A novel bivalent DNA vaccine encoding both spike protein receptor-binding domain and nucleocapsid protein of SARS-CoV-2 to elicit T cell and neutralising antibody responses that cross react with variants (preprint)

The efficacy of vaccines targeting SARS-CoV-2 is becoming apparent now that the mRNA and adenovirus vector vaccines that have been approved for emergency use are showing promise. However, the longevity of the protective immune response and its efficacy against emerging variants remains to be determined. To improve longevity and future protection against variants, we have designed a DNA vaccine encoding both the SARS-CoV-2 spike (S) protein receptor-binding domain (RBD) and its nucleocapsid (N) protein, the latter of which is highly conserved amongst beta coronaviruses. The vaccine elicits strong pro-inflammatory CD4 Th1 and CD8 T-cell responses to both proteins, with these responses being significantly enhanced by fusing the nucleocapsid sequence to a modified Fc domain. We have shown that the vaccine also stimulates high titre antibody responses to RBD which efficiently neutralise in both a pseudotype and live virus neutralisation assay and show cross reactivity with S proteins from the emerging variants Alpha (B.1.1.7) and Beta (B.1.351). This DNA platform can be easily adapted to target variant RBD and N proteins and we show that a vaccine variant encoding the B.1.351 RBD sequence stimulates cross-reactive humoral and T-cell immunity. These data support the translation of this DNA vaccine platform into the clinic, thereby offering a particular advantage for targeting emerging SARS-CoV-2 variants.

The impact of real-time whole genome sequencing in controlling healthcare-associated SARS-CoV-2 outbreaks (preprint)

Background Nosocomial infections have posed a significant problem during the COVID-19 pandemic, affecting bed capacity and patient flow in hospitals. Effective infection control measures and identifying areas of highest risk is required to reduce the risk of spread to patients who are admitted with other illnesses. This is the first pandemic where whole genome sequencing (WGS) has been readily available. We demonstrate how WGS can be deployed to help identify and control outbreaks. Aims & Methods Swabs performed on patients to detect SARS-CoV-2 underwent RT-PCR on one of multiple different platforms available at Nottingham University Hospitals NHS Trust. Positive samples underwent WGS on the GridION platform using the ARTIC amplicon sequencing protocol at the University of Nottingham. Results Phylogenetic analysis from WGS and epidemiological data was used to identify an initial transmission that occurred in the admissions ward. It also showed high prevalence of asymptomatic staff infection with genetically identical viral sequences which may have contributed to the propagation of the outbreak. Actions were taken to help reduce the risk of nosocomial transmission by the introduction of rapid point of care testing in the admissions ward and introduction of portable HEPA14 filters. WGS was also used in two instances to exclude an outbreak by discerning that the phylotypes were not identical, saving time and resources. Conclusions In conjunction with accurate epidemiological data, timely WGS can identify high risk areas of nosocomial transmission, which would benefit from implementation of appropriate control measures. Conversely, WGS can disprove nosocomial transmission, validating existing control measures and maintaining clinical service, even where epidemiological data is suggestive of an outbreak.

Immunogenicity of a new gorilla adenovirus vaccine candidate for COVID-19 (preprint)

The COVID-19 pandemic caused by the emergent SARS-CoV-2 coronavirus threatens global public health and there is an urgent need to develop safe and effective vaccines. Here we report the generation and the preclinical evaluation of a novel replication-defective gorilla adenovirus-vectored vaccine encoding the pre-fusion stabilized Spike (S) protein of SARS-CoV2. We show that our vaccine candidate, GRAd- COV2, is highly immunogenic both in mice and macaques, eliciting both functional antibodies which neutralize SARS-CoV-2 infection and block Spike protein binding to the ACE2 receptor, and a robust, Th1- dominated cellular response in the periphery and in the lung. We show here that the pre-fusion stabilized Spike antigen is superior to the wild type in inducing ACE2-interfering, SARS-CoV2 neutralizing antibodies. To face the unprecedented need for vaccine manufacturing at massive scale, different GRAd genome deletions were compared to select the vector backbone showing the highest productivity in stirred tank bioreactors. This preliminary dataset identified GRAd-COV2 as a potential COVID-19 vaccine candidate, supporting the translation of GRAd-COV2 vaccine in a currently ongoing Phase I clinical trial (NCT04528641).

