virion numbers

The number of virus particles on Earth is frequently reported in the scientific literature and in general-interest publications as being on the order of 10³¹, with some confusion about whether this is a high or low estimate. This number is often given without a source, although it should be attributed to a paper by Hendrix et al. published in 1999 (R. W. Hendrix, M. C. Smith, R. N. Burns, M. E. Ford, and G. F. Hatfull, Proc...