title: Molecular determinants of the ratio of inert to infectious virus particles.
abstract: The ratio of virus particles to infectious units is a classic measurement in virology and ranges widely from several million to below 10 for different viruses. Much evidence suggests a distinction be made between infectious and infecting particles or virions: out of many potentially infectious virions, few infect under regular experimental conditions, largely because of diffusion barriers. Still, some virions are inert from the start; others become defective through decay. And with increasing cell- and molecular-biological knowledge of each step in the replicative cycle for different viruses, it emerges that many processes entail considerable losses of potential viral infectivity. Furthermore, all-or-nothing assumptions about virion infectivity are flawed and should be replaced by descriptions that allow for spectra of infectious propensities. A more realistic understanding of the infectivity of individual virions has both practical and theoretical implications for virus neutralization, vaccine research, antiviral therapy, and the use of viral vectors.
authors.affiliation: Department of Microbiology and Immunology, Weill Cornell Medical College, Cornell University, New York, USA. Electronic address: pek2003@med.cornell.edu.
authors.forename: P J
authors.initials: PJ
authors.lastname: Klasse
mesh_terms: D000818:Animals; D006801:Humans; D008954:Models, Biological; D014771:Virion / Q000235:genetics* / Q000472:pathogenicity*; D014777:Virus Diseases / Q000821:virology*
keywords: Attachment; Defective particles; Endocytosis; Entry; Fusion; Gene therapy; HIV; Infectious unit; Restriction; Transcription; Uncoating; Virion; Viruses