# M13 Virus

M13 is a bacteriophage, a virus that infects bacteria. It consists of a protein capsid containing circular single-strand DNA. The DNA is comprised of 6407 nucleotides. The protein capsid is formed from a couple thousand copies of a 50-amino-acid protein called P8. The size of the wild virus is a cylinder about 1$\mu$ in length and ~10nm in diameter. M13 infects the E. Coli bacteria and is of significant interest and use in research utilizing recombinant DNA and phage displays.