INVENTING THE NATURE OF VIRUSES

When faced with contradictory evidence, simply reinvent the concept in order to suit the present needs. 🤷‍♂️

For the greater part of the first 50 years of the 20th century, there was no agreed upon definition for what the invisible entities labelled as a “virus” actually were nor how these agents looked, formed and functioned. Some researchers believed that these entities were endogenous processes produced within the host while others envisioned them as exogenous invaders that came from outside and attacked from within. There were arguments over whether “viruses” were corpuscular in nature or whether they were a soluble liquid. Debates centered around whether these agents were alive or if they were simply inanimate and non-living. While there were researchers who believed “viruses” were a ferment or a chemical molecule of some kind, the majority believed that these invisible entities were just smaller unseen bacterium. According to biochemist and historian of science Ton van Helvoort's 1996 paper When Did Virology Start?, the “virus” concept lacked clarity and certainty over the first half of the 20th century. However, the link between bacteriology and “viruses” was so strong at this time that these unseen entities were not considered conceptually distinct from bacteria:

“I have come to believe that, despite its widespread appearance in textbooks and journals of that era, the early concept of the “filterable virus” lacked clarity and certainty. More importantly, I also believe that during the 1930s and 194Os, the links between the study of filterable viruses and bacteriology were so strong that viruses were still considered merely another form of bacteria-not conceptually distinct, as they now are.”

The reason for these many contradictory ideas about the nature of the “virus” was a direct result of the fact that the researchers never had a physical entity on hand in order to study. The “virus” was nothing more than a fluid concept that was open to the interpretation of those who claimed to be working with them. Most of these researchers came from a bacteriological or chemistry background, and thus, they viewed the “virus” concept through their own lens and paradigms. Regardless, there was no way to actually determine the true nature of something that could not be seen or studied in reality and that only existed within the realm of the imagination.

Thus, it shouldn't be hard to understand why virologists often have a difficult time answering simple questions such as “What is a virus?” or “Is it alive or dead?” This is exactly the argument made in the appropriately titled 2014 article Inventing Viruses by William Summers, a retired Professor of Therapeutic Radiology, Molecular Biophysics & Biochemistry, and History of Medicine. While being able to define what a “virus” is should be an easy task for any virologist, simple questions about the nature of a “virus” are not ones that are simple for them to answer. In the opening of his paper, Summers asked a more subtle question about the invention of the “virus” category:

“…how generations of microbiologists arrived at the idea that some of the entities they dealt with fell into a category that differed in fundamental ways from others. In other words, how did they invent the category of “virus” as we now know it?”

Summers looked to investigate how the idea that “viruses” are a separate entity that requires its own category away from bacteriology came to be. In doing so, he admitted that our beliefs, understandings, and conceptions of what a “virus” is changes over time. This is because “viruses” are whatever a virologist tells us that they are. The concept and the nature of the “virus” was invented, and continually reinvented, by virologists as part of the normal progress of their (pseudo) science. In other words, the idea of the “virus” is able to change at any time based upon whatever a virologist wants a “virus” to be at any given moment:

“Even so, how did the category “virus” come to be recognized, and what are its essential, defining qualities? Viruses are natural objects, but our beliefs, understanding, and conceptions of them change over time on the basis of new information, new points of view, and new scientific values and standards. In a very real way, a virus is what virologists say it is. It is a product of the way virologists talk about viruses—that is, the way facts about viruses are organized in their discourse. It can be said that virologists invent (and continually reinvent) the concept of a virus as part of the normal progress of their science.”

The deliberate ever-changing concept of the “virus” shifted away from its original invention as an agent of disease transmission to its modern day concept as a genetic assembly that sometimes causes disease when it integrates into its host in order to survive. This reinvention of the concept happened in 1957 when French microbiologist Andre Lwoff took many competing and contradictory ideas and mashed them together into the modern definition of a “virus” based upon work done with bacteriophages. Prior to his reinvention of the concept, in 1953, Lwoff actually questioned whether a bacteriophage was a “virus” and wanted to know exactly what a “virus” was. He even noted that “viruses” are defined to be exogenous (coming from outside of the body) while bacteriophages are “always formed inside its host” and “could therefore be described as endogenous,” i.e. originating from within the host. In fact, Lwoff stated that “if prophage is phylogenetically endogenous, the temperate phage produced by a lysogenic bacterium must be described as endogenous,” meaning that the phage is from within the host, thus negating it as an exogenous entity in line with the definition of a “virus.” Ironically, after redefining the “virus” as a genetic code in 1957, Lwoff would ultimately warn in 1991 that virology was “in danger of losing its soul, since viruses now show a strong tendency to become sequences.” He also argued that the abundance of discoveries was causing “the very concept of virus” to waver “on its foundations,” noting that the “problem today and in future is to keep abreast of its whereabouts.”

Regardless, Summers stated that his paper was not about the “triumphant accumulation of knowledge by the heroic scientists” of the past. Rather, it was an examination of the “continual struggle to understand and organize observations.” This struggle was showcased by Lwoff's own attempts to rationalize and combine contradictory evidence in order to create the modern genetic concept of the “virus” from an entity that did not meet the necessary requirements:

“Nobelist Andre Lwoff, perhaps in a Gertrude Stein frame of mind, famously answered “viruses are viruses” (9), but the question “What is virus?” has been notoriously fraught since the role of virus in late nineteenth-century germ theories became central to medicine, and later, in the midtwentieth-century, to biology in general. The evolution, or perhaps deliberate and continuous reformulation, of the meaning of “virus” from an agent of disease transmission in the nineteenth century to a molecular assembly with remarkable properties by the end of the twentieth century is the subject of this article. This is not a story of the triumphant accumulation of knowledge by the heroic scientists of the past so much as it is an examination of the continual struggle to understand and organize observations that challenged and made obsolete the comfortable certainties of the often recent past. This examination requires consideration of past science on its own terms, without judgment in light of present-day understanding, and it requires consideration of the context and extent of background knowledge of the particular period considered.”

