Quantitative 3D video microscopy of HIV transfer across T cell virological synapses

Area of Science:

• Virology
• Immunology
• Cell Biology

Background:

• Cell-cell adhesions, known as virological synapses, significantly enhance human immunodeficiency virus (HIV) spread between immune cells.
• The precise mechanisms driving this enhanced viral dissemination have remained largely unclear.

Purpose of the Study:

• To elucidate the mechanisms by which HIV utilizes virological synapses for efficient cell-to-cell transmission.
• To visualize and characterize the dynamics of HIV Gag protein during viral transfer across synapses.

Main Methods:

• Utilized an infectious, fluorescent clone of HIV for live imaging of Gag protein movement in CD4 T cells.
• Employed quantitative, high-speed three-dimensional (3D) video microscopy to capture viral translocation events.
• Applied electron microscopy to examine the ultrastructure of viral particles at the virological synapse.

Main Results:

• Observed the direct translocation of HIV across the virological synapse.
• Identified the rapid formation of micrometer-sized
• buttons
• composed of oligomerized viral Gag protein.
• Found these Gag
• buttons
• were densely packed with budding viral crescents and facilitated virus-laden internal compartment formation within target cells.
• Demonstrated preferential infection occurred through these synapses via viral endocytosis.

Conclusions:

• HIV dissemination is significantly enhanced by virological synapse-mediated cell adhesion.
• Viral transfer involves the formation of Gag-rich structures that facilitate endocytosis and subsequent infection of target cells.
• Understanding these mechanisms provides insights into HIV pathogenesis and potential therapeutic targets.