Vectors

A transfer vector for inserting a gene encoding a subunit of a protein complex into a genetic locus of a baculovirus sequence comprising:

• a structure represented by the formula A-B-C-D-E-F-A′, wherein
• B comprises an expression cassette comprising a eukaryotic promoter operably linked to the gene encoding the submit of the protein complex;
• C-D-E-F comprises a bipartite selection cassette removable by homologous recombination due to the presence of C and F, wherein C and F comprise a first LoxP recombination sequence and a second LoxP recombination sequence, respectively, wherein the first and the second LoxP recombination sequences comprise at least one modification to ensure that only a single round of recombination can occur, and wherein D comprises
• an expressible sequence encoding a first selectable marker whose expression is indicative of transformation of the baculovirus and E comprises
• an expressible sequence encoding a second selectable marker whose expression is indicative of transformation of the baculovirus;
• and
• A and A′ comprise sequences flanking both the expression cassette and the bipartite selection cassettes, wherein each flanking sequence is complementary to different sequences of the genetic locus within the baculovirus sequence such that both the expression cassette and the bipartite selection cassette are transferred into the genetic locus of the baculovirus.