Phenotypic and genotypic characterization of the neurovirulence and neuroinvasiveness of a large-plaque attenuated Japanese encephalitis virus isolate.
The virulent phenotypes of Japanese encephalitis virus (JEV) can be divided into neuroinvasiveness (NI) and neurovirulence (NV). In this study, two JEV antigenic variants, CH2195LA (large-plaque, attenuated) and CH2195SA (small-plaque, non-attenuated), were passaged in suckling mice by intracerebral inoculation. Viruses at passage two and four were characterized in terms of NV and NI in weaning mice, as well as their in vitro growth characteristics in six cell lines. Following two brain-brain passages in mice, the attenuated variant CH2195LA was found to significantly restore the NV and NI by approximately 90% and 20-40%, respectively. The increased titers in THP-1 monocytic cells but not IMR-32 and Neuro-2A neuroblastoma cells were more correlated with the phenotypic changes of NI and NV in mice. Entire genomic sequencing was further performed to demonstrate that 14 nucleotides were altered in the attenuated variant CH2195LA following four brain-brain passages in mice, giving 12 amino acid changes, in prM-73, prM-80, E-161, E-170, E-276, NS2A-136, NS2A-215, NS3-346, NS4A-128, NS4B-196, NS4B-197, NS4B-198. This study indicated a cluster of amino acids which is involved in NV and NI of the JEV for mice and, perhaps, for humans. Elucidating the molecular basis of virulence of flaviviruses can provide valuable information for live-attenuated vaccine development.
Wu
Suh-Chin
SC
Department of Life Science, Institute of Biotechnology, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC. scwu@life.nthu.edu.tw
Lin
Cheng-Wen
CW
Lee
Shiang-Chi
SC
Lian
Wei-Cheng
WC
D000818:Animals; D002460:Cell Line; D002490:Central Nervous System / Q000821:virology*; D002522:Chlorocebus aethiops; D009033:Culicidae / Q000166:cytology; D004664:Encephalitis Virus, Japanese / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity*; D005814:Genes, Viral; D005838:Genotype; D006801:Humans; D051379:Mice; D010641:Phenotype; D017421:Sequence Analysis; D012692:Serial Passage; D014613:Vaccines, Attenuated; D014709:Vero Cells; D014765:Viral Vaccines; D014774:Virulence; D014779:Virus Replication
D014613:Vaccines, Attenuated; D014765:Viral Vaccines