Publications by year
In Press
James-Pemberton P, Shaw A, Lapinska U, Hyde C (In Press). Accuracy and Precision Analysis for a Biophotonic Assay of C-Reactive Protein. The Analyst
2023
James-Pemberton P (2023). Biophotonic Sensor Technologies for Systems Biology.
Abstract:
Biophotonic Sensor Technologies for Systems Biology
Profiling of complex systems responses requires multiplexed testing of analytes, ideally with rapid results from low volumes. The ability to analyse samples at the point of collection is especially important when testing frangible samples, where systems such as the complement cascade or acute phase response have been activated. The combination of rapid sampling near the point of collection also allows for evolving systems to be evaluated in near real-time.
The system used for this work was based on a gold nanoparticle sensor, with the specificity of response provided by functionalising the nanoparticles with proteins to allow an immuno-kinetic sandwich assay to be observed in real-time.
The first study utilised a biosensor for C-reactive protein (CRP), a sensitive marker for the acute phase response, as it has proven use in diagnostics and an already working assay was assembled. The assay provided results in 8 minutes from a sample of 5 μL of whole blood. The analytical performance showed an accuracy of 0.42 mg L-1 (95% Confidence Interval – from here referred to as CI -14.7-13.8 mg L-1) (and precision of a CV of 10.6% (CI 0.9-20.2%) over the diagnostically useful range of 2-160 mg L-1.
With the emergence of SARS-CoV-2, the flexible, multiplexed nature of the biophotonic LiScAR platform allowed for the CRP assay to be extended to include a profile of the antibody response to infection. During testing at St. Thomas’ Hospital in March 2020, this semi-quantitative assay, conducted for IgM, IgA and IgG antibody concentrations against nucleocapsid (N), spike 1 (S1), spike 2 (S2), membrane (M) and envelope (E) proteins, was found to have a clinical sensitivity of 95% (CI 71- 97%) when compared to RT-PCR results. This assay was then developed into a fully quantitative assay for IgG against S, S (omicron), N and receptor binding domain (RBD) proteins that received a CE Mark in 2021, and a protective threshold of 3.4 mg L-1 calculated.
As SARS-CoV-2 variants evolved, an assay was constructed to measure the quantitative IgG response to the S variants from Wuhan, Alpha, Beta, Gamma, Delta, BA.1, BA.2.12.1, BA.2.75, BA.4 and BA.5. The analysis of the concentration profile for each variant led to a classification of the serology response into a series of endotypes with the universal positive endotypes, U(+), having a prevalence of 22% (CI 12-37%) in the double-vaccinated cohort rising to 54% (CI 39-68%) in the triple-vaccinated cohort, compared to 11% (CI 4-25%) in the cohort infected with the Wuhan strain.
Finally, a prospective cohort study was performed for a cohort of educational staff profiling both the concentration and pH-dependent affinity of the IgG response to the ten variant proteins. This found a U(+) prevalence of 78% (CI 60-88%), but fell to 25% (CI 13-43%) when only high-affinity antibodies were measured, potentially signifying a vulnerability masked by simple concentration measurements. Signs of antibody maturation against prevalent variants were also observed.
Multiplexed profiling of the immune serological response to SARS-CoV-2 infection across different virus variants and patient cohorts has provided new information on the changing immune response to vaccination and disease which may be of help in managing the ‘immunity shield’ as SARS-CoV-2 becomes an endemic disease similar to influenza or respiratory syncytial virus.
Abstract.
2022
James-Pemberton PH, Helliwell MW, Olkhov RV, Kohli S, Westlake AC, Farrar BM, Shaw AM (2022). Fully Quantitative Measurements of the Antibody Levels for SARS-CoV-2 Infections and Vaccinations calibrated against the NISTmAb Standard IgG Antibody.
