This TWiV episode, "Swedish models and agent 007," discusses two scientific papers and recent news in virology. The first paper explores how the 2009 H1N1 influenza pandemic disrupted the biennial respiratory syncytial virus (RSV) epidemic pattern in Northern Stockholm, concluding through mathematical modeling that transient viral interference from influenza's innate immune response was the primary cause. The second paper presents the development of broad-spectrum synthetic carbohydrate receptors (SCRs), particularly SCR007, that target N-glycans on viral glycoproteins. These small molecules effectively inhibit the entry of diverse enveloped viruses (coronaviruses, filoviruses, paramyxoviruses) and even rotavirus in vitro, and show significant prophylactic efficacy in a lethal SARS-CoV-2 mouse model, reducing morbidity, mortality, and viral loads. The episode also touches on current political challenges to vaccine mandates in Florida, the CDC's credibility, and COVID-19 vaccine access, alongside a detailed critique of human data from a prior study on COVID's link to cancer recurrence.
Summary:
0:00 - Podcast Introduction & Weather: The hosts introduce TWiV 1251 and share their local weather conditions, a recurring segment that some listeners skip.
3:48 - MicrobeTV Support & Political News: The hosts encourage listener support due to the absence of ads and discuss the political landscape impacting public health.
4:41 - Vaccine Mandates in Florida: Florida's Surgeon General and Governor are moving to end vaccine mandates for school-aged children, a highly political move aimed at votes. This includes previously required vaccines like MMR and polio, though some require legislative action.
7:24 - Importance of Mandates: The hosts emphasize that school vaccine mandates are effective public health tools, and the reasons for lifting them are ideological, not health-based, potentially jeopardizing children's health.
10:10 - RFK Jr. & CDC Credibility: RFK Jr.'s influence has led to concerns about the CDC's recommendations, prompting states like California, Oregon, and Washington to form a West Coast Health Alliance to issue their own health guidance.
11:20 - COVID Vaccine Access Issues: Lack of clear guidance from the CDC's ACIP has led to uneven COVID vaccine access, with some states requiring prescriptions while others (e.g., New York, Massachusetts, Colorado) have passed measures to ensure accessibility.
13:45 - Paper 1: Viral Interference and RSV Epidemics: Discussion of a Nature Communications paper on the disruption of RSV epidemics in Northern Stockholm.
14:59 - RSV Pattern: In Northern Stockholm, RSV activity typically follows a biennial pattern, with large epidemics in odd-numbered seasons and smaller ones in even years.
17:27 - 2009 H1N1 Pandemic's Impact: This pattern was significantly altered after the 2009 H1N1 influenza pandemic, shifting large epidemics to even-numbered years.
18:15 - Hypotheses & Modeling: Three hypotheses were tested using mathematical models: a sudden increase in birth rates (2009-2011), extremely low temperatures (2010-2011), and viral interference from the H1N1 pandemic.
23:57 - Findings: Modeling showed that neither birth rate increases nor temperature fluctuations could explain the pattern shift. Only models incorporating influenza interference accurately captured the altered dynamics, with the 2009 pandemic being the key factor.
25:36 - Mechanism: The theory suggests that influenza infection induces a transient innate immune/interferon response, providing about a week of protection against RSV, which is enough to disrupt RSV's population-level dynamics.
29:30 - Discussion & Takeaway: The hosts ponder the reasons for RSV's biennial pattern (likely population immunity) and the one-way nature of the interference (flu interferes with RSV, but not vice versa, possibly due to flu's interferon antagonists). This highlights how finely tuned viral ecosystems are and the potential for one virus to affect another's seasonality, with implications for vaccine strategies.
37:04 - Paper 2: Broad-Spectrum Synthetic Carbohydrate Receptors (SCRs): Review of a Science Advances paper on novel antiviral compounds.
39:50 - Goal & Challenge: The aim is to develop broad-spectrum small-molecule antivirals for pandemic preparedness, addressing the challenge of finding virus-specific targets that avoid host toxicity and resist mutation.
41:38 - Target: The compounds, called Synthetic Carbohydrate Receptors (SCRs), target N-glycans (five-sugar core linked to asparagine) on viral glycoproteins.
