When a virus infects a cell, it hijacks resources of the cell to manufacture and release a new generation of progeny virus particles. Yet despite its central importance, methods to precisely quantify virus production at the cellular level are lacking. Most approaches measure the production of virus by sampling from a population of infected cells, providing average values that mask the potentially wide-ranging and significant behaviors of individual cells.
Within a laboratory culture of virus-infected cells, or within a tissue of an infected host, individual cells can diverge in behavior from the average or majority of infected cells. However, these rare cells may nevertheless contribute importantly to the long-term behavior of the infection, well beyond their initial encounter with the virus. Because these rare cell behaviors are generally obscured during average-cell measures of infection, they highlight the need for single-cell measures of behavior that can be readily performed on many individual cells to reveal the extent of cell heterogeneity. This paper demonstrates a method to measure the kinetics of virus production from individual cells, without confounding effects from secondary infections. The method combines a series of simple steps that can be performed in any cell biology or virology facility, without reliance on specialized equipment.
Kinetics of virus production from single cells. Virology. 03 Jan 2012
The production of virus by infected cells is an essential process for the spread and persistence of viral diseases, the effectiveness of live-viral vaccines, and the manufacture of viruses for diverse applications. Yet despite its importance, methods to precisely measure virus production from cells are lacking. Most methods test infected-cell populations, masking how individual cells behave. Here we measured the kinetics of virus production from single cells. We combined simple steps of liquid-phase infection, serial dilution, centrifugation, and harvesting, without specialized equipment, to track the production of virus particles from BHK cells infected with vesicular stomatitis virus. Remarkably, cell-to-cell differences in latent times to virus release were within a factor of two, while production rates and virus yield spanned over 300-fold, highlighting an extreme diversity in virus production for cells from the same population. These findings have fundamental and technological implications for health and disease.