Label-free detection and discrimination of respiratory pathogens based on electrochemical synthesis of biomaterials-mediated plasmonic composites and machine learning analysis.

Seasonal outbreaks of respiratory viral infections remain a global concern, with increasing morbidity and mortality rates recorded annually. Timely and false responses contribute to the widespread of respiratory pathogenic diseases owing to similar symptoms at an early stage and subclinical infection. The prevention of emerging novel viruses and variants is also a big challenge. Reliable point-of-care diagnostic assays for early infection diagnosis play a critical role in the response to threats of epidemics or pandemics. We developed a facile method for specifically identifying different viruses based on surface-enhanced Raman spectroscopy (SERS) with pathogen-mediated composite materials on Au nanodimple electrodes and machine learning (ML) analyses. Virus particles were trapped in three-dimensional plasmonic concave spaces of the electrode via electrokinetic preconcentration, and Au films were simultaneously electrodeposited, leading to the acquisition of intense and in-situ SERS signals from the Au-virus composites for ultrasensitive SERS detection. The method was useful for rapid detection analysis (<15 min), and the ML analysis for specific identification of eight virus species, including human influenza A viruses (i.e., H1N1 and H3N2 strains), human rhinovirus, and human coronavirus, was conducted. The highly accurate classification was achieved using the principal component analysis-support vector machine (98.9%) and convolutional neural network (93.5%) models. This ML-associated SERS technique demonstrated high feasibility for direct multiplex detection of different virus species for on-site applications.

Evaluation of a biotin-based surrogate virus neutralization test for detecting postvaccination antibodies against SARS-CoV-2 variants in sera.

A severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) surrogate virus neutralization test (sVNT) was used to determine the degree of inhibition of binding between human angiotensin converting enzyme 2 (hACE2) and the receptor binding domain (RBD) of spike protein by neutralizing antibodies in a biosafety level 2 facility. Here, to improve the sensitivity and specificity of the commercial sVNT, we developed a new biotin based sVNT using biotinylated RBD and HRP conjugated streptavidin instead of HRP conjugated RBD for direct detection in an ELISA assay that strongly correlated to the FDA approved cPass sVNT commercial kit (R2 = 0.8521) and pseudo virus neutralization test (R2 = 0.9006) (pVNT). The biotin based sVNT was evaluated in 535 postvaccination serum samples corresponding to second and third boosts of AZD1222 and BNT162b2 vaccines of the wild type strain. We confirmed that the neutralizing antibodies against SARS-CoV-2 variants in second vaccination sera decreased after a median of 141.5 days. Furthermore, vaccination sera from BNT162b2-BNT162b2 vaccines maintained neutralizing antibodies for longer than those of AZD1222 only vaccination. In addition, both vaccines maintained high neutralizing antibodies in third vaccination sera against Omicron BA.2 after a median of 27 days, but neutralizing antibodies significantly decreased after a median of 141.5 days. Along with the cPass sVNT commercial kit, biotin based sVNTs may also be suitable for specifically detecting neutralizing antibodies against multiple SARS-CoV-2 variants; however, to initially monitor the neutralizing antibodies in vaccinated sera using high throughput screening, conventional PRNT could be replaced by sVNT to circumvent the inconvenience of a long test time.

In-situ fabrication of 3D interior hotspots templated with a protein@Au core–shell structure for label-free and on-site SERS detection of viral diseases

Nanoscale plasmonic hotspots play a critical role in the enhancement of molecular Raman signals, enabling the sensitive and reliable trace analysis of biomedical molecules via surface-enhanced Raman spectroscopy (SERS). However, effective and label-free SERS diagnoses in practical fields remain challenging because of clinical samples' random adsorption and size mismatch with the nanoscale hotspots. Herein, we suggest a novel SERS strategy for interior hotspots templated with protein@Au core–shell nanostructures prepared via electrochemical one-pot Au deposition. The cytochrome c and lysates of SARS-CoV-2 (SLs) embedded in the interior hotspots were successfully functionalized to confine the electric fields and generate their optical fingerprint signals, respectively. Highly linear quantitative sensitivity was observed with the limit-of-detection value of 10−1 PFU/mL. The feasibility of detecting the targets in a bodily fluidic environment was also confirmed using the proposed templates with SLs in human saliva and nasopharyngeal swabs. These interior hotspots templated with the target analytes are highly desirable for early and on-site SERS diagnoses of infectious diseases without any labeling processes.

Immunogenicity and Durability of Antibody Responses to Homologous and Heterologous Vaccinations with BNT162b2 and ChAdOx1 Vaccines for COVID-19.

