Fig. 2.

Schematic diagram demonstrating the TDS method for integrating a modified IBV sequence into the full-length IBV cDNA within the genome of a recombinant vaccinia virus (vNotI-IBVFL). The diagram shows a potential first single-step recombination event between the modified IBV sequence within pGPTNEB193 and the IBV cDNA within vNotI-IBVFL. In order to guarantee a single-step recombination event any potential recombinant vaccinia viruses are selected in the presence of MPA ; only vaccinia viruses expressing the Ecogpt gene are selected. The main IBV genes are indicated, the replicase, spike (S), membrane (M), and nucleocapsid (N) genes. The IBV gene 3 and 5 clusters that express three and two gene products, respectively, are also indicated. In the example shown a modified region of the S gene is being introduced into the IBV genome