This struggle to answer the question “What is a virus?” was ongoing, even in the so-called “modern age” of virology. There was no consensus as to the true nature of a “virus.” Summers shared a quote by Joseph Beard that stated that the “virus” was a fabric of concepts that had been “woven of a plethora of woof and a paucity of warp.” In weaving terms, this makes for an unstable foundation upon which to weave. Another example was of plant virologist N.W. Pirie who was considered “agnostic” (impossible to know one way or the other) on whether a “virus” was a molecule or a microbe. However, he seemed to argue that the variability in the chemical composition of the same “virus” went against the modern molecular hypothesis. Thus, we can see that there was no agreement on the nature of the “virus:”

The construction of the virus as a living molecule in the middle decades of the twentieth century generated wide debate as to the correct answer to the question, “What is a virus?” Having rejected filterability, negative growth properties, and size as defining characteristics, microbiologists searched for new ways to think about viruses. Even at the beginning of what might be called the modern era, there was remarkably little consensus on this subject. Joseph Beard, in 1945, famously remarked, “Viruses are said to be living molecules and autocatalytic enzymes and are likened to genes and mitochondria—in short, a fabric of concepts has been woven of a plethora of woof with a paucity of warp” (quoted in 47, p. 332). N.W. Pirie, one of the pioneers in the study of plant viruses, even in 1949 was agnostic as to whether viruses were microbes or molecules. In a long review of the problem in the British Medical Bulletin (47), he argued that the variation in chemical composition reported for the same virus suggested a level of heterogeneity not compatible with the molecular hypothesis. He noted that “all the viruses purified so far have contained nucleoprotein, but this generalization may lack significance because the viruses that have been studied are a group selected to some extent on a chemical basis.”

Summers ultimately concluded that each generation of virologists will look at “viruses” in their own way and will alter the concept of the “virus” based upon the “science” of the time. Thus, the “virus” is left to be a concept that is allowed to be continually reinvented at the whims of the researchers:

“Although “viruses are viruses,” each generation of scientists looks anew at these fascinating entities in its own way, endowing them with properties, relationships, and capacities that reflect the science of the time. Truly, they are microbes being continually reinvented by their most ardent admirers.”

In his summary, Summers laid out 5 very revealing points to end his paper on. Sharing similar sentiments as van Helvoort, he stated that the “virus” concept is an unstable one that “evolved,” not due to an accumulation of facts, but rather due to an ongoing reformulation of the “virus” concept on the basis of “scientific” focus at a given time. This reinvention was determined by technological advances rather than scientific understanding. Thus, the answer as to what a “virus” is will depend upon the discourse at the time moreso than the “known” characteristics of “viruses:”

The concept of a virus has not been stable and has evolved since its introduction in the latter half of the nineteenth century.

This evolution has been not a linear accumulation of facts but rather an ongoing reformulation of the virus concept on the basis of scientific focus at a given time, e.g., growth, metabolism, chemical composition, genetics, or physical structure.

The concept of a virus has particularly been determined by technological advances rather

than scientific understanding.

The answer to the question “What is a virus?” is one that depends on the particular scientific discourse at a given time.

The discourse with respect to the physical object “virus” is based on the particular concerns and problems of interest at a given time more than on any one set of intrinsic characteristics known about viruses.

Why is it so difficult for virologists to simply explain basic questions about a “virus” such as whether the “virus” is living or dead? Why must the concept of what a “virus” is change depending upon the researchers and technology of the time? What physical organism changes in concept after over a century of supposed study? The answer to all of these questions is actually fairly easy to grasp. As the researchers have never actually had any physical entities on hand in order to study, the concept of what the assumed invisible entities are was allowed to constantly change in order to suit the needs and evidence of the researchers of the time. There was no solid foundation for virology to stand upon from the very beginning in order to definitively state what the nature of a “virus” truly is.

While Summers paper on the invention of the “virus” offers some great modern insight into the problems related to defining the nature of the invisible beast, there is a much earlier paper by prominent virologist Thomas Rivers from 1932 that details the many issues with trying to give life to the imaginary shortly after its conception. You may know Rivers due to his 1937 proclamation that “It is obvious that Koch’s postulates have not been satisfied in viral diseases.” This shockingly honest admittance that the essential logical criteria considered necessary in order to prove a microbe causes disease remains unfulfilled for “viruses” continues to haunt virology to this day. As it is a rather long 18 pages that I have reproduced here, I will try to keep my commentary throughout brief. However, what Rivers highlighted as key problems in 1932 during the formative years of virology compliments Summers 2014 paper on why virologists needed to invent, and then continually reinvent, the concept of the “virus” that was dreamt up in the late 1800s.

1. Inventing Viruses: https://www.annualreviews.org/doi/10.1146/annurev-virology-031413-085432?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub++0pubmed

2. Inventing the Nature of "Viruses": https://mikestone.substack.com/p/inventing-the-nature-of-viruses

3. William Summers joins the TWiV team to discuss some virology history, including the ever-changing concept of "virus" and the contribution of phage research to the study of animal viruses. https://asm.org/Podcasts/TWiV/Episodes/Inventing-viruses-TWiV-573