Serum anti-Spike antibody titers before and after heterologous booster with mRNA-1273 SARS-CoV-2 vaccine following two doses of inactivated whole-virus CoronaVac vaccine

Background: The inactivated whole-virus vaccine CoronaVac (SinoVac) is the COVID-19 vaccine most administered worldwide. However, data on its immunogenicity and reactogenicity to heterologous boosting with mRNA vaccines are lacking. Methods: In a cohort of hospital staff in Jakarta, Indonesia, who received two-dose CoronaVac six months prior (median 190 days, IQR165-232), we measured anti-Spike IgG titers on paired serum samples taken before and 28 days after a 100μg mRNA-1273 (Moderna) booster. We performed correlations and multivariable ordinal regressions. Findings: Among 304 participants, the median age was 31 years (range 21-59), 235 (77.3%) were women, 197 (64.8%) had one or more previous SARS-CoV-2 infections (including 155 [51.0%] who had a post-CoronaVac breakthrough infection. Pre-boost IgG titers correlated negatively with the time since the latest documented virus exposure (either by the second CoronaVac or SARS-CoV-2-infection whichever most recent). Previous SARS-CoV-2 infection and a longer time interval between second vaccine and mRNA-1273 boost were associated with a higher pre-boost IgG titer. Post-booster, the median IgG titer increased 9.3-fold, from 250 (IQR32-1389) to 2313 (IQR1226-4324) binding antibody units (BAU/mL) (p<0.001). All participants, including seven whose pre-boost IgG was below assay detection limits, became seropositive and all reached a substantial post-boost titer (≥364 BAU/mL). Post-boost IgG was not associated with pre-boost titer or previous SARS-CoV-2 infection. Booster reactogenicity was acceptable, with 7.9% of participants experiencing short-lived impairment of activities of daily living (ADL). Interpretation: A heterologous, high-dose mRNA-1273 booster after two-dose CoronaVac was highly immunogenic and safe, including in those most in need of improved immunity. Funding: Wellcome Trust, UK Keywords SARS-CoV-2; COVID-19; inactivated vaccine; CoronaVac; mRNA-1273; antibodies

Safety, Tolerability and Immunogenicity of Oxford-AstraZeneca ChAdOx1 Vaccine Among Polish School-Teachers

Background Polish teachers, as the priority group, were offered the ChAdOx1-S vaccine since February 2021. The objective was to investigate safety, tolerability and immunogenicity of this vaccine following two vaccine doses. Methods Teachers were invited for serological testing ≥8 weeks after second vaccination. Quantitative post-vaccination anti-spike antibody responses were measured using the Abbott SARS-CoV-2 IgG II Quant assay (detection threshold: ≥7.1 BAU/ml). Multivariable logistic regression methods were used to identify predictors of immunogenicity. Results Of 192 teachers, mean age 50.5±8.3 years, 83.9% were females. Median (range) dosing interval was 50 (14-95) days; median interval between the second dose and immunogenicity test was 69 days (range: 57–111). More than a half of teachers (58.3%) reported they would change the product for another (mostly mRNA) vaccine if there was such an opportunity. Adverse reactions after receiving the vaccine (either the first or the second dose) were reported by 79.2% teachers, more frequently after the first dose (84.9%), and were similar in nature to those previously reported: feeling feverish (44.8%), headache (41.7%), malaise, chills (both: 38.0%), injection-site tenderness (37.5%) and pain (32.3%). Less males than females (54.8% vs 80.1%) and older (aged ≥50 years) than younger teachers (65.7% vs 90.4%) reported side effects (p<0.002; p<0.0001, respectively). By ≥8 weeks after the boost dose, all teachers had neutralizing antibody responses. The median (range) anti-spike IgG reading was 525.0 BAU/mL (20.6-5680.0 BAU/mL); 1008.02 (115.3–5680.0) BAU/mL in teachers with evidence of prior infection and 381.42 BAU/mL (20.6–3108.8) in those without (p=0.001). Previous infection with SARS-CoV-2 and longer dose interval were both positive predictors of higher immunologic response (p<0.0001; p=0.01, respectively), with no evidence of differences by age, gender, BMI, smoking or comorbidities. Conclusions The results demonstrated good safety, tolerability and immunogenicity of the ChAdOx1-S vaccine. Immunization led to detectable anti-spike antibodies in all teachers. Our study justifies the longer dose interval as an important factor to enhance higher antibody response. Findings suggest that in immunocompetent vaccine recipients with an evidence of previous infection a delay regarding the second dose could be considered when careful management in the use of vaccine resources is needed.

