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Objectives HTLV-1 transmission from mother to child predominantly occurs by prolonged breastfeeding. However, breast milk is known to protect against many other types of infection. In this study, we asked whether breast milk fractions also impact HTLV-1 cell-to-cell transmission. Methods Co-culture experiments between fluorescently-labelled acceptor cells (+/- breast milk fractions) and chronically HTLV-1-infected cells, followed by flow cytometry; Gag p19 ELISA; virological PCR diagnostics of breast milk samples. Results To test whether breast milk impacts HTLV-1 cell-to-cell transmission, breast milk specimens from healthy donors negative for milkborne viruses (HTLV-1, HIV-1, HCMV) were separated into the fat, skim milk and cell fractions. While pre-incubation of acceptor Jurkat T-cells with the cell fraction did not impair HTLV-1 cell-to-cell transfer from chronically infected C91/PL cells, skim milk significantly reduced HTLV-1 cell-to-cell transmission. This step was temperature sensitive since skim milk subjected to holder pasteurization (62°C, 30 min) lost its antiviral activity while skim milk pretreated at 37° C or -20 °C was antiviral. When skim milk was spiked with chronically HTLV-1-infected C91/PL cells, a similar impairment of HTLV-1 cell-to-cell transmission could be observed. Pre-incubation of acceptor Jurkat T-cells with several commercially available formula milk powders including pre-milk (PRE), follow on milk (1), and advanced follow on milk (2) also impaired HTLV-1 cell-to-cell transmission, albeit at lower levels than skim milk from human breast milk. Shedding light on the mechanism, we found that skim milk significantly enhanced the release of HTLV-1 Gag p19 into the supernatant of chronically-infected C91/PL cells, providing a potential explanation for impaired HTLV-1 cell-to-cell transmission, which is strictly dependent on cell-associated virus. Conclusion Although HTLV-1 is transmitted via this route, skim milk contains antiviral properties impairing HTLV-1 cell-to-cell transfer, providing a promising starting point to develop milk-derived antivirals. [ABSTRACT FROM AUTHOR]

Objectives The HTLV-1 accessory protein p8 is a plasma membrane-resident protein that induces cellular protrusions through which both p8 and HTLV-1 are transferred to target cells, thereby increasing viral persistence and infectivity. To date, p8-transfer is poorly understood and little is known about immune cell populations susceptible to p8-transfer. Methods To quantitate p8-transfer, we recently established a flow cytometry-based co-culture assay between transiently transfected p8-expressing donor cells and fluorescently labelled acceptor cells. To improve understanding of p8-transfer we synthesized fluorescein-labelled peptides of full-length p8. Results Here we report that p8-transfer significantly increased with the frequency of p8-positive donor cells, while enhancing p8 expression in those cells did not increase p8-transfer. Hence, this suggests that the number of cell-cell contacts is more important than p8 expression levels for efficient transfer. Furthermore, we found that p8 was transferred to various T- and B-cell lines including Jurkat, Molt-4, Raji, and Bjab cells and to primary human CD4+ and CD8+ T-cells within one hour of co-culture. Use of synthetic p8 peptides indicated that both Jurkat T-cells and 293T cells take up synthetic p8 at high frequencies reaching up to 90 % peptide-positive cells. p8 peptide expression was stable over five days without affecting cell viability. More importantly, p8 peptides were also transferred between Jurkat T-cells at frequencies comparable to previous findings using p8 expression plasmids. Current assays analyse whether p8 is transferred to other immune cell populations such as monocytes, macrophages or NK cells to strengthen the hypothesis that p8 indeed hampers immune responses towards HTLV-1-infected CD4+ T-cells, thus promoting viral persistence. Conclusion This study is the first to broadly characterize the conditions of p8-transfer, therefore allowing the identification of susceptible immune cell populations. Moreover, synthetic p8 peptides are a suitable tool to monitor p8-transfer between cells. [ABSTRACT FROM AUTHOR]

Abstract  Computational simulation techniques have been extensively used to investigate physical phenomena in semiconductor devices with similar techniques utilized for the study of their competitors, ionic devices [1]. This paper is focusing on models based on the physics of carrier transport referring also shortly to equivalent circuit models, a much celebrated tool in the area of ionics. [ABSTRACT FROM AUTHOR]

Abstract  A computer model is used to study charge transport in ionic materials upon the application of an electrochemical potential gradient. The model incorporates both the diffusion and drift mechanisms, permitting the evaluation of the contribution of each mechanism. Each mechanism is shown to be dominant depending on the material parameters and the experimental conditions. The results obtained are compatible with experimental and theoretical ones as reported in the literature, suggesting that in several cases studying the transport of mobile species in ionic materials upon the application of an electrochemical potential gradient, the existence of an internal field cannot be ignored. [ABSTRACT FROM AUTHOR]