Virus particles (green) entering cells, computer artwork. The cell nuclei (dark blue) are also seen. The spikes on the virus particles are surface proteins that help them to attach to the cell membranes. Once in the cell the viral genetic material is released. This travels to the cell nucleus where it combines with the cell's genetic material. The cell then reads the genetic instructions and the cell's biochemical mechanisms build new virus particles. These new virus particles erupt from the cell, killing it. The viral infection spreads as the cycle repeats.