20 - 60 atm
||Weitz, Joshua S. Quantitative Viral Ecology, Dynamics of Viruses and Their Microbial Hosts, Princeton University press, Chapter two. Viral Life History Traits p.26 2nd paragraph
||Ivanovska, I., Wuite, G., Jönsson, B., and Evilevitch, A. (2007). Internal DNA pressure modifies stability of WT phage. Proceedings of the National Academy of Sciences of the United States of America , 104: 9603–9608. DOI: 10.1073/pnas.0703166104PubMed ID17535894
||P.26 2nd paragraph: "Following successful adsorption, the virus genetic material, either DNA or RNA, enters the host. For phage, the genetic material is injected as a result of biophysical and biochemical processes. Viral heads are pressurized for example, the internal pressure exerted by the phage λ genome on its capsid is estimated to vary between 20 and 60 atm (primary source). Internal pressures inside capsids are higher than that of the bacterial cytoplasm, estimated to vary from a few atmospheres to approximately 10 atm (BNID 113062). The pressure in a virus head represents the end results of packaging, with the aid of a “packaging force” (Inamdar et al. 2006)."