Polymer Microarrays Rapidly Identify Competitive Adsorbents of Virus-like Particles (VLPs) (preprint)

The emergence of SARS-CoV-2 highlights the global need for platform technologies to enable rapid development of diagnostics, vaccines, treatments, and personal protective equipment (PPE). However, many current technologies require the detailed mechanistic knowledge of specific material-virion interactions before they can be employed, for example to aid in the purification of vaccine components, or in design of more effective PPE. Here we show that an adaption of polymer micro array method for screening bacterial-surface interactions allows for screening of polymers for desirable material-viron interactions. Non-pathogenic virus like particles including fluorophores are exposed to the arrays in aqueous buffer as a simple model of virons carried to the surface in saliva/sputum. Competitive binding of Lassa and Rubella particles is measured to probe the relative binding properties of a selection of copolymers. This provides the first step in the development of a method for discovery of novel materials with promise for viral binding, with the next being development of this method to assess absolute viral adsorption and assessment of the attenuation of the activity of live virus which we propose would be part of a material scale up step carried out in biological laboratory safety level 4 facilities and the use of more complex media to represent biological fluids.

Potent anti-SARS-CoV-2 Antibody Responses are Associated with Better Prognosis in Hospital Inpatient COVID-19 Disease (preprint)

COVID-19 continues to cause a pandemic, having infected more than 20 million people globally. Successful elimination of the SARS-CoV-2 virus will require an effective vaccine. However, the immune correlates of infection are currently poorly understood. While neutralizing antibodies are believed to be essential for protection against infection, the contribution of the neutralizing antibody response to resolution of SARS-CoV-2 infection has not yet been defined. In this study the antibody responses to the SARS-CoV-2 spike protein and nucleocapsid proteins were investigated in a UK patient cohort, using optimised immunoassays and a retrovirus-based pseudotype entry assay. It was discovered that in severe COVID-19 infections an early antibody response to both antigens was associated with improved prognosis of infection. While not all SARS-CoV-2-reactive sera were found to possess neutralizing antibodies, neutralizing potency of sera was found to be greater in patients who went on to resolve infection, compared with those that died from COVID-19. Furthermore, viral genetic variation in spike protein was found to influence the production of neutralizing antibodies. Infection with the recently described spike protein variant 614G produced higher levels of neutralizing antibodies when compared to viruses possessing the 614D variant. These findings support the assertion that vaccines targeting generation of neutralizing antibodies may be useful at limiting SARS-CoV-2 infection. Assessment of the antibody responses to SARS-CoV-2 at time of diagnosis will be a useful addition to the diagnostic toolkit, enabling stratification of clinical intervention for severe COVID-19 disease.

Retrospective screening of routine respiratory samples revealed undetected community transmission and missed intervention opportunities for SARS-CoV-2 in the United Kingdom (preprint)

In the early phases of the SARS coronavirus type 2 (SARS-CoV-2) pandemic, testing focused on individuals fitting a strict case definition involving a limited set of symptoms together with an identified epidemiological risk, such as contact with an infected individual or travel to a high-risk area. To assess whether this impaired our ability to detect and control early introductions of the virus into the UK, we PCR-tested archival specimens collected on admission to a large UK teaching hospital who retrospectively were identified as having a clinical presentation compatible with COVID-19. In addition, we screened available archival specimens submitted for respiratory virus diagnosis, and dating back to early January 2020, for the presence of SARS-CoV-2 RNA. Our data provides evidence for widespread community circulation of SARS-CoV2 in early February 2020 and into March that was undetected at the time due to restrictive case definitions informing testing policy. Genome sequence data showed that many of these early cases were infected with a distinct lineage of the virus. Sequences obtained from the first officially recorded case in Nottinghamshire - a traveller returning from Daegu, South Korea - also clustered with these early UK sequences suggesting acquisition of the virus occurred in the UK and not Daegu. Analysis of a larger sample of sequences obtained in the Nottinghamshire area revealed multiple viral introductions, mainly in late February and through March. These data highlight the importance of timely and extensive community testing to prevent future widespread transmission of the virus.