title: Generation and Application of SARS-CoV-2 Pseudo-typed Viral Particle System to Assess the Neutralising Ability of Sera from Mild and Severe COVID-19 Study Cohorts in the First Year of the Pandemic
Creators: name: Roper, Kelly
Publisher: name: University of Liverpool Repository
Year: 2023

description: Severe acute respiratory syndrome virus 2 (SARS-CoV-2) first emerged in Wuhan, China, at 
the end of 2019 and quickly resulted in a global pandemic responsible for over seven million 
deaths to date. A major advancement has been the development of efficient vaccines against 
SARS-CoV-2, with more than 13.5 billion doses of vaccines administered worldwide. 
However, without fundamental research to understand immune responses against SARS-CoV 2 infections, the rapid development and subsequent administration of vaccines would have been 
halted. Specifically, quantification of the neutralising antibody (nAb) responses generated after 
SARS-CoV-2 infection is crucial to fully understand long-term immunity and protection 
against SARS-CoV-2. In this thesis, the nAb responses generated against SARS-CoV-2 were 
studied. To assess nAb responses a lentiviral pseudo-typed viral particle (PVP) system 
expressing SARS-CoV-2 spike protein was used. The first results chapter details the 
optimisation of the PVP neutralisation assay and demonstrates the reliability of the assay. The 
second results chapter describes the nAb responses within the sera of a cohort of hospitalised 
patients recruited through the ISARIC4C consortium during the first wave of SARS-CoV-2 
infections. It was observed that older and male patients experienced the most severe disease. 
Strong nAb responses were produced very early on in infection, especially in patients who 
experienced more severe disease but ultimately survived their infection. The third result chapter 
studied the nAb responses within sera obtained from individuals who experienced mild SARS CoV-2 infection at the end of the first year of the pandemic. The nAb responses in this cohort 
of individuals were much lower than the responses observed within the ISARIC4C cohort but 
positively correlated with the number of symptoms experienced. Taken together, it is clear that 
nAb responses generated following infection with SARS-CoV-2 range and the severity of 
COVID-19 experienced plays a role in this. In the final results chapter, the use of filter paper 
as a medium to study serological responses against the SARS-CoV-2 spike was investigated. 
nAb responses in sera, venous blood and fingerstick blood stored on filter paper were measured
and good agreement was observed between the nAb responses measured in eluates and paired 
sera. The stability of nAb responses was also observed in sera stored on filter paper at room 
temperature for 28 days. The finding that filter paper can be effectively used to store serological 
samples without loss of neutralising ability holds promise for a more convenient way to store 
and ship samples. Overall, this thesis details the study of a novel emergent virus during its first 
wave of infections within the UK population. The knowledge gained and techniques 
established may be beneficial and informative for studying future emergent viruses.