Spodoptera frugiperda nuclear polyhedrosis virus was highly pathogenic to both S. frugiperda and S. exigua. Plaque-purified variants from two of the original isolates showed much greater differences in pathogenicity to the two insect species than the original isolates. Plaque-purified variants from one of the isolates (D) nearly lost pathogenicity for S. exigua while remaining pathogenic for S. frugiperda. Some of the plaque-purified variants produced atypical symptoms, even in S. frugiperda. These variants did not liquefy larvae and release polyhedra when the larvae died as is typical for nuclear polyhedrosis infections in Lepidoptera. These variants also produced fewer polyhedra per g larval weight and often had fewer virions per polyhedron. Light and electron microscopical studies of S. frugiperda and S. exigua infected with one of the original isolates (A) and two of the plaque-purified variants (B2 and D7) indicated that only S. frugiperda infected with isolate A had the highly productive infection and viral morphogenesis typical of nuclear polyhedrosis viruses. Exposure of S. frugiperda to isolate B2 or D7 resulted in a slightly delayed infection characterized by increased amounts of abnormal viral morphogenesis and polyhedra of decreased size. S. exigua infected with isolate A or B2 had greatly reduced and delayed infections that were accompanied by highly variable abnormal viral morphogenesis; virtually no normal polyhedra were produced in these instances. Isolate D7 produced neither nucleocapsids nor polyhedra in S. exigua. Large paracrystalline aggregates of nucleocapsids were common in S. frugiperda infected with isolates B2 or D7 and in S. exigua infected by isolate A. Infection of S. exigua by isolate A or B2 was typified by the accumulation of large amounts of excess envelope membrane in the form of strands and vesicles of various sizes. Normal virogenic stromata were characteristics only of S. frugiperda infected with isolate A or B2. Polyhedra produced in S. exigua by even the most pathogenic isolates (A and B2) contained few if any normal virions and were not infective for either S. frugiperda or S. exigua.
AndrewsR. E.,
SpenceK. D.,
MillerL. K.1980; Virulence of cloned variants of Autographa califomica nuclear polyhedrosis virus. Applied and Environmental Microbiology 39:932–933
ChungK. L.,
BrownM.,
FaulknerP.1980; Studies on the morphogenesis of polyhedral inclusion bodies of a baculovirus Autographa californica NPV. Journal of General Virology 46:335–347
HammJ. J.1968; Comparative histopathology of a granulosis and a nuclear polyhedrosis virus of Spodoptera frugiperda. Journal of Invertebrate Pathology 10:320–326
HammJ. J.1982; Relative susceptibility of several noctuid species to a nuclear polyhedrosis virus from Heliothis armiger. Journal of Invertebrate Pathology 39:255–256
HinkW. F.,
VailP. V.1973; A plaque assay for titration of alfalfa looper nuclear polyhedrosis virus in a cabbage looper (TN368) cell line. Journal of Invertebrate Pathology 22:168–174
HirumiH.,
HirumiK.,
McintoshA. H.1975; Morphogenesis of a nuclear polyhedrosis virus of the alfalfa looper in a continuous, cabbage looper cell line. Annals of the New York Academy of Sciences 266:302–326
HunterD. K.,
HoffmannD. F.,
CollierS. J.1973; Cross-infection of a nuclear polyhedrosis virus of the almond moth to the Indian meal moth. Journal of Invertebrate Pathology 22:186–192
KnellJ. D.,
SummersM. D.1981; Investigation of genetic heterogeneity in wild isolates of Spodoptera frugiperda nuclear polyhedrosis virus by restriction endonuclease analysis of plaque-purified variants. Virology 112:190–197
KnudsonD. L.,
HarrapK. A.1976; Replication of a nuclear polyhedrosis virus in a continuous cell culture of Spodoptera frugiperda: microscopy study of the sequence of events of the virus infection. Journal of Virology 17:254–268
MackinnonE. A.,
HendersonJ. F.,
StoltzD. B.,
FaulknerP.1974; Morphogenesis of nuclear polyhedrosis virus under conditions of prolonged passage in vitro. Journal of Ultrastructure Research 49:419–435
PotterK. N.,
FaulknerP.,
MackinnonE. A.1976; Strain selection during serial passage of Trichoplusia ni nuclear polyhedrosis virus. Journal of Virology 18:1040–1050
RamoskaW. A.,
HinkW. F.1974; Electron microscope examination of two plaque variants from a nuclear polyhedrosis virus of the alfalfa looper, Autographa californica. Journal of Invertebrate Pathology 23:197–201
SummersM. D.,
ArnottH. J.1969; Ultrastructural studies on inclusion formation and virus occlusion in nuclear polyhedrosis and granulosis virus-infected cells of Trichoplusia ni (Hiibner). Journal of Ultrastructure Research 28:462–480
TompkinsG. J.,
VaughnJ. L.,
AdamsJ. R.,
ReichelderferC. F.1981; Effects of propagating Autographa californica nuclear polyhedrosis virus and its Trichoplusia ni variant in different hosts. Environmental Entomology 10:801–806
VailP. V.,
JayD. L.1973; Pathology of a nuclear polyhedrosis virus of the alfalfa looper in alternate hosts. Journal of Invertebrate Pathology 21:198–204
VailP. V.,
JayD. L.,
StewartF. D.,
MartinezA. J.,
DulmageH. T.1978; Comparative susceptibility of Heliothis virescens and H. zea to the nuclear polyhedrosis virus isolated from Autographa californica. Journal of Economic Entomology 71:293–296
VailP. V.,
KnellJ. D.,
SummersM. D.,
CowanD. K.1982; In vivo infectivity of Baculovirus isolates, variants, and natural recombinants in alternate hosts. Environmental Entomology 11:1187–1192