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Sociovirology

 Sociovirology

The following presentation is based on this paper, which looked at social interactions between viruses and the application of social evolution theory to observed virus behaviour:

Díaz-Muñoz, S. L., Sanjuán, R., & West, S. (2017). Sociovirology: Conflict, Cooperation, and Communication among Viruses. Cell host & microbe, 22(4), 437–441. https://doi.org/10.1016/j.chom.2017.09.012

Sociovirology © 2022 by E. Nomi is licensed under CC BY-NC-SA 4.0

The University of Nomi

February 07, 2024
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  1. Photo: electron micrograph of West Nile virus by Cynthia Goldsmith, USCDCP on Pixnio
    Feb 2022

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  2. Photo: adapted from today.cofc.edu/wp-content/uploads/2019/07
    Preface: Key Concepts in Evolution
    ⁍ “Survival of the fittest”
    ⁍ Natural selection
    determines which genes
    are passed on through the
    generations
    ⁍ Random genetic
    mutations can give rise to
    novel phenotypes

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  3. Red Queen Hypothesis
    Photo: commons.wikimedia.org/wiki/Category:Lotka–Volterra_equations
    Evolution between species driven by predator/prey dynamics1,2
    Photo: © Words & Unwords from zazzle.com

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  4. Black Queen Hypothesis
    ⁍ Theory of reductive evolution1,2
    ⁍ Loss of redundant genes where
    a population’s resources are
    pooled (“public goods”)1,2
    ⁍ Members of population
    experience cost/benefit trade-
    offs
    Photo: plektix.fieldofscience.com

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  5. ⁍ Gene-centered view of evolution3
    ⁍ Fundamental units of natural selection3:
    1. Gene, or “replicator”
    2. Organism, or “vehicle”
    ⁍ Genes act to replicate themselves and
    those most similar3
    The Selfish Gene Theory
    Photo: crickhollowbooks.com.au

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  6. Social Evolution Theory
    ⁍ Originally developed to explain animal behavior
    ⁍ Explains social behavior in terms of evolution4
    ⁍ Can be applied to microorganisms4
    Photo: “Sociobiology: The New Synthesis.” Wilson, Edward O. Cambridge MA: Belknap Press of Harvard University Press, 1975. Accessed from raptisrarebooks.com.

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  7. Social Evolution Theory
    Photo: “Sociobiology: The New Synthesis.” Wilson, Edward O. Cambridge MA: Belknap Press of Harvard University Press, 1975. Accessed from raptisrarebooks.com.
    ⁍ Cooperative traits that benefit others are favored by natural
    selection if they benefit the fitness of the individual performing
    them5.
    ⁍ Cooperative traits cannot evolve merely by providing a
    benefit to a population5.

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  8. ⁍ Microbes are known to
    communicate and coordinate
    behavior5:
    – Quorum sensing
    – Biofilm formation
    – Chemical warfare
    Social Evolution Applied to Microbiology
    Photo: CC BY-NC-SA 3.0 "An electron microscopy image shows an E. coli biofilm" North Dakota State
    University. https://www.ag.ndsu.edu/news/newsreleases/2011/april-25-2011/ndsu-researcher-studies-
    disease-causing-bacteria/an-electron-microscopy-image-shows-an-e.coli-biofilm/view
    E. coli forming a biofilm

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  9. ⁍ Viruses have been observed to interact5:
    – Co-infecting viruses
    – Bacteriophages communicate to
    regulate cell lysis
    ⁍ Behave more in accordance with the
    Selfish Gene Theory
    Social Evolution Applied to Virology​
    ?
    Sociovirology
    T2 phages attached to E. coli cells
    Photo: © Lee D. Simon on pixels.com

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  10. Sociovirology

    ⁍ Socio-” implies:
    – Anthropomorphic
    – Personal motives
    – Political motives
    Photo: vecteezy.com

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  11. ⁍ Socio-” implies:
    – Anthropomorphic
    – Personal motives
    – Political motives
    Sociovirology
    ⁍ Behavior is algorithmic Photo: adapted from youtube.com/watch?v=mpLkNIf-Wxo

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  12. Sociovirology
    ⁍ Arguably, viruses aren’t
    even alive6
    – Replicates only within
    living cells by pirating
    cellular machinery
    – Principal biological
    function is to replicate
    Photo: adapted from youtube.com/watch?v=mpLkNIf-Wxo

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  13. ⁍ Players: Viruses
    ⁍ Goal: self-replication
    ⁍ Challenge: viral gene
    transmission at cost to host
    The “Game”
    Photo: © 2000, American Society for Microbiology

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  14. Photo: electron micrograph of hepatitis by USCDCP on Pixnio
    And now, onto the article

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  15. Definition of an “Individual”
    DNA virus: single infectious
    viral genome.
    Example: adenovirus
    RNA virus: due to high
    mutation rate, consensus
    sequence or “quasispecies.”
    Example: coronavirus
    Coronavirus
    From Figure 2 on pediaa.com/difference-between-dna-and-rna-viruses
    From Figure 5, Mandary et al., 2019 on mdpi.com
    Adenovirus

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  16. Interactions Between Individuals

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  17. (A.) Production of public
    goods through
    transcription/translation
    and sharing of viral
    products needed for
    replication.
    Interactions Between Individuals

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  18. (B.) Blocking the entry
    of other viruses into the
    cell, especially those
    with low genetic
    similarity.
    Interactions Between Individuals

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  19. (C.) Inducing host
    immune changes that
    favor the transmission of
    all viruses.
    Interactions Between Individuals

