Watch the animation on the left side of the screen to see how different viral strains can be generated by a process called subunit reassortment. The animation was adapted from a demonstration developed by HHMI investigator Donald E. Ganem, M.D., for the HHMI's 1999 Holiday Lectures on Science, 2000 and Beyond: Confronting the Microbe Menace.

To view the animation, use the controls at the bottom of the view screen. Expect several pauses as each section of the animation loads and the text in this panel updates to describe the relevant step in the animation.

Part 1: Introduction

Reassortment is the exchange of entire RNA segments, also called subunits, between genetically related viruses. This animation depicts a single human cell infected concurrently with two strains of influenza virus. Once inside the cell the eight RNA subunits of each virus replicate to produce additional RNA subunits. Different combinations of the RNA segments generated from each parental virus are incorporated into progeny viruses. Click on "Play" to start the animation.