This episode of "This Week in Virology" (TWiV 1223) covers a range of timely topics in virology and public health. The hosts critically analyze RFK Jr.'s "Make America Healthy Again" report, pointing out its reliance on non-existent citations, potentially generated by AI. They also discuss a newly identified fungus that poses an additional threat to North American bat populations. A significant portion of the episode is dedicated to two research papers from Nature Communications: one detailing comprehensive surveillance of avian influenza viruses through bird guano in under-sampled remote regions of the Global South, revealing H5N1 prevalence, transmission dynamics, and zoonotic risk factors; and another exploring the Pipistrellus abramus bat ACE2 protein as a key receptor for HKU5 coronaviruses, utilizing a novel pseudovirus system and structural analyses. The episode concludes with listener questions, comments, and weekly science picks spanning topics from cat genetics to global health ethics and the impact of funding cuts on scientific research.
TWiV 1223: Navigating Misinformation, Bat Conservation, Avian Flu Surveillance, and Coronavirus Receptors
0:00 Introduction & Support for Science: Hosts Vincent Racaniello, Kathy Spindler, and Brianne Barker introduce the episode, emphasizing MicrobeTV's commitment to factual science education and inviting listener support.
2:34 ASV 2025 Meeting Update: Kathy Spindler provides details on the American Society for Virology (ASV) 2025 meeting in Montreal, highlighting changes to the schedule and the upcoming June 12th deadline for residence hall reservations.
5:23 Critique of RFK Jr.'s Report: The hosts discuss RFK Jr.'s "Make America Healthy Again" report, which is found to contain citations to non-existent studies. Brianne Barker suggests this could be a result of generative AI "hallucinating" sources, a common issue with such tools.
7:53 New Fungal Threat to Bats: A New York Times article highlights the discovery of a new fungal species that could further endanger North American bat populations, already severely impacted by White-nose disease caused by Pseudogymnoascus destructans.
9:37 Paper 1: Avian Influenza Surveillance in the Global South:
Study Focus: A Nature Communications paper reports on a broad surveillance study of avian influenza (AI) viruses using over 27,000 bird guano samples from 10 remote countries in the Global South (e.g., Indonesia, Madagascar, Maldives, Papua New Guinea) collected between December 2021 and February 2023. This effort aims to address the lack of surveillance in low- and middle-income countries.
15:25 Prevalence & Dominant Subtype: 1.33% of samples contained AI viral RNA. H5N1 was the most prevalent subtype detected, with the majority belonging to clade 2.3.4.4b, which is currently circulating in US dairy cattle.
21:14 Subtype Diversity & Migration: Papua New Guinea showed the highest diversity of AI subtypes. Phylogenetic analysis revealed that viral clustering patterns closely aligned with major global bird migration pathways, demonstrating how viruses spread across continents.
24:10 Unreported Presence & Antiviral Resistance: Highly pathogenic AI sequences were found in several regions where no official disease outbreaks in birds had been reported, suggesting inadequate surveillance. Some H5N1 samples also carried an H275Y mutation in neuraminidase, linked to resistance to antiviral drugs like Tamiflu.
29:13 Transmission Pathways: The discussion emphasizes how various wild bird species (e.g., whistling ducks, sandpipers, gulls, crows) facilitate transmission by interacting with domestic poultry in diverse environments like rice fields, wetlands, and markets.
33:25 Episodic Activity & Ecological Impact: Viral activity showed a biphasic, episodic pattern rather than continuous circulation, likely driven by seasonal ecological events. Furthermore, ecological changes such as mining, logging, and infrastructure projects, along with civil conflicts, are increasing human-wildlife contact and exacerbating the risk of HPAI transmission to humans and poultry.
Key Takeaway: The study highlights the critical need for enhanced, equitable, and seasonally adapted surveillance in under-monitored remote regions to effectively understand and mitigate zoonotic disease risks.
40:48 Paper 2: ACE2 Receptor for HKU5 Coronaviruses:
Research Question: Another Nature Communications paper investigates the entry receptors for various Merbecoviruses (a subgenus of beta-coronaviruses that includes MERS-CoV, which uses DPP4 as its receptor).
Methodology - MerbecoType System: Researchers developed a "MerbecoType" pseudovirus system, allowing them to test the receptor binding domains (RBDs) from 34 unique Merbecovirus spike sequences across different cell lines expressing various animal and human receptors.
1:08:30 HKU5 and Bat ACE2: The study conclusively found that clade 2 Merbecoviruses, specifically the HKU5 group, efficiently use the ACE2 protein from Pipistrellus abramus (Japanese house bats) as their receptor for cell entry. This was confirmed with both pseudoviruses and an infectious HKU5 clone.
1:17:01 Structural Insights & Synanthropic Bats: Structural analysis identified key interactions between the HKU5 RBD and the bat ACE2. Pipistrellus abramus bats are "synanthropic," meaning they live in close proximity to humans, increasing the potential for human exposure to these viruses, although current HKU5 RBDs show low affinity for human ACE2.
Key Takeaway: This research significantly advances the understanding of Merbecovirus entry mechanisms, identifies a specific bat ACE2 as a key receptor for HKU5 viruses, and underscores the ongoing risk posed by bats living near human populations.
1:24:33 Listener Emails & Feedback: The hosts read a selection of emails from listeners, covering topics such as: the availability of Wendy Carlos's "Switched on Bach," the effectiveness of measles vaccines, personal experiences applying TWiV knowledge in medical settings, historical articles on the role of science, the definition of ethology, a recommended book on global health ethics, the negative impact of federal funding cuts on NIH labs, a humorous take on scientific writing, and a proposal for Democratic-led states to collectively offset federal NIH funding cuts through millionaire taxes.
1:39:39 Weekly Picks:
Brianne: An article about a newly discovered non-coding mutation that gives orange cats their distinct color.
Kathy: An inspiring story about a middle schooler whose STEM project on goose poop led to the discovery of a bacterium with antibiotic properties and an anti-cancer compound.
Vincent: An opinion piece by Michelle Goldberg titled "Elon Musk’s Legacy Is Disease, Starvation and Death," critiquing the negative impact of cuts to USAID.
Listener Pick (David): Carl Sagan's 1995 book, "The Demon-Haunted World: Science as a Candle in the Dark," and a hypothetical question about obtaining vaccines/medical care abroad if access is removed in the US.