Recombinant human respiratory syncytial virus (RSV) from cDNA and construction of subgroup A and B chimeric RSV

Infectious human respiratory syncytial virus (RSV) was produced from a cDNA clone that contains 15,222 nucleotides of RSV genome derived from the A2 strain of subgroup A. Recovery of infectious RSV from cDNA required cotransfection of only three expression plasmids encoding the nucleoprotein (N), the phosphoprotein (P), and the major polymerase protein (L). Inclusion of the M2-1 plasmid was not required in the transfection reaction and if included did not significantly increase the rescue efficiency. However, a single nucleotide substitution in the RSV leader region (C to G at position 4 in the antigenomic sense), greatly increased the amount of infectious virus recovered from cDNA. A recombinant RSVA2 virus that expresses an additional structural G protein derived from a subgroup B RSV was also obtained. Both A2 and B strain G glycoproteins were expressed in cells infected with the chimeric RSV. A chimeric RSV that expresses a heterologous subgroup antigen in a live attenuated vaccine candidate may be important for prevention of diseases associated with both RSV subgroup A and subgroup B infection.