Biology subjects

Melief, E.

Publications and source records attributed to Melief, E..

5 recordsLinked to original sources

bioRxiv2026

Wobble Vaccines: Cross-Strain Protection Through Epitope Hierarchy Manipulation

Vaccination remains the most successful preventative measure against viral infection, but methods to stably deter rapidly-evolving pathogens have remained elusive. Vaccines capable of incorporating and anticipating viral evolution could address current challenges in seasonal vaccination efforts against SARS-CoV-2 and influenza where economic and disease burdens remain high despite decades of combined study. Rare epitope suppression (RES) is an underutilized concept within vaccine design, where humoral epitope targeting can be molded using complex antigen pools. Based in mRNA vaccine technology, wobble vaccines represent the novel application of RES to human pathogens designed to anticipate and resist viral evolution. To establish this platform, public SARS-CoV-2 sequencing data was compiled from the first two years of the COVID-19 pandemic to identify high-diversity sites across the receptor binding domain (RBD) of the spike protein. Wobble RBD (WobbRBD) libraries reflecting that entropy were synthesized and incorporated into established self-amplifying (SA) vaccine constructs. Animals immunized with these complex antigen pools showed no obvious adverse effects. By three days-post vaccination, WobbRBD stimulated robust primary immune activation with distinctive characteristics compared to traditional single-strain vaccine modalities. By day 14, germinal centers, class switching, and antibody-secreting cells were induced, creating potent SARS-CoV-2 spike-binding IgG antibodies. Despite similar overall activation profiles, WobbRBD generated significantly increased breadth against SARS-CoV-2 variant spikes in comparison to single-strain controls - even against future-emerging strains. Taken together, wobble vaccines represent a novel method for anticipating and preventing viral escape with promising applications in SARS-CoV-2, influenza, HIV, and beyond.

immunology↗

bioRxiv2025

A Spray Dried Replicon Vaccine Platform for Pandemic Response

The recent COVID-19 pandemic, as well as the threat of a global pandemic caused by H5N1 avian influenza virus, has highlighted the need for the development of thermostable vaccines that can be manufactured and distributed rapidly to combat the next global pandemic. To address this need, we previously developed a replicon vaccine platform that utilizes a nanostructured lipid carrier (NLC) to protect and efficiently deliver antigen-expressing replicon molecules in vivo. The replicon-NLC vaccine platform uses readily sourced components and can be rapidly manufactured at scale with the potential for stockpiling, thus enhancing pandemic preparedness. Spray drying is a promising method of vaccine desiccation with reduced costs and increased scale-up capabilities compared to lyophilization. As proof of concept, we demonstrate for the first time the successful spray drying of a replicon-NLC vaccine complex designed to protect against H5N1 avian influenza A virus to enhance its long-term thermostability while maintaining vaccine immunogenicity in an in vivo mouse model. Several glass-forming disaccharide excipients were screened for formulation and process compatibility under low-temperature spray drying conditions, and it was determined that a suitable shell-forming excipient, L-leucine, was necessary to prevent excessive accumulation of replicon-NLC vaccine complexes on the dry powder surface and a subsequent loss in process yield. The spray dried replicon-NLC vaccine powders were chemically stable for 1 month of storage at 40{degrees}C. Immunogenicity of the spray dried drug product was also well maintained for at least 3 months of storage at 4{degrees}C when administered intramuscularly into C57BL/6 mice as a reconstituted liquid. Finally, we demonstrate the ability to precisely control the aerodynamic particle size of the spray dried vaccine product to generate dry powders that are theoretically suitable for nasal or pulmonary delivery without reconstitution. This work establishes the feasibility of spray drying a thermostable replicon-NLC vaccine for rapid pandemic response.

immunology↗

bioRxiv2025

Development of an Intranasally- and Intramuscularly-Administrable Replicon Vaccine Efficacious Against H5N1 Influenza Virus

