Jesse Erasmus

Jesse Erasmus

@jesseerasmus.bsky.social

Director of Virology at HDT Bio. Developing RNA platform for emerging infectious diseases. 🇿🇦🇰🇷

2.3K followers1K following176 posts

Excited to contribute to this effort. Solving this problem will require multiple shots on goal. We at HDT Bio will be contributing our experience in manufacturing of long RNA molecules and simplified formulation with LION to create safe, yet potent, personalized drugs. More information to come soon!

Ryan Cross@scienceboss.bsky.social

ARPA-H grants up to $125M for making custom RNA therapies on demand, with applications in gene editing and cancer vaccines. One of the recipients is Waterfall Scientific, cofounded by former Moderna CSO Melissa Moore. Details in my story for @endpts.com: endpoints.news/arpa-h-award...

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11/ In a mouse challenge model, repRNA-delivered VHH-Fc significantly reduced viral titers (lung + nasal cavity) in a dose-dependent manner compared to an irrelevant repRNA-VHH control, outperforming VHH monomer or dimeric IgA formats

12/ Takeaway: this is a full RNA→RNA pipeline: RNA immunization → VHH discovery → structural validation → RNA encoding → in vivo efficacy Compact antibody formats + RNA delivery are functionally enabling. Shout out to Eddie Hodge and Jacob Archer who did a lot of the heavy lifting here!

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9/ With the Kuhn lab, we obtained a 1.4 Å structure: G12 VHH binds the VP1 canyon region, engaging BC, EF, and GH antigenic loops near a conserved functional site, where the bulky Fc domain likely contributes to steric hindrance. The spheres in the map below represent the binding footprint of G12

10/ We then closed the loop with RNA delivery. repRNA encoding VHH or VHH-Fc and delivered with LION via IM route demonstrated: 1) rapid in vivo expression, 2) detectable serum levels within a day, and 3) functional neutralization activity

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5/ To build the front end of the workflow: We worked with the Shoemaker lab at Tufts University to immunize alpacas with a hexavalent vaccine (each encoding EV-D68 VLPs) covering the 6 subclades of EV-D68, inducing cross-clade neutralizing responses.

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3/ In that prior work, we identified that canonical IgG formats are not ideal for RNA expression in vivo. Here we show that removing the CH1 domain (moving to compact formats like scFv/VHH-Fc) significantly boosts expression, likely by avoiding BiP retention during expression/folding.

4/ To capitalize on that finding, we established a VHH discovery workflow to support the development of repRNA-encoded VHHs using EV-D68 as a model pathogen. We recently completed a full vaccine development campaign for that virus described here: www.science.org/doi/abs/10.1...

science.orgA self-amplifying RNA vaccine prevents enterovirus D68 infection and disease in preclinical modelsA self-amplifying RNA vaccine for enterovirus D68 elicits neutralizing antibodies in mice and nonhuman primates and protects mice from disease.

Jesse Erasmus reposted

Excited to announce our new ARPA-H award to “Close the DOORs” mapping how viruses exploit human cells and learning how to shut them. Grateful to @arpa-h.bsky.social and our amazing team! 🔗 www.mountsinai.org/about/newsro... #ARPAH #Virology #HostPathogen #Innovation #Science

mountsinai.orgMount Sinai Awarded Up to $11.8 Million From ARPA-H to Close the Doors in Human Cells That Viruses Exploit to Infect, Replicate, and Spread

Jesse Erasmus reposted

Follow up publication describing immunogenicity and efficacy in NHPs of historical and contemporary H5N1 vaccine compositions against challenge with contemporary cattle virus isolate. What we concluded in mice did not translate to NHPs. www.science.org/doi/10.1126/...

science.orgA replicating RNA vaccine protects cynomolgus macaques against lethal clade 2.3.4.4b influenza A H5N1 virus challengeLION-delivered replicating RNA vaccines are immunogenic and protect cynomolgus macaques against lethal influenza A (H5N1) virus challenge.
Jesse Erasmus@jesseerasmus.bsky.social

New paper! In collaboration with NIAID, we asked: how effective are vaccines designed against historical #H5N1 viruses in naïve mice challenged with the contemporary cattle virus? Turns out that the new isolates are different enough to warrant further evaluation of updated vaccine compositions. 🧪

Happy to announce that we have initiated a phase I clinical trial to evaluate safety and immunogenicity of our LION/repRNA vaccine against #CCHF. This is the culmination of a great partnership with NIAID, UTMB, and our federal sponsors. More to come! www.prnewswire.com/news-release...

prnewswire.comFDA Greenlights HDT Bio's First-in-Class HDT-321 for the Prevention of Deadly Tick-Borne Disease/PRNewswire/ -- HDT Bio Corporation, a U.S.-based clinical-stage biotechnology company advancing immune-enhancing solutions for global health, biodefense, and...
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Jesse Erasmus@jesseerasmus.bsky.social

Another update on our #CCHF vaccine that is marching towards phase I clinical trial. Here we report on the durability of protection in a mouse model of CCHFV infection. Excellent work from our colleagues at RML/NIAID🧪 www.nature.com/articles/s41...

Happy to announce that we have initiated a phase I clinical trial to evaluate safety and immunogenicity of our LION/repRNA vaccine against #CCHF. This is the culmination of a great partnership with NIAID, UTMB, and our federal sponsors. More to come! www.prnewswire.com/news-release...

prnewswire.comFDA Greenlights HDT Bio's First-in-Class HDT-321 for the Prevention of Deadly Tick-Borne Disease/PRNewswire/ -- HDT Bio Corporation, a U.S.-based clinical-stage biotechnology company advancing immune-enhancing solutions for global health, biodefense, and...

