This animation shows how influenza viruses can combine their genetic information to produce new viral strains.

When two different strains of a virus infect the same host cell, their genetic material can mix and produce a new, recombinant strain. The animation illustrates an example of this process using the influenza virus. Many influenza strains originate in birds and do not reproduce well in humans. However, avian strains can recombine with strains from other species to create new strains that infect humans.

This animation is a clip from a 1999 Holiday Lecture Series, 2000 and Beyond: Confronting the Microbe Menace. Depending on students’ background, it may be helpful to pause the animation at various points to discuss different parts of the recombination process.