Visualization of HIV virus dynamics in cells with dual fluorescence

Two latent patterns identified by HIV-Tocky. Due to the four-hour maturation half-life of the blue-red chromophore of the Timer protein, we can detect reactivated or recently silenced proviruses using Timer fluorescence with high sensitivity. HIV-Tocky has identified two latent patterns: direct latency and late latency, which initially has transient expression. Image credit: Communication biology (2024). DOI: 10.1038/s42003-024-06025-8

Researchers at Kumamoto University have developed a novel viral reporter system called HIV-Tocky (Timer of Cell Kinetics and Activity). This innovative system enables real-time visualization of HIV dynamics after viral infection.

HIV-Tocky utilizes fluorescent timer protein technology and features dual fluorescence that changes from blue to red to illuminate the process of provirus silencing and reactivation. This improved temporal resolution exceeds that of conventional green fluorescent protein (GFP) systems, providing important insights into HIV-1 latency mechanisms and providing a basis for developing eradication strategies.

The study was published in Communication biology.

The major challenge with the current standard HIV-1 cure strategy of combined antiretroviral therapy (cART) is that although cART can inhibit reverse transcription, it cannot completely eradicate virus-infected cells. Some infected cells contain HIV-1 proviruses that remain latent and can evade the host immune system. If cART is interrupted, the provirus can reactivate under certain conditions, leading to the production of progeny virions and potentially a recurrence of infection.

“Understanding the dynamic transition of the HIV-1 provirus to latency is crucial for developing eradication strategies. For this reason, we developed HIV-Tocky to analyze these temporal dynamics in vivo,” said lead author Yorifumi Satou, a professor at the Joint Research Center for Human Retrovirus Infection, Kumamoto University.

By synchronizing the change in the emission spectrum of the fluorescent timer protein with provirus expression, HIV-Tocky enables precise tracking of the temporal dynamics of the provirus from expression to silencing. This unique feature, with its highly sensitive fluorescence shift from blue to red, enables for the first time the identification of two latent patterns: an immediate latency and a later latency that initially shows transient expression.

Further analysis of the integration sites revealed that these two latency patterns are governed by different regulatory determinants, with the former being more stochastic and the latter more epigenetically controlled, providing further clues to the molecular mechanism of provirus silencing and expression.

Overall, HIV-Tocky is a novel tool that captures the kinetics of provirus silencing, which was not previously possible with GFP. It enables the analysis of the complex nature of HIV-1 latency by visualizing the real-time dynamics of provirus expression. The study also demonstrated its potential for drug screening, particularly for the evaluation of latency-promoting agents (LPAs).

Dr. Satou noted that the next challenge will be to apply HIV-Tocky in primary myeloid and lymphoid cells, which could provide further information on latency dynamics and determinants in different tissues and anatomical reservoirs.

More information:
Omnia Reda et al, HIV-Tocky system for visualizing proviral expression dynamics, Communication biology (2024). DOI: 10.1038/s42003-024-06025-8

Provided by Kumamoto University

Quote: New HIV reporter model: Visualizing HIV viral dynamics in cells with dual fluorescence (2024, June 7), accessed June 7, 2024 from

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