Virus-Like Particle: Evolving Meanings in Different Disciplines

Abstract

Virus-like particle (VLP) is a term that has been in use for about 80 years. Usually, VLP has meant a particle that is like a virus, generally by appearance, but without either proven or actual virus functionality. Initially VLP referred to particles seen in electron microscope images of tissues. More recently, VLP has come to mean other things to other researchers. A key divergence has been use of VLP in association with vaccine and biotechnology applications versus use of VLP in enumeration of viruses in environmental samples. To these viral ecologists, a VLP is a particle that is virus sized, has nucleic acid, and could be a functional virus. But to vaccine developers and biotechnology researchers a VLP instead is a viral structure that intentionally lacks a viral genome. In this study, we look at the history of use of VLP, following changes in meaning as the technology to study VLPs changed.

Keywords: direct counts; electron microscopy; environmental virology; medical microbiology; phage ecology; vaccine.

FIG. 1.

Major uses of “VLP.” (A) Viruses and related particles seen in tissue samples by electron microscopy. Micrograph is of Zika virus particles in cells. Arrow indicates a single VLP. Image is adapted from an original image in the CDC Public Health Image Library, image 20487 provided by Cynthia Goldsmith (https://phil.cdc.gov/Details.aspx?pid=20487). (B) Empty virions used for vaccines and biotechnology applications. Image is of Merkel cell polyomavirus VLPs assembled from VP1 and VP2 capsid proteins. Micrograph adapted from an original image by Locusceruleus (https://nl.m.wikipedia.org/wiki/Merkelcelpolyomavirus). (C) Viruses and related particles as seen by epifluorescence microscopy. Image shows both VLPs (smaller fainter spots) and cells (larger brighter spots) collected from lake water, concentrated by filtration and stained with SYBR Gold. Image created and generously provided by Sophie Jurgensen and Jennifer Brum (Louisiana State University, Baton Rouge, LA). VLP, virus-like particle.