Molecular and Serological Characterization of Hepatitis B Virus (HBV)-Positive Samples with Very Low or Undetectable Levels of HBV Surface Antigen

Background: Gaps remain in the detection of nucleic acid test (NAT) yield and occult hepatitis B virus (HBV) infection (OBI) by current HBV surface antigen (HBsAg) assays. The lack of detection may be due to HBsAg levels below current assay detection limits, mutations affecting HBsAg assays or HBsAg levels, or the masking of HBsAg by antibody to HBsAg (anti-HBs). In this study, we evaluate the incremental detection of NAT yield and OBI from five diverse geographic areas by an improved sensitivity HBsAg assay and characterize the samples relative to the viral load, anti-HBs status, and PreS1–S2–S mutations. Included is a comparison population with HBV DNA levels comparable to OBI, but with readily detectable HBsAg (High Surface–Low DNA, HSLD). Methods: A total of 347 samples collected from the USA, South Africa, Spain, Cameroon, Vietnam, and Cote D’Ivoire representing NAT yield (HBsAg(−), antibody to HBV core antigen (anti-HBc)(−), HBV DNA(+), N = 131), OBI (HBsAg(−), anti-HBc(+), HBV DNA(+), N = 188), and HSLD (HBsAg(+), anti-HBc(+), HBV DNA(+), N = 28) were tested with ARCHITECT HBsAg NEXT (HBsAgNx) (sensitivity 0.005 IU/mL). The sequencing of the PreS1–S2–S genes from a subset of 177 samples was performed to determine the genotype and assess amino acid variability, particularly in anti-HBs(+) samples. Results: HBsAgNx detected 44/131 (33.6%) NAT yield and 42/188 (22.3%) OBI samples. Mean HBV DNA levels for NAT yield and OBI samples were lower in HBsAgNx(−) (50.3 and 25.9 IU/mL) than in HBsAgNx(+) samples (384.1 and 139.5 IU/mL). Anti-HBs ≥ 10 mIU/mL was present in 28.6% HBsAgNx(+) and 45.2% HBsAgNx(−) OBI, and in 3.6% HSLD samples. The genotypes were A1, A2, B, C, D, E, F, and H. There was no significant difference between HBsAgNx(−) and HBsAgNx(+) in the proportion of samples harboring substitutions or in the mean number of substitutions per sample in PreS1, PreS2, or S for the NAT yield or OBI (p range: 0.1231 to >0.9999). A total of 21/27 (77.8%) of HBsAgNx(+) OBI carried S escape mutations, insertions, or stop codons. HSLD had more PreS1 and fewer S substitutions compared to both HBsAgNx(−) and HBsAgNx(+) OBI. Mutations/deletions associated with impaired HBsAg secretion were observed in the OBI group. Conclusions: HBsAgNx provides the improved detection of NAT yield and OBI samples. Samples that remain undetected by HBsAgNx have exceptionally low HBsAg levels below the assay detection limit, likely due to low viremia or the suppression of HBsAg expression by host and viral factors.

Performance Decay of Molecular Assays Near the Limit of Detection: Probabilistic Modeling using Real-World COVID-19 Data

ABSTRACTThe gold standard for diagnosis of COVID-19 is detection of SARS-CoV-2 RNA by RT-PCR. However, the effect of systematic changes in specimen viral burden on the overall assay performance is not quantitatively described. We observed decreased viral burdens in our testing population as the pandemic progressed, with median sample Ct values increasing from 22.7 to 32.8 from weeks 14 and 20, respectively. We developed a method using computer simulations to quantify the implications of variable SARS-CoV-2 viral burden on observed assay performance. We found that overall decreasing viral burden can have profound effects on assay detection rates. When real-world Ct values were used as source data in a bootstrap resampling simulation, the sensitivity of the same hypothetical assay decreased from 97.59 (95% CI 97.3-97.9) in week 12, to 74.42 (95% CI 73.9-75) in week 20. Furthermore, simulated assays with a 3-fold or 10-fold reduced sensitivity would both appear to be >95% sensitive early in the pandemic, but sensitivity would fall to 85.55 (95% CI 84.9-86.2) and 74.38 (95% CI 73.6-75.1) later in the pandemic, respectively. Our modeling approach can be used to better quantitate the impact that specimen viral burden may have on the clinical application of tests and specimens.

