High expression of the classical swine fever virus (CSFV) envelope protein E2 by a single amino acid mutation and its embedded in the pseudorabies virus (PRV) vector for immunization

• Published in: Virus research Vol. 331; p. 199111
• Main Authors: Sun, Yang-yang, Liu, Ke-shu, Yun, Tao, Ni, Zheng, Zhu, Yin-chu, Chen, Liu, Bao, Hai-li, Ye, Wei-cheng, Hua, Jiong-gang, Huo, Su-xin, Wang, Hong-yu, Bao, En-dong, Zhang, Cun
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 02.07.2023; Elsevier
• Subjects: A transmembrane region; Amino Acids - genetics; Animals; Antibodies, Viral; Bivalent vaccine; Classical Swine Fever; Classical Swine Fever Virus - genetics; E2 protein; Herpesvirus 1, Suid - genetics; Immunization; Mice; Mutation; Pseudorabies - prevention & control; Pseudorabies virus; Rabbits; Swine; Swine Diseases; Viral Envelope Proteins - genetics; Viral Vaccines - genetics; Bivalent vaccine; Pseudorabies virus; E2 protein; A transmembrane region; Classical swine fever
• ISSN: 0168-1702; 1872-7492
• DOI: 10.1016/j.virusres.2023.199111

•High expression of full-length E2 protein was achieved by mutating an amino acid in the transmembrane region of E2.•The hydrophobicity score of E2 transmembrane region is the key to determine whether it can be expressed.•PRV expressed full-length E2 produces higher antibody than truncated E2 without transmembrane region.•Immunization with PRV-E2 could induce cellular immunity against E2. Pseudorabies (PR) and classical swine fever (CSF) are economically important infectious diseases in pigs. Most pig farms in China are vaccinated against these two diseases. Gene-deleted pseudorabies virus (PRV) can be used to develop promising and economical multivalent live attenuated viral vector vaccines. It has been reported that recombinant PRV can express a truncated E2 protein (1–338 aa), but it has not been reported that recombinant PRV can express a full-length E2 protein. We constructed nine groups of E2 proteins with different expression forms and found that the E2 protein could be expressed in vitro only when the transmembrane region of E2 was removed and the signal peptide was added. Analysis of the transmembrane region of E2 revealed that the high hydrophobicity of the E2 transmembrane region was the main reason for its inability to express. By mutating an amino acid to reduce the hydrophobicity of the transmembrane region, it was found that the full-length mutant of E2 (E2FL-muta3 or E2FL-muta4) could be expressed. The expressed full-length mutant E2 could also localize to the cell membrane. Mice immunized with a PRV vector vaccine expressing E2FL-muta3 or E2FL-muta4 developed specific cellular immunity to the E2 protein and stimulated higher levels of E2 antibody than mice immunized with a PRV vector expressing truncated E2. After immunizing the rabbits, the lethal challenge by PRV-ZJ2013 and the febrile response elicited by CSFV were simultaneously prevented. These results suggest that rPRV-dTK/gE-E2FL-muta4 is a promising bivalent vaccine against CSFV and PRV infections.