43:52 - Compounds & Screening: A library of 57 SCRs was screened against pseudovirus particles featuring glycoproteins from SARS-CoV-1/2, MERS, Nipah, Hendra, Ebola, and Rotavirus.
48:33 - SCR007 Efficacy: SCR007, dubbed "Agent 007," emerged as the most potent, with IC50s between 10 and 40 Β΅M, showing broad inhibition of viral entry for multiple enveloped viruses and rotavirus.
49:31 - Cytotoxicity & Selectivity: Cytotoxicity in cell culture was observed at higher microM concentrations (selectivity index 5.5-16), indicating a need for careful dosing.
51:24 - In Vivo Tolerability: In mice, 10 mg/kg caused no adverse effects, but 100 mg/kg led to transient 10% weight loss and a 20% increase in liver enzymes, suggesting off-target effects at high doses.
54:50 - Prophylactic Efficacy in Mice: In a lethal SARS-CoV-2 mouse model, prophylactic (intra-nasal) administration of SCR007 (3 mg/kg) resulted in 90% survival, reduced weight loss, and significantly decreased viral loads in both lung and brain, as well as reduced lung histopathology.
1:04:14 - Mechanism of Action: SCR007 binds to N-glycans on the receptor-binding domain of the SARS-CoV-2 spike protein, blocking viral attachment. For Nipah virus, it primarily interferes with fusion.
1:06:29 - The "In Cellulo" Debate: A humorous interlude discussing the controversial term "in cellulo" used in the paper, advocating for "in cells" or "in cultured cells" instead.
1:13:33 - Discussion & Future Directions: The hosts discuss the potential for resistance (loss of glycosylation sites), the importance of glycosylation context for specificity, and the need for further optimization, pharmacokinetics, and toxicity studies. The compounds' additional anti-inflammatory effects are noted as a positive.
1:19:33 - Lori: Shared her experience in a rabies vaccine trial where hives after the second dose led to her early exit, likely due to concerns about an allergic reaction.
1:21:54 - Conrad: Praised the Stanley Plotkin interview and noted that TWiV podcasts serve as a valuable journal club, reminding him of his professional career.
1:23:21 - Lisa: Shared a personal connection to aviation, similar to Stanley Plotkin, and a song about flight. Alan Dove shared his own decision to stop flying due to environmental concerns and a harrowing spin experience.
1:26:42 - Felicia: Highlighted efforts by the Society for Medical Anthropology to combat disinformation and advocate for public health.
1:28:06 - Jennifer (Epidemiologist): Provided a detailed critique of a previous TWiV discussion on a Nature paper linking COVID-19 to cancer reactivation. Jennifer argued that the human data in the paper was not as strong as presented, suggesting that increased cancer mortality was primarily due to COVID as an underlying cause, not cancer recurrence. She also questioned the low COVID infection rates reported in EHR data. Her research found no significant overall increase in cancer deaths during the pandemic, stressing that cancer survivors' higher risk of death is from COVID itself, not cancer recurrence, aiming to alleviate anxiety for cancer survivors.
1:35:43 - Angela: A news article and Nature paper on engineered yeast providing essential sterols to boost honeybee colony production and fertility, addressing honeybee deficits and crop production.
1:38:35 - Kathy: The New York Times obituary of Margaret Rosser, a historian who documented women's exclusion from science and coined the term "Matilda effect."
1:42:06 - Rich: A PBS NewsHour segment on tracking humpback whale migration using AI to identify individuals by their fluke patterns, linking to the "Happy Whale" website.
1:44:59 - Alan: His recently published fiction story and a blog post titled "You're Probably Using the Wrong Dictionary," advocating for the Webster's 1913 edition for its detailed linguistic nuances for writers.
1:49:54 - Vincent: An MMWR report from the CDC about a child in San Francisco infected with H5N1 avian influenza with no known exposure, highlighting the CDC's crucial surveillance and contact tracing work despite current political challenges to the institution.
1:54:17 - Conclusion: The hosts wrap up the episode, thank the listeners and contributors, and encourage support for MicrobeTV.