Detection of active infection of Sf9 insect cells by recombinant baculoviruses

Production of different recombinant proteins in baculovirus AcMNPV (BV)-infected cells may be facilitated by the availability of immunoassays to monitor active infection of Sf9 insect cells. To this end, two hybridomas secreting mouse monoclonal antibodies (mAbs) were established to different BV-related products. The proteins recognized by mAb SM22 and SM62 were easily detectable by immunoblotting and immunostaining in Sf9 cells infected with recombinant BV (rBV), but not in non-infected cells. Their production paralleled that of the recombinant proteins analyzed but was independent of the type of recombinant protein expressed. Thus, immunoassays with these mAbs allow: (1) daily monitoring of the infection occurring in small and large scale cultures of Sf9 cells using a defined rBV; (2) preliminary assessment of active rBV infection in the absence of a specific reagent for the recombinant protein and (3) single-reagent comparison of the infection achieved in Sf9 cells exposed to rBVs expressing different recombinant proteins.