Viral replicon is a kind of self-replicating viral RNA sourced from viral genome, which contains viral non-structural genes that are critical for viral genome replication with structural proteins deleted or replaced by foreign genes. Kunjin virus is a member of the Flavivirida family, Flavivirus genus, and Kunjin virus replicon is the first and the clearly defined flavivirus replicon. Kunjun virus replicon has been regarded as an excellent viral vector on account of its high expression, lower cytotoxicity and genetic stability. These unique characteristics of kunjin virus replicons make them suitable for the study of viral genome replication, recombinant proteins production, vaccine development and gene therapy. In this article, recent progress in the development, properties and applications of kunjin virus replicon system was briefly reviewed.
Genetic Vectors ; genetics ; Genome, Viral ; Recombination, Genetic ; Replicon ; genetics ; Virus Replication ; physiology ; West Nile virus ; genetics ; metabolism

Beijing has been one of the epicenters attacked most severely by the SARS-CoV (severe acute respiratory syndrome-associated coronavirus) since the first patient was diagnosed in one of the city's hospitals. We now report complete genome sequences of the BJ Group, including four isolates (Isolates BJ01, BJ02, BJ03, and BJ04) of the SARS-CoV. It is remarkable that all members of the BJ Group share a common haplotype, consisting of seven loci that differentiate the group from other isolates published to date. Among 42 substitutions uniquely identified from the BJ group, 32 are non-synonymous changes at the amino acid level. Rooted phylogenetic trees, proposed on the basis of haplotypes and other sequence variations of SARS-CoV isolates from Canada, USA, Singapore, and China, gave rise to different paradigms but positioned the BJ Group, together with the newly discovered GD01 (GD-Ins29) in the same clade, followed by the H-U Group (from Hong Kong to USA) and the H-T Group (from Hong Kong to Toronto), leaving the SP Group (Singapore) more distant. This result appears to suggest a possible transmission path from Guangdong to Beijing/Hong Kong, then to other countries and regions.
Genome, Viral ; Haplotypes ; Humans ; Mutation ; Open Reading Frames ; Phylogeny ; SARS Virus ; genetics

We report a complete genomic sequence of rare isolates (minor genotype) of the SARS-CoV from SARS patients in Guangdong, China, where the first few cases emerged. The most striking discovery from the isolate is an extra 29-nucleotide sequence located at the nucleotide positions between 27,863 and 27,864 (referred to the complete sequence of BJ01) within an overlapped region composed of BGI-PUP5 (BGI-postulated uncharacterized protein 5) and BGI-PUP6 upstream of the N (nucleocapsid) protein. The discovery of this minor genotype, GD-Ins29, suggests a significant genetic event and differentiates it from the previously reported genotype, the dominant form among all sequenced SARS-CoV isolates. A 17-nt segment of this extra sequence is identical to a segment of the same size in two human mRNA sequences that may interfere with viral replication and transcription in the cytosol of the infected cells. It provides a new avenue for the exploration of the virus-host interaction in viral evolution, host pathogenesis, and vaccine development.
Base Sequence ; China ; Cluster Analysis ; Gene Components ; Genetic Variation ; Genome, Viral ; Genotype ; Molecular Sequence Data ; Phylogeny ; Reverse Transcriptase Polymerase Chain Reaction ; SARS Virus ; genetics ; Sequence Analysis, DNA ; Severe Acute Respiratory Syndrome ; genetics