Describe the baculovirus expression system for recombinant protein production.

The baculovirus expression vector system (BEVS) uses insect cells (Sf9, Hi5) infected with recombinant Autographa californica baculovirus. Gene of interest is inserted under strong late promoters (polyhedrin, p10). Modern systems (Bac-to-Bac) use site-specific transposition in E. coli for recombinant virus generation. Advantages include high expression levels, proper eukaryotic folding and most PTMs (though glycosylation differs from mammalian), biosafety (virus doesn't replicate in vertebrates), and scalability. Limitations include lytic infection (finite production window), different glycosylation patterns, and technical complexity. Multi-gene expression enables production of protein complexes (MultiBac system).