Some related posts below. bsky.app/profile/jess...

Jesse Erasmus@jesseerasmus.bsky.social

Just published! Here we report immunogenicity and efficacy of our replicon RNA vaccine against Crimean-Congo hemorrhagic fever in a cynomolgus macaque model of #CCHFV infection. Stay tuned as we advance this candidate in clinical trials. www.thelancet.com/journals/ebi...

Even our project, which directly addressed the tolerability and upper respiratory tract immunity gaps highlighted by RFK Jr, was impacted by this decision. They clearly didn’t review the 22 contracts/grants and the data already generated under taxpayer investment. We are 3 yrs into our program…

Helen Branswell 🇨🇦@helenbranswell.bsky.social

Pandemic preparedness in the US has been leveled a crippling blow with the cancellation of multiple #BARDA contracts to help develop mRNA vaccines. No other vaccine platform produces vaccine so quickly; without mRNA, Americans will have a long wait for pandemic vax. www.statnews.com/2025/08/05/m...

Excited to meet the D2R community!

D2R | DNA to RNA@d2rmcgill.bsky.social

🧬 Register for D2R’s next hybrid seminar: Industry Insights with @jesseerasmus.bsky.social from HDT Bio 📅 Date: July 16th 🕰 Time: 1:00 - 2:00 PM 📍 Location: Zoom & in person 🔗 Register now: buff.ly/AayfR7c #RNA #Biotechnology

🧪 New paper from our team at HDT Bio highlighting that combo repRNA vaccines can lead to excessive innate activation that ultimately inhibits vaccine effectiveness in NHPs. Use of repRNA formulations with restricted biodistribution can alleviate systemic innate response and restore effectiveness.

cell.comAntigen-dependent interplay of formulation, systemic innate responses, and antibody responses to multi-component replicon RNA vaccinationLipid nanoparticles (LNPs) are a modular, non-viral nucleic acid delivery system. Here, Eygeris and colleagues report that addition of saponin molecules, such as quillaic acid, to LNP formulations can...

I didn’t realize you could filter the posts of who you follow! The paper feed is just what I was looking for.

Alex Crits-Christoph@acritschristoph.bsky.social

There is so, so much good science being shared and discussed on bsky right now. The news of its demise is quite backwards. If you are having trouble finding it among all of the very important political news, use the papersky feed that filters posts you follow to just papers: bsky.app/profile/pape...

Shook Nelson Mandela’s hand when I was 10 years old at some kind of gathering in a community park. Just remember him getting off a helicopter and walking through a crowd shaking hands, including mine.

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Collab btwn NIAID (Dr. Andrea Marzi’s lab) and HDT Bio just published! 🧪 Filovirus gold-standard VSV vax platform compared to LION/repRNA (each encoding same antigen seq) for ability to provide single-dose protection in guinea pigs against Sudan virus challenge 🧵(1/2) www.nature.com/articles/s41...

nature.comSingle-dose replicon RNA Sudan virus vaccine uniformly protects female guinea pigs from disease - Nature CommunicationsSudan virus (SUDV) outbreaks in Uganda created public health concerns due to a lack of approved vaccines. In this study, the authors develop a repRNA SUDV vaccine and demonstrate full protection of a ...

Summary: 1) LION/repRNA (don’t confuse with LNP/mRNA) can indeed confer protection on par with the VSV platform (at least in guinea pigs) after one shot. 2) LION & VSV elicited similar IgG titers but with a unique effector profile. LION induced higher ADCP & ADNP activity but lower ADCD. (2/2)

I noticed this statement from NIH regarding durability of the inactivated approach. I didn’t see any durability data in the published studies of this candidate. Anyone aware of durability studies performed using inactivated virus platforms? I did one experiment in grad school (in thread below).

Helen Branswell 🇨🇦@helenbranswell.bsky.social

There are a lot of questions being asked about the awarding of a $500M grant to an #NIH team to develop a new (old) vaccine platform that could be used for a "universal" #flu vaccine. www.statnews.com/2025/05/03/n...

Mice were protected from death and viremia (panels d and e) in the inactivated vaccine group but not from morbidity (panels b and c), suggesting some nuance in the quality of immune response between authentic and inactivated versions. Lots of potential explanations out there.

Just published! Here we report immunogenicity and efficacy of our replicon RNA vaccine against Crimean-Congo hemorrhagic fever in a cynomolgus macaque model of #CCHFV infection. Stay tuned as we advance this candidate in clinical trials. www.thelancet.com/journals/ebi...

thelancet.comA replicating RNA vaccine confers protection against Crimean-Congo hemorrhagic fever in cynomolgus macaquesOur data demonstrate that our repNP vaccine and NP-specific antibody can protect against CCHFV in non-human primates.

Jesse Erasmus reposted

There are days in life that shake you. I’m shattered 💔 to share that I just found out that the US Government terminated my 2024 NIH Director’s Early Independence Award (~$2 million), threatening my long-promised assistant professor job at Columbia University & academic career... 1/🧵

To those who attack vaccines over rare adverse events (observed in consenting populations) and defend SpaceX after spaceship explosions put populations at risk (without consent): science, whether in medicine or aerospace, relies on observation & iteration to improve safety. We need science!

Jesse Erasmus reposted

Today, along with 2,000 other NIH employees, I had to clear out my office 😭 It was truly the honor of my life to work with such incredibly passionate people focused on improving human health. I’ve never experienced a more positive culture where *everyone* cared about their job and serving others.

Jesse Erasmus reposted

This account is for sharing info with US scientists, both extramural and intramural to NIH, about attacks on science in the US. Education is power, and we can help advocate for science and medicine together. 💪🧪 We are a team of NIH people. Please ask us questions you might have.