During the COVID-19 pandemic, vaccines were developed based on various platform technologies and were approved for emergency use. However, the comparative analysis of immunogenicity and durability of vaccine-induced antibody responses depending on vaccine platforms or vaccination regimens has not been thoroughly examined for mRNA- or viral vector-based vaccines. In this study, we assessed spike-binding IgG levels and neutralizing capacity in 66 vaccinated individuals prime-boost immunized either by homologous (BNT162b2-BNT162b2 or ChAdOx1-ChAdOx1) or heterologous (ChAdOx1-BNT162b2) vaccination for six months after the first vaccination. Despite the discrepancy in intervals for the prime-boost vaccination regimen of different COVID-19 vaccines, we found stronger induction and relatively rapid waning of antibody responses by homologous vaccination of the mRNA vaccine, while weaker boost effect and stable maintenance of humoral immune responses were observed in the viral vector vaccine group over 6 months. Heterologous vaccination with ChAdOx1 and BNT162b2 resulted in an effective boost effect with the highest remaining antibody responses at six months post-primary vaccination.

3D interior hotspots embedded with viral lysates for rapid and label-free identification of infectious diseases

In recent decades, biomedical sensors based on surface-enhanced Raman spectroscopy (SERS), which reveals unique spectral features corresponding to individual molecular vibrational states, have attracted intensive attention. However, the lack of a system for precisely guiding biomolecules to active hotspot regions has impeded the broad application of SERS techniques. Herein, we demonstrate the irreversible active engineering of three-dimensional (3D) interior organo-hotspots via electrochemical (EC) deposition onto metal nanodimple (ECOMD) platforms with viral lysates. This approach enables organic seed-programmable Au growth and the spontaneous bottom-up formation of 3D interior organo-hotspots simultaneously. Because of the net charge effect on the participation rate of viral lysates, the number of interior organo-hotspots in the ECOMDs increases with increasingly positive polarity. The viral lysates embedded in the ECOMDs function as both a dielectric medium for field confinement and an analyte, enabling the highly specific and sensitive detection of SARS-CoV-2 lysates (SLs) at concentrations as low as 10–2 plaque forming unit/mL. The ECOMD platform was used to trace and detect the SLs in human saliva and diagnose severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2);the results indicate that the proposed platform can provide point-of-care diagnoses of infectious diseases.

Germinal Center-Induced Immunity Is Correlated With Protection Against SARS-CoV-2 Reinfection But Not Lung Damage.

Germinal centers (GCs) elicit protective humoral immunity through a combination of antibody-secreting cells and memory B cells, following pathogen invasion or vaccination. However, the possibility of a GC response inducing protective immunity against reinfection following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remains unknown. We found GC activity was consistent with seroconversion observed in recovered macaques and humans. Rechallenge with a different clade of virus resulted in significant reduction in replicating virus titers in respiratory tracts in macaques with high GC activity. However, diffuse alveolar damage and increased fibrotic tissue were observed in lungs of reinfected macaques. Our study highlights the importance of GCs developed during natural SARS-CoV-2 infection in managing viral loads in subsequent infections. However, their ability to alleviate lung damage remains to be determined. These results may improve understanding of SARS-CoV-2-induced immune responses, resulting in better coronavirus disease 2019 (COVID-19) diagnosis, treatment, and vaccine development.

Initial investigation of test-retest reliability of home-to-home teleneuropsychological assessment in healthy, English-speaking adults.

Prior teleneuropsychological research has assessed the reliability between in-person and remote administration of cognitive assessments. Few, if any, studies have examined the test-retest reliability of cognitive assessments conducted in sequential clinic-to-home or home-to-home teleneuropsychological evaluations - a critical issue given the state of clinical practice during the COVID-19 pandemic. This study examined this key psychometric question for several cognitive tests administered over repeated videoconferencing visits 4-6 months apart in a sample of healthy English-speaking adults.A total of 44 participants (ages 18-75) completed baseline and follow-up cognitive testing 4-6 months apart. Testing was conducted in a home-to-home setting over HIPAA-compliant videoconferencing meetings on participants' audio-visual enabled laptop or desktop computers. The following measures were repeated at both virtual visits: the Controlled Oral Word Association Test (FAS), Category Fluency (Animals), and Digit Span Forward and Backward from the Wechsler Adult Intelligence Scale, Fourth Edition. Intraclass correlation coefficients (ICC), Pearson correlations, root mean square difference (RMSD), and concordance correlation coefficients (CCC) were calculated as test-retest reliability metrics, and practice effects were assessed using paired-samples t-tests.Some tests exhibited small practice effects, and test-retest reliability was marginal or worse for all measures except FAS, which had adequate reliability (based on ICC and r). Reliability estimates with RMSD suggested that change within +/- 1 SD on these measures may reflect typical test-retest variability.The included cognitive measures exhibited questionable reliability over repeated home-to-home videoconferencing evaluations. Future teleneuropsychology test-retest reliability research is needed with larger, more diverse samples and in clinical populations.