A CpG-adjuvanted intranasal enterovirus 71 vaccine elicits mucosal and systemic immune responses and protects human SCARB2-transgenic mice against lethal challenge

Abstract

Enterovirus 71 (EV71) is an aetiological agent responsible for seasonal epidemics of hand-foot-and-mouth disease, which causes considerable mortality among young children. Mucosal vaccines can efficiently induce secretory IgA at mucosal surfaces and thereby prevent or limit infection at the site of virus entry. CpG oligodeoxynucleotides (ODNs), which resemble bacterial DNA, can induce the innate immune response through activation of Toll-like receptor 9. Here, we used CpG ODNs as adjuvants to investigate an EV71 mucosal vaccine in mice. In the EV71 + CpG group, the EV71-specific IgG and IgA titres in the serum, nasal wash, bronchoalveolar lavage fluid, and faeces were substantially higher than those in the EV71- and phosphate-buffered saline-treated groups. Moreover, the number of EV71-specific IgG- and IgA-producing cells was also higher in the EV71 + CpG group. Furthermore, T-cell proliferative responses and interleukin-17 secretion were markedly increased when CpG-adjuvanted EV71 was delivered intranasally. More importantly, the induced antibodies neutralised infection by EV71 of the C2 genotype and crossneutralised infection by EV71 of the B4 and B5 genotypes. Lastly, human scavenger receptor class B, member 2-transgenic mice intranasally immunised with the CpG-adjuvanted EV71 vaccine resisted a subsequent lethal challenge with EV71, indicating that CpG was an effective intranasal adjuvant for EV71 mucosal-vaccine development.

Intranasal immunization with coxsackievirus A16 virus-like particles confers protection against lethal infection in neonatal mice

“…CpG can induce the innate immune response through recognition by Toll-like receptor 9 on plasmacytoid dendritic cells and B cells [34]. CpG has been used as an excellent systematic and mucosal adjuvant that increases the production of antibodies [35][36][37]. In this study, CpG was used as an adjuvant for nasally delivered CV-A16 VLPs to induce mucosal as well as systemic serological and cellular immune responses.…”

A Polysaccharide Purified From Ganoderma lucidum Acts as a Potent Mucosal Adjuvant That Promotes Protective Immunity Against the Lethal Challenge With Enterovirus A71

“…As shown in our previous study ( 35 ), microplates (Nunc) were coated overnight with inactivated EV-A71 and blocked with TBST-1% BSA. Then, serum, saliva, nasal wash, BALF, or feces extract were added and incubated for 2 h. Subsequently, plates were washed and the HRP-conjugated goat anti-mouse IgG (1:10000, Bethyl Laboratories, Inc.) or anti-mouse IgA (1:5000, Bethyl Laboratories, Inc.) was added.…”

“…The serum was heat-inactivated for 30 min at 56°C, after which 50 μl of 2-fold diluted serum was mixed with 50 μl of 100-fold TCID 50 EV-A71 in a 96-well plate, and incubated for 1 h at 37°C ( 35 ). Then, a mixture containing 2 × 10 4 RD cells in 100 μl of α-MEM-2% FBS was added to the mixture, and its cytopathic effects was determined after 4 days.…”

“…According to our previous study ( 35 ), Enzyme-linked immunospot (ELISPOT) was used to detect EV-A71-specific IgG- and IgA-secreting cells. We coated 96-well microplates (Millipore, United States) with purified EV-A71 virions (10 μg/ml) overnight and blocked the wells with 3% BSA in PBS.…”

“…Single cell suspensions from the spleens or Peyer’s patches of immunized mice were cultured in the presence or absence of 10 μg/ml of inactivated purified EV-A71 in RPMI-1640/10% FBS ( 35 ). For cytokine detection, cells were cultured at 37°C for 72 h, and supernatants were collected for IFN-γ, IL-17, and IL-4 assay (R&D Systems).…”