Conserved HA-peptide NG34 formulated in pCMV-CTLA4-Ig reduces viral shedding in pigs after a heterosubtypic influenza virus SwH3N2 challenge

Abstract

Swine influenza viruses (SIVs), the causal agents of swine influenza, are not only important to control due to the economic losses in the swine industry, but also can be pandemic pathogens. Vaccination is one of the most relevant strategies to control and prevent influenza infection. Current human vaccines against influenza induce strain-specific immunity and annual update is required due to the virus antigenic shift phenomena. Previously, our group has reported the use of conserved hemagglutinin peptides (HA-peptides) derived from H1-influenza virus as a potential multivalent vaccine candidate. Immunization of swine with these HA-peptides elicited antibodies that recognized and neutralized heterologous influenza viruses in vitro and demonstrated strong hemagglutination-inhibiting activity. In the present work, we cloned one HA-peptide (named NG34) into a plasmid fused with cytotoxic T lymphocyte-associated antigen (CTLA4) which is a molecule that modifies T cell activation and with an adjuvant activity interfering with the adaptive immune response. The resulting plasmid, named pCMV-CTLA4-Ig-NG34, was administered twice to animals employing a needle-free delivery approach. Two studies were carried out to test the efficacy of pCMV-CTLA4-Ig-NG34 as a potential swine influenza vaccine, one in seronegative and another in seropositive pigs against SIV. The second one was aimed to evaluate whether pCMV-CTLA4-Ig-NG34 vaccination would overcome maternally derived antibodies (MDA). After immunization, all animals were intranasally challenged with an H3N2 influenza strain. A complete elimination or significant reduction in the viral shedding was observed within the first week after the challenge in the vaccinated animals from both studies. In addition, no challenged heterologous virus load was detected in the airways of vaccinated pigs. Overall, it is suggested that the pCMV-CTLA4-Ig-NG34 vaccine formulation could potentially be used as a multivalent vaccine against influenza viruses.

Influenza NG-34 T cell conserved epitope adjuvanted with CAF01 as a possible influenza vaccine candidate

“…NG-34 epitope predicted by ISM was synthesized by GL Biochem Ltd, Shanghai, China. Its sequence corresponds with 34 amino acids in the HA1 region from the strain A/Catalonia/63/2009 (pH1N1) [GenBank ACS36215] [11].…”

“…Its role in inducing specific antibodies as well as CD4 T cells in the pig model has been documented. Recently, it has been shown that NG-34 was effective as a pig influenza vaccine in combating against a heterologous challenge by reducing shedding and inducing neutralizing antibodies against a SwH3N2 virus [11]. In poultry, another study supported its cross-protective effect against an H7 HPAIV strain [15].…”

“…Nonetheless, these epitope-based vaccines usually confer short-lived protection and are compromised compared to current licensed vaccines [10]. In the present experimental study, we evaluated a suitable adjuvant candidate (novel and registered) immunologically to be mixed with a well-studied HA-epitope by our group [11], the NG-34. The study pursued a prototype for a universal vaccine, thus the murine model was used in preliminary research.…”

Skin-Based Vaccination: A Systematic Mapping Review of the Types of Vaccines and Methods Used and Immunity and Protection Elicited in Pigs

“…A skin-based approach can be beneficial and there is an increasing focus on this route for influenza vaccines in pigs. We identified 20 studies including both human and swine vaccines using the skin route [ 109 , 110 , 111 , 115 , 118 , 129 , 136 , 146 , 156 , 178 , 179 , 180 , 181 , 182 , 183 , 184 , 185 , 186 , 187 , 188 ] compared to approximately 60 studies evaluating either the intramuscular or subcutaneous routes for influenza vaccines in pigs, the latter also identified in a PubMed search. Some studies focus on inducing mucosal immunity by intradermal vaccine administration [ 115 , 118 , 182 ].…”

Targeting Hemagglutinin: Approaches for Broad Protection against the Influenza A Virus

“…Alphavirus-vectored HA subunit vaccines, delivering a monovalent or bivalent HA, have been tested to be able to provide efficient homo/heterosubtypic protection [158]. A plasmid fused with anti-head peptide (NG34) and cytotoxic T lymphocyte-associated antigen (CTLA4) has been shown to be protective against the heterosubtypic H3N2 virus in swine [159]. Furthermore, for efficient HA-based vaccine design, complexities such as the efficiency of HA epitopes and antibody interference, should be taken into consideration [160,161,162].…”