Poly I:C adjuvanted inactivated swine influenza vaccine induces heterologous protective immunity in pigs

Abstract

Swine influenza is widely prevalent in swine herds in North America and Europe causing enormous economic losses and a public health threat. Pigs can be infected by both avian and mammalian influenza viruses and are sources of generation of reassortant influenza viruses capable of causing pandemics in humans. Current commercial vaccines provide satisfactory immunity against homologous viruses; however, protection against heterologous viruses is not adequate. In this study, we evaluated the protective efficacy of an intranasal Poly I:C adjuvanted UV inactivated bivalent swine influenza vaccine consisting of Swine/OH/24366/07 H1N1 and Swine/CO/99 H3N2, referred as PAV, in maternal antibody positive pigs against an antigenic variant and a heterologous swine influenza virus challenge. Groups of three-week-old commercial-grade pigs were immunized intranasally with PAV or a commercial vaccine (CV) twice at 2 weeks intervals. Three weeks after the second immunization, pigs were challenged with the antigenic variant Swine/MN/08 H1N1 (MN08) and the heterologous Swine/NC/10 H1N2 (NC10) influenza virus. Antibodies in serum and respiratory tract, lung lesions, virus shedding in nasal secretions and virus load in lungs were assessed. Intranasal administration of PAV induced challenge viruses specific-hemagglutination inhibition- and IgG antibodies in the serum and IgA and IgG antibodies in the respiratory tract. Importantly, intranasal administration of PAV provided protection against the antigenic variant MN08 and the heterologous NC10 swine influenza viruses as evidenced by significant reductions in lung virus load, gross lung lesions and significantly reduced shedding of challenge viruses in nasal secretions. These results indicate that Poly I:C or its homologues may be effective as vaccine adjuvants capable of generating cross-protective immunity against antigenic variants/heterologous swine influenza viruses in pigs.

Porcine Dendritic Cells as an In Vitro Model to Assess the Immunological Behaviour of Streptococcus suis Subunit Vaccine Formulations and the Polarizing Effect of Adjuvants

“…Thus, studies suggest that Quil A ® behaves as a type 1 adjuvant in swine, and our in vitro data supports this concept. Albeit not completely characterized, when used as adjuvant in swine anti-viral vaccines [48,49,50], Poly I:C was suggested to induce a type 1 protective response; results with porcine bmDCs confirm this hypothesis, at least when combined with protein antigens. …”

Mesenchymal stem cell-derived extracellular vesicles attenuate influenza virus-induced acute lung injury in a pig model

“…Pigs had a hemagglutination inhibition (HI) antibody titer of 1:12 ± 4 against SwIV before infection. In our previous study, infection of 8-week-old commercial pigs with SwIV (5 × 10 6 TCID 50 per pig) induced extensive lung lesions [33]. Twelve hours after SwIV infection, pigs in groups 2 and 3 were administered intratracheally with DMEM and MSC-EVs (80 μg/kg body weight (BW)), respectively.…”

“…A 10% (w/v) lung homogenate was prepared from left apical lobe lung tissue and virus titer was determined by titration in MDCK cells as described [33]. Virus titers were calculated by the Reed and Muench method.…”

A Novel Bacterium-Like Particle-Based Vaccine Displaying the SUDV Glycoprotein Induces Potent Humoral and Cellular Immune Responses in Mice

“…ISA 201VG, which was developed for commercial products made with water-in-oil-in-water emulsions, can effectively improve immune response and protection [46]. Poly (I:C) has been demonstrated to be a potent adjuvant with the ability to enhance host innate and adaptive immune responses [36,47,48]. Immunization of mice with ISA 201VG mixed with Poly (I:C)-adjuvanted SBLP resulted in significant increases in SUDV GP-specific IgG, IgG1, and IgG2a and SUDV pseudotyped virus-neutralizing antibody titers, which are considered to be important correlates of protection [34,49].…”