Proactive Software

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Victorio Galindo

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Aug 3, 2024, 6:09:18 PM8/3/24

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People who tend to react to a problem only when it's gotten serious could be called reactive people. Until recently, reactive (in this sense) didn't really have an antonym. So proactive was coined to describe the kind of person who's always looking into the future in order to be prepared for anything. A good parent attempts to be proactive on behalf of his or her children, trying to imagine the problems they might be facing in a few months or years. A company's financial officers study the patterns of the company's earnings to make sure it won't risk running short of cash at any point in the next year or two. Proactive has only been around a few decades, and it can still sometimes sound like a fashionable buzzword.

City Council approved a new Proactive Apartment Inspections Program. Starting April 2, 2023, the Code Enforcement Section will proactively inspect apartment complexes to provide safer housing conditions and ensure they meet minimum code standards.

A registry of apartment complexes that have been cited for code violations will be maintained. Any apartment complex with five or more units within San Antonio city limits could be required to be listed on the registry if they:

If you would like to receive courtesy notifications for code violations that could qualify your property for this program, fill out the application. This listing is voluntary and will be only used by the Code Enforcement Section.

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Nanoscale organization is a key signal for the programming of immune responses1,2,3. Highly multivalent display of antigens on virus-like particles (VLPs) or other nanoparticles enhances the strength and persistence of immune responses, facilitating lymph node uptake and increasing B cell receptor (BCR) clustering1,2. VLP manufacturing uses existing facilities for microbial fermentation to facilitate large-scale production4 and can avoid the need for a cold-chain5, and VLPs have shown a good balance of safety and efficacy6.

Existing vaccination strategies have shown success in reducing death and serious illness from SARS-CoV-2 (SARS2)7. Nevertheless, waning vaccine protection, continuing emergence of new variants and uncertain efficacy of therapeutics mean that new vaccine strategies are still urgently needed8,9. It is also important to protect against new pandemic threats from coronaviruses, which previously led to SARS-CoV (SARS1) and MERS-CoV outbreaks10. Other zoonotic coronaviruses such as WIV1 and SHC014 have been identified as having pandemic potential11. Immunizing with a single antigen typically induces a narrow strain-specific immune response, which may not protect against diverse pre-existing strains or newly arising variants of that pathogen12.

In a recently introduced approach, VLPs display a panel of protein variants arranged stochastically on their surface, to drive expansion of B cells recognizing common features of the different antigens. A mosaic of different hemagglutinin heads on ferritin nanoparticles elicited cross-reactive antibodies against diverse influenza strains within the H1 subtype13. This approach has been applied to SARS2, with mosaic nanoparticles displaying multiple RBDs from the Spike of different sarbecoviruses12,14,15. Sarbecoviruses are the subgenus of betacoronaviruses that includes SARS1 and SARS2. RBDs can be multimerized on VLPs through genetic fusion15 or isopeptide coupling12. Fusion of a set of sarbecovirus RBDs with SpyTag003 facilitates simple nanoassembly onto the SpyCatcher003-mi3 VLP12 (Fig. 1a). SpyCatcher003 is a protein that we engineered to rapidly form an isopeptide bond with SpyTag peptide16. mi3 is a 60-mer hollow protein nanocage, computationally designed to self-assemble into a stable dodecahedron17,18.

In our previous study, the broadest immune response came from mosaic particles displaying eight different RBDs12,14. These Mosaic-8 nanoparticles elicited neutralizing antibodies against a variety of sarbecoviruses in mouse and rhesus macaque models. Critically, responses were not limited to viruses whose RBDs were represented on Mosaic-8 nanoparticles and included mismatched responses against heterologous sarbecoviruses12,14. Mosaic-8 nanoparticles have gained support from the Coalition for Epidemic Preparedness Innovations to enter clinical trials. However, the need to produce nine different components (eight RBDs and SpyCatcher003-mi3) at Good Manufacturing Practice level creates a challenge for broad scaling.

Here, we establish the production of multiviral Quartet Nanocages (Fig. 1a). Initially we express a multiviral Quartet from RBDs of four different viruses, concatenated as a single polypeptide chain. These antigenic Quartets are assembled via a terminal SpyTag to extend out from SpyCatcher003-mi3 nanocages, creating a protein nanoparticle with a branched morphology. This nanoassembly route reduces the number of vaccine components, as well as creating an architecture that allows a greater number of RBDs to be displayed on each nanocage. We measure antibody responses to the range of sarbecoviruses displayed on the Quartet Nanocage, to sarbecoviruses not present within the chain, as well as to SARS2 variants of concern (VOCs). Comparing different nanoassemblies, we dissect the breadth of antibody binding to different sarbecoviruses, neutralization potency and the ability to boost a broad response following focused priming. The magnitude and breadth of antibody induction show that Quartet Nanocages may provide a scalable route to induce neutralizing antibodies across a range of related viruses, to prepare for emerging outbreak disease threats.

