The elemental composition of virus particles: implications for marine biogeochemical cycles

Virus-mediated lysis of host cells results in the generation of dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) via a process that is known as the 'viral shunt'.Previous quantitative estimates of the contribution of the viral shunt to biogeochemical cycles focused on host cellular constituents and overlooked the contribution of virus particles.In this Analysis article, we develop a biophysical scaling model that predicts the elemental contents and compositions of virus particles.This scaling model was validated using detailed sequence and structural contents of intact bacteriophage particles.Viruses are predicted to be enriched in phosphorus, so much so that the total phosphorus content in a burst of released viruses may approach that of the phosphorus content in an uninfected host.As a consequence, cellular debris may be depleted in phosphorus compared with the stoichiometry of hosts.Furthermore, by extrapolating the model to the ecosystem scale, marine viruses are predicted to contain an important fraction (for example, >5%) of the total DOP pool in some systems (for example, in surface waters, when virus density exceeds 3.5 × 1010 and the DOP concentration is approximately 100 nM).