Quantifying Neutralizing Antibodies in Patients with COVID-19 by a Two-Variable Generalized Additive Model

Considering the urgent demand for faster methods to quantify neutralizing antibody titers in patients with coronavirus (CoV) disease 2019 (COVID-19), developing an analytical model or method to replace the conventional virus neutralization test (NT) is essential. Moreover, a "COVID-19 immunity passport" is currently being proposed as a certification for people who travel internationally. Therefore, an enzyme-linked immunosorbent assay (ELISA) was designed to detect severe acute respiratory syndrome CoV 2 (SARS-CoV-2)-neutralizing antibodies in serum, which is based on the binding affinity of SARS-CoV-2 viral spike protein 1 (S1) and the viral spike protein receptor-binding domain (RBD) to antibodies. The RBD is considered the major binding region of neutralizing antibodies. Furthermore, S1 covers the RBD and several other regions, which are also important for neutralizing antibody binding. In this study, we assessed 144 clinical specimens, including those from patients with PCR-confirmed SARS-CoV-2 infections and healthy donors, using both the NT and ELISA. The ELISA results analyzed by spline regression and the two-variable generalized additive model precisely reflected the NT value, and the correlation between predicted and actual NT values was as high as 0.917. Therefore, our method serves as a surrogate to quantify neutralizing antibody titer. The analytic method and platform used in this study present a new perspective for serological testing of SARS-CoV-2 infection and have clinical potential to assess vaccine efficacy. IMPORTANCE Herein, we present a new approach for serological testing for SARS-CoV-2 antibodies using innovative laboratory methods that demonstrate a combination of biology and mathematics. The traditional virus neutralization test is the gold standard method; however, it is time-consuming and poses a risk to medical personnel. Thus, there is a demand for methods that rapidly quantify neutralizing antibody titers in patients with COVID-19 or examine vaccine efficacy at a biosafety level 2 containment facility. Therefore, we used a two-variable generalized additive model to analyze the results of the enzyme-linked immunosorbent assay and found the method to serve as a surrogate to quantify neutralizing antibody titers. This methodology has potential for clinical use in assessing vaccine efficacy.

Relative COVID-19 Viral Persistence and Antibody Kinetics

A total of 15 RT-PCR confirmed COVID-19 patients were admitted to our hospital during the in-itial outbreak in Taiwan. The average time of virus clearance was delayed in seven patients, 24.14 ± 4.33 days compared to 10.25 ± 0.56 days post-symptom onset (PSO) in the other eight pa-tients. There was strong antibody response in patients with viral persistence at the pharynx, with peak values of serum antibody 677.2 ± 217.8 vs. 76.70 ± 32.11 in patients with delayed versus rapid virus clearance. The patients with delayed viral clearance had excessive antibodies of compromised quality in an early stage with the delay in peak virus neutralization efficacy, 34.14 ± 7.15 versus 12.50 ± 2.35 days PSO in patients with rapid virus clearance. Weak antibody re-sponse of patients with rapid viral clearance was also effective, with substantial and comparable neutralization efficacy, 35.70 ± 8.78 versus 41.37 ± 11.49 of patients with delayed virus clearance. Human Cytokine 48-Plex Screening of the serial sera samples revealed elevated concentrations of proinflammatory cytokines and chemokines in a deceased patient with delayed virus clear-ance and severe disease. The levels were comparatively less in the other two patients who suf-fered from severe disease but eventually survived.

SARS-CoV-2 genomic surveillance in Taiwan revealed novel ORF8-deletion mutant and clade possibly associated with infections in Middle East

Taiwan experienced two waves of imported infections with Coronavirus Disease 2019 (COVID-19). This study aimed at investigating the genomic variation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Taiwan and compared their evolutionary trajectories with the global strains. We performed culture and full-genome sequencing of SARS-CoV-2 strains followed by phylogenetic analysis. A 382-nucleotides deletion in open reading frame 8 (ORF8) was found in a Taiwanese strain isolated from a patient on February 4, 2020 who had a travel history to Wuhan. Patients in the first wave also included several sporadic, local transmission cases. Genomes of 5 strains sequenced from clustered infections were classified into a new clade with ORF1ab-V378I mutation, in addition to 3 dominant clades ORF8-L84S, ORF3a-G251V and S-D614G. This highlighted clade also included some strains isolated from patients who had a travel history to Turkey and Iran. The second wave mostly resulted from patients who had a travel history to Europe and Americas. All Taiwanese viruses were classified into various clades. Genomic surveillance of SARS-CoV-2 in Taiwan revealed a new ORF8-deletion mutant and a virus clade that may be associated with infections in the Middle East, which contributed to a better understanding of the global SARS-CoV-2 transmission dynamics.