Detection of EGFR Mutations From Plasma of NSCLC Patients Using an Automatic Cartridge-Based PCR System

The introduction of liquid biopsies for the detection of EGFR mutations in non-small cell lung cancer patients (NSCLC) has revolutionized the clinical care. However, liquid biopsies are technically challenging and require specifically trained personnel. To facilitate the implementation of liquid biopsies for the detection of EGFR mutations from plasma, we have assessed a fully automated cartridge-based qPCR test that allows the automatic detection of EGFR mutations directly from plasma. We have analyzed 54 NSCLC patients and compared the results of the cartridge-base device to an FDA-approved assay. Detection of EGFR mutations was comparable but slightly lower in the cartridge-based device for L858R mutations (14/15 detected, 93%) and exon 19 deletions (18/20 detected, 90%). Unfortunately, 8/54 (15%) tests failed but increasing the proteinase K volume helped to recover 3/4 (75%) unsuccessful samples. In summary, the fully automated cartridge-based device allowed the detection of EGFR mutations directly from plasma in NSCLC patients with promising accuracy. However, protocol adjustments are necessary to reduce a high test failure rate.

Two Cu(ii)-based coordination polymers: Crystal structures and treatment activity on periodontitis

Two new Cu(ii)-based coordination polymers (CPs) with the chemical formulae of [CuL(bimmb)0.5] n (1, bimmb is 4-bis(imidazole-1-ylmethyl)benzene) and [CuL(bbibp)] n (2, bbibp is 4,4'-bis(benzoimidazo-1-yl)biphenyl) have been successfully prepared by the reaction of 3,3'-azodibenzoic acid (H2L) ligand and metal salt Cu(NO3)2·3H2O in the presence of different nitrogen-donor coligands. In the bioactive evaluation experiments, the treatment activity of the prepared CPs against periodontitis was examined. Enzyme-linked immunosorbent assay detection was used to test interleukin-18 (IL-18) and IL-6 contents released into the gingival crevicular fluid after the treatment of above CPs, and the real-time reverse transcription polymerase chain reaction was subsequently performed to measure the relative expression level of HmuY gene in the Porphyromonas gingivalis.

Abstract 16095: Plasma NT-proBNP Concentrations are Two-fold Lower in Pacific versus European Population Samples: Evidence for Glycosylation Impacting Assay Detection and/or ProBNP Processing

Introduction: Pacific Islanders in New Zealand (NZ) have high rates of cardiovascular and metabolic disorders. The Pasifika Heart Study (PHS) recorded ethnic-specific clinical and biomarker data to inform clinical management in community care. Methods: For the PHS, Pacific adults (n=200) aged 20-64 years were selected from patients of a Pacific-led health centre in Christchurch, NZ, and screened for existing cardio-metabolic disorders and risk factors. Circulating concentrations of NT-proBNP (Roche Cobas NT-proBNP II), total proBNP and proBNP not glycosylated at Threonine 71 (T71) residue (both by in-house Luminex assays) were measured. Assay data were compared with European participants in the INSPIRE study (n=103 healthy volunteers, 20-70 years). Results: PHS participants had a mean age (SD) of 41.7 (11.5) years, 48% were male, mostly of Samoan and Tongan ethnicities (44% and 32% respectively). INSPIRE European participants had a mean age of 46.8 (15.0) years, 46% were male. NTproBNP concentrations measured by Cobas were two-fold lower in the PHS (median = 18.4 ng/L, IQR = [7.3, 35.8]) compared with INSPIRE (40.0 ng/L [19.8, 70.2]) (p<0.001). Moreover, consistently lower concentrations were observedin PHS across a spectrum of either age or BMI (see Figure). In contrast, total proBNP concentrations exhibited a broad range in both cohorts, but did not differ between PHS (192.8 [35.7, 414.2] ng/L) and INSPIRE (36.1 [36.1, 225.1] ng/L, p<0=0.278). This suggests that in the PHS, either the Cobas assay underestimates NT-proBNP due to glycosylation of antibody-binding sites and / or proBNP is not processed to NTproBNP due to glycosylation at the T71 cleavage site. As evidence for the latter, only 8% of PHS had proBNP not glycosylated at T71 versus 31% of INSPIRE (p<0.001). Conclusions: Use of NT-proBNP thresholds based on European reference ranges to assess cardiovascular risk in community care may lead to under-diagnosis of evolving heart failure in Pacific Islanders.

