title: Envelope Protein Mutations L107F and E138K Are Important for Neurovirulence Attenuation for Japanese Encephalitis Virus SA14-14-2 Strain.
abstract: The attenuated Japanese encephalitis virus (JEV) strain SA14-14-2 has been successfully utilized to prevent JEV infection; however, the attenuation determinants have not been fully elucidated. The envelope (E) protein of the attenuated JEV SA14-14-2 strain differs from that of the virulent parental SA14 strain at eight amino acid positions (E107, E138, E176, E177, E264, E279, E315, and E439). Here, we investigated the SA14-14-2-attenuation determinants by mutating E107, E138, E176, E177, and E279 in SA14-14-2 to their status in the parental virulent strain and tested the replication capacity, neurovirulence, neuroinvasiveness, and mortality associated with the mutated viruses in mice, as compared with those of JEV SA14-14-2 and SA14. Our findings indicated that revertant mutations at the E138 or E107 position significantly increased SA14-14-2 virulence, whereas other revertant mutations exhibited significant increases in neurovirulence only when combined with E138, E107, and other mutations. Revertant mutations at all eight positions in the E protein resulted in the highest degree of SA14-14-2 virulence, although this was still lower than that observed in SA14. These results demonstrated the critical role of the viral E protein in controlling JEV virulence and identified the amino acids at the E107 and E138 positions as the key determinants of SA14-14-2 neurovirulence.
authors.affiliation: Department of Viral Vaccine, Chengdu Institute of Biological Products Co., Ltd., China National Biotech Group, Chengdu 610023, China. jiany74@163.com.|Department of Microbiology and Immunology, North Sichuan Medical College, Nanchong 637007, China. jiany74@163.com.
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Viral Vaccine, Chengdu Institute of Biological Products Co., Ltd., China National Biotech Group, Chengdu 610023, China. yang-anan@163.com.
authors.forename: Huiqiang
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Viral Vaccine, Chengdu Institute of Biological Products Co., Ltd., China National Biotech Group, Chengdu 610023, China. changdc123@sina.com.
authors.forename: Zhushi
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Viral Vaccine, Chengdu Institute of Biological Products Co., Ltd., China National Biotech Group, Chengdu 610023, China. suntina926@163.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Viral Vaccine, Chengdu Institute of Biological Products Co., Ltd., China National Biotech Group, Chengdu 610023, China. scciqlh@126.com.
authors.forename: Hua
authors.initials: H
authors.lastname: Lin
authors.affiliation: Department of Viral Vaccine, Chengdu Institute of Biological Products Co., Ltd., China National Biotech Group, Chengdu 610023, China. linaliu@163.com.
authors.forename: Lina
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Viral Vaccine, Chengdu Institute of Biological Products Co., Ltd., China National Biotech Group, Chengdu 610023, China. nqz1986@126.com.
authors.forename: Qianzhi
authors.initials: Q
authors.lastname: Ni
authors.affiliation: Department of Arbovirus Vaccine, National Institutes for Food and Drug Control, Beijing 100050, China. xinyuliu@hotmail.com.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Viral Vaccine, Chengdu Institute of Biological Products Co., Ltd., China National Biotech Group, Chengdu 610023, China. zengxw64@163.com.
authors.forename: Xianwu
authors.initials: X
authors.lastname: Zeng
authors.affiliation: China National Biotech Group, Beijing 100029, China. wuyonglin@sinopharm.com.
authors.forename: Yonglin
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Viral Vaccine, Chengdu Institute of Biological Products Co., Ltd., China National Biotech Group, Chengdu 610023, China. liyuhua@nifdc.org.cn.|Department of Arbovirus Vaccine, National Institutes for Food and Drug Control, Beijing 100050, China. liyuhua@nifdc.org.cn.|State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610000, China. liyuhua@nifdc.org.cn.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Li
mesh_terms: D000818:Animals; D004252:DNA Mutational Analysis; D004195:Disease Models, Animal; D004664:Encephalitis Virus, Japanese / Q000235:genetics* / Q000472:pathogenicity*; D004672:Encephalitis, Japanese / Q000473:pathology / Q000821:virology; D051379:Mice; D020125:Mutation, Missense; D059386:Reverse Genetics; D013489:Suppression, Genetic; D014759:Viral Envelope Proteins / Q000235:genetics* / Q000378:metabolism*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D014759:Viral Envelope Proteins; D037521:Virulence Factors
keywords: Japanese encephalitis virus; SA14-14-2; attenuation mechanism; neuroinvasiveness; neurovirulence