Reasons for failure of noninvasive prenatal test for cell-free fetal DNA in maternal peripheral blood.

BACKGROUND: To explore reasons for the failure of noninvasive prenatal test (NIPT) for cell-free fetal DNA (cffDNA) in maternal peripheral blood, and discuss appropriate treatment schemes after the failure of the test. METHODS: Altogether 41,136 pregnant women participated in NIPT. Blood samples were taken again from pregnant women who failed the first blood collection upon their informed consent. Prenatal genetic counseling or prenatal diagnosis was recommended for pregnant women with final NIPT failure. RESULTS: The first failure rate of NIPT was 0.737% (303/41136), and the reason for the failure was the low ratio of cffDNA in 135 (44.6%) of the 303 pregnant women. After the second or third blood sampling, the final failure rate was 0.182% (75/41136). The low ratio of cffDNA was the main reason for test failure in 42 (56.0%) of the 75 pregnant women who finally failed NIPT, among whom 44 (58.7%) had underlying diseases, including 21 (47.7%) with more than two coexisting underlying diseases. Only 27 (36.0%) of the 75 pregnant women with NIPT failure underwent interventional prenatal diagnosis. CONCLUSIONS: The main reason for NIPT failure was the low ratio of cffDNA. Postponing the gestational weeks of blood collection may improve the success rate. Resampling and retesting upon informed consent in pregnant women who failed the first test could improve the success rate. For pregnant women who finally failed NIPT, it is suggested strengthening the genetic counseling, prenatal examination, and ultrasound evaluation, and carry out interventional prenatal diagnosis if necessary.

A new and improved method of library preparation for non-invasive prenatal testing: plasma to library express technology.

OBJECTIVES: This study aims to develop a novel library preparation method, plasma to library express technology (PLET), to construct next-generation sequencing (NGS) libraries directly from plasma without cell-free DNA (cfDNA) isolation. METHODS: Peripheral blood samples (600) were obtained from a retrospective cohort of 300 pregnant women prior to invasive diagnostic testing. The samples were subsequently distributed between library preparation methodologies, with 300 samples prepared by PLET and 300 by conventional methods for non-invasive prenatal testing (NIPT) to screen for common trisomies using low-pass whole genome next generation sequencing. RESULTS: NIPT conducted on PLET libraries demonstrated comparable metrics to libraries prepared using conventional methods, including 100% sensitivity and specificity. CONCLUSIONS: Our study demonstrates the potential utility of PLET in the clinical setting and highlights its significant advantages, including dramatically reduced process complexity and markedly decreased turnaround time.

Inactivated Vaccines Against SARS-CoV-2: Neutralizing Antibody Titers in Vaccine Recipients.

Background: Although effective vaccines have been developed against coronavirus disease 2019 (COVID-19), the level of neutralizing antibodies (NAbs) induced after vaccination in the real world is still unknown. The aim of this work was to evaluate the level and persistence of NAbs induced by two inactivated COVID-19 vaccines in China. Methods: Serum samples were collected from 1,335 people aged 18 years and over who were vaccinated with an inactivated COVID-19 vaccine at Peking University People's Hospital from January 19 to June 23, 2021, for the detection of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies. Results: The positive rate for NAbs against SARS-CoV-2 was 79-91% from the first month to the second month after the second vaccine dose. The gradual decline in positivity rate for NAb response was observed from 78% at 3 months post-vaccination to 0% at 12 months post-vaccination. When there was a 21-day interval between the two doses of vaccine, the NAb positivity rate was 0% 6 months after the second dose. NAb levels were significantly higher when the interval between two doses were 3-8 weeks than when it was 0-3 weeks (χ2 = 14.04, p < 0.001). There was a linear correlation between NAbs and IgG antibodies in 1,335 vaccinated patients. NAb levels decreased in 31 patients (81.6%) and increased in 7 patients (18.4%) over time in the series of 38 patients after the second vaccination. The NAb positivity rate was significantly higher in 18- to 40-year-old subjects than in 41- to 60-year-old subjects (t = -1.959, p < 0.01; t = 0.839, p < 0.01). Conclusion: The NAb positivity rate was the highest at the first and second month after the second dose of vaccine, and gradually decreased over time. With a 21-day interval between two doses of vaccine, neutralizing antibody levels persisted for only 6 months after the second dose of vaccine. Therefore, a third vaccine dose is recommended. Our results suggest that in cases in which NAbs cannot be detected, IgM/IgG antibodies can be detected instead. The level of NAbs produced after vaccination was affected by age but not by sex. Our results suggest that an interval of 21 to 56 days between shots is suitable for vaccination.

