title: Human T-cell leukemia viruses are highly unstable over a wide range of temperatures.
abstract: The biological properties of human T-cell leukemia virus type I (HTLV-I) and HTLV type II (HTLV-II) are not well elucidated as cell-free viruses. We established new assay systems to detect the infectivity of cell-free HTLVs and examined the stability of cell-free HTLVs at different temperatures. HTLVs lost infectivity more rapidly than did bovine leukemia virus (BLV), which is genetically related to HTLVs. The half-lives of three HTLV-I strains (two cosmopolitan strains and one Melanesian strain) at 37 °C were approximately 0.6 h, whereas the half-life of a BLV strain was 8.5 h. HTLV-I rapidly lost infectivity unexpectedly at 0 and 4 °C. We examined the stability of vesicular stomatitis virus pseudotypes with HTLV-I, HTLV-II or BLV Env proteins, and the Env proteins of HTLVs were found to be more unstable at 4 and 25 °C than the Env proteins of the BLV. Over the course of the viral life cycle, heat treatment inhibited HTLV-I infection at the phase of attachment to the host cells, and inhibition was more marked upon entry into the cells. The HTLV-I Env surface (SU) protein (gp46) was easily released from virions during incubation at 37 °C. However, this release was inhibited by pre-treatment of the virions with N-ethylmaleimide, suggesting that the inter-subunit bond between gp46 SU and gp21 transmembrane (TM) proteins is rearranged by disulfide bond isomerization. HTLVs are highly unstable over a wide range of temperatures because the disulfide bonds between the SU and TM proteins are labile.
authors: 21st Century COE Program, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma 371-8511, Japan.|Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Masahiko
authors: M
authors: Shinagawa
authors: Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Atsushi
authors: A
authors: Jinno-Oue
authors: Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Nobuaki
authors: N
authors: Shimizu
authors: Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Bibhuti Bhusan
authors: BB
authors: Roy
authors: Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Akira
authors: A
authors: Shimizu
authors: Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Sk Ariful
authors: SA
authors: Hoque
authors: 21st Century COE Program, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma 371-8511, Japan.|Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Hiroo
authors: H
authors: Hoshino
mesh_terms: D004220:Disulfides / Q000737:chemistry; D015368:Human T-lymphotropic virus 1 / Q000472:pathogenicity / Q000528:radiation effects*; D015367:Human T-lymphotropic virus 2 / Q000472:pathogenicity / Q000528:radiation effects*; D006801:Humans; D001909:Leukemia Virus, Bovine / Q000472:pathogenicity / Q000528:radiation effects; D050296:Microbial Viability / Q000528:radiation effects*; D055550:Protein Stability; D021122:Protein Subunits / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D014759:Viral Envelope Proteins / Q000737:chemistry
chemical_list: D004220:Disulfides; D021122:Protein Subunits; D014759:Viral Envelope Proteins