The recombinant truncated envelope protein of West Nile virus adjuvanted with Alum/CpG induces potent humoral and T cell immunity in mice

West Nile virus (WNV) is a mosquito-transmitted flavivirus distributed globally for decades and can cause dis-ease in humans and animals. So far, no WNV vaccine has been licensed for human use. Therefore, the devel-opment of novel candidate vaccines and the improvement of vaccination strategies is imperative. As the WNV envelope (E) glycoprotein plays an important role in mediating viral binding to cellular receptors and virus-cell membrane fusion, it is a critical target for the host humoral response. Here, we prepared a recombinant trun-cated envelope protein of WNV (rWNV-80E) and developed a WNV subunit vaccine formulation with a com-bination of aluminum hydroxide (alum) and a synthetic oligonucleotide CpG as adjuvants. C57BL/6 mice were immunized twice intramuscularly at 28-day intervals with 5 mu g purified rWNV-80E adjuvanted with Alum/ CpG. WNV E-specific IgG was detected by enzyme-linked immunosorbent assay and neutralizing antibodies (nAbs) was detected using single-round infectious particles of WNV. Furthermore, T cell immunity was detected by enzyme-linked immunospot assay and intracellular cytokine staining assay. Notably, rWNV-80E was highly immunogenic and elicited potent humoral and cell immunity, as evidenced by significant levels of IFN-gamma and TNF-alpha secretion in the T cells of mice. In summary, the Alum/CpG-adjuvanted rWNV-80E subunit vaccine elicited potent and balanced B-and T-cell immunity in mice, and therefore it is a promising candidate vaccine that warrants further investigation for use in human or veterinary applications.(c) 2023 Chinese Medical Association Publishing House. Published by Elsevier BV. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).