The risk of a respiratory viral pandemic is significant, including from the now widespread panzootic H5N1 influenza virus, highlighting the need for effective, stable, and inexpensive vaccine technologies that elicit strongly protective immunity. Intranasal vaccines can stimulate local immune responses at the site of natural respiratory viral infection, a key characteristic that can not only reduce morbidity and mortality caused by respiratory viruses but also potentially reduce viral transmissibility to limit outbreaks. Nucleic acid vaccines are now a valuable tool in pandemic responses, with high potency and rapid adaptability to target circulating or emerging viral strains; however, data are limited on which vaccine attributes are needed for efficient transmucosal delivery and immune stimulation following intranasal delivery. To demonstrate proof of concept, here we have developed a replicon vaccine expressing an H5 influenza antigen that uses a nanostructured lipid carrier (NLC) delivery system. A relationship was established between the molar ratio of positive charges on the NLC to the negative charges on the nucleic acid (N:P ratio) and the immunogenicity of the vaccine formulations, with higher N:P ratios resulting in an increase in vaccine immunogenicity. We demonstrated the ability of this replicon vaccine to be administered via intramuscular and intranasal routes with a singular vaccine formulation. The vaccine induced systemic immunity when dosed intramuscularly or intranasally in an immunocompetent mouse model, whereas intranasal dosing uniquely stimulated a strong mucosal immune response. Moreover, a mixed intramuscular/intranasal dosing strategy using this unified formulation stimulated a balanced systemic and mucosal immune response. Finally, we demonstrated the protective efficacy of this intranasally and intramuscularly/intranasally delivered H5 replicon-NLC vaccine against morbidity and mortality in a lethal H5N1 influenza challenge ferret model. This work establishes the replicon-NLC vaccine platform as a potential novel intranasal technology for rapid pandemic response.

immunology↗

bioRxiv2025

An intranasal, NLC-delivered self-amplifying RNA vaccine establishes protective immunity against pre-pandemic H5N1 and H7N9 influenza

Seasonal and pandemic influenzas are continuous threats to human health, requiring rapid development of vaccines to multiple evolving viral strains. New RNA vaccine technologies have the adaptability and manufacturability to facilitate pandemic preparedness but have limited flexibility in their route of administration, reducing the ability to establish local protective immune responses such as respiratory mucosal immunity. Here, we describe monovalent and bivalent self-amplifying RNA (saRNA) vaccines against A/Vietnam/1203/2004 H5N1 and A/Anhui/2013 H7N9. These saRNA vaccines express either H5 or H7 hemagglutinin and are formulated with a nanostructured lipid carrier (NLC) that permits both intramuscular (IM) and intranasal (IN) dosing. In mice, IM vaccination established systemic humoral and cellular responses but no detectable mucosal response, while IN administration induced robust systemic and mucosal immunity. The saRNA-NLC vaccines provided complete protection against morbidity and mortality in ferret challenge models, establishing this intranasally-administered saRNA-NLC vaccine platform as a potential pandemic response tool. ONE SENTENCE SUMMARYA self-amplifying RNA-NLC vaccine, delivered intranasally, induces robust mucosal immunity in mice and protects against H5N1 and H7N9 in ferrets

immunology↗

bioRxiv2018

Activation of 2,4-diaminoquinazoline in Mycobacterium tuberculosis by Rv3161c, a putative dioxygenase

The diaminoquinazoline series has good potency against Mycobacterium tuberculosis. Resistant isolates have mutations in Rv3161c, a putative dioxygenase. We carried out metabolite analysis on wild-type and an Rv3161c mutant strain after exposure to a diaminoquinazoline. The parental compound was found in intracellular extracts from the mutant, but not the wild-type. A metabolite consistent with a mono-hydroxylated form was identified in the wild-type. These data support the hypothesis that Rv3161c metabolizes diaminoquinazolines in M. tuberculosis.

microbiology↗