Antigenic cartography of SARS-CoV-2 reveals that Omicron BA.1 and BA.2 are antigenically distinct

The emergence and rapid spread of SARS-CoV-2 variants may affect vaccine efficacy substantially. The Omicron variant termed BA.2, which differs substantially from BA.1 based on genetic sequence, is currently replacing BA.1 in several countries, but its antigenic characteristics have not yet been assessed. Here, we used antigenic cartography to quantify and visualize antigenic differences between early SARS-CoV-2 variants (614G, Alpha, Beta, Gamma, Zeta, Delta, and Mu) using hamster antisera obtained after primary infection. We first verified that the choice of the cell line for the neutralization assay did not affect the topology of the map substantially. Antigenic maps generated using pseudo-typed SARS-CoV-2 on the widely used VeroE6 cell line and the human airway cell line Calu-3 generated similar maps. Maps made using authentic SARS-CoV-2 on Calu-3 cells also closely resembled those generated with pseudo-typed viruses. The antigenic maps revealed a central cluster of SARS-CoV-2 variants, which grouped on the basis of mutual spike mutations. Whereas these early variants are antigenically similar, clustering relatively close to each other in antigenic space, Omicron BA.1 and BA.2 have evolved as two distinct antigenic outliers. Our data show that BA.1 and BA.2 both escape vaccine-induced antibody responses as a result of different antigenic characteristics. Thus, antigenic cartography could be used to assess antigenic properties of future SARS-CoV-2 variants of concern that emerge and to decide on the composition of novel spike-based (booster) vaccines.

Development of Safety Processes for Design and Manufacture of Small Liquid Propellant Engines and Launch Vehicles

The Cal Poly Pomona (CPP) Liquid Rocket Lab project teams in the 2020-2021 academic year further developed the planning of the engine injector water flow testing, oxygen compatibility and cleaning procedures and further advanced the Mobile Rocket Engine Test Stand piping and structural design. Failure Modes and Effects Analysis were also performed on the system elements to be able to target the critical components for failure mitigation design and procedure development. The CPP revised system for FMEAs is shown. These items were needed to be accomplished in order to perform an engine hot firing for the Bronco 1 Launch Vehicle. This paper describes briefing some the status of the CPP FAR-Mars competition progress and the vehicle systems manufacturing and assembly modifications related to safety developed during our program activity. Some of our testing objectives were postponed due to the COVID19 activity constraints. © 2021, American Institute of Aeronautics and Astronautics Inc.. All rights reserved.

Design and testing of advanced vehicle system additions for a small liquid propellant engine with lessons learned

The Liquid Rocket Launch Vehicle and Engine Teams of the Cal Poly Pomona Liquid Rocket Lab in the 2019-2020 academic year developed two additional support system elements which were needed for use with the vehicle/engine hot fire testing. The first support system element was alternate engine start valves, developed for use in the engine testing due to problems that were encountered with the original engine start valves (pyro actuated inline valves) during cold flows of the LV. The second vehicle support system was the strongback LV erector. This special LV support system was needed to accomplish the hot engine firing under the constraints of the FAR-Mars competition rules. This paper describes the status of the CPP FAR-Mars competition progress and these two new vehicle systems modifications developed during our program activity. Some of our testing objectives were postponed due to the COVID19 activity constraints. © 2020, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.