Virus particles, computer artwork. The spikes (red-tipped) on the virus particles are surface proteins that help them to attach to cell membranes. Once attached, the virus particles release genetic material into the cell (not seen). 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.