Protective efficacy of inactivated reverse genetics based equine influenza vaccine candidate adjuvanted with Montanide^TM Pet Gel in murine model

Abstract

Equine influenza is a leading cause for respiratory illness in equines. Major control measures involve vaccination which requires continuous harmonization owing to antigenic drift. The present study focused on assessing the protective efficacy of an inactivated recombinant equine influenza virus (rgEIV) vaccine candidate adjuvanted with Montanide TM Pet Gel in murine model. The rgEIV was generated using reverse genetics by incorporating HA and NA segments from EIV/H3N8, clade 2-Florida sublineage in an A/WSN/33 /H1N1 backbone and inactivated by formalin. The vaccine was prepared by mixing inactivated rgEIV with Montanide TM Pet Gel adjuvant followed by intranasal inoculation into BALB/c mice intranasally. The immune responses and protective efficacy of the vaccine was evaluated by measurement of antibody titer, immunoglobulin subtyping, cytokines, clinical signs and pathological lesions after immunization and challenge with wild EIV. Serology and cytokine expression pattern indicated that the vaccine activated mixed Th1-and Th2-like responses of vaccine. Booster immunization stimulated strong antibody responses (HAI titre:192±28.6) at 42 days post immunization and the predominant antibody subtype was IgG1. Upregulation of IFN-gamma, IL-12 and IL-2 levels indicates effective induction of Th1 type response. We found that vaccination has protected mice against equine influenza virus challenge as adjudged through a lack of nonappearance of visible clinical signs of disease, no loss of body weight loss, reduced pathology in the lungs and markedly reduced virus shedding from the respiratory tract. Therefore, we conclude that recombinant EIV vaccine candidate adjuvanted with Montanide TM Pet Gel could aid in quick harmonization of the vaccines through replacement of HA and NA genes for control of EIV outbreaks.

Screening immune adjuvants for an inactivated vaccine against Erysipelothrix rhusiopathiae

“…GEL is a new type of water-soluble polymer adjuvant, the main component of which is polyethylene acrylic acid sodium. The excellent effects of the GEL adjuvant have been verified in vaccines against several viruses, including an inactivated Porcine circovirus vaccine ( 44 ), an inactivated Porcine reproductive and respiratory syndrome virus vaccine ( 35 ), an inactivated equine influenza virus vaccine ( 45 ), a live attenuated porcine epidemic encephalitis vaccine ( 34 ), and a Bovine herpesvirus DNA vaccine ( 46 ). However, this adjuvant showed a poor adjuvant effect in an inactivated sheep paratuberculosis vaccine ( 30 ), a Rhodococcusequi subunit vaccine ( 47 ), and a bovine mite disease subunit vaccine ( 48 ).…”

Progress in the Development of Universal Influenza Vaccines

“…The mechanism of action of adjuvants may rely upon a combination of various mechanisms including formation of a depot, induction of cytokines and chemokines, recruitment of immune cells, enhancement of antigen uptake and presentation, and promotion of antigen transport to draining lymph nodes [ 96 , 97 ]. Adjuvants include interferon pathway activators Poly I:C and cGAMP, cytokines including interferon and interleukin, and bacterial structural components flagellin and lipopolysaccharide (LPS) along with immunoregulatory oligonucleotide sCPG and synthetic chemical substances that play a role in immunological enhancement [ 51 , 95 , 98 , 99 , 100 , 101 , 102 , 103 , 104 ]. However, as universal influenza vaccines have been developed into multiple vaccine types—e.g., viral vectors, DNA, and subunit—to express influenza cocktail proteins such as HA stem, chimeric HA, M1, M2e, NP and epitope peptide ( Figure 3 ), suitable adjuvants should be selected according to the vaccine strategy and type of desired immune response activation.…”

Immunogenicity of Calvenza-03 EIV/EHV® Vaccine in Horses: Comparative In Vivo Study

“…There are several whole-inactivated virus-based vaccines [ 12 , 13 , 14 , 15 ], subunit vaccines, canarypox vectored vaccines [ 16 ] and modified live viral vaccines that are commercially available ( Table 1 ) [ 17 , 18 , 19 , 20 ]. Reverse genetic-based modified live-attenuated EI vaccines are currently under study [ 21 , 22 ]. Current vaccines are able to reduce clinical signs and viral shedding in vaccinated animals; however, sub-clinical shedding of the virus is a major problem [ 11 ].…”