Genus: Alphabaculovirus


Genus: Alphabaculovirus

Distinguishing features 

OBs measure 0.15 to 5 µm in size and are generally polyhedral, although morphology may vary (Adams and McClintock 1991).  They mature within the nuclei of infected cells and characteristically contain many enveloped virions (Figure 1.Alphabaculovirus). The occluded virions are packaged with either single or multiple nucleocapsids within a single viral envelope. Members of some virus species manifest both phenotypes. A number of genes that influence nucleocapsid packaging are known, but in members of some species, packaging may be variable (Rohrmann 2014, Yang et al., 2014). Single (S) and multiple (M) designations in common names have been retained for species where variability has not been reported and for distinct viruses that would otherwise have identical designations under the current nomenclature. During viral entry, nucleocapsids are transported through the nuclear membrane and into the nucleus (Au et al., 2016), where uncoating and viral replication occur.

Figure 1.Alphabaculovirus. Occlusion bodies of baculoviruses in the genus Alphabaculovirus. Scanning electron micrographs of Autographa californica multiple nucleopolyhedrovirus (A) and Operophtera brumata nucleopolyhedrovirus (B) occlusion bodies are shown, along with transmission electron micrographs of Autographa californica multiple nucleopolyhedrovirus (C) and Trichoplusia ni single nucleopolyhedrovirus (D) occlusion bodies containing occlusion-derived virus consisting of multiple and single nucleocapsids per envelope, respectively.  Scale bars: (A, B) 2 µm; (C, D) 0.5 µm.  Micrographs in panels (A) and (D) courtesy of J. R. Adams (USDA).

Virion

Morphology

Nucleocapsid length appears to be proportional to genome size (Fraser 1986).

Genome organization and replication

In addition to the family Baculoviridae core genes, the alphabaculoviruses and betabaculoviruses appear to share an additional 23 homologs (Garavaglia et al., 2012).

Biology

Species of this genus have been isolated only from the insect order Lepidoptera. 

Species demarcation criteria

Traditionally, species distinctions have been broadly based on host range and specificity, DNA restriction profiles, DNA sequences from various regions of the genome, and predicted protein sequence similarities.  More recently, species demarcation criteria for alpha- and betabaculoviruses have been proposed that rely upon pairwise nucleotide distances estimated with the Kimura-2-parameter substitution model from partial sequences of three conserved baculovirus genes: late expression factor-8 (lef-8) and late expression factor-9 (lef-9), which encode subunits of the baculovirus RNA polymerase, and polyhedrin/granulin (polh/gran), which encodes the viral occlusion body matrix protein (Jehle et al., 2006b). If nucleotide distances between two viruses at these loci are less than 0.015 substitutions/site, the two baculoviruses are considered to belong to the same species. If nucleotide distances between two viruses are greater than 0.05 substitutions/site, the viruses are considered to belong to different species. If the nucleotide distances lie between 0.015 and 0.050 substitutions/site, additional characteristics of the two viruses (i.e. host range) must be considered to make a decision about their taxonomic status. The proposed criteria were originally based on an alignment of sequences from 117 separate baculovirus isolates and the phylogeny inferred from this alignment. Researchers have applied this criterion to other isolates to identify many new baculovirus species and variants of currently recognized species. A more recent examination of pairwise nucleotide distances for all 38 baculovirus core genes among 172 completely sequenced baculovirus genomes has confirmed the current species classification based on pairwise distances for lef-8lef-9, and polh loci (Wennmann et al., 2018).

