The retrovirus family contains several important human and animal pathogens, including the human immunodeficiency virus (HIV), the causative agent of acquired immunodeficiency syndrome (AIDS). Studies with retroviruses were instrumental to our present understanding of the cellular entry of enveloped viruses in general. For instance, studies with alpharetroviruses defined receptor engagement, as opposed to low pH, as a trigger for the envelope protein‑driven membrane fusion. The insights into the retroviral entry process allowed the generation of a new class of antivirals, entry inhibitors, and these therapeutics are at present used for treatment of HIV/AIDS. In this chapter, we will summarize key concepts established for entry of avian sarcoma and leukosis virus (ASLV), a widely used model system for retroviral entry. We will then review how foamy virus and HIV, primate‑ and human retroviruses, enter target cells, and how the interaction of the viral and cellular factors involved in the cellular entry of these viruses impacts viral tropism, pathogenesis and approaches to therapy and vaccine development.
Enveloped viruses rely on fusion proteins in their envelope to fuse the viral membrane to the host‑cell membrane. This key step in viral entry delivers the viral genome into the cytoplasm for replication. Although class II fusion proteins are genetically and structurally unrelated to class I...
The entry of herpesviruses into their target cells is complex at many levels. Virus entry proceeds by a succession of interactions between viral envelope glycoproteins and molecules on the cell membrane. The process is divided into distinct steps: attachment to the cell surface, interaction...
The family Paramyxoviridae consists of a group of large, enveloped, negative‑sense, single‑stranded RNA viruses and contains many important human and animal pathogens. Molecular and biochemical characterization over the past decade has revealed an extraordinary breadth of biological...
As obligate intracellular parasites, viruses must bind to, and enter, permissive host cells in order to gain access to the cellular machinery that is required for their replication. The very large number of mammalian viruses identified to date is reflected in the fact that almost every human...
Mammalian orthoreoviruses (reoviruses) are members of the Reoviridae. Reoviruses contain 10 double‑stranded (ds) RNA gene segments enclosed in two concentric protein shells, called outer capsid and core. These viruses serve as a versatile experimental system for studies of viral replication...
As a major pathogen of human and certain animal species, influenza virus causes wide spread and potentially devastating disease. To initiate infection, the virus first binds to cellular receptors comprising either ‑(2,3) or ‑(2,6) linked sialic acid. Recent advances in our understanding of...
The essential event in picornavirus entry is the delivery of the RNA genome to the cytoplasm of a target cell, where replication occurs. In the past several years progress has been made in understanding the structural changes in the virion important for uncoating and RNA release. In addition,...
A number of advances in recent years have significantly furthered our understanding of filovirus attachment and cellular tropism. For example, several cell‑surface molecules have been identified as attachment factors with the potential to facilitate the in vivo targeting of particular cell...
The retrovirus family contains several important human and animal pathogens, including the human immunodeficiency virus (HIV), the causative agent of acquired immunodeficiency syndrome (AIDS). Studies with retroviruses were instrumental to our present understanding of the cellular entry of...
Entry is the first step in the infectious life cycle of a virus. In the case of rhabdoviruses, entry is facilitated exclusively by the envelope glycoprotein G and its interactions with the host cell. For vesicular stomatitis virus (VSV), attachment to the cell surface was thought to be...