Initial human T-cell leukemia virus type 1 infection of the salivary gland epithelial cells requires a biofilm-like structure

• Published in: Virus research Vol. 269; p. 197643
• Main Authors: Nakamura, Hideki, Shimizu, Toshimasa, Takatani, Ayuko, Suematsu, Takashi, Nakamura, Tatsufumi, Kawakami, Atsushi
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2019
• Subjects: Biofilm; cell lines; coculture; epithelial cells; extracellular matrix; fluorescent antibody technique; galectins; HTLV-1; humans; image analysis; leukemia; patients; Primate T-lymphotropic virus 1; Salivary gland epithelial cell; salivary glands; scanning electron microscopy; synapse; T cell; T-lymphocytes; transmission electron microscopy; virion; viruses; Biofilm; HTLV-1; Salivary gland epithelial cell; T cell
• ISSN: 0168-1702; 1872-7492; 1872-7492
• DOI: 10.1016/j.virusres.2019.197643

•The HTLV-1-infected cells have the extracellular matrix and linker proteins on their surface.•Biofilm-like components including agrin and tetherin were involved in transmission of HTLV-1 toward SGECs.•An electron microscopy confirmed transmission of virions at the interface between HCT-5 cells and SGECs. The initial phase of the human T cell leukemia virus-1 (HTLV-1) infection of salivary gland epithelial cells (SGECs) was examined. SGECs of patients with Sjögren’s syndrome (SS) and non-SS subjects were co-cultured with the HTLV-1-infected cell line HCT-5 or MOLT-4, then immunofluorescence (IF), scanning and transmission electron microscopy (SEM/TEM) were employed. The extracellular matrix and linker proteins galectin-3, agrin, and tetherin were expressed on the surfaces of both HCT-5 and MOLT-4 cells. HTLV-1 Gag-positive spots were observed on adjacent SGECs after 1 h of co-culture with HCT-5. Both in subjects with and those without SS, agrin and tetherin were co-expressed with HTLV-1 Gag on SGECs after co-culture with HCT-5, although no polarization of HTLV-1 Gag and relevant molecules was observed. SEM showed HTLV-1 virions that were found on HCT-5 were observed in the interfaces between HCT-5 cells and SGECs. TEM imaging showed that HTLV-1 virions were transmitted to SGECs at the interface with thin film-like structure, while HTLV-1 virions were released from the surface of HCT-5 cells. No endogenous retroviruses were observed. These results showed that the initial phase of HTLV-1 infection toward SGECs of SS was mediated not by viral synapses, but by biofilm-like components.