Development of mRNA manufacturing for vaccines and therapeutics: mRNA platform requirements and development of a scalable production process to support early phase clinical trials.

Kevin O. Saunders, PhD, graduated from Davidson College in 2005 with a Bachelor of Science in biology. At Davidson College, he trained in the laboratory of Karen Hales, PhD, identifying the genetic basis of infertility. Saunders completed his doctoral research on CD8+ T cell immunity against HIV-1 infection with Georgia Tomaras, PhD, at Duke University in 2010. He subsequently trained as a postdoctoral fellow in the laboratories of Drs. Gary Nabel and John Mascola at the National Institutes of Health (NIH) National Institute of Allergy and Infectious Diseases (NIAID) Vaccine Research Center.

In 2014, Saunders joined the faculty at the Duke Human Vaccine Institute as a medical instructor. In this role, he analyzed antibody responses in vaccinated macaques, which led to the identification of glycan-dependent HIV antibodies induced by vaccination. Dr. Saunders was appointed as a non-tenure track assistant professor of surgery and the director of the laboratory of protein expression in the Duke Human Vaccine Institute in 2015. He successfully transitioned to a tenure-track appointment in 2018 and was later promoted to the rank of associate professor in surgery in 2020. In 2022, Saunders became an associate professor with tenure. He rose to the rank of professor with tenure in 2024 and was subsequently awarded the Norman L. Letvin, MD Professor in Immunology and Infectious Diseases Research in Surgery and the Duke Human Vaccine Institute distinguished professorship. Saunders previously served as DHVI's associate director of research, director or research, and currently serves as the associate director for DHVI. Additionally, Saunders serves as the faculty chairperson for DHVI's Diversity, Equity, and Inclusion Committee.

Saunders has given invited lectures at international conferences such as HIVR4P and the Keystone Symposia for HIV Vaccines. He has authored book chapters and numerous journal articles and holds patents on vaccine design concepts and antiviral antibodies. As a faculty member at Duke, Saunders has received the Duke Human Vaccine Institute Outstanding Leadership Award and the Norman Letvin Center For HIV/AIDS Vaccine Immunology and Immunogen Discovery Outstanding Investigator Award, Ruth and A. Morris Williams Faculty Research Prize, and the Duke Medical Alumni Emerging Leader Award. His current research interests include vaccine and antibody development to combat HIV-1, coronavirus, and other emerging viral infections.

About the Saunders Laboratory
The Saunders laboratory aims to understand the immunology of broadly protective antibodies and the molecular biology of their interaction with viral glycoprotein. The laboratory utilizes single B cell PCR, bulk B cell sequencing, and antigen-specific next-generation sequencing to probe the antibody repertoire during natural infection and after vaccination. The lab's overall goal is to develop protective antibody-based vaccines; therefore, the laboratory is divided into two sections–Immunoprofiling and Vaccine/Therapeutics design. They employ a reverse vaccinology approach to vaccine design where they study broadly protective antibodies in order to design vaccines that elicit such antibodies. To elicit broadly protective antibody responses, the Saunders laboratory utilizes epitope-focused nanoparticle vaccines. While eliciting broad protection is their overall goal, they are also interested in the immunologic mechanisms that make the vaccines successful.

Anti-glycan HIV-1 antibody biology. Their research premise is that vaccine-elicited antibodies will broadly neutralize HIV-1 if they can bind directly to the host glycans on Env. However, Env glycans are poorly immunogenic and require specific targeting by a vaccine immunogen to elicit an antibody response. Using this technique they identified two monoclonal antibodies from HIV Env vaccinated macaques called DH501 and DH502 that bind directly to mannose glycans and to HIV-1 envelope (Env). They have characterized these antibodies using glycan immunoassays, antibody engineering, and x-ray crystallography to define the mechanisms of Env-glycan interaction by these antibodies. Glycan-reactive HIV antibodies have mostly been found in the repertoire as IgG2 and IgM isotypes—similar to known natural glycan antibodies. Therefore they are examining whether vaccines mobilize antibodies from the natural glycan pool that affinity mature to interact with HIV-1 envelope. During this work, they discovered that Man₉GlcNAc₂ is the glycan preferred by early precursors in broadly neutralizing antibody lineages. They translated this finding into a vaccine design strategy that they have termed “glycan learning.” This approach modifies the number of glycans and type of glycosylation of HIV-1 Env immunogens to be optimal for engagement of the precursor antibody. The Env glycosylation sites and glycan type are then modified on subsequent Env immunogens to select antibodies that are maturing towards a broadly neutralizing phenotype. They have developed cell culture procedures and purification strategies combined with mass spectrometry analyses to create Env immunogens with specific glycosylation profiles. While the overall goal is to elicit protective neutralizing antibodies in vivo, they use these Env antigens in vitro to investigate the biology of B cell receptor engagement. 

HIV-1 Sequential vaccine design. The discovery of lineages of broadly neutralizing antibodies in HIV-infected individuals has provided templates for vaccine design. Utilizing viral sequences from individuals that make broadly neutralizing antibodies, we further engineer the viral protein to preferentially bind the desired type of antibody. The Saunders lab partners heavily with structural biologists and bioinformaticians to design optimized vaccine immunogens for in vitro and preclinical testing. They are investigating the hypothesis that broadly neutralizing antibodies can be engaged with envelope immunogens specifically designed to target them, and that engineered envelopes can select for the broadly neutralizing antibody precursors to develop into a broadly neutralizing antibody. They examine antibody responses in vaccinated humanized mice and monkeys to discern if the vaccine elicits antibodies that are similar to the known human broadly neutralizing antibody targets. Vaccines that are effective in animal models are translated for manufacturing and evaluation in Phase I clinical trials.

Pancoronavirus vaccine development. During the COVID-19 pandemic, the Saunders lab and DHVI as a whole worked to isolate broadly neutralizing antibodies against SARS-CoV-2 and related viruses. These antibodies then served as a template for the development of receptor binding domain nanoparticle vaccines we call RBD-scNP. These vaccines protected monkeys and mice from SARS-CoV-2 and animal coronaviruses. This vaccine has been translated to GMP manufacturing and will be examined in a Phase I clinical trial. The lab continues to apply similar approaches against other targets on coronaviruses to ultimately generate protective immunity against most coronaviruses. The lab explores different delivery methods including slow-release technology and nucleoside-modified mRNA delivery.

Taken together, our research program is an interdisciplinary approach to understanding the molecular biology underlying antibody recognition of viral glycoproteins in order to produce protective vaccines.