Human T-cell lymphotropic virus type 1 open reading frame II-encoded p30II is required for in vivo replication: evidence of in vivo reversion.
Human T-cell lymphotropic virus type 1 (HTLV-1) causes adult T-cell leukemia/lymphoma and exhibits high genetic stability in vivo. HTLV-1 contains four open reading frames (ORFs) in its pX region. ORF II encodes two proteins, p30(II) and p13(II), both of which are incompletely characterized. p30(II) localizes to the nucleus or nucleolus and has distant homology to the transcription factors Oct-1, Pit-1, and POU-M1. In vitro studies have demonstrated that at low concentrations, p30(II) differentially regulates cellular and viral promoters through an interaction with CREB binding protein/p300. To determine the in vivo significance of p30(II), we inoculated rabbits with cell lines expressing either a wild-type clone of HTLV-1 (ACH.1) or a clone containing a mutation in ORF II, which eliminated wild-type p30(II) expression (ACH.30.1). ACH.1-inoculated rabbits maintained higher HTLV-1-specific antibody titers than ACH.30.1-inoculated rabbits, and all ACH.1-inoculated rabbits were seropositive for HTLV-1, whereas only two of six ACH.30.1-inoculated rabbits were seropositive. Provirus could be consistently PCR amplified from peripheral blood mononuclear cell (PBMC) DNA in all ACH.1-inoculated rabbits but in only three of six ACH.30.1-inoculated rabbits. Quantitative competitive PCR indicated higher PBMC proviral loads in ACH.1-inoculated rabbits. Interestingly, sequencing of ORF II from PBMC of provirus-positive ACH.30.1-inoculated rabbits revealed a reversion to wild-type sequence with evidence of early coexistence of mutant and wild-type sequence. Our data provide evidence that HTLV-1 must maintain its key accessory genes to survive in vivo and that in vivo pressures select for maintenance of wild-type ORF II gene products during the early course of infection.
Silverman
Lee R
LR
Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210, USA.
Phipps
Andrew J
AJ
Montgomery
Andrew
A
Ratner
Lee
L
Lairmore
Michael D
MD
D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D001483:Base Sequence; D002460:Cell Line; D004279:DNA, Viral / Q000235:genetics; D005814:Genes, Viral; D015490:HTLV-I Infections / Q000276:immunology / Q000821:virology; D015368:Human T-lymphotropic virus 1 / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D007963:Leukocytes, Mononuclear / Q000821:virology; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D011533:Proviruses / Q000235:genetics / Q000302:isolation & purification; D011817:Rabbits; D012191:Retroviridae Proteins / Q000235:genetics* / Q000502:physiology*; D014779:Virus Replication / Q000235:genetics / Q000502:physiology
D000914:Antibodies, Viral; D004279:DNA, Viral; D012191:Retroviridae Proteins; C072814:tof protein, Human T-lymphotropic virus 1