Development of a recombinant infectious bronchitis virus vaccine expressing infectious laryngotracheitis virus multiple epitopes

Guanming Shao; Jun Fu; Yun Pan; Shiying Gong; Chaoyi Song; Sheng Chen; Keyu Feng; Xinheng Zhang; Qingmei Xie

doi:10.1016/j.psj.2024.104578

Development of a recombinant infectious bronchitis virus vaccine expressing infectious laryngotracheitis virus multiple epitopes

Poult Sci. 2024 Nov 22;104(1):104578. doi: 10.1016/j.psj.2024.104578. Online ahead of print.

Authors

Guanming Shao¹, Jun Fu², Yun Pan¹, Shiying Gong³, Chaoyi Song², Sheng Chen³, Keyu Feng¹, Xinheng Zhang¹, Qingmei Xie⁴

Affiliations

¹ State Key Laboratory of Swine and Poultry Breeding Industry & Heyuan Branch, Guangdong Provincial Laboratory of Lingnan Modern Agricultural Science and Technology, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China; Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China; Guangdong Engineering Research Center for Vector Vaccine of Animal Virus, Guangzhou 510642, PR China; Zhongshan Innovation Center of South China Agricultural University, Zhongshan 528400, PR China.
² State Key Laboratory of Microbial Technology, Helmholtz International Lab for Anti-Infectives, Institute of Microbial Technology, Shandong University-Helmholtz Institute of Biotechnology, Shandong University, Qingdao, PR China.
³ State Key Laboratory of Swine and Poultry Breeding Industry & Heyuan Branch, Guangdong Provincial Laboratory of Lingnan Modern Agricultural Science and Technology, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China; Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China; Guangdong Engineering Research Center for Vector Vaccine of Animal Virus, Guangzhou 510642, PR China.
⁴ State Key Laboratory of Swine and Poultry Breeding Industry & Heyuan Branch, Guangdong Provincial Laboratory of Lingnan Modern Agricultural Science and Technology, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China; Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China; Guangdong Engineering Research Center for Vector Vaccine of Animal Virus, Guangzhou 510642, PR China; Zhongshan Innovation Center of South China Agricultural University, Zhongshan 528400, PR China. Electronic address: qmx@scau.edu.cn.

Abstract

Infectious laryngotracheitis (ILT) is a highly contagious disease, usually controlled by vaccination with live attenuated vaccines. However, the latent infection and adverse reactions caused by the live attenuated vaccines against infectious laryngotracheitis virus (ILTV) have limited its use in poultry. Infectious bronchitis virus (IBV) is considered a potential vector for vaccine development, but the issue of poor stability in recombinant IBV expressing foreign genes has not yet been resolved. In this study, we designed a multi-epitope cassette (gD-T/B) containing multiple T and B cell epitopes of ILTV gD protein. The genetic stability of the full-length gD gene and the gD-T/B multi-epitope cassette replacing non-essential genes in IBV was systematically analyzed. We found that, at the same insertion site, the stability of inserting gD-T/B multi-epitope cassette was consistently higher compared to the full-length gD gene. This difference may be related to the presence of more signals affecting virus replication or transcription in larger heterologous genes. In addition, the stability of recombinant IBV varied depending on the genome region being replaced. When the gene 5 was replaced, rH120-Δ5ab-gD-T/B was maintained up to at least passage 20 (P20). Compared with the parental virus H120 strain, rH120-Δ5ab-gD-T/B showed similar growth kinetics. Clinical observations and scoring of clinical signs in the vaccination-challenge experiment showed that rH120-Δ5ab-gD-T/B provided 90% protection against virulent ILTV, effectively alleviating clinical signs caused by infection with a virulent strain of ILTV. Furthermore, rH120-Δ5ab-gD-T/B significantly reduced the replication and shedding of ILTV in the trachea. Overall, this study suggests that rH120-Δ5ab-gD-T/B is a promising candidate vaccine against ILTV.

Keywords: Infectious bronchitis virus; Infectious laryngotracheitis virus; Multiple epitopes; Stability; Vector vaccine.