ity of Alphabaculoviruses (Table 2).
Ac30: ac30, unknown function
The ac30 gene codes for a protein (54.7 kDa, 463 aa) with unknown function. Transcripts are present during viral infection (287). Homologous are present in some but not all Alpha-and Betabaculoviruses (Table 2 and Table 3).
Ac31: sod, superoxide dismutase
Transcription of the sod gene results in two RNAs of 1.4 and 1.5 kb which are detectable at 24-48 h and 12-48 h p.i., respectively (263). The encoded superoxide dismutase (16.2 kDa, 151 aa) is not essential for virus replication in cell culture or in larvae (263). Homologs are found in almost every Alphabaculovirus and in a few Betabaculoviruses (Table 2 and Table 3). The sod gene, therefore, may have an important function in the Alphabaculovirus' life cycle (109).
Ac32: fgf, fibroblast growth factor
The fgf gene encodes a fibroblast growth factor homolog (FGF; 20.6 kDa, 181 aa) and homologs are only present in baculoviruses that infect lepidopteran insects (Alpha-and Betabaculoviruses) (48). FGFs have an important role in angiogenesis, cell proliferation, differentiation, and cell migration (110). AcMNPV FGF is also functional in cell culture, as it is secreted and able to enhance cell migration (48). An fgf deletion mutant showed no differences in production of infectious BV nor in DNA replication in Sf21 cells nor did the mutant have a replication advantage (50). In insect larvae of S. frugiperda and T. ni death was delayed compared to the wild type virus with oral feeding, but not with intrahemocoelic injection (49). These results suggest that FGF plays a role in the systemic spread of the virus from the midgut (49).
Ac33: hisp, histidinol-phosphatase
The gene hisp codes for a protein (20.8 kDa, 182 aa) with putative histidinol-phosphatase activity due to the presence of a conserved haloacid dehalogenaselike hydrolase domain. The function of histidinolphosphatase is to catalyze the dephosphorylation of L-histidinol phosphate and such enzymes have been characterized mainly in prokaryotes (211). This gene is represented in the transcriptome (287).
Ac34: ac34, unknown function
The gene ac43 encodes a hypothetical protein of 24.9 kDa (215 aa) with a conserved domain with unknown function according to the CDD database (176). Homologs are found in all Alphabaculoviruses except Spodoptera litura (Splt) NPV (Table 2).
Ac35: v-ubi, viral ubiquitin
The gene v-ubi encodes the viral ubiquitin (V-UBI) protein (8.7 kDa, 77 aa). The protein has 70% identity to eukaryotic ubiquitin proteins and is produced at maximal levels between 14 and 18 h p.i., indicating that the gene is a late gene (82). The gene has been classified as an auxiliary gene and the encoded ubiquitin is likely involved in signaling the degradation of proteins by the 26S proteome (197). Homologs are present in all Alpha-and Betabaculoviruses except Leucania separate (Ls)NPV (Table 2 and Table 3).
Ac36: 39K/pp31, nuclear matrix associated phosp-hoprotein
The gene pp31 (also known as 39K) encodes a phosphoprotein (31.3 kDa, 112 aa) that can bind in a non-specific way to ssDNA and dsDNA with equal affinity and is essential for late gene expression, i.e. it serves as a late expression factor (22, 86). In addition, a pp31-null mutant was prepared of AcMNPV, and microarray and quantitative PCR showed that pp31 is not essential for viral DNA replication. However, the deletion resulted in a minor down-regulation of a subset of both early and late genes and, as for BmNPV (77), in decreased BV production (287).
Ac37: lef-11, late expression factor 11
Lef-11 codes for the late expression factor-11 (LEF-11) with a calculated mass of 13.1 kDa (112 aa). Its messenger RNA is present from 3 to 36 h p.i., while LEF-11 is detected until 72 h p.i. and localizes within a dense region of infected nuclei (158). LEF-11 is not essential for DNA replication in transient replication assays (169), but is necessary for the activity of late gene promoters (262). An AcMNPV lef-11 null mutant was not able to replicate in Sf9 cells and late gene transcription was absent (157).
Ac3