Immune Responses Induced by Recombinant Bacillus Subtilis Expressing the Hemagglutinin Protein of H5N1 in chickens

Abstract

To develop an effective, safe, and convenient vaccine for the prevention of highly pathogenic avian influenza (HPAI) H5N1, we have constructed a recombinant Bacillus subtilis strain (B.S.-HA) expressing the hemagglutinin (HA) protein. Then we evaluated the immune function in chicken bone marrow derived dendritic cells (BM-DCs), and the immune response after oral immunization. Our results show that the recombinant Bacillus subtilis B.S.-HA could be sampled by BM-DCs in vitro and increase the BM-DCs major histocompatibility complex (MHC) II phenotype. The weight, height of the small intestine villus, and lymphoid tissue area of the ileum increased significantly in B.S.-HA immunized chickens (P < 0.05 or P < 0.01). B.S.-HA induced the secretion of cytokines and the expression of Toll-like receptors in the trachea and small intestine (P < 0.05 or P < 0.01). In addition, B.S.-HA elevated the specific IgA titers in the trachea, IgG and HI antibody titers in serum (P < 0.05 or P < 0.01). Therefore, B.S.-HA provides a potential novel strategy and approach for developing an H5N1 vaccine.

Immune response in piglets orally immunized with recombinant Bacillus subtilis expressing the capsid protein of porcine circovirus type 2

“…The capsid protein is the most immunogenic of PCV2 [6][7][8], and B. subtilis is widely used as a live vaccine vehicle for heterologous antigen delivery. It effectively elicits mucosal and systemic immune responses [42,[54][55][56], and itself possesses adjuvant-like properties enhancing the level of local and systemic immune responses [37,57,58]. Wang et al reported that in mice, oral vaccination with Lactococcus lactis Fig.…”

“…Bacteria, plasmids, virus, and animals B. subtilis WB800N and the pHT43 expression vector [42] (E. coli-B. subtilis shuttle vector) used to express recombinant proteins in B. subtilis were kindly provided by Dr. Xuewen Gao.…”

“…The pHT43 vector (control) and the pHT43-Cap recombinant plasmid were transformed into B. subtilis by electroporation as previously described [42,44]. The transformed strains were designated B. subtilis and B. subtilis-Cap, respectively.…”

Effects of intranasal administration with Bacillus�subtilis on immune cells in the nasal mucosa and tonsils of piglets

“…A total of 6 1-month-old male piglets were randomly equally divided into two groups (n=3) as follows: The control group was intranasally administrated with PBS (500 µl/nostril) and the B. subtilis group was intranasally administrated with Dylight 488 (Life Technologies; Thermo Fisher Scientific, Inc., Waltham, MA, USA)-labeled B. subtilis WB800 spores (10 8 cfu/nostril). The procedure was repeated after 1 h. Piglets were euthanized by intravenous injection of sodium pentobarbital (100 mg/kg) 2 h later as previously described ( 22 ). All procedures were approved by the Institutional Animal Care and Use Committee of Nanjing Agricultural University (Nanjing, China) and followed the National Institutes of Health guidelines for the performance of animal experiments.…”

“…No pigs succumbed during the experiment. The B. subtilis group was intranasally administrated with 200 µl/nostril B. subtilis WB800 (10 10 cfu/ml) on day 3, 500 µl/nostril on day 12 and 1 ml/nostril on day 21; these doses were selected from previous studies ( 22 – 26 ). The control group was treated with the same volumes of PBS.…”