Figure 4.

Postulated mechanism leading to high-molecular-weight concatemers of the rep and cap expression cassettes. In uninfected stable Sf9 cells, the rep and cap expression cassettes are integrated as two or more head-to-tail concatemers into the host genome. Baculovirus infection promotes high-frequency homologous recombinations assumedly exploiting the repeated hr elements as cis signals and a rolling circle replication mechanism initiated at the homologous regions (hr), leading to long continuous DNA molecules that contain multiple copies of the rep or cap expression construct.