Bacterial Schlafens mediate anti-phage defense

Human Schlafen proteins restrict viral replication by cleaving tRNA, thereby suppressing protein synthesis. Although the ribonuclease domain of Schlafen proteins is conserved across all domains of life, its function in prokaryotes has remained unclear. Here, we show that prokaryotic Schlafen nucleases (pSlfns) are widespread antiviral effectors that protect bacteria from phages. These nucleases are fused to diverse protein domains that sense phage infection. We focus on a system where Schlafen nuclease is fused to a previously unknown immunoglobulin-like sensor domain and demonstrate that it recognizes T5-like phage tail assembly chaperones and cleaves both bacterial and viral tRNA, triggering abortive infection. Our findings redefine Schlafens as an ancient, mechanistically conserved family of immune effectors, revealing the deep evolutionary origin of tRNA-targeting antiviral immunity in humans. ### Competing Interest Statement A. Nemudryi and A. Nemudraia are inventors on patents and patent applications related to CRISPR-Cas and Schlafen immune systems and applications thereof. National Institutes of Health, R00AI171893

Howard G. Smith MD, AM on Instagram: "Nasal Spray Turbocharges Immunity A multipurpose vaccine in a nasal spray could someday protect against life-threatening viruses including flu, pneumonia, even CoVid as well as multiple allergies. It works by boosting your lungs’ immune defenses rather than targeting a specific virus or allergen. That’s a fascinating development from microbiologists and immunologists at Stanford Medicine, published in the journal Science. Instead of chasing constantly mutating viruses, this approach “trains” the immune system to stay on high alert for months. The study was conducted in mice, not humans. In experimental groups receiving the nasal vaccine—up to three doses spaced one week apart—animals are protected from viruses for at least three months, with viral levels reduced by about 700-fold. All vaccinated mice survive infection, with minimal weight loss and minimal lung inflammation. In contrast, unvaccinated control mice develop severe illness, significant weight loss, high viral loads, and often die. Besides working against viruses, the vaccine also protects against bacterial infections like Staphylococcus aureus and, wait for it, reduces allergic airway inflammation. So its an allergy medicine too. For the average person, this research suggests a future where one nasal spray could potentially replace multiple seasonal vaccines and provide rapid protection against new respiratory threats. However, this is still early-stage animal research, and human trials are just beginning. If successful, the approach could simplify vaccination and improve pandemic preparedness—but it’s not available yet. https://med.stanford.edu/news/all-news/2026/02/universal-vaccine.html https://www.sciencedaily.com/releases/2026/02/260222092258.htm #viruses #allergen #immunity #nasalspray"

0 likes, 0 comments - drhowardsmithreports on March 10, 2026: "Nasal Spray Turbocharges Immunity A multipurpose vaccine in a nasal spray could someday protect against life-threatening viruses including flu, pneumonia, even CoVid as well as multiple allergies. It works by boosting your lungs’ immune defenses rather than targeting a specific virus or allergen. That’s a fascinating development from microbiologists and immunologists at Stanford Medicine, published in the journal Science. Instead of chasing constantly mutating viruses, this approach “trains” the immune system to stay on high alert for months. The study was conducted in mice, not humans. In experimental groups receiving the nasal vaccine—up to three doses spaced one week apart—animals are protected from viruses for at least three months, with viral levels reduced by about 700-fold. All vaccinated mice survive infection, with minimal weight loss and minimal lung inflammation. In contrast, unvaccinated control mice develop severe illness, significant weight loss, high viral loads, and often die. Besides working against viruses, the vaccine also protects against bacterial infections like Staphylococcus aureus and, wait for it, reduces allergic airway inflammation. So its an allergy medicine too. For the average person, this research suggests a future where one nasal spray could potentially replace multiple seasonal vaccines and provide rapid protection against new respiratory threats. However, this is still early-stage animal research, and human trials are just beginning. If successful, the approach could simplify vaccination and improve pandemic preparedness—but it’s not available yet. https://med.stanford.edu/news/all-news/2026/02/universal-vaccine.html https://www.sciencedaily.com/releases/2026/02/260222092258.htm #viruses #allergen #immunity #nasalspray".

#Development and Characterization of Candidate #Vaccine #Viruses against High Pathogenicity Avian #Influenza #H5 Viruses for Rapid #Pandemic Response