Virus-induced aggregates in infected cells

Abstract

During infection, many viruses induce cellular remodeling, resulting in the formation of insoluble aggregates/inclusions, usually containing viral structural proteins. Identification of aggregates has become a useful diagnostic tool for certain viral infections. There is wide variety of viral aggregates, which differ by their location, size, content and putative function. The role of aggregation in the context of a specific virus is often poorly understood, especially in the case of plant viruses. The aggregates are utilized by viruses to house a large complex of proteins of both viral and host origin to promote virus replication, translation, intra- and intercellular transportation. Aggregated structures may protect viral functional complexes from the cellular degradation machinery. Alternatively, the activation of host defense mechanisms may involve sequestration of virus components in aggregates, followed by their neutralization as toxic for the host cell. The diversity of virus-induced aggregates in mammalian and plant cells is the subject of this review.

Figure 1

Cellular targets of viral infection induced aggregation. The scheme represents the different types of virus-induced aggregates discussed in the current review, as well as their cellular localization. Typical examples for each type are presented.

Figure 2

Localization of coat protein (CP) in cross-sections of midribs of infected leaves from susceptible tomatoes. A primary anti-CP antibody and Cy3-labeled secondary antibody (appears as red) were used for fluorescence microscopy. Nuclei are DAPI stained and appear as blue. CP localized in nuclei appears as pink (arrows). Inserts: composite image of fluorescent and transmission microscope settings, e: epidermis, p: phloem, pm: palisade mesophyll, sm: spongy mesophyll, x: xylem. CP associated fluorescence 14 (early), 28 (middle), and 49 (late) days after inoculation (dpi). Bars: 100 µm (upper panel) and 100, 200 µm (lower panel).