Darwin Day: When Evolution Turns Against Us — Humans vs. Viruses

How has evolution shaped viral infection? How does humanity cope with viral diseases? Why do vaccines work well against one disease but not another? Why are drugs that work against bacteria ineffective against viruses? And how optimistic can we allow ourselves to be about the future?

These questions were addressed recently by Dr. Yotam Bar-On of the Ruth and Bruce Rappaport Faculty of Medicine at a Technion event. We are pleased to publish the main points of his lecture in honor of Darwin Day, observed annually on February 12 and dedicated to Charles Darwin’s contribution to our understanding of life on Earth. The date marks Darwin’s birthday; he was born in Britain in 1809.

Evolution, in general, is a long-term process spanning millions and even billions of years, since the emergence of life on Earth approximately four billion years ago. However, when it comes to viruses, evolution is astonishingly rapid. Mutations arise, viral traits change, and subsequent viral lineages become more resistant to the immune system and to human-made vaccines.

Unlike bacteria, viruses are absolute parasites that cannot reproduce without a host cell. They invade the cell and commandeer it to produce thousands of copies of themselves, that is, new viruses, thereby preventing the cell from carrying out its original functions. At the end of the process, they accelerate the cell’s suicide mechanisms (apoptosis), leading to its destruction.

“The rapid evolution of viruses challenges the immune system, which must contend with this pace of change,” Dr. Bar-On said in his lecture. “It’s evolution versus evolution, and the two operate at different speeds. This mutation rate also challenges us—scientists and vaccine developers—who want the vaccines we develop to remain effective over time despite rapid changes in viral traits. In general, vaccines are our primary tool in the fight against viral diseases, and they have already saved hundreds of millions of lives. But for many diseases, this is an ongoing effort.”

Vaccines work by prompting the body to produce antibodies specific to the attacking virus, along with immune memory that helps the body respond quickly in the future if exposed again to similar viruses. “Viral illness itself also generates antibodies and immune memory, and often does so even better than vaccines, but we want to be immunized without first becoming ill, especially in the case of dangerous diseases.”

Dr. Bar-On also referred to mRNA vaccines, which came to public attention during the COVID-19 pandemic. “These vaccines, which are replacing traditional ones, are based on injecting not proteins but rather a ‘code’ into the muscle that instructs the body’s cells to produce the viral protein themselves. mRNA vaccines are not more effective than traditional vaccines; they are simply easier and cheaper to manufacture on a large scale. That is why the scientific community is now working on mRNA vaccines for a variety of other viral diseases.”

Dr. Bar-On also criticized aspects of the scientific and pharmacological community’s conduct during the pandemic. “There is no doubt today that COVID-19 vaccines saved many lives, and it was right to administer them. However, the responsible authorities should have been more transparent about side effects, rare as they may be. These side effects were extremely rare and do not detract from the vaccines’ importance, but concealing them increased vaccine hesitancy, created a sense of an aggressive campaign and public condescension, and ultimately undermined the crucial effort to expand vaccination.”

“Another mistake was the excessive investment in research and development channels that were not particularly relevant. One example was surface disinfection; enormous budgets were allocated to this area. Today we know that transmission via surfaces was almost nonexistent in the context of COVID; infections occurred almost entirely through respiratory droplets expelled when we speak, sneeze, and so on.”

Dr. Bar-On explained the differences between diseases in terms of vaccine effectiveness. “Ultimately, one of the key factors in eradicating epidemics is the virus’s rate of evolution—the slower it is, the more effective the vaccine. Some viruses change relatively slowly, for example, measles, polio, and smallpox. As a result, we have managed to eradicate them completely or almost completely. For the same reason, the COVID vaccine was so effective. By contrast, vaccines against HIV have not been effective because of the virus’s rapid mutation rate and its ability to enter a dormant state. Fortunately, combination therapy, a ‘cocktail’ treatment, was developed that curbed HIV infection and significantly reduced mortality.”

Returning to the lecture’s title, Dr. Bar-On concluded: “Evolution is an endless game. Viruses win in the short term because of their rapid rate of change, but with science, technology, and vaccines, we can win in the long term.”

Dr. Yotam Bar-On is a senior researcher at the Ruth and Bruce Rappaport Faculty of Medicine. He joined the Technion faculty after completing a postdoctoral fellowship at Rockefeller University in New York, where he studied the immune evasion mechanisms of HIV. In his Technion laboratory, he investigates the interaction between viruses and the immune system. His research integrates molecular biology, evolutionary theory, and advanced computational tools, with the goal of developing new strategies to understand infectious diseases and improve our ability to respond to the spread of viruses in a changing world.