Recovery of a chemically synthesized Japanese encephalitis virus reveals two critical adaptive mutations in NS2B and NS4A.

A full-length genome infectious clone is a powerful tool for functional assays in virology. In this study, using a chemical synthesized complete genome of Japanese encephalitis virus (JEV) strain SA14 (GenBank accession no. U14163), we constructed a full-length genomic cDNA clone of JEV. The recovered virus from the cDNA clone replicated poorly in baby hamster kidney (BHK-21) cells and in suckling mice brain. Following serial passage in BHK-21 cells, adaptive mutations within the NS2B and NS4A proteins were recovered in the passaged viruses leading to viruses with a large-plaque phenotype. Mutagenesis analysis, using a genome-length RNA and a replicon of JEV, demonstrated that the adaptive mutations restored replication to different degrees, and the restoration efficiencies were in the order: NS2B-T102M

Development and evaluation of neutralizing antibodies for cross-protection against West Nile virus and Japanese encephalitis virus.

Background: West Nile virus is a severe zoonotic pathogen that can cause severe central nervous system symptoms in humans and horses, and is fatal for birds, chickens and other poultry. With no specific drugs or vaccines available, antibody-based therapy is a promising treatment. This study aims to develop neutralizing antibodies against West Nile virus and assess their cross-protective potential against Japanese encephalitis virus. Methods: Monoclonal antibodies against WNV and JEV were isolated by hybridoma technology. The therapeutic efficacy of these antibodies was evaluated using a mouse model, and a humanized version of the monoclonal antibody was generated for potential human application. Results: In this study, we generated eight monoclonal antibodies that exhibit neutralizing activity against WNV. Their therapeutic effects against WNV were validated both in vivo and in vitro. Among these antibodies, C9-G11-F3 also exhibited cross-protective activity against JEV. We also humanized the antibody to ensure that it could be used for WNV infection treatment in humans. Conclusion: This study highlights the importance of neutralizing antibodies as a promising approach for protection against West Nile virus infection and suggests their potential utility in the development of therapeutic interventions.

[Construction of molecular clone of chimeric porcine circovirus(PCV1-2) and identification of its infectivity].

Porcine circovirus type 2(PCV2) recently emerged as an important infectious pathogen for pigs in the world. Unfortunately, there is no efficient method to deal with PCV2 infection until now. In this study, chimeric porcine circovirus molecular clone (pSK2PCV1-2) was constructed by cloning capsid gene of PCV2 into the backbone of PCV1. PK-15 cells was transfected with pSK2PCV1-2 and then cultivated in plate for five passages. mRNA of PCV1 ORF1 and PCV2 ORF2 were detected in the fifth passage, but mRNA of PCV1 ORF2 and PCV2 ORF1 were not detected in the cells. On the other hand, capsid protein of PCV2 was also detected in the nucleolus of transfected cells by IIF. This study indicated that pSK2PCV1-2 could form infectious virus in transfected cells. It will provide base for further study on biological characteristic of chimeric porcine circovirus.

[Recombination and expression of ORF1 and ORF2 gene of porcine circovirus type 2 and gene of pseudorabies virus].

ORF1 and ORF2 gene of porcine circovirus type 2 were cloned by PCR with the specific primers designed according to genome of PCV2 (AY035820). Following extraction and digestion, PCR products were subsequently inserted into universal transfer vector plECMV (deleted partial gE and gI of pseudorabies virus) to generate recombinant transfer plasmid pIEORF1-ORF2. The genomic DNA of PRV TK-/gE- /LacZ+ strain and pIEORF1-ORF2 were co-transfected into IBRS-2 cells with lipofectin, and recombinant virus TK- /gE- /gI- /ORF1-ORF2+ was selected by PCR with ORF1 gene and ORF2 gene primers respectively. The recombinant virus was analyzed with Southern blotting and Western blotting. The results indicated that ORF1 and ORF2 gene of PCV2 had been inserted into the genome of TK- /gE- /LacZ+ strain and the expressed ORF1-ORF2 fusion protein could react with PCV2 positive sera. Result of virus titers detection showed the insertion of ORF1 and ORF2 gene did not influence propagation of recombinant virus.