in (predicted molecular mass 45.4 kDa, 409 aa) has O-glycosidically linked N-acetylglucosamine (GlcNAc) residues and is present between the envelope membrane and the nucleocapsids of ODVs (277). A thermosensitive (ts) gp41 mutant causes single-cell-infections, which progress through the very late phase including the formation of OBs. However, infection does not spread to neighboring cells (210), indicating that BV production is affected in the ts-mutant, although GP41 is only found in ODVs (277). Ac80 is conserved in all baculovirus genomes.
Ac81: ac81, unknown function
The ac81 gene is highly conserved and belongs to the baculovirus core genes. The gene product has a predicted mass of 26.9 kDa (238 aa) and the homologous protein in BmNPV (Bm67) is detected neither in BVs nor ODVs. Immunofluoresence analysis showed that the Bm67 protein is present in the cytoplasm and interacts with the host protein actin A3 (31). Bm67 is required for the production of infectious BV (71). Bm67 mutations negatively affect viral DNA synthesis and the stability of nascent viral DNA. Nucleocapsids with a wild type morphology are hardly found and nucleocapsids are only occasionally exported to the cytoplasm. The envelopment of nucleocapsids is also abnormal with these Bm67 mutants (71).
Ac82: tlp, telokin-like protein-20
The gene ac82 encodes a protein with a predicted molecular mass of 20 kDa (19.8 kDa, 180 aa). In Western blot analysis it shows a size of 28 kDa and reacts with an antibody specific against the smooth muscle protein telokin, hence the name telokin-like protein or TLP (232). However, no amino acid sequence similarity exists between TLP-20 and telokin. 3-D structure analysis of TLP-20 showed a seven-stranded antiparallel β-barrel flanked on the basis by two additional β-strands and on the top by an α-helix. As such, TLP-20 does not resemble the structure of any other known protein (101).
Ac83: p95, viral capsid associated protein, VP91
The gene p95 encodes a protein (96.2 kDa, 847 aa), with two conserved domains: a viral capsid protein 91 and a chitin-binding peritrophin-A domain, respectively. The p95 gene belongs to the baculovirus core genes (Table 2 and Table 3). VP91 is associated with the capsid and envelope of ODVs (240). The second conserved domain belongs to the family of chitin peritrophic binding proteins and is able to bind chitin, which is present in a matrix lining the gut of most insects (58, 246).
Ac84: ac84, unknown function
The gene ac84 codes for a hypothetical protein (21.7 kDa, 188 aa) without any known conserved domain. The gene is transcribed (287).
Ac85: ac85, unknown function
Ac86: pnk/pnl polynucleotide kinase/ligase
The gene pnk/pnl is an immediate early gene encoding a protein (80.8 kDa, 694 aa) that contains two conserved domains: a kinase and a T4 RNA ligase domain (55). Deletion of pnk/pnl has no effect on virus replication in Sf21 cells or on protein production (55). The effect in pathogenesis in larvae is unknown.
Ac87: p15, unknown function
The gene p15 codes for a 15.0 kDa protein (126 aa) of unknown function. The protein does not contain known conserved domains, but homologs can be found in eight other Alphabaculoviruses (Table 2). For BmNPV P15 a function as a viral capsid protein was proposed due to high similarity with other viral capsid proteins. The transcription of the bm70 gene is regulated in time with a short early and a longer late transcript (171).
Ac88: cg30; unknown function
The ac88 gene product (30.1 kDa, 264 aa) harbors a zinc-finger-like and a leucine zipper motif, a characteristic found in proteins involved in gene regulation (215). cg30 is transcribed as an early monocistronicRNA and as the second cistron of an abundant late bicistronicRNA together with vp39 (259), but a CG30-beta-galactosidase fusion proteinwasmainly observed early in the infection process (215). cg30 is not essential for virus replication in vitro and in vivo, but the wild type virus accumulated to slightly higher titers over the cg30 deletion mutant after several passages in cell culture (215).
Ac89: vp3