Pseudovirions

Pseudovirions are non-infectious viral particles that resemble authentic virions in their physical structure but lack the genetic material necessary for replication. They can be formed during viral replication when a host cell packages a cellular RNA or a foreign RNA into a viral capsid instead of the viral genome. This process can occur spontaneously or be induced by specific conditions.

The formation of pseudovirions is a consequence of the complex mechanisms that govern viral genome packaging. Viral capsids, the protein shells that enclose the genetic material, have specific recognition sites that bind to the viral genome. However, under certain circumstances, these recognition sites can also bind to other nucleic acid molecules present in the cell. When this happens, the cellular or foreign RNA is mistakenly incorporated into the capsid, leading to the production of a pseudovirion.

Despite being non-infectious, pseudovirions can still interact with host cells. They can bind to cell surface receptors, potentially triggering cellular responses or interfering with the entry of authentic viruses. In some cases, they may be taken up by cells through endocytosis. Their presence can also elicit immune responses, as the viral capsid proteins are recognized as foreign. The study of pseudovirions is important for understanding viral assembly and for developing strategies to combat viral infections, such as using them as decoys to distract the immune system or as platforms for gene delivery.