Читать книгу Principles of Virology - Jane Flint, S. Jane Flint - Страница 228

Virus particle attachment to certain cell surface proteins may not mediate entry into that particular cell but might facilitate dissemination within a host. An example is the lectin DC-SIGN (dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin), a tetrameric lectin present on the surface of dendritic cells (Fig. 5.3). This lectin binds high-mannose, N-linked glycans, such as those produced in insect cells. Viruses that reproduce in insects are delivered to the human skin via a bite and may bind and sometimes infect dendritic cells. These cells then carry the viruses to other parts of the body, particularly lymph nodes. However, not all viruses that bind DC-SIGN replicate in insect cells. In humans, DC-SIGN on the surface of dendritic cells binds human immunodeficiency virus type 1 virus particles, but cell entry does not take place. In cells in culture, dendritic cells can store and release infectious virus. Therefore, while the interaction of human immunodeficiency virus type 1 with DC-SIGN is nonproductive, it may lead to viral dissemination in the host when dendritic cells migrate to lymph nodes rich in the virus target, CD4⁺ T cells (see Chapter 13).

Figure 5.9 Multiple receptors for herpes simplex virus 1 (HSV-1). Six (of 15) viral surface glycoproteins are shown, four of which are essential for entry. Initial attachment to HSPG (heparan sulfate glycosaminoglycans) is mediated by gC and gB. gD engages the main receptor, which can be either nectin-1, HVEM (herpesvirus entry mediator), or 3-OS-HS (3-O-sulfated heparan sulfate). Subsequently, gD binds the gH/gI heterodimer, which then activates gB to mediate fusion. The entry route can differ depending on the cell. For example, the gK protein enables fusion at the plasma membrane of neurons.