Pathological Test Type and Chemical Detection Using Deep Neural Networks: A Case Study Using ELISA and LFA Assays

Purpose The gradual increase in geriatric issues and global imbalance of the ratio between patients and healthcare professionals has created a demand for intelligent systems with the least error-prone diagnosis results to be used by less medically trained persons and save clinical time. This paper aims at investigating the development of an image-based colourimetric analysis. The purpose of recognising such tests is to support wider users to begin a colourimetric test to be used at homecare settings, telepathology, etc. Design/methodology/approach The concept of an automatic colourimetric assay detection is delivered by utilising two cases. Training Deep Learning (DL) models on thousands of images of these tests using transfer learning, this paper i) classifies the type of the assay, and ii) classifies the colourimetric results. Findings This paper demonstrated that the assay type can be recognised using DL techniques with 100% accuracy within a fraction of a second. Some of the advantages of the pre-trained model over the calibration-based approach are robustness, readiness and suitability to deploy for similar applications within a shorter period of time. Originality/value To the best of our knowledge, this is the first attempt to provide Colourimetric Assay Type Classification (CATC) using DL. Humans are capable to learn thousands of visual classifications in their life. Object recognition may be a trivial task for humans, due to photometric and geometric variabilities along with the high degree of intra-class variabilities it can be a challenging task for machines. However, transforming visual knowledge into machines, as proposed, can support non-experts to better manage their health and reduce some of the burdens on experts.

Temporal Detection Limits of Remnant Larval Bloodmeals in Nymphal Ixodes scapularis (Say, Ixodida: Ixodidae) Using Two Next-Generation Sequencing DNA Barcoding Assays

Using next-generation sequencing DNA barcoding, we aimed to determine: 1) if the larval bloodmeal can be detected in Ixodes scapularis nymphs and 2) the post-moult temporal window for detection of the larval bloodmeal. Subsets of 30 nymphs fed on a domestic rabbit (Oryctolagus cuniculus Linnaeus, Lagomorphia: Leporidae) as larvae were reared and frozen at 11 time points post-moult, up to 150 d. Vertebrate DNA was amplified using novel universal (UP) and species-specific primers (SSP) and sequenced for comparison against cytochrome c oxidase subunit I barcodes to infer host identification. Detectable bloodmeals decreased as time since moult increased for both assays. For the SSP assay, detection of bloodmeals decreased from 96.7% (n = 29/30) in day 0 nymphs to 3.3% (n = 1/30) and 6.7% (n = 2/30) at 4- and 5-mo post-moult, respectively. A shorter temporal detection period was achieved with the UP assay, declining from 16.7% (n = 5/30) in day 0 nymphs to 0/30 in 3-d-old nymphs. Bloodmeal detection was nonexistent for the remaining cohorts, with the exception of 1/30 nymphs at 2-mo post-moult. Host detection was significantly more likely using the SSP assay compared to the UP assay in the first three time cohorts (day 0: χ 2 = 39.1, P &lt; 0.005; day 2: χ 2 = 19.2, P &lt; 0.005; day 3: χ 2 = 23.3, P &lt; 0.005). Regardless of the primer set used, the next-generation sequencing DNA barcoding assay was able to detect host DNA from a larval bloodmeal in the nymphal life stage; however, a short window with a high proportion of detection post-moult was achieved.