, mUTPI, and serum glycodelin-A. The combination of maternal age, ultrasound (fetal heart activity and mUTPI), and biochemical (glycodelin-A) markers achieved the highest area under the curve (AUC: 0.918, 95% CI 0.866-0.955), with estimated detection rates of 54.2% and 70.8% for miscarriage before 13 weeks' gestation, at fixed false positive rates of 5% and 10%, respectively. CONCLUSIONS: A combination of maternal age, fetal heart activity, mUTPI, and serum glycodelin-A at 6 weeks' gestation could effectively identify IVF/ET pregnancies at risk of first trimester miscarriage.

Assessment of embryo morphology following perinatal exposure to aspirin, ibuprofen and paracetamol using whole embryo culture system.

BACKGROUND: Recent evidence from a meta-analysis indicates that maternal prenatal exposure, single or repeated, to non-steroidal anti-inflammatory drugs (NSAIDs) or non-opioid painkillers, is associated with increased risk of cerebral palsy and cognitive-behavioral disorders in offspring. One potential route of action is interference with the neurulation process and hence early brain development. OBJECTIVE: To examine the effect of prenatal exposure to common NSAIDs and non-opioid drugs on neurulation using an in vitro whole embryo culture system. METHODS: Mouse embryos from in-bred Institute of Cancer Research albino strain mice were exteriorized on embryonic day 7.5 and cultured for 48 h in either 1 mL heat-inactivated rat serum + 0.1% dimethyl sulfoxide ("Control") or 1 mL of rat serum supplemented with six increasing concentrations of laboratory-grade aspirin, paracetamol, and ibuprofen ("Experimental"). After culture, embryo morphological and developmental parameters were documented using standardized scoring systems at each dosage concentration. The assessed concentration in rat serum culture ranged from 1.23 to 13.57 mg/mL for aspirin and 0.06-4.93 mg/mL for paracetamol and ibuprofen. The equivalent respective human dosages were 600-6600 mg and 30-2400 mg. RESULTS: Between-group comparisons ("Control" vs "Experimental") and post-hoc pair-wise tests, adjusted for multiple comparisons, indicating no statistically significant effect on crown-rump length (p > .21), head length (p > .28), somite number (p > .25), incidence of absent hindlimb buds (p > .18), yolk sac circulation score (p > .07) and posterior neuropore closure (p > .35) in the aspirin, paracetamol and ibuprofen experiments. All embryos had forelimb buds, closed anterior neuropores and none had neural tube defects. CONCLUSION: This study has demonstrated that there are no safety concerns regarding high-dose aspirin, ibuprofen, and paracetamol on mice's embryonic development.

Clinical and virological course of infection with haemagglutinin D222G mutant strain of 2009 pandemic influenza A (H1N1) virus.

BACKGROUND: Aspartic acid to glycine substitution (D222G) of haemagglutinin subunit (HA1) was associated with adverse outcomes in 2009 pandemic influenza A (H1N1) infections. OBJECTIVES: To characterize the virological profile and antiviral response of patients infected with the HA1 D222G mutant. STUDY DESIGN: Sixty-three adults admitted for pandemic influenza in Hong Kong were tested for D222G mutation by direct sequencing. Nasopharyngeal viral concentration on presentation was measured by real-time PCR to evaluate shedding from the upper respiratory tract. Serial upper and lower respiratory tract specimens were monitored to determine preferential tropism and document virological response to treatment. RESULTS: The frequency of D222G infection was 17.4% among cases with severe pneumonia, and 26.7% among cases requiring intensive care. Altogether, four sporadic D222G cases spread across the first and second waves in Hong Kong were detected. A significant association between D222G infection with severe pneumonia (100% vs. 32.2%, P=0.015) and intensive care admission (100% vs. 18.6%, P=0.002) was observed. D222G was associated with lower concentrations of virus in the upper respiratory tract compared to wildtype, but persisted in the lower respiratory tract at high concentrations, despite clearance from the upper respiratory tract following antiviral treatment. CONCLUSIONS: These observations suggest that D222G can arise de novo, sheds less virus from the upper respiratory tract and may be less transmissible, but more pneumotropic and more resistant to antiviral treatment. D222G is associated with a higher chance of developing critical disease. Lower respiratory tract specimen is needed for a reliable detection of this mutant.

