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J. Virol., Apr 1995, 2031-2037, Vol 69, No. 4
B Tao and PN Fultz
A prototypic simian immunodeficiency virus (SIVsmm9), isolated from a
naturally infected sooty mangabey (Cercocebus atys), was passaged in vivo
in a pig-tailed macaque (Macaca nemestrina) having the identifier PBj. When
PBj died of a typical AIDS-like syndrome 14 months after infection, the
virus isolated from its tissues was subsequently shown to differ from
SIVsmm9 genetically and biologically. Most notably, this isolate,
SIVsmmPBj14 (SIV-PBj14), is the most virulent primate lentivirus known: it
induces acute disease and death within 6 to 10 days after intravenous
inoculation into pig-tailed macaques. Between the time of infection with
SIVsmm9 and isolation of SIV-PBj14, isolates were obtained periodically
from peripheral blood mononuclear cells of PBj. To establish the temporal
relationship between evolution of new biologic properties and fixation of
specific mutations in the virus population, these sequential SIV-PBj
isolates were characterized for unique properties of SIV-PBj14 that
appeared to correlate with acute lethal disease. These properties included
the ability to replicate in quiescent macaque peripheral blood mononuclear
cells, to activate and induce proliferation of CD4+ and CD8+ cells, and to
exhibit cytopathicity for mangabey CD4+ lymphocytes. Consistent with
earlier studies, a major change in biologic properties occurred between 6
(SIV- PBj6) and 10 (SIV-PBj10) months, with the SIV-PBj8 quasispecies
exhibiting properties of both earlier and later isolates. Multiple biologic
clones derived from the 6-, 8-, and 10-month isolates also exhibited
diverse phenotypes. For example, one SIV-PBj10 biologic clone resembled
SIVsmm9 phenotypically, whereas three other biologic clones resembled
SIV-PBj14. To evaluate genetic changes, proviral DNA of the biologic clones
generated from SIV-PBj6, -PBj8, and -PBj10 was amplified by PCR in the U3
enhancer portion of the long terminal repeats (LTR) and the V1 region of
env, where the greatest nucleotide diversity between SIVsmm9 and SIV-PBj14
resided. Nucleotide sequence data indicated that all biologically cloned
viruses are distinct and that insertions/duplications of 3 to 27
nucleotides (in multiples of three) had accumulated stepwise in the env V1
region, beginning with SIV-PBj8. In addition, one of four SIV-PBj8 biologic
clones had a 22-bp duplication in the LTR which is characteristic of
SIV-PBj14. When virus mixtures containing different proportions of two
SIV-PBj10 biologic clones with opposite phenotypes were tested, the
SIV-PBj14 phenotype was clearly dominant, since mixtures with as few as 10%
of the viruses being SIV-PBj14-like exhibited all the properties of the
lethal isolate.(ABSTRACT TRUNCATED AT 400 WORDS)
Copyright © 1995, American Society for Microbiology
Molecular and biological analyses of quasispecies during evolution of a virulent simian immunodeficiency virus, SIVsmmPBj14
Department of Microbiology, University of Alabama at Birmingham 35294.
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