Abstract:
Fully Quantitative Measurements of the Antibody Levels for SARS-CoV-2 Infections and Vaccinations calibrated against the NISTmAb Standard IgG Antibody
AbstractHumanised recombinant antibodies specific to the SARS-CoV-2 Spike protein were calibrated against the NISTmAb standard human antibody to produce a fully quantitative antibody assay. The assay allows comparative studies between patient cohorts to be performed from which common properties may be derived. Two cohorts comparing patient vaccine response to AstraZeneca ChAdOx1-S (AZ, 35 patients) and Pfizer/BioNTech BNT162b2 (Pfizer, 25 patients) shows close association of the 31st percentile of the AZ distribution (2.90 ± 1.10 mg/L) and the 7th percentile of the Pfizer distribution (1.11 ± 1.10 mg/L) corresponding to the efficacy of the vaccines at preventing infection. The AZ IgG response distribution varies from 0.6 mg/L–25.4 mg/L with an average (mode) of 3.3 ± 1.0 mg/L; the Pfizer response distribution varies from 0.6 mg/L to 33.1 mg/L with a mode of 3.7 ± 1.0 mg/L. A third patient cohort looked at the recovery of 195 SARS-CoV-2 RT-PCR-positive patient samples and 200 pre-pandemic patient samples. A fourth patient cohort reviewed the NIBSC Anti-SARS-CoV-2 Verification Panel. The diagnostic cut-off for RT-PCR-positive patient samples was 1.34 ± 1.10 mg/L and the NIBSC panel separated seropositive and seronegative samples at 1.90 ± 1.10 mg/L. The mean value of the two prevention and two recovery thresholds is 1.8 mg/L with 95% confidence limits of 0.2–3.4 mg/L. In recovery and, critically, infection prevention, an antibody concentration threshold estimate of 3.4 mg/L appears mechanistically important. An antibody immunity threshold predicting a mucosal concentration preventing SARS-CoV-2 colonisation of the nasopharyngeal cavity is discussed.
Abstract.
2021
James-Pemberton P, Westlake A, Helliwell M, Kohli S, Olkhov R, Farrar B, Shaw A (2021). Utilising a Multiplexed Gold Nanoparticle-Based. Sensor for Antibody and Antigen Detection.
Abstract:
Utilising a Multiplexed Gold Nanoparticle-Based. Sensor for Antibody and Antigen Detection
Using a multiplexed sensor, based on a gold nanoparticle
array, to quantify SARS-CoV-2 antibodies in serum and
SARS-CoV-2 antigens in saliva.
Abstract.
2020
Shaw AM, Hyde C, Merrick B, James-Pemberton P, Squires BK, Olkhov RV, Batra R, Patel A, Bisnauthsing K, Nebbia G, et al (2020). Real-world evaluation of a novel technology for quantitative simultaneous antibody detection against multiple SARS-CoV-2 antigens in a cohort of patients presenting with COVID-19 syndrome.
Analyst,
145(16), 5638-5646.
Abstract:
Real-world evaluation of a novel technology for quantitative simultaneous antibody detection against multiple SARS-CoV-2 antigens in a cohort of patients presenting with COVID-19 syndrome.
An evaluation of a rapid portable gold-nanotechnology measuring SARS-CoV-2 IgM, IgA and IgG antibody concentrations against spike 1 (S1), spike 2 (S) and nucleocapsid (N) was conducted using serum samples from 74 patients tested for SARS-CoV-2 RNA on admission to hospital, and 47 historical control patients from March 2019. 59 patients were RNA(+) and 15 were RNA(-). A serum (±) classification was derived for all three antigens and a quantitative serological profile was obtained. Serum(+) was identified in 30% (95% CI 11-48) of initially RNA(-) patients, in 36% (95% CI 17-54) of RNA(+) patients before 10 days, 77% (95% CI 67-87) between 10 and 20 days and 95% (95% CI 86-100) after 21 days. The patient-level diagnostic accuracy relative to RNA(±) after 10 days displayed 88% sensitivity (95% CI 75-95) and 75% specificity (95% CI 22-99), although specificity compared with historical controls was 100% (95%CI 91-100). This study provides robust support for further evaluation and validation of this novel technology in a clinical setting and highlights challenges inherent in assessment of serological tests for an emerging disease such as COVID-19.
Abstract.
Author URL.