In Silico Characterization of VNAR–VP1 Interactions for Potential Norovirus Detection and Immunotherapy

Richard Olivares, Universidad de Antofagasta

Carlos Garrido¹ ³, Angello Retamal-Díaz¹ ² ³, Mariella Rivas¹ ³, Carlos Bustamante⁴ and Margarita K Lay¹ ² ³. 1. Department of Biotechnology, University of Antofagasta, Antofagasta, Chile. 2. Millennium Institute on Immunology and Immunotherapy, University of Antofagasta, Chile. 3. Research Center for Immunology and Biomedical Biotechnology of Antofagasta (CIIBBA), University of Antofagasta, Antofagasta, Chile. 4. Fisheries Biology Laboratory, Faculty of Marine Sciences and Biological Resources, CHALLWA, Alexander von Humboldt Institute of Natural Sciences, University of Antofagasta, Antofagasta, Chile.

Advances in diagnostics and detection

Noroviruses are the leading cause of acute gastroenteritis worldwide, characterized by high transmissibility and remarkable genetic diversity, which complicate the development of effective therapeutic strategies. Their main structural protein, VP1, forms the viral capsid and contains highly conserved functional domains such as P2, responsible for host recognition, making it an attractive target for immunotherapy and detection. However, the application of conventional antibodies against noroviruses is limited by their large size and low stability under variable environmental conditions. In this context, VNARs, the variable domains of shark IgNAR antibodies, emerge as a promising alternative due to their small size (~12 kDa), high physicochemical stability, and ability to recognize cryptic epitopes. In this study, VNARs previously obtained and modeled in silico from Mustelus mento were employed, and three-dimensional models of the VP1 protein from norovirus genogroup GII.4 were generated through structural prediction and complemented with reference structures from the literature. Structural simulations were used to predict potential binding sites within the P2 domain and to calculate binding stability (ΔG) and affinity (Kᴅ) parameters for VNAR–VP1 complexes, identifying clones with acceptable affinity and potential applicability in specific detection and viral neutralization. The findings support the feasibility of employing VNARs derived from non-model shark species as versatile agents for norovirus immunotherapy and detection, with potential use in both biomedical contexts and environmental surveillance. Moreover, this approach highlights the value of bioinformatic strategies for guiding and optimizing early-stage antibody–antigen interaction studies in the absence of experimental structures.