CpG-adjuvanted SARS-CoV-2 virus vaccine

#The instant application contains a Sequence Listing which has been submitted in ASCII format via EFS-Web and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Sep. 8, 2021, is named IO422.70138US00-SEQ-JRV, and is 662,996 bytes in size.

#The disclosure relates to CpG-adjuvanted SARS-CoV-2 vaccines and compositions and methods for producing said vaccines and administering the vaccines to subjects for the generation of an anti-SARSCoV-2 immune response.

#SARS-CoV-2 (hereinafter the “virus”) was detected for the first time in China around November 2019. Since then, the virus has caused a global pandemic. The natural reservoir are bats and the virus belongs to the Coronaviridae family, genus Betacoronavirus (betaCoV). The virus has a ssRNA genome composed of 29,903 bp (Wuhan-Hu-1: Genbank Reference sequence: NC_045512.2), which encode a 9,860 amino acid polyprotein, comprising 25 non-structural proteins and 4 structural proteins: spike (S), envelope (E), membrane (M) and nucleocapsid (N) proteins. The virus particle has a variable diameter of between 60 and 140 nm. It is enveloped and sensitive to UV, heat, and lipid solvents. It has 89% nucleotide sequence identity with bat SARS-like-CoVZXC21 and 82% nucleotide sequence identity with human SARS-CoV (Chan et al. 2020). Evidence suggests that this virus spreads when an infected person coughs small droplets—packed with the virus—into the air. These can be breathed in, or cause an infection if one touches a surface they have landed on, then the eyes, nose or mouth. In addition, other vectors may exist, and the virus may be transmitted by blood transfusion, transplacentally, and through sexual transmission. Though infection with SARS-CoV-2 may result in only mild symptoms, such as, typically, a fever and a cough, or even be asymptomatic; in the other extreme, it can be fatal. The key symptoms are usually high temperature, cough and breathing difficulties. There is currently no specific treatment or vaccine for the virus, and the only preventative methods involve social distancing. SARS-CoV-2 presents a substantial public health threat. The Imperial College COVID-19 (disease caused by SARS-CoV-2) Response Team published in Mar. 16, 2020, a report evaluating all possible methods available to stop or delay the spread of the virus, which could ultimately lead to the break-down of the healthcare system and hundreds of thousands of deaths in the UK alone. The report stated that only population-wide social distancing has a chance to reduce effects to manageable levels and these measures need to be followed until a vaccine is available. This recommendation would mean for most of the population quarantine for at least 18 months. The report concluded that a mass-producible vaccine is the only option to stop this pandemic, other than a willingness to sacrifice the elderly population. In view of the dramatic situation, there is an absolute urgent need for an effective vaccine against SARS-CoV-2 as fast as possible. Furthermore, various escape mutants have emerged (e.g. UK_B.1.1.7; South African_B.1.351; Californian_B.1.427/B.1.429 and Brazilian_P.1 variants, see also FIG. 2) which further worsen the situation and thus addressing this unfortunate development needs to be addressed as well.

#The accompanying drawings are not intended to be drawn to scale. The figures are illustrative only and are not required for enablement of the disclosure. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

#FIG. 1. The process for production of the inactivated SARS-CoV-2 vaccine of the current invention. Steps include cell buildup of Vero host cells, infection of Vero cells with SARS-CoV-2, virus harvest, DNA reduction, primary inactivation, purification, optional secondary inactivation and formulation with adjuvant. The virus may be formulated with or without aluminium hydroxide. The CpG adjuvant may be included in the same vial with the virus (and optional alum) or mixed with the virus before administration.

#FIG. 2. During the course of the SARS-CoV-2 pandemic, SARS-CoV-2 genomic sequences from isolates from around the world have been reported including the recent new variants or lineages such as the UK B 1.1.7, Brazilian P1, Californian B.1.427/B.1.429 and South African B.1.351 lineages. The accession numbers and origins of complete SARS-CoV-2 genomic sequences are provided in tabular form, along with accession numbers for the corresponding orflab polyprotein and S protein, when available (− or no entry=not available).

#Embodiments of the present invention are directed to a SARS-CoV-2 vaccine or immunogenic composition comprising inactivated SARS-CoV-2 particles in combination with a CpG adjuvant. Typically, the inactivated SARS-CoV-2 particles are whole, inactivated particles, i.e. the inactivated virus particles are derived from whole native SARS-CoV-2 particles that have been inactivated. As used herein, “SARS-CoV-2” refers to the SARS-CoV-2 virus and “SARS-CoV-2 particles” typically refers to whole SARS-CoV-2 viral particles, i.e. virions.

#In one embodiment, the inactivated SARS-CoV-2 particles are combined with the Th1 response-directing adjuvant CpG, preferably CpG 1018. As used herein, “CpG” refers to a cytosine-phospho-guanosine (CpG) motif-containing oligodeoxynucleotide (or CpG-ODN), e.g. which is capable of acting as a toll-like receptor 9 (TLR9) agonist. The CpG motif refers to an unmethylated cytidine-phospho-guanosine dinucleotide sequence, e.g. which is capable of binding to TLR9. Th1 response-directing adjuvants such as CpG promote the induction of a predominantly T helper type 1 (i.e. Th1) immune response in an immunized subject (rather than a Th2 type response), i.e. a “Th1-biased response”. The Th1- or Th2-directing properties of commonly used vaccines are known in the art. It has surprisingly been found that using an adjuvant that promotes a Th1 response, e.g., CpG 1018, can improve immunogenicity of the vaccine and thus antiviral responses, as well as reducing the risk of disadvantageous effects such as immunopathology (which may result from a predominantly Th2 type response possibly due to hypersensitivity against viral components). In one embodiment, the SARS-CoV-2 vaccine of the current invention also comprises the Th2-stimulating adjuvant alum, which has a known tendency for Th2 skewing in humans. Neutralizing antibodies, the production of which is critical for anti-viral immunity, are strongly stimulated by Th2-stimulating adjuvants, such as e.g. alum. Also important for anti-viral immunity are cellular immune responses, which are only weakly stimulated by alum. Delivered together, alum and Th1-inducing adjuvants, such as CpG, can provide a potent anti-viral response. In short, the use of CpG and alum together in a vaccine formulation can provide a more balanced immune response to antigens, including both humoral and cellular components, and may have less deleterious effects than alum alone with a predominantly Th2 response.

#In one embodiment, the CpG adjuvant comprised in the vaccine of the invention is a class A, class B or class C CpG (see Table A-1), preferably a class B CpG. Class B CpG molecules include CpG 1018, CpG 1826 and CpG 7909 (SEQ ID Nos: 4, 7 and 8, respectively; Table A-2). Most preferred is CpG 1018.