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J. Virol., 04 1995, 2024-2030, Vol 69, No. 4
TM Zhao, MA Robinson, FS Bowers and TJ Kindt
An infectious molecular clone of human T-cell leukemia virus type I
(HTLV-I) was derived from an HTLV-I-transformed rabbit T-cell line, RH/K30,
obtained by coculture of rabbit peripheral blood mononuclear cells (PBMC)
with the human HTLV-I-transformed cell line MT-2. The RH/K30 cell line
contained two integrated proviruses, an intact HTLV-I genome and an
apparently defective provirus with an in-frame stop codon in the env gene.
A genomic DNA fragment containing the intact HTLV-I provirus was cloned
into bacteriophage lambda (K30 phi) and subcloned into a plasmid vector
(K30p). HTLV-I p24gag protein was detected in culture supernatants of human
and rabbit T-cell and fibroblast lines transfected with these clones, at
levels comparable to those of the parental cell line RH/K30. Persistent
expression of virus was observed in one of these lines, RL-5/K30p, for more
than 24 months. Biologic characterization of this cell line revealed the
presence of integrated HTLV-I provirus, spliced and unspliced mRNA
transcripts, and typical extracellular type C retrovirus particles. As
expected, these virus particles contained HTLV-I RNA and reverse
transcriptase activity. The transfected cells also expressed surface major
histocompatibility complex class II, whereas no expression of this molecule
was detected in the parental RL-5 cell line. Virus was passaged by
cocultivation of irradiated RL-5/K30p cells with either rabbit PBMC or
human cord blood mononuclear cells, demonstrating in vitro infectivity. The
virus produced in these cells was also infectious in vivo, since rabbits
injected with RL-5/K30p cells became productively infected, as evidenced by
seroconversion, amplification of HTLV-I-specific sequences by PCR from PBMC
DNA, and virus isolation from PBMC. Availability of infectious molecular
clones will facilitate functional studies of HTLV- I genes and gene
products.
Copyright © 1995, American Society for Microbiology
Characterization of an infectious molecular clone of human T-cell leukemia virus type I
Laboratory of Immunogenetics, NIAID Twinbrook II Facility, Rockville, Maryland 20852.
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