essential for virus replication in cell culture (166). Together with the products of the genes ie-1 (ac147), pe38 (ac153), he65 (ac105), ac4, and ac152, P12 is involved in transport of G-actin into the nucleus during baculovirus infection (202).
Ac103: p48, unknown function
The 5' end of the p48 transcript maps to consensus baculovirus late transcription start sites (ATAAG) (166). Attempts to prepare p48 mutant viruses were not successful suggesting that the gene is essential for virus replication in cell culture (166). More recently, detailed analysis of a p48 deletion mutant confirmed that this gene is essential for BV production and ODV envelopment (290). Homologs of ac103 can be found in the genomes of all Alpha-, Beta-and Gammabaculoviruses (Table 2 and Table 3).
Ac104: vp80, capsid-associated protein VP80
A late 2.1 kb transcript was mapped to ac104 which encodes a 79.9 kDa protein (691 aa). VP80 is a structural capsid-associated protein as confirmed with anti-BV sera (164). VP80 interacts with the viral protein, 38K (see ac98) (281). In BmNPV, VP80 is essential for BV production and nucleocapsid maturation. The BmNPV vp80 could not functionally be replaced by AcMNPV vp80 (256). In the case of Choristoneura fumiferana (Cf) MNPV, the VP80 protein appears as a 82 kDa protein in samples from ODVs and as an 72/82 kDa doublet from BVs (151). Homologs of the vp80 gene are only found in Alphabaculoviruses (Table 2).
Ac105: he65, HE65 protein
The designation he65 stems from the size of the predicted protein (65.6 kDa, 553 aa) and the genomic location of this ORF, being flanked by an EcoRI site and the hr4 left region. He65 is a delayed early gene and mRNA is detectable from 2 h p.i.. Transcript levels remain stable into the late phases of infection (12). HE65, together with Ac102, mediates nuclear localization of monomeric G-actin, a process promoting nuclear F-actin formation, which is required for progeny virus production (202). Localization of G-actin within the nucleus is a temporally regulated process. Transactivators encoded by ie-1 (ac147), pe38 (ac153), ac4 and ac152 are essential for expression of he65 and ac102 (202).
Ac106/107: ac106/107, unknown function
Partial resequencing of AcMNPV showed that the original ac106 and ac107 together form one ORF (92). The combined ORF encodes a 28.3 kDa (243 aa) protein and has homologs in all Alpha-and Betabaculoviruses (Table 2 and Table 3) (100). Together these homologs form the DUF816 superfamily (176), a family of baculovirus proteins with unknown function.
Ac108: ac108, P11 protein
Ac108 is a putative late gene, expressing a 11.8 kDa (105 aa) protein belonging to the baculovirus 11 kDa protein family according to the CDD database (176). Its homologs in Antheraea pernyi (Anpe)NPV and SpltNPV are ODV structural proteins, with envelope localization shown for SpltMNPV P11 (32, 247). Association with ODVs has not been found for Ac108 (20). P11 is transcribed from a late promoter motif in AnpeNPV and from an early promoter in SpltNPV, with concordant differences in initiation of transcription.
Ac109: ac109, occlusion derived structural protein
The ac109 gene belongs to the baculovirus core genes. It encodes a 44.8 kDa (390 aa) protein which is present within or associated with the ODV (20). Its homolog in Helicoverpa armigera (Hear)NPV (ha94) is a late gene encoding the structural ODV component ODV-EC43 (66). The conserved part of this protein is known as DUF673 domain according to the CDD database (176).
Ac110: ac110, unknown function
Ac110 codes for a small 6.8 kDa (56 aa) protein of unknown function. Homologs are present in all Alpha-baculoviruses and most Betabaculoviruses (Table 2 and Table 3) and the conserved part of the protein is designated as DUF1448 domain (176). Transcripts from this region have been reported (287).
Ac111: ac111, unknown function
The gene ac111 is probably an early gene encoding a 8.2 kDa (67 aa) protein with undetermined function. The ORF is represented in the transcriptome of Ac-MNPV (287). Homologs of this ORF form the baculovirus 8 kDa gene fam