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  20. (D.) Inducing host cell to
    produce molecules
    essential for viral
    transmission to
    neighboring cells.
    Interactions Between Individuals

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  21. (E.) Communicating cell
    infection status,
    signaling the availability
    of host cells for
    infection.
    Interactions Between Individuals

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  22. (F.) Manipulating host
    immune signals to
    induce distant cells to
    differentially express
    receptors favoring
    entry of some viruses
    over others.
    Interactions Between Individuals

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  23. Social Evolution Framework
    ⁍ Social interactions between viruses occur when the traits of one
    individual influence the fitness of another.
    – Driven by natural selection
    ⁍ Exist on a spectrum:
    Conflict Cooperation

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  24. Conflict
    Occurs more frequently with:
    – Decreasing genetic relatedness
    – Increasing competition
    – Diverging evolutionary interests
    – Greater genetic diversity between viruses
    infecting the same host, also called
    multiplicity of infection (MOI)

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  25. Conflict
    Can lead to emergence of “selfish” behavior
    or “cheats”
    – Optimizes its own fitness in coinfections
    – Contributes few or no public goods
    – Parasitism
    – Reduces average population fitness

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  26. Conflict
    Example of “selfish” behavior in defective
    interfering particles (DIP):
    – Viruses with large deletions in genome
    – Require “helper” viruses to reproduce
    – Act as virus parasites, cause net
    depletion of population’s resources
    – Numbers increase with increasing
    diversity of MOI
    Defective interfering particles of Semliki
    Forest virus (a) vs. standard Semliki Forest
    virus (b)
    Photo: Barrett et al. 1984

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  27. Cooperation
    Occurs more frequently with:
    – Increasing genetic relatedness
    (kin selection)
    – Decreasing competition
    – Shared interests
    – Mutual compensation for genetic
    defects (genetic complementation)

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  28. Cooperation
    Can lead to emergence of “heterotypic
    cooperation”
    – Mutually beneficial cooperation
    between genetically distinct individuals
    – Overall population fitness increases
    with higher incidence of cooperation
    – Found in viruses that act as co-
    infections, such as influenza viruses

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  29. Cooperation
    Example of heterotypic cooperation in
    influenza viruses:
    – One strain has a more efficient
    hemagglutinin (cell adhesion)
    – Another has a more efficient
    neuraminidase (release of virions)
    H1N1 influenza virus
    Photo: Micrograph of H1N1 by CDC from cbc.ca

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  30. The Problem of Cooperation
    = Cooperator. Individual performing cooperative action.
    = Selfish cheater. Does not perform cooperative action.

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  31. The Problem of Cooperation
    ⁍ A selfish cheater arises in a population through mutation or coinfection.
    ⁍ Benefits from cooperative behavior of cooperators without contributing.

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  32. The Problem of Cooperation
    ⁍ The selfish cheater increases frequency in subsequent generations.
    ⁍ The result is a reduction of average population fitness.

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  33. Testing Social Interactions Using Social Evolution Theory
    ⁍ Strains made to compete in isolation and in combination to quantify
    fitness and confirm social traits.

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  34. Testing Social Interactions Using Social Evolution Theory
    ⁍ When grown as a single infection, a population of cooperators
    observed to achieve higher growth than a population of cheaters.

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  35. Testing Social Interactions Using Social Evolution Theory
    ⁍ In coinfection, population growth observed to be lower than a
    homogeneous population of cooperators.

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  36. Testing Social Interactions Using Social Evolution Theory
    ⁍ Cheater constituents within the coinfection population initially
    increase growth by exploiting the cooperator constituents; in time
    growth stalls as the population is dominated by cheaters.
    Constituent
    population of
    cheaters
    Constituent
    population of
    cooperators

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  37. Conclusions
    ⁍ Viruses are observed to have social interactions that can be understood
    using social evolution theory
    ⁍ Targeting virus-virus interactions can lead to new treatment strategies
    – Attenuated vaccines of DIPs could increase cheating behaviors and reduce
    fitness of virus populations
    – Epidemiologists could consider the population fitness effects of “cheating”
    to predict the best strategies for limiting transmission of infectious viruses
    – Knowledge of bacteriophage interactions could improve phage therapy

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  38. References
    1. Morris, J. J., Lenski, R. E., & Zinser, E. R. (2012). The Black Queen Hypothesis: evolution of dependencies through adaptive gene
    loss. mBio, 3(2), e00036-12. https://doi.org/10.1128/mBio.00036-12
    2. Mas, A., Jamshidi, S., Lagadeuc, Y., Eveillard, D., & Vandenkoornhuyse, P. (2016). Beyond the Black Queen Hypothesis. The ISME
    journal, 10(9), 2085–2091. https://doi.org/10.1038/ismej.2016.22
    3. Dawkins, R. (2006). The Selfish Gene. Oxford University Press.
    4. West, S., Griffin, A., Gardner, A., Diggle, S. P. (2006). Social evolution theory for microorganisms. Nat Rev Microbiol, 4, 597–607.
    https://doi.org/10.1038/nrmicro1461
    5. Díaz-Muñoz, S. L., Sanjuán, R., & West, S. (2017). Sociovirology: Conflict, Cooperation, and Communication among Viruses. Cell host
    & microbe, 22(4), 437–441. https://doi.org/10.1016/j.chom.2017.09.012
    6. Koonin, E. V. & Starokadomskyy, P. (2016). Are viruses alive? The replicator paradigm sheds decisive light on an old but misguided
    question. Stud Hist Philos Biol Biomed Sci, 59, 125-34. https://doi.org/10.1016/j.shpsc.2016.02.016

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