Prevention and control measures significantly curbed the SARS-CoV-2 and influenza epidemics in China.

At the end of 2019, an outbreak of pneumonia took place caused by a new coronavirus (SARS-CoV-2 virus), named coronavirus disease 2019 (COVID-19). A series of strict prevention and control measures were then implemented to reduce the spread of the epidemic. Influenza, another respiratory tract virus, may also respond to these measures. To assess the impact of these measures, we used the total number of passengers movement in mainland China from 2018 to 2020 and daily number of railway passenger flow during the 2020 Spring Festival travel rush to reflect the population movement and to analyze newly and cumulatively confirmed COVID-19 and influenza cases. We found that implementing the series of measures against COVID-19 mitigated both COVID-19 and influenza epidemics in China. Prevention and control measures for COVID-19 might be used to control respiratory tract infections to reduce the national health economic burden caused by these pathogens.

Occult HBV infection in patients with autoimmune hepatitis: A virological and clinical study.

BACKGROUND/PURPOSE: Occult HBV infection (OBI) could have serious clinical consequences in patients receiving immunosuppressive therapy. We aimed to investigate the prevalence of OBI in Chinese patients with autoimmune hepatitis (AIH) and to analyze its clinical and virological features. METHODS: 103 AIH cases were enrolled. Hepatitis B virus (HBV) serological markers were screened by chemiluminescence. HBV-DNA were detected by nest-PCR and real-time PCR. HBV genotyping and mutation analysis were performed by Sanger sequencing. RESULTS: Twenty-four out of 103 (23.30%) AIH patients had OBI as evidenced by positive HBV-DNA and negative hepatitis B surface antigen (HBsAg). HBV genotype C is the predominant genotype (57.89%), which had more amino acid (AA) substitutions in S region than that of B-genotype group (P = 0.001). The distribution of AA substitution in the 'α' determinant region between genotype C and B were significantly different (P = 0.042). In addition to those already reported OBI-associated AA substitutions (e.g., sG145R and sV184A), some new OBI-associated AA substitutions (e.g., sV106A, sC137* and sL176P) were found in AIH patients in our study. Three out of 24 (12.50%) OBI patients were diagnosed as decompensated cirrhosis, one patient with S deletion mutation and two patients with HBV extensive AA substitutions. CONCLUSIONS: There was a higher proportion of AIH patients with OBI than the general population in China, which can be either seropositive or seronegative-OBI in AIH patients is associated with some specific AA substitutions. The presence of deletion mutations and the extent of AA substitutions in the HBV S region may have predictive clinical implications.

Direct antiviral agents upregulate natural killer cell potential activity in chronic hepatitis C patients.

Direct antiviral agents (DAAs) can eliminate hepatitis C virus rapidly and make chronic hepatitis C (CHC) curable. The changes in the innate immune system during treatment with DAAs are still in dispute. To investigate how the functions of natural killer (NK) cells change during and after treatment with DAAs in each NK cell subset. Thirteen CHC patients were treated with sofosbuvir/ledipasvir, and the expression levels of NKp46 and NKG2A were tested via flow cytometry at baseline, at 2, 4, 8 and 12 weeks during the therapy and 12 and 24 weeks after the end of treatment; expression levels were compared between CHC patients and 13 healthy controls. A redirected killing assay was used to detect the cytotoxicity of NK cells. After coculturing NK cells with JFH-Huh7 cells for 72 h, HCV RNA was tested to analyze the inhibition ability of NK cells. All patients achieved sustained virologic response. The expression of the activating receptor NKp46 was decreased first at week 8 during therapy with DAAs and then increased and normalized to levels in healthy controls after treatment with DAAs. The expression of the inhibitory receptor NKG2A was decreased during and after treatment with DAAs. Each NK cell subset has a similar changing trend during and after treatment with DAAs, although some differences can be found earlier and later. The ratio of NKp46 and NKG2A was upregulated after treatment with DAAs. CD56bright NK cells have less amplitude in the frequency ratio changes after treatment with DAAs. The coculture results showed that both the specific lysis and the inhibition of HCV replication were significantly upregulated after treatment with DAAs. DAA treatments can affect patients' NK cell function. After DAA treatments, the expression of functional markers is downregulated, but the potential activity of NK cells is upregulated. The function of NK cells is normalized to levels in healthy controls. CD56bright NK cells play an important role in this process.

