Search

Hemagglutinin (HA) has been demonstrated as an effective candidate vaccine antigen against AIVs. Dendritic cell-targeting peptide (DCpep) can enhance the robustness of immune responses. The purpose of this study was to evaluate whether DCpep could enhance the immune response against H9N2 AIV when utilizing Lactobacillus plantarum NC8 (NC8) to present HA-DCpep in mouse and chicken models. To accomplish this, a mucosal vaccine of a recombinant NC8 strain expressing HA and DCpep that was constructed in a previous study was employed. Orally administered NC8-pSIP409-HA-DCpep elicited high serum titers of hemagglutination-inhibition (HI) antibodies in mice and also induced robust T cell immune responses in both mouse and chicken models. Orally administered NC8-pSIP409-HA-DCpep elicited high serum titers of hemagglutination-inhibition (HI) antibodies in mice and also induced robust T cell immune responses in both mouse and chicken models. These results revealed that recombinant L. plantarum NC8-pSIP409-HA-DCpep is an effective vaccine candidate against H9N2 AIVs. [ABSTRACT FROM AUTHOR]

The H9N2 avian influenza virus (AIV) has become increasingly concerning due to its role in severe economic losses in the poultry industry. Transmission of AIV to mammals, including pigs and humans, has accelerated efforts to devise preventive strategies. To develop an effective oral vaccine against H9N2 AIV, a recombinant Lactobacillus plantarum NC8 strain expressing the hemagglutinin (HA) gene of H9N2 AIV was constructed in this study. Mice were orally immunized with the recombinant NC8-pSIP409-HA strain, and sIgA, IgG and HI antibodies were produced by the NC8-pSIP409-HA strain, which also induced CD8 + T cell immune responses. Most importantly, oral administration produced complete protection against challenge with mouse-adapted H9N2 virus. These results indicate that the recombinant NC8-pSIP409-HA was more effective at inducing the mucosal, humoral and cellular immune responses. Therefore, L. plantarum NC8-pSIP409-HA could become a promising oral vaccine candidate against H9N2 AIV. [ABSTRACT FROM AUTHOR]

Abstract To evaluate the efficiency of preventing pathogenic avian influenza by vaccination with recombinant Lactobacillus plantarum (L. plantarum) that expresses conserved antigens, the mucosal and systemic immune responses in animals vaccinated with recombinant L. plantarum NC8-409-1 (NC8-pSIP409-pgsA'-HA2) and NC8-409-2 (NC8-pSIP409-pgsA'-3M2e-HA2) were evaluated. Our results showed that recombinant L. plantarum NC8-409-1 and NC8-409-2 could substantially stimulate the specific IgA titer in the intestine and the specific IgG antibody titer in the serum. We also found that recombinant L. plantarum induced increases in the number of B220+ IgA+ cells in Peyer's patches (PPs), in lymphocyte proliferation and in the number of IFN-γ+ producing CD8+ T cells after immunization in mice. Most importantly, the mice that were vaccinated with recombinant L. plantarum NC8-409-2 and NC8-409-1 were to some extent protected against infection challenge with the H9N2 and H1N1 viruses. In particular, NC8-409-2 provided up to 80% protection against the H9N2 virus, and NC8-409-1 provided up to 60% protection. Lung tissue pathology was also reduced. Therefore, recombinant L. plantarum NC8-409-2 and NC8-409-1 may be candidate oral vaccines against bird flu. [ABSTRACT FROM AUTHOR]