A pilot study on primary cultures of human respiratory tract epithelial cells to predict patients' responses to H7N9 infection

Avian influenza A(H7N9) virus infections frequently lead to acute respiratory distress syndrome and death in humans. We aimed to investigate whether primary cultures of human respiratory tract epithelial cells are helpful to understand H7N9 virus pathogenesis and tissue tropism, and to evaluate how patient-related characteristics can affect the host's response to infection. Normal human bronchial epithelial cells (isolated from two different donors) and primary epithelial cells (harvested from 27 patients undergoing airway surgery) were experimentally infected with H7N9 and/or H1N1pdm for 72 h. After virus infection, the culture media were collected for viral RNA quantitation and cytokine detection. Both H7N9 and H1N1pdm viruses replicated and induced a cytokine response differently for each donor in the normal human bronchial epithelial model. H7N9 replicated equivalently in epithelial cells harvested from the inferior turbinate and paranasal sinus, and those from the larynx and bronchus, at 72 h post-infection. Viral RNA quantity at 72 h was significantly higher in patients aged 21-64 years than in patients aged ≥ 65 years; however, no effects of sex, medical comorbidities, and obesity were noted. H7N9-infected cultured cells released multiple cytokines within 72 h. Levels of interleukin-1β, interleukin-6, interleukin-8, interferon-γ, and tumor necrosis factor-α were associated differently with patient-related characteristics (such as age, sex, obesity, and medical comorbidities). In the era of precision medicine, these findings illustrate the potential utility of this primary culture approach to predict a host's response to H7N9 infection or to future infection by newly emerging viral infections, and to dissect viral pathogenesis.

Increased seroprevalence of HBV DNA with mutations in the s gene among individuals greater than 18 years old after complete vaccination

BACKGROUND & AIMS

Despite the success of a universal vaccination program against hepatitis B virus (HBV) in Taiwan, a small but substantial proportion of individuals remain infected by mutant viruses that escape the vaccine. We investigated the seroepidemiology and genotypic characteristic of HBV for long periods after neonatal vaccination.

METHODS

We measured hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen (anti-HBc), and antibody to hepatitis B surface antigen (anti-HBs) in 1214 serum samples collected throughout Taiwan from individuals 0.6-87.8 years old in 2007. HBV DNA was detected using polymerase chain reaction and sequence analysis in vaccine recipients who tested positive for anti-HBc and/or HBsAg.

RESULTS

The overall seroprevalence of HBsAg and anti-HBc was significantly lower among individuals born after the initiation of the nationwide vaccination program (P < .001). However, we observed increasing seroprevalence of anti-HBc and isolated anti-HBs when subjects were grouped by age: at 10-14, 14-18, to 18-21 years of age, values were 0.4%, 1.9%, and 8.1% (P = .0135) and 43.7%, 55.4%, and 59.6% (P = .0093), respectively (χ(2) test for trend). A large increase was observed in the percentage of patients who tested positive for HBV DNA at 18-21 years of age (3.0% vs 0.2% [P = .002] for all eligible subjects and 5.7% vs 0.3% [P < .001] for subjects vaccinated with ≥3 doses). Five of 8 completely vaccinated individuals who were seropositive for HBV DNA carried variants with mutations in the S gene.

CONCLUSIONS

Universal vaccination effectively controls HBV infection in children and adolescents. However, after adolescence, there is a significant increase in the seroprevalence of anti-HBs, anti-HBc, and HBV DNA, indicating that new preventative strategies are needed for adults.

Clinical and genetic characterization of severe influenza B-associated diseases during an outbreak in Taiwan

BACKGROUND

Mismatches between circulating and vaccine strains of influenza virus had been observed in Taiwan. A comprehensive clinical and genetic analysis of influenza B viruses-associated important diseases was lacking.

OBJECTIVES

Clinical and phylogenetic analysis of influenza B viruses during an outbreak in Taiwan.

STUDY DESIGNS

Clinical manifestations of hospitalized, culture-confirmed patients were analyzed from July 2004 to June 2005. Partial genome sequence analysis of hemagglutinin (HA), neuraminidase (NA), and nonstructural (NS) genes were performed in 54 influenza B isolates during the study period, and nine srandomly chosen isolates during 2000 and 2003.

RESULTS

Three specific diseases were found in these patients, including 13 of encephalitis/encephalopathy, 28 of influenza-associated myositis (IAM), and one of acute respiratory distress syndrome (ARDS). Three phylogenetic groups were identified, including reassortant strains-group 1 (Victoria lineage of HA, Yamagata lineage of NA, clade A of NS), group 2 (Yamagata lineage of HA, Yamagata lineage of NA, clade A of NS), and group 3 (Yamagata lineage of HA, Yamagata lineage of NA, clade B of NS).

CONCLUSIONS

Severe influenza B-associated disease in children was not rare and might be fatal. We offered the evidence of co-circulation of the two HA lineages in the same outbreak.