Inactive

DEVELOPMENT OF MONOCLONAL ANTIBODIES AND IMMUNOASSAYS TO SPIKE VARIANTS Background The emergence of SARS-CoV-2 Variants of Concern (VOCs) and corresponding mutations in 2020, notable (Alpha, Beta, Gam... DEVELOPMENT OF MONOCLONAL ANTIBODIES AND IMMUNOASSAYS TO SPIKE VARIANTS Background The emergence of SARS-CoV-2 Variants of Concern (VOCs) and corresponding mutations in 2020, notable (Alpha, Beta, Gamma and Delta) has attracted urgency to reassess vaccine efficacy, therapeutic treatments, and existing diagnostic reagents and assays. Pathogen mutation is a constant feature of viral spread through a population with COVID-19. Immediate targets for SARS- CoV-2 include the new Omicron B.1.1.529 lineage along with other established mutations of clinical relevance. As more of the population becomes immune through natural infection or vaccination, it is important to track potential escape mutants and their ability to evade antibody binding. These variants can be assayed through both functional/binding assays by development of panels of monoclonal antibodies capable of detecting sequence-specific and structural changes associated with independent and combined point mutations and deletions especially in the event that our existing library of standard anti-RBD & anti-S2 Spike wt. mAbs lose function. Purpose The purpose of this requirement is the immediate development of recombinant protein and antibodies targeted against SARS-CoV-2 spike mutations that define VOCs. The list includes Conserved Spike mutations - A67V, ?69-70, T95I, G142D/?143-145, ?211/L212I, ins214EPE, G339D, S371L, S373P, S375F, K417N, N440K, G446S, S477N, T478K, E484A, Q493K, G496S, Q498R, N501Y, Y505H, T547K, D614G, H655Y, N679K, P681H, N764K, D796Y, N856K, Q954H, N969K and L981F identified in human populations. Some of these mutations have been reported to modulate RBD interaction with ACE2r as well as immune response from natural infection. Adjustment of these targets may be necessary as new data are received on emerging variants. Scope of Work Independently and not as an agent of the Government, the Contractor shall provide the facilities, personnel, equipment, tools, materials, supplies and supervision for the development of recombinant proteins and antibodies targeted against SARS-CoV- 2 spike mutation variants listed above. Significant Steps in the Project The significant steps are as follows: Target generation (combination of Centers for Disease Control and Prevention (CDC) & the Contractor) The contractor shall produce PP7 virus-like particles (VLPs) displaying peptides (typically 15 amino acids in length) containing the mutation of interest. Up to three variations of each construct will be prepared, involving chemically synthesized peptides attached to the particle at one end, genetically encoded C-terminal extensions to the VLP capsid protein, and genetically encoded loop inserts in the capsid protein. The Contractor will produce cell culture (cell-free delivered) expressing spike protein domain polypeptides containing those same mutations. Mice will be immunized at the contractor laboratory first with the VLPs and boosted with the corresponding polypeptides according to previously established protocols as well as purified Spike polypeptides. Immune responses will be monitored against wild- type and mutant polypeptide sequences to select those animals producing a potential response against the sequence of interest. The process of immunization and evaluation requires 30 days per immunogen (VLP-polypeptide and synthetic peptide) and will be performed in parallel to achieve the greatest possible throughput. Spike Polypeptide and Hybridoma Generation (CDC and Contractor) The Contractor laboratory will provide the Immunodiagnostic Development team (IDD) with cell culture (cell-free) for purification of Spike mutation recombinant polypeptides and B-cell splenocytes from selected mice. Using chromatography and protein purification techniques IDD will produce purified recombinant polypeptides for evaluation. Using high-throughput methods for hybridoma generation and culture, IDD will produce IgG-generating clones for evaluation. IDD will provide synthetic polypeptides for mouse boosting by Contractor. Candidate Screening (combination of CDC & the Contractor) Spike recombinant polypeptides with various mutations and hybridoma supernatants will be screened for target binding by ELISA and bio-layer interferometry. Selected monoclonal antibody (mAb) candidates will be expressed and purified by IDD for final validation by these same techniques against Spike recombinant polypeptides and inactivated SARS-CoV-2 virions. Antibody Sequencing (combination of CDC & the Contractor) RNA from selected clones will be provided by IDD and sequenced by the Contractor laboratory. Monthly Written Updates and Conference Calls Monthly written updates will be provided and monthly conference calls will be held with the Contractor to inform the CDC and document project progress throughout the award period. Tasks to be Performed The Contractor shall provide the following tasks: Task 1 Generate virus-like particles and cell-free culture supernatant displaying/expressing the polypeptide sequences of interest. Task 2 Contractor will immunize mice with these virus-like particles, and continue immunization with synthetic and recombinant polypeptides provided by the CDC. Task 3 Contractor will monitor immune responses during these experiments to select animals showing the most potent IgG response to the target antigens. Task 4 Contractor will provide splenocytes to the CDC from selected animals. CDC will generate hybridomas from splenocytes. Task 5 Contractor and CDC will assess the binding properties of hybridoma supernatants and purified monoclonal antibodies provided by CDC. Task 6 Contractor will provide monthly written updates and hold monthly conference calls to update CDC on project status. Task 7 Contractor and CDC will provide an expanded written report at the end of the project. Government Furnished Property SARS-CoV-2 spike proteins or protein domains containing mutant amino acids of interest will be provided to the contractor laboratory by the CDC. In addition, gamma-irradiation inactivated virions including the mutant sequences of interest, when available, will also be provided. This notice is a request for competitive quotations. Any quotation/response should be emailed to Rebecca Rasool Contract Specialist (CTR), at MSO9@cdc.gov by12:30EST 25 January 2022.