Correlation between polymerase activity and pathogenicity in two duck H5N1 influenza viruses suggests that the polymerase contributes to pathogenicity.

The influenza RNA polymerase is known to be important in pathogenicity and adaptation of avian influenza viruses to mammalian hosts. However, the molecular mechanisms responsible are only partly understood. Here we investigated the role of the polymerase in two different, closely related, H5N1 influenza viruses - a high pathogenic, A/duck/Fujian/01/2002 (FJ) strain and a low pathogenic, A/duck/Guangxi/53/2002 (GX) strain. The polymerase activity of the FJ strain was significantly greater than the GX strain. Experiments with hybrid polymerase constructs - both in vitro and in ribonucleoprotein cell-based assays, suggested that the PA and to a lesser extent the PB2 subunits of the polymerase, were responsible for increased polymerase activity of the high pathogenic strain. However, promoter binding was inversely correlated with polymerase activity implying that excessive promoter binding inhibited polymerase activity by preventing promoter clearance. Overall, we suggest that the influenza polymerase is one of the determinants of pathogenicity of duck H5N1 viruses.

A quantitative strategy to detect changes in accessibility of protein regions to chemical modification on heterodimerization.

We describe a method for studying quantitative changes in accessibility of surface lysine residues of the PB1 subunit of the influenza RNA polymerase as a result of association with the PA subunit to form a PB1-PA heterodimer. Our method combines two established methods: (i) the chemical modification of surface lysine residues of native proteins by N-hydroxysuccinimidobiotin (NHS-biotin) and (ii) the stable isotope labeling of amino acids in cell culture (SILAC) followed by tryptic digestion and mass spectrometry. By linking the chemical modification with the SILAC methodology for the first time, we obtain quantitative data on chemical modification allowing subtle changes in accessibility to be described. Five regions in the PB1 monomer showed altered reactivity to NHS-biotin when compared with the [PB1-PA] heterodimer. Mutational analysis of residues in two such regions-at K265 and K481 of PB1, which were about three- and twofold, respectively, less accessible to biotinylation in the PB1-PA heterodimer compared with the PB1 monomer, demonstrated that both K265 and K481 were crucial for polymerase function. This novel assay of quantitative profiling of biotinylation patterns (Q-POP assay) highlights likely conformational changes at important functional sites, as observed here for PB1, and may provide information on protein-protein interaction interfaces. The Q-POP assay should be a generally applicable approach and may detect novel functional sites suitable for targeting by drugs.

The N-terminal region of the PA subunit of the RNA polymerase of influenza A/HongKong/156/97 (H5N1) influences promoter binding.

BACKGROUND: The RNA polymerase of influenza virus is a heterotrimeric complex of PB1, PB2 and PA subunits which cooperate in the transcription and replication of the viral genome. Previous research has shown that the N-terminal region of the PA subunit of influenza A/WSN/33 (H1N1) virus is involved in promoter binding. METHODOLOGY/PRINCIPAL FINDINGS: Here we extend our studies of the influenza RNA polymerase to that of influenza strains A/HongKong/156/97 (H5N1) and A/Vietnam/1194/04 (H5N1). Both H5N1 strains, originally isolated from patients in 1997 and 2004, showed significantly higher polymerase activity compared with two classical human strains, A/WSN/33 (H1N1) and A/NT/60/68 (H3N2) in vitro. This increased polymerase activity correlated with enhanced promoter binding. The N-terminal region of the PA subunit was the major determinant of this enhanced promoter activity. CONCLUSIONS/SIGNIFICANCE: Overall we suggest that the N-terminal region of the PA subunit of two recent H5N1 strains can influence promoter binding and we speculate this may be a factor in their virulence.

Hsp90 inhibitors reduce influenza virus replication in cell culture.

The viral RNA polymerase complex of influenza A virus consists of three subunits PB1, PB2 and PA. Recently, the cellular chaperone Hsp90 was shown to play a role in nuclear import and assembly of the trimeric polymerase complex by binding to PB1 and PB2. Here we show that Hsp90 inhibitors, geldanamycin or its derivative 17-AAG, delay the growth of influenza virus in cell culture resulting in a 1-2 log reduction in viral titre early in infection. We suggest that this is caused by the reduced half-life of PB1 and PB2 and inhibition of nuclear import of PB1 and PA which lead to reduction in viral RNP assembly. Hsp90 inhibitors may represent a new class of antiviral compounds against influenza viruses.