Member species

SpeciesVirus name(s)Exemplar isolateExemplar accession numberExemplar RefSeq numberAvailable sequenceOther isolatesOther isolate accession numbersVirus abbreviationIsolate abbreviation
Adoxophyes honmai nucleopolyhedrovirusAdoxophyes honmai nucleopolyhedrovirusADN001AP006270NC_004690Complete genomeAdhoNPV
Agrotis ipsilon multiple nucleopolyhedrovirusAgrotis ipsilon multiple nucleopolyhedrovirusIllinoisEU839994NC_011345Complete genomeAgipMNPV
Agrotis segetum nucleopolyhedrovirus AAgrotis segetum nucleopolyhedrovirus APolishDQ123841NC_007921Complete genomeAgseNPV-A
Agrotis segetum nucleopolyhedrovirus BAgrotis segetum nucleopolyhedrovirus BEnglishKM102981NC_025960Complete genomeAgseNPV-B
Antheraea pernyi nucleopolyhedrovirusAntheraea pernyi nucleopolyhedrovirusLiaoningDQ486030NC_008035Complete genomeAnpeNPV
Anticarsia gemmatalis multiple nucleopolyhedrovirusAnticarsia gemmatalis multiple nucleopolyhedrovirus2DDQ813662NC_008520Complete genomeAgMNPV
Anticarsia gemmatalis multiple nucleopolyhedrovirusAnticarsia gemmatalis multiple nucleopolyhedrovirus37KR815466AgMNPV
Autographa californica multiple nucleopolyhedrovirusAutographa californica multiple nucleopolyhedrovirusC6L22858NC_001623Complete genomeAcMNPV
Autographa californica multiple nucleopolyhedrovirusPlutella xylostella multiple nucleopolyhedrovirusCL3DQ457003PlxyMNPV
Bombyx mori nucleopolyhedrovirusBombyx mori nucleopolyhedrovirusT3L33180NC_001962Complete genomeBmNPV
Bombyx mori nucleopolyhedrovirusBombyx mandarina nucleopolyhedrovirusS1FJ882854BomaNPV
Buzura suppressaria nucleopolyhedrovirusBuzura suppressaria nucleopolyhedrovirusHubeiKF611977NC_023442Complete genomeBuzuNPV
Catopsilia pomona nucleopolyhedrovirusCatopsilia pomona nucleopolyhedrovirus416KU565883NC_030240Complete genomeCapoNPV
Choristoneura fumiferana DEF multiple nucleopolyhedrovirusChoristoneura fumiferana DEF multiple nucleopolyhedrovirusAY327402NC_005137Complete genomeCfDEFMNPV
Choristoneura fumiferana multiple nucleopolyhedrovirusChoristoneura fumiferana multiple nucleopolyhedrovirusIrelandAF512031NC_004778Complete genomeCfMNPV
Choristoneura murinana nucleopolyhedrovirusChoristoneura murinana nucleopolyhedrovirusDarmstadtKF894742NC_023177Complete genomeChmuNPV
Choristoneura rosaceana nucleopolyhedrovirusChoristoneura rosaceana nucleopolyhedrovirusNB_1KC961304NC_021924Complete genomeChroNPV
Chrysodeixis chalcites nucleopolyhedrovirusChrysodeixis chalcites nucleopolyhedrovirusAY864330NC_007151Complete genomeChchNPV
Chrysodeixis includens nucleopolyhedrovirusPseudoplusia includens single nucleopolyhedrovirusIEKJ631622NC_026268Complete genomePsinSNPV
Clanis bilineata nucleopolyhedrovirusClanis bilineata nucleopolyhedrovirusDZ1DQ504428NC_008293Complete genomeClbiNPV
Ectropis obliqua nucleopolyhedrovirusEctropis obliqua nucleopolyhedrovirusA1DQ837165NC_008586Complete genomeEcobNPV
Epiphyas postvittana nucleopolyhedrovirusEpiphyas postvittana nucleopolyhedrovirusAY043265NC_003083Complete genomeEppoNPV
Euproctis pseudoconspersa nucleopolyhedrovirusEuproctis pseudoconspersa nucleopolyhedrovirusHangzhouFJ227128NC_012639Complete genomeEupsNPV
Helicoverpa armigera nucleopolyhedrovirusHelicoverpa armigera nucleopolyhedrovirusG4AF271059NC_002654Complete genomeHearNPV
Helicoverpa armigera nucleopolyhedrovirusHelicoverpa armigera nucleopolyhedrovirusC1AF303045HearNPV
Helicoverpa armigera nucleopolyhedrovirusHelicoverpa armigera nucleopolyhedrovirusNNg1AP010907HearNPV
Hemileuca species nucleopolyhedrovirusHemileuca sp. nucleopolyhedrovirusMEMKF158713NC_021923Complete genomeHespNPV-MEM
Hyphantria cunea nucleopolyhedrovirusHyphantria cunea nucleopolyhedrovirusN9AP009046NC_007767Complete genomeHycuPV
Lambdina fiscellaria nucleopolyhedrovirusLambdina fiscellaria nucleopolyhedrovirusGR15KP752043NC_026922Complete genomeLafiNPV
Leucania separata nucleopolyhedrovirusLeucania separata nucleopolyhedrovirusAH1AY394490NC_008348Complete genomeLeseNPV
Lonomia obliqua nucleopolyhedrovirusLonomia obliqua multiple nucleopolyhedrovirusSP/2000KP763670NC_043520Complete genomeLoobNPV-SP/2000
Lymantria dispar multiple nucleopolyhedrovirusLymantria dispar multiple nucleopolyhedrovirus5/6AF081810NC_001973Complete genomeLdMNPV
Lymantria xylina nucleopolyhedrovirusLymantria xylina multiple nucleopolyhedrovirus5GQ202541NC_013953Complete genomeLyxyMNPV
Mamestra brassicae multiple nucleopolyhedrovirusMamestra brassicae multiple nucleopolyhedrovirusK1JQ798165NC_023681Complete genomeMbMNPV
Mamestra configurata nucleopolyhedrovirus AMamestra configurata nucleopolyhedrovirus A90/2U59461NC_003529Complete genomeMacoNPV-A
Mamestra configurata nucleopolyhedrovirus AMamestra configurata nucleopolyhedrovirus A90/4AF539999MacoNPV-A
Mamestra configurata nucleopolyhedrovirus BMamestra configurata nucleopolyhedrovirus B96BAY126275NC_004117Complete genomeMacoNPV-B
Maruca vitrata nucleopolyhedrovirusMaruca vitrata nucleopolyhedrovirusMV-8EF125867NC_008725Complete genomeMaviNPV
Mythimna unipuncta nucleopolyhedrovirusMythimna unipuncta nucleopolyhedrovirus#7MF375894NC_043530Complete genomeMyunNPV#7
Operophtera brumata nucleopolyhedrovirusOperophtera brumata nucleopolyhedrovirusMAMF614691NC_040621Complete genomeOpbuNPV-MA
Orgyia leucostigma nucleopolyhedrovirusOrgyia leucostigma nucleopolyhedrovirusCFS-77EU309041NC_010276Complete genomeOrleNPV
Orgyia pseudotsugata multiple nucleopolyhedrovirusOrgyia pseudotsugata multiple nucleopolyhedrovirusU75930NC_001875Complete genomeOpMNPV
Oxyplax ochracea nucleopolyhedrovirusOxyplax ochracea nucleopolyhedrovirus435MF143631NC_043529Complete genomeOxocNPV-435
Peridroma saucia nucleopolyhedrovirusPeridroma species nucleopolyhedrovirusGR167KM009991NC_024625Complete genomePespNPV-GR167
Perigonia lusca nucleopolyhedrovirusPerigonia lusca single nucleopolyhedrovirusKM596836NC_027923Complete genomePeluSNPV
Spodoptera exigua multiple nucleopolyhedrovirusSpodoptera exigua multiple nucleopolyhedrovirusUS1AF169823NC_002169Complete genomeSeMNPV
Spodoptera frugiperda multiple nucleopolyhedrovirusSpodoptera frugiperda multiple nucleopolyhedrovirus3AP2EF035042NC_009011Complete genomeSfMNPV
Spodoptera littoralis nucleopolyhedrovirusSpodoptera littoralis nucleopolyhedrovirusAN1956JX454574NC_038369Complete genomeSpliNPV
Spodoptera litura nucleopolyhedrovirusSpodoptera litura nucleopolyhedrovirusG2AF325155NC_003102Complete genomeSpltNPV
Sucra jujuba nucleopolyhedrovirusSucra jujuba nucleopolyhedrovirus473KJ676450NC_028636Complete genomeSujuNPV
Thysanoplusia orichalcea nucleopolyhedrovirusThysanoplusia orichalcea nucleopolyhedrovirusp2JX467702NC_019945Complete genomeThorNPV
Trichoplusia ni single nucleopolyhedrovirusTrichoplusia ni single nucleopolyhedrovirusDQ017380NC_007383Complete genomeTnSNPV
Wiseana signata nucleopolyhedrovirusWiseana signata nucleopolyhedrovirusAF016916NC_038370Partial genomeWisiNPV

