H9N2 Influenza Whole Inactivated Virus Combined with Polyethyleneimine Strongly Enhances Mucosal and Systemic Immunity after Intranasal Immunization in Mice

Abstract

Influenza whole inactivated virus (WIV) is more immunogenic and induces protective antibody responses compared with otherformulations, like split virus or subunit vaccines, after intranasal mucosal delivery. Polyethyleneimine (PEI), an organic polycation, is widely used as a reagent for gene transfection and DNA vaccine delivery. Although PEI recently has demonstrated potent mucosal adjuvant activity for viral subunit glycoprotein antigens, its immune activity with H9N2 WIV is not well demonstrated. Here, mice were immunized intranasally with H9N2 WIV combined with PEI, and the levels of local respiratory tract and systemic immune responses were measured. Compared to H9N2 WIV alone, antigen-specific IgA levels in the local nasal cavity, trachea, and lung, as well as levels of IgG and its subtypes (IgG1 and IgG2a) in the serum, were strongly enhanced with the combination. Similarly, the activation and proliferation of splenocytes were markedly increased. In addition, PEI is superior as an H9N2 WIV delivery system due to its ability to greatly increase the viral adhesion to mucosal epithelial cells and to enhance the cellular uptake and endosomal escape of antigens in dendritic cells (DCs) and further significantly activate DCs to mature. Taken together, these results provided more insights that PEI has potential as an adjuvant for H9N2 particle antigen intranasal vaccination.T he rise and spread of the low-pathogenic avian H9N2 influenza virus have seriously increased the risk of a new influenza pandemic. H9N2 viruses have prevailed in chickens in China in recent years and have constantly undergone reassortment, and novel genotypes have continued to emerge (1-3). A novel H7N9 reassortant subtype was recently found to cause severe human respiratory infections in China (4). Bioinformatic analyses for the H7N9 virus revealed that its six internal genes were from H9N2 avian influenza viruses of chickens (5). Thus, the elimination of low-pathogenic avian H9N2 influenza virus in poultry becomes even more important in influenza prevention.The nasal cavity of the respiratory tract is the primary entry site of the H9N2 influenza virus, and the viral infection could be discontinued if intranasal immunity is well established (6). Compared with live attenuated influenza vaccines or subunit influenza vaccines (such as purified viral hemagglutinin [HA]) or neuraminidase [NA]) proteins), whole inactivated H9N2 influenza vaccines have more advantages, including an improved safety profile, higher immunogenicity, more effective ability of establishing cross-protection at the pathogen's entry site, and stronger crosspresentation of antigens by dendritic cells (DCs) for a CD8 ϩ T cell response against viruses (7-9). However, mucosal immunization by intranasal delivery with inactivated virus alone is often poorly effective. Unlike systemic immunization, nasal antigens must cross various barriers (compact epithelium, mucociliary clearance, and mucus) before they contact with submucosal immune cells (10). Many researchers used various ...

Inhibition of H9N2 Virus Invasion into Dendritic Cells by the S-Layer Protein from L. acidophilus ATCC 4356

“…The influenza virus (A/Duck/NanJing/01/1000 [H9N2]) was generously supplied by the Jiangsu Academy of Agricultural Sciences (Nanjing China) (Qin et al, 2015). C57BL/6 mice (4 weeks old, specific-pathogen-free [SPF]) were purchased from the Animal Research Centre of Yangzhou University.…”

Polyethylenimine-based micro/nanoparticles as vaccine adjuvants

“…It is not clear from these studies whether the improved immune efficiency was solely due to antigen protection (vaccine delivery vehicle) or due to the intrinsic adjuvant property (immunostimulator) of PEI. 25,56,78,95 Moreover, in the case of PEI-coated polyplex, PEI together with the NPs/MPs should be regarded as a whole to take effects. When encapsulated inside, it was even more difficult to prove the adjuvanticity of PEI.…”

Evaluation in broilers of aerosolized nanoparticles vaccine encapsulating imuno-stimulant and antigens of avian influenza virus/Mycoplasma gallisepticum

“…The lowest recovery of tracheal MG and H9N2 from challenged birds was in those allocated to TRT 3 (Table 4), who had the appropriate priming that led to the highest MG and H9N2 -specific IgA and IgG in their tracheobronchial washings at the challenge age of 28 d (Table 3). Previous reports documented the role of IgA and IgG in local protection against tracheal infection of broilers by the two organisms [21,22,50,51,52], emphasizing the role of mucosal immunity in projects targeting the control of these two pathogens in poultry.…”

“…Scientists are currently searching for alternatives to the costly injectable killed vaccines, and to the injurious approach of administering live vaccine strains of H9N2 and MG in poultry. Preliminary attempts in deliverance of soluble antigens through the nasal passage, for immunization against AI [21,22] and MG [23], are documented. Such attempts led to sporadic acquirement of immune responses [21][22][23], with a need to augment the induction of local immunity in the respiratory tract, and to establish a relationship between this augmentation and protection against coinfection by MG and H9N2.…”