Are There 10³¹ Virus Particles on Earth, or More, or Fewer?

Area of Science:

• Environmental microbiology
• Virology
• Ecology

Background:

• The global abundance of virus particles is frequently cited as 10^31.
• This estimate, often lacking a clear source, originates from Hendrix et al. (1999).
• There is ongoing discussion regarding the accuracy and implications of this viral abundance estimate.

Purpose of the Study:

• To trace the origin and derivation of the 10^31 virus particle estimate.
• To evaluate the current validity of the Hendrix et al. estimate using contemporary data.
• To provide an updated perspective on the global number of viruses.

Main Methods:

• Literature review of the historical 10^31 estimate.
• Analysis of recent data on bacterial and viral populations in diverse ecosystems.
• Synthesis of current evidence to reassess global viral abundance.

Main Results:

• The 10^31 estimate for global virus particles is attributed to Hendrix et al. (1999).
• Recent assessments of microbial and viral loads in various environments support the original estimate.
• The number of virus particles on Earth is robustly estimated to be approximately 10^31.

Conclusions:

• The 10^31 estimate, or "the Hendrix product," remains the most reliable figure for global virus abundance.
• Current scientific evidence does not necessitate a significant revision of this estimate.
• The global viral load is a critical factor in ecological processes.