Reverse engineering has offered new ways of studying the pathology of RNA viral infections, new more efficient devices of synthesizing recombinant viruses and developing vaccines and also demonstrated the versatility and efficiency of RNA dependent RNA polymerase RDRP system as an expression system. However, the currently used methods require a repertoire of complex, difficult-to-use tools. Present invention describes, a simpler plasmid based mammalian expression system that uses the RDRP enzyme activity for expression of recombinant proteins or RNA from viral minigenomes and rescue of recombinant viruses from cDNAs encoding entire genome(s) of negative stranded RNA viruses. This system will be useful for expression of recombinant proteins, therapeutic RNA molecules including anti-sense and/or selecting interfering RNA and Ribozymes. This system can also be used for gene therapy and producing recombinant viruses for production of new vaccines.

The present disclosures relate to the establishment of a plasmid-based reverse genetic system for TiLV and use of the system to rescue recombinant and reporter TiLVs. The present disclosures also relate to the plasmids used for the rescue of TiLV and the recombinant and reporter TiLVs generated using the methods disclosed herein.

The present invention relates to a low-serum medium composition for culturing Vero cells, and a method for culturing Vero cells and a method for producing a virus, both using the same.