After boosting, we similarly found the strongest response against SARS2 from Quartet Nanocage, followed by Uncoupled Quartet, Homotypic Nanocage and finally Uncoupled RBD (Fig. 2c and Supplementary Figs. 6 and 7). This pattern is retained for SARS2 Wuhan, Beta and Delta Spikes (Supplementary Fig. 5b). Uncoupled RBD and Homotypic Nanocage immunization raised low responses against the panel of sarbecovirus RBDs, with the greatest Homotypic Nanocage cross-reactive response against the closely related RaTG13 RBD (Fig. 2c). In contrast, we saw substantial responses against all tested RBDs with Uncoupled Quartet and most substantially Quartet Nanocage immunization (Fig. 2c). This included a strong heterotypic response against BM-4831 and SARS1 RBDs, which were absent from the chain and elicited titres only slightly lower than Homotypic Nanocage against SARS2 Wuhan (Fig. 2c). These results suggest the potential of this Quartet Nanocage approach to induce antibodies against a broad range of sarbecoviruses. We had hypothesized that RBDs at the tip of the Quartet would give stronger responses than RBDs nearer the nanocage surface. In fact, we saw no obvious relationship between RBD chain location and antibody titre (Fig. 2c).

Dynamic light scattering (DLS) validated that each immunogen homogeneously assembled with SpyCatcher003-mi3 (Fig. 3c). Negative-stain transmission electron microscopy (TEM) confirmed the integrity of the Quartet Nanocages. The visible particle diameter was equivalent between uncoupled, Mosaic-8 and Quartet Nanocages, consistent with dynamic arrangement of the RBD quartet on the nanocage surface (Supplementary Fig. 9).

To relate antibody level to antibody efficacy, we tested neutralization of SARS2 Wuhan or Delta virus. We saw that the strongest neutralization was induced by Quartet Nanocage in each case, while Homotypic Nanocage gave higher responses than Uncoupled Quartet (Fig. 4a,b). We compared SARS1 pseudovirus neutralization induced by Quartet and Mosaic antigens, giving insight into neutralization breadth, as SARS1 was a mismatch for all tested immunogens. Pseudotyped virus neutralization correlates well with neutralization of authentic virus20. Dual Quartet Nanocage gave the strongest neutralizing response to SARS1. This was followed Quartet Nanocage and Mosaic-8 which induced similar, relatively strong anti-SARS1 responses (Fig. 4c).

While the motivation of this approach is protection against future zoonotic pathogens, the ideal vaccine candidate would also protect against circulating SARS2 variants. We produced an updated Kraken Quartet containing SARS2 XBB.1.5 in place of SARS2 Wuhan (Supplementary Fig. 8d). Mouse immunizations were performed with Homotypic Nanoparticles, Mosaic-8 nanoparticles and Quartet Nanocages that contained either SARS2 Wuhan or XBB.1.5, in addition to a Dual Quartet Nanocage that contained only the Wuhan RBD (Supplementary Fig. 18). All the Quartet and Mosaic immunogens produced greater antibody binding against zoonotic coronaviruses than their homotypic counterparts (Supplementary Fig. 18). There was substantial antibody binding against SARS2 VOCs with no statistically significant difference between antibody binding raised by Quartet and Mosaic immunogens against any tested SARS2 VOC (Wuhan, Delta, XBB.1.5 and BQ.1.1) (Supplementary Fig. 18). Immunogens containing XBB.1.5 provided substantially improved neutralization of SARS2 XBB.1.5 pseudovirus relative to Wuhan-containing counterparts (Supplementary Fig. 19). This result highlights the capacity to update the Quartet Nanocage, to protect against recently evolved antibody-escape variants. Both the Kraken- and Wuhan-containing Quartet Nanocage and Mosaic-8 provided greater neutralization of the mismatched SARS1 pseudovirus than their homotypic counterparts (Supplementary Fig. 19).

Priming with SARS2 Wuhan Spike raised the expected narrow strain-specific response against SARS2 Wuhan RBD (Fig. 5b) and negligible response to SARS1 or BtKY72 (Supplementary Fig. 20). Surprisingly, the different boosts (Fig. 5b) raised similar responses against SARS2, despite SARS2 RBD being absent in Quartet Nanocage [SARS1] and Dual Quartet Nanocage [SARS1] (Fig. 5b). As expected, Quartet Nanocage [SARS1] and Dual Quartet Nanocage [SARS1] raised the strongest response against SARS1 RBD (Fig. 5c). Quartet Nanocage and Mosaic-8 raised greater antibody response than Homotypic Nanocage or Spike boost against SARS1 and BtKY72 (Fig. 5c). Mismatched responses to SARS1 and BtKY72 raised by Mosaic-8 and Quartet Nanocage were similar to the SARS1 response from a single dose of these candidates in naive mice (Supplementary Fig. 10b). Overall, Quartet Nanocages achieve broad anti-sarbecovirus response, despite animals being prebiased to a specific viral antigen. In addition, Quartet Nanocage lacking SARS2 still induces a good level of anti-SARS2 antibodies, while stimulating broad responses across sarbecoviruses.