O custo energético na "construção" de um vírus

sábado, maio 27, 2017

Energetic cost of building a virus

Gita Mahmoudabadia, Ron Milob, and Rob Phillipsa,c,1

Author Affiliations

aDepartment of Bioengineering, California Institute of Technology, Pasadena, CA 91125;

bDepartment of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel;

cDepartment of Applied Physics, California Institute of Technology, Pasadena, CA 91125

Edited by Ned S. Wingreen, Princeton University, Princeton, NJ, and accepted by Editorial Board Member Curtis G. Callan Jr. April 19, 2017 (received for review January 30, 2017)"


Human hepegivirus 1 has parts of both hepatitis C virus (above) and human pegivirus.


Viruses rely entirely on their host as an energy source. Despite numerous experimental studies that demonstrate the capability of viruses to rewire and undermine their host’s metabolism, we still largely lack a quantitative understanding of an infection’s energetics. However, the energetics of a viral infection is at the center of broader evolutionary and physical questions in virology. By enumerating the energetic costs of different viral processes, we open the door to quantitative predictions about viral evolution. For example, we predict that, for the majority of viruses, translation will serve as the dominant cost of building a virus, and that selection, rather than drift, will govern the fate of new genetic elements within viral genomes.


Viruses are incapable of autonomous energy production. Although many experimental studies make it clear that viruses are parasitic entities that hijack the molecular resources of the host, a detailed estimate for the energetic cost of viral synthesis is largely lacking. To quantify the energetic cost of viruses to their hosts, we enumerated the costs associated with two very distinct but representative DNA and RNA viruses, namely, T4 and influenza. We found that, for these viruses, translation of viral proteins is the most energetically expensive process. Interestingly, the costs of building a T4 phage and a single influenza virus are nearly the same. Due to influenza’s higher burst size, however, the overall cost of a T4 phage infection is only 2–3% of the cost of an influenza infection. The costs of these infections relative to their host’s estimated energy budget during the infection reveal that a T4 infection consumes about a third of its host’s energy budget, whereas an influenza infection consumes only ≈ 1%. Building on our estimates for T4, we show how the energetic costs of double-stranded DNA phages scale with the capsid size, revealing that the dominant cost of building a virus can switch from translation to genome replication above a critical size. Last, using our predictions for the energetic cost of viruses, we provide estimates for the strengths of selection and genetic drift acting on newly incorporated genetic elements in viral genomes, under conditions of energy limitation.

viral energetics viral evolution T4 influenza cellular energetics


1To whom correspondence should be addressed. Email: phillips@pboc.caltech.edu.

Author contributions: G.M., R.M., and R.P. designed research, performed research, analyzed data, and wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission. N.S.W. is a guest editor invited by the Editorial Board.

This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1701670114/-/DCSupplemental.

Freely available online through the PNAS open access option.