Replication-deficient Sendai virus expressing human norovirus capsid protein elicits robust NoV-specific antibody and T-cell responses in mice.

Human norovirus (HuNoV) is a major global cause of acute gastroenteritis, with vaccine development facing several challenges. Despite years of research, there are currently no licensed vaccines available for controlling HuNoVs. Here, we describe the construction and testing of a replication-deficient Sendai virus (SeV) vector as a potential vaccine candidate against the HuNoV GII.4 genotype. SeV was chosen as the vaccine backbone due to its non-pathogenic nature in humans, its capability for long-term antigen expression in mammalian cells, and its suitability for mucosal administration. By inserting the HuNoV GII.4 capsid gene, VP1, into the SeV genome, we generated a replication-deficient SeV (SeV/dP.VP1) vector. The resultant SeV/dP.VP1 virus were observed to successfully express the inserted NoV VP1 gene upon infection. Inoculating the vaccine into wild-type mice elicited NoV-specific IgG antibodies, along with INF-γ and IL-2-producing T cells, through both intranasal (i.n.) and intramuscular (i.m.) immunization. Furthermore, a significant level of NoV-specific IgA was detected in lung homogenates after i.n. immunization, particularly using a high dose of the viral vector. Additionally, a synergistic effect was observed with heterologous prime-boost regimens using SeV/dP.VP1 and MVA.VP1 vectors, indicating the potential for more robust immune responses when the vaccine design is optimized. Our study demonstrates the potential of a SeV vaccine candidate in eliciting a broad immune response and lays the foundation for further exploration of the SeV vector platform's potential as a HuNoV vaccine. Additionally, the results emphasize the importance of vaccine dosage and administration route, highlighting the need for tailored immunization strategies.