Virus names, the choice of exemplar isolates, and virus abbreviations, are not official ICTV designations.

Related, unclassified viruses

Virus name

Accession number

Virus abbreviation

Apocheima cinerarium nucleopolyhedrovirus

FJ914221

ApciNPV

Cerapteryx graminis nucleopolyhedrovirus

HQ603182, HQ603183, HQ603184

CegrNPV

Condylorrhiza vestigialis multiple nucleopolyhedrovirus

KJ631623

CoveMNPV

Dasychira pudibunda nucleopolyhedrovirus

KP747440

DapuNPV-ML1

Helicoverpa armigera multiple nucleopolyhedrovirus

EU730893

HearMNPV

Lacanobia oleracea nucleopolyhedrovirus

LaolNPV

Leucoma salicis multiple nucleopolyhedrovirus

AY729808, AY729809, AY729810

LesaMNPV

Malacosoma californicum pluviale nucleopolyhedrovirus

AF535137

McplNPV

Malacosoma neustria nucleopolyhedrovirus

AY519243, AY519244, AY519245

ManeNPV

Orgyia pseudotsugata single nucleopolyhedrovirus

AY895150, AY895151, AY895152, AY895153

OpSNPV

Panolis flammea nucleopolyhedrovirus

D00437

PaflNPV

Philosamia cynthia nucleopolyhedrovirus

JX404026

PhcyNPV

Rachiplusia ou multiple nucleopolyhedrovirus

AY145471

RoMNPV-R1

Spodoptera litura nucleopolyhedrovirus II

EU780426

SpltNPV-II

Urbanus proteus nucleopolyhedrovirus

KR011717

UrprNPV-Southern Brazil

Virus names and virus abbreviations, are not official ICTV designations.