Construction with recombinant epitope-expressing baculovirus enhances protective effects of inactivated H9N2 vaccine against heterologous virus.

Vet Microbiol

National and Regional Joint Engineering Laboratory for Medicament of Zoonosis Prevention and Control, Guangdong Provincial Key Laboratory of Zoonosis Prevention and Control, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642,  PR China; UK-China Centre of Excellence for Research on Avian Diseases, Guangzhou 510642, PR China. Electronic address:

Published: December 2024

AI Article Synopsis

  • - The study aimed to improve the effectiveness of inactivated H9N2 avian influenza vaccines by combining them with a recombinant baculovirus containing multiple T and B cell epitopes, showing better immune response than using the vaccine alone.
  • - Results indicated that the combined immunization led to significantly higher levels of antibodies and T cell responses, particularly after exposure to a heterologous virus, which suggests a robust immune boost.
  • - The InV+BV-BNT group showed lower viral loads and virus positivity rates in samples taken after infection, highlighting its potential as a supplementary vaccine to enhance protection against H9N2 avian influenza.

Article Abstract

Although the use of inactivated vaccines has kept avian influenza (AI) outbreaks largely under control, they fail to prevent virus shedding. To enhance the efficacy of inactivated H9N2 AIV vaccines (InV), we constructed a multi-epitope recombinant baculovirus (BV-BNT) containing two B cell epitopes and nine T cell epitopes of H9N2 AIV for combined immunization with InV. The results showed that HI titer, IgG and IgM levels, and the percentage of B cells, CD4 T cells, CD8 T cells, and CD4CD8 T cells were significantly higher in the InV+BV-BNT immunization group than the InV immunization group. Besides, the expression levels of IL-1β, IFN-γ, IFN-α, IL-4, IL-13, and CXCLi1 were significantly higher in the InV+BV-BNT group than the InV group. Moreover, four conservative peptides (NP, NP, NS, and NP) significantly stimulated splenocytes to express IFN-γ in the InV+BV-BNT group instead of InV group. After heterologous virus challenging, the percentages of CD4 T and CD8 T cells were significantly upregulated in the InV+BV-BNT group compared to Inv group at 3 DPI. Viral loads in oropharyngeal of the InV+BV-BNT group was significantly lower than that in the InV group at 3 days post-infection (DPI). Furthermore, compared to the InV group, the virus positivity rate of oropharyngeal and cloacal swabs in the InV+BV-BNT group was lower at 5 DPI, with none positive at 7 DPI. Hence, this study indicated that the combined immunization of InV and BV-BNT could induce stronger humoral and cellular immune responses, shorten the detoxification period and reduce viral load compared to Inv alone, which suggests BV-BNT could act as a supplementary vaccine to potentially address the protection deficiency of the H9N2 inactivated vaccine.

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Source
http://dx.doi.org/10.1016/j.vetmic.2024.110337DOI Listing

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