Viral synapse (or virological synapse) is a molecularly organized cellular junction that is similar in some aspects to

immunological synapse In immunology, an immunological synapse (or immune synapse) is the interface between an antigen-presenting cell or target cell and a lymphocyte such as a T/B cell or Natural Killer cell. The interface was originally named after the neuronal syna ...

s. Many viruses including

herpes simplex virus Herpes simplex virus 1 and 2 (HSV-1 and HSV-2), also known by their taxonomical names '' Human alphaherpesvirus 1'' and ''Human alphaherpesvirus 2'', are two members of the human ''Herpesviridae'' family, a set of viruses that produce viral in ...

(HSV),

human immunodeficiency virus The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immun ...

(HIV) and

human T-lymphotropic virus The human T-lymphotropic virus, human T-cell lymphotropic virus, or human T-cell leukemia-lymphoma virus (HTLV) family of viruses are a group of human retroviruses that are known to cause a type of cancer called adult T-cell leukemia/lymphoma and ...

(HTLV) have been shown to instigate the formation of these junctions between the infected ("donor") and uninfected ("target") cell to allow cell-to-cell transmission. As viral synapses allow the virus to spread directly from cell to cell, they also provide a means by which the virus can escape

neutralising antibody A neutralizing antibody (NAb) is an antibody that defends a cell from a pathogen or infectious particle by neutralizing any effect it has biologically. Neutralization renders the particle no longer infectious or pathogenic. Neutralizing antibo ...

Formation and function

Formation of these synapses has been shown to involve reorientation of the

cytoskeleton The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is co ...

, which is triggered by engagement of

ICAM-1 ICAM-1 ( Intercellular Adhesion Molecule 1) also known as CD54 (Cluster of Differentiation 54) is a protein that in humans is encoded by the ''ICAM1'' gene. This gene encodes a cell surface glycoprotein which is typically expressed on endothelial ...

on the infected cell's surface and expression of several viral proteins. Viruses use the microtubule cytoskeleton to migrate to the viral synapse. By recruiting the receptors and viral particles at the point of contact, these synaptic structures significantly enhance the likelihood of a productive infection. Viral synapses are thought to explain how cell-to-cell transfer can operate in the HIV infection even when there is a low number of viral particles and a relatively low number of

CD4 In molecular biology, CD4 (cluster of differentiation 4) is a glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). CD4 is found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic ce ...

receptors. Recent study proposes that the primary “killing units” of CD4 T cells leading to CD4 T-cell depletion and progression to

AIDS Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual ma ...

are infected cells (not cell-free viral particles) residing in lymphoid tissues that mediate cell-to-cell spread of the virus via virological synapses. These findings highlight a previously unappreciated role for the virological synapse in HIV pathogenesis.

References

{{Reflist Virology