Evaluation of an antigen assay for diagnosing acute and chronic hepatitis E genotype 4 infection.

BACKGROUND AND AIM: Results obtained from different hepatitis E virus (HEV) tests are usually inconsistent. The detection of serum HEV antigen (Ag) has been suggested to be more sensitive for the diagnosis of genotypes 1 and 3 HEV. METHODS: We compared the diagnostic accuracies of serum HEV Ag and HEV RNA by using 202 serum samples from patients suspected acute viral hepatitis. RESULTS: The HEV Ag assay was 100% specific. The lower detected levels of viremia ranged from 102 to 103  copies/mL. The sensitivity of the HEV Ag test was 90.5%. One of the 42 cases was negative for anti-HEV IgM, but HEV Ag was still detectable. The detectable period of HEV Ag was in concordance with the detectable period of HEV RNA. Serum HEV Ag was persistently detected in two cases of chronic hepatitis E, confirmed by the persistent presence of HEV RNA despite being negative for anti-HEV IgM. HEV Ag demonstrated good consistency with positive HEV RNA (k = 0.938, P < 0.001). Receiver operating characteristic analysis of HEV Ag suggested a second cut-off value of >0.095 to predict HEV patients with 95.24% sensitivity and 98.75% specificity, and the area under the curve was 0.9887, which was higher than that of three commercial anti-HEV IgM ELISA tests. CONCLUSIONS: The presence of HEV Ag has good consistency with HEV RNA in both acute and chronic genotype 4 hepatitis E. HEV Ag is a more promising serum marker to identify active genotype 4 HEV infection than anti-HEV IgM and HEV RNA.

HBsAg stimulates NKG2D receptor expression on natural killer cells and inhibits hepatitis C virus replication.

BACKGROUND: Higher hepatitis B surface antigen (HBsAg) facilitates hepatitis C virus (HCV) clearance in patients with hepatitis B virus (HBV)/HCV co-infection. We investigated the effect of exogenous HBsAg on the inhibition of HCV replication mediated by natural killer (NK) cells. METHODS: After isolated from peripheral blood of 42 chronic hepatitis B (CHB) patients and 16 healthy individuals, NK cells were co-cultured with HCV-infected Huh7 cells, respectively, with or without HBsAg. Three days later, the co-cultured supernatants were collected and HCV RNA levels were measured by real-time quantitative PCR. NKG2D, NKp46 and NKG2A expression levels were measured by flow cytometry. NKG2D on NK cells from CHB responsive subgroup was blocked and HCV RNA levels were examined again. RESULTS: HCV RNA levels in the co-cultured system were significantly reduced by NK cells isolated from healthy donors (P < 0.01) but not from CHB patients. However, HCV RNA levels in CHB cultures were significantly decreased following HBsAg addition (P < 0.05), whereas no such effect was seen in control cultures. No significant difference was observed in basic NKG2D expression between the CHB patients and healthy donors. On NK cells from CHB patients, the expression of NKG2D was increased significantly by HBsAg stimulation (P < 0.01), and higher than that from healthy controls (P < 0.05). HCV RNA levels were increased significantly after the blockage of NKG2D on NK cells from responsive CHB patients in the co-cultured system (P < 0.05). CONCLUSION: Exogenous HBsAg stimulated NKG2D expression on NK cells from CHB patients which inhibit HCV replication, suggesting that HBsAg may facilitate the clearance of HCV in patients with HBV/HCV co-infection.