Intranasal vaccination with gB adjuvanted by poly(I:C) induces complete protection against pseudorabies virus in swine.

Abstract

Pseudorabies virus (PRV) is an important swine pathogen causing severe economic losses worldwide. Nasal mucosa serves as the initial entry site for PRV, highlighting the importance of nasal mucosal immunity in limiting infection. Here, we investigated the immune responses and protection against PRV for the intranasal vaccination of glycoprotein B (gB) subunit vaccine adjuvanted with poly(I:C). In piglets, immunohistochemistry showed rapid uptake of the gB by the nasal mucosa within 2 h, supporting subsequent immune activation. Upon challenge with the PRV variant ZJ01, intranasal gB vaccination provided complete clinical protection with the absence of clinical signs, substantially reduced virus load in tissues and viral shedding, and no pathological lesions. Relative to intramuscular gB or the live attenuated Bartha-K61 vaccination, intranasal gB vaccination elicited stronger mucosal antibody responses and greater infiltration of CD3⁺ T cells, CD19⁺ B cells, and IgA-secreting cells in the nasal cavity. Notably, intranasal immunization followed by challenge promoted the formation of tertiary lymphoid structure (TLS) in the turbinate, providing a local niche for adaptive immune responses. Consistent with histological observation, transcriptomic profiling of nasal mucosa revealed activation of the IL-17 and TNF signaling pathways, which are implicated in the formation and maintenance of TLS. These findings demonstrate that intranasal gB vaccination might represent a promising mucosal vaccination strategy for controlling PRV infection in swine.