Firstly, an infected T cell can transmit virus directly to a target T cell via a virological synapse. Secondly, an antigen-presenting cell (APC), such as a macrophage or dendritic cell, can transmit HIV to T cells by a process that either involves productive infection (in the case of macrophages) or capture and transfer of virions in trans (in the case of dendritic cells). Whichever pathway is used, infection by cell-to-cell transfer is reported to be much more efficient than cell-free virus spread. A number of factors contribute to this increased efficiency, including polarised virus budding towards the site of cell-to-cell contact, close apposition of cells, which minimizes fluid-phase diffusion of virions, and clustering of HIV entry receptors on the target cell towards the contact zone. Cell-to-cell spread is thought to be particularly important in lymphoid tissues, where CD4+ T cells are densely packed and likely to interact frequently. Intravital imaging studies have supported the concept of the HIV virological synapse in vivo. The many dissemination mechanisms available to HIV contribute to the viruss ongoing replication in spite of anti-retroviral therapies. Genetic variability
HIV differs from many viruses in that it has very high genetic variability.
See also
Nasal septum deviation

References
Different surgical treatments for nasal septal perforation and their outcomes
Septal Perforation Closure Utilizing the External Septorhinoplasty Approach
A Review of 25-Year Experience of Nasal Septal Perforation Repair


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