Okay, here is the abstract and summary for the TWiV 1209 transcript:
Abstract:
This episode of This Week in Virology (TWiV 1209) reviews recent science news and research papers. Topics include critiques of RFK Jr.'s comments on 'single antigen' vaccines and his deadline for autism research, and a debunking of claims about resurrecting dire wolves. The primary focus is on norovirus, covering two related studies published in Science Translational Medicine. The first study details a Phase 1 clinical trial of an oral, adenovirus-vectored norovirus vaccine tablet (VXA-G1.1) designed to induce mucosal immunity, showing safety and immunogenicity in older adults (55-80 years). The second study identifies broadly neutralizing human monoclonal antibodies (including VX-22) against pandemic GII.4 norovirus variants, isolated from individuals immunized with a similar Vaxart vaccine. The research explores antibody evolution, identifies conserved epitopes, and reveals a neutralization mechanism involving virus particle disassembly, offering insights for future vaccine design and potential therapeutics. Listener emails and science picks conclude the episode.
TWiV 1209: Norovirus Vaccines, Antibodies, and Science News
[0:00] Introductions & Weather: The hosts introduce themselves and share local weather updates.
[2:05] Announcements: Call for listener support and reminders about upcoming deadlines for the American Society for Virology (ASV) 2025 meeting.
[3:25] RFK Jr. on Novavax & Single Antigen Vaccines: Discussion of RFK Jr.'s comments questioning the efficacy of 'single antigen' vaccines like Novavax. Key Takeaway: The hosts refute this, pointing out that many effective vaccines (COVID-19 mRNA, Shingrix, RSV) are single-antigen based.
[6:21] Dire Wolf "Resurrection" Debunked: Alan clarifies that recent news about resurrecting dire wolves by Colossal Biosciences involves genetically engineering gray wolves, not true resurrection.
[8:19] RFK Jr.'s Autism Deadline Criticized: The hosts critique RFK Jr.'s deadline for understanding the cause of rising autism diagnoses. Key Takeaway: They argue the rise is likely due to better diagnosis, not a recent environmental cause, and scientific discovery doesn't adhere to arbitrary deadlines.
[11:43] Study 1: Oral Norovirus Vaccine Tablet (VXA-G1.1 Phase 1): Introduction to the first paper (Sci Transl Med) on an oral, adenovirus-vectored (Ad5) norovirus vaccine tablet (Vaxart platform), focusing on the need for vaccines effective in older adults and inducing mucosal immunity.
[12:22] Vaccine Details & Trial Design: The vaccine is a thermostable, enteric-coated oral tablet using a non-replicating Ad5 vector expressing the G1.1 VP1 capsid protein and a dsRNA adjuvant. The Phase 1 trial assessed safety and immunogenicity in adults aged 55-80.
[14:27] Safety Results: The vaccine was well-tolerated, with only mild-to-moderate adverse events reported at similar rates to the placebo group, indicating good safety in older adults.
[24:01] Immunogenicity - Serum Responses: The vaccine induced significant serum IgA and IgG responses, including functional antibodies measured by surrogate neutralization assays (histo-blood group antigen blocking). Responses were durable (up to Day 210) and comparable across the 55-65 and 66-80 age groups.
[30:06] Immunogenicity - Cellular & Mucosal Markers: The vaccine generated antibody-secreting B cells, including plasma blasts expressing gut-homing markers. Crucially, it induced VP1-specific IgA in saliva and nasal lining fluid, suggesting induction of mucosal immunity.
[37:45] Vaccine Potential & Next Steps: The oral tablet successfully induced systemic and mucosal immune responses in older adults without significant safety issues. A Phase 2 trial with a bivalent (G1.1/G2.4) version is ongoing. The oral format offers potential advantages for distribution and acceptance.
[41:36] Study 2: Broadly Neutralizing Norovirus Monoclonal Antibodies: Introduction to the second paper (Sci Transl Med) aimed at identifying broadly neutralizing antibodies against diverse norovirus strains, particularly the dominant GII.4 genotype, using individuals immunized with a GII.4 Vaxart oral vaccine.
[43:40] Methodology: Researchers analyzed antibody responses in two individuals immunized with a GII.4 Vaxart oral vaccine who exhibited exceptionally broad serum neutralization. They used sophisticated techniques (mass spec proteomics, single-cell B cell sequencing) to identify and characterize monoclonal antibodies.
[55:31] Antibody Deconvolution & Characterization: The studies deconvoluted the antibody repertoires, identifying dominant clonotypes boosted by vaccination ("back-boosting" or recall responses). Antibodies were characterized for neutralization breadth against various GII.4 variants (including the divergent HK2019) and their epitopes mapped.
[1:00:28] Identification of Broad Neutralizers (VX-22): Antibodies from participant B showed broader cross-genotype neutralization. Key monoclonal antibody VX-22 was identified, capable of neutralizing at least seven different GII genotypes.
[1:08:43] Antibody Evolution & Structural Analysis: "Antibody evolution trajectory analysis" suggested VX-22 arose through sequential somatic hypermutation affecting light and heavy chains following multiple exposures. Cryo-EM structure of VX-22 bound to VP1 was solved.
[1:14:12] Mechanism of Action & Implications: The VX-22 epitope is conserved but distant from receptor-binding sites. Structural and experimental data revealed its neutralization mechanism involves disrupting the virus particle (disassembly). Key Takeaway: VX-22 is a candidate for passive immunotherapy and informs rational design of broadly protective vaccines targeting conserved epitopes.
[1:18:03] Listener Emails: Discussion of emails covering shingles vaccine and dementia link, shingles in younger individuals, a listener from Guadeloupe connecting "Pluviôse" (rainy month) to the podcast title and mentioning the Thiomargarita magnifica discovery there, and the potential use of monoclonal antibodies for measles post-exposure prophylaxis.
[1:28:16] Picks of the Week: Brienne: Updated Miller-Urey experiment showing amino acid formation via micro-lightning/static electricity. Kathy: Astronomy Picture of the Day (ISS transiting Venus) and apps for spotting the ISS. Alan: Mason bees as effective native pollinators. Vincent: Ancient DNA analysis revealing medieval book covers were made of seal skin.