Heroism in microbiology and medical duty
Starting from the 18th century, the doctrine of medical duty—medical deontology—began to take shape within microbiology. The establishment of this discipline is inextricably linked to the unprecedented self-sacrifice of researchers. Scientists knowingly took on colossal risks by conducting experiments on themselves and intentionally exposing themselves to infection.
The primary goal of these heroic actions was to establish precise facts about the pathogenicity of microorganisms, prove the transmission routes of infections, and verify the safety of vaccines under development. History has preserved the names of many prominent scientific figures:
- G.N. Minkh and O.O. Mochutkovsky — heroically investigated epidemic typhus on themselves.
- V.P. Smirnov — conducted research on plague.
- M.N. Chumakov — worked with the poliovirus.
- M.S. Baloyan — studied the hepatitis A virus.
A tremendous contribution to science was also made by I.V. Savchenko and N.F. Gamaleya. These feats laid a solid ethical foundation for modern infectiology.
How viruses were discovered
The late 19th century marked a revolutionary breakthrough: scientists encountered pathogens of a fundamentally new nature. A key date in the history of biology was 1892, when the distinguished Russian botanist D.I. Ivanovsky made his epoch-making discovery.
While studying tobacco mosaic disease, the researcher discovered unique infectious agents. Unlike bacteria known at the time, these new microorganisms passed freely through the minute pores of bacterial filters, leading to them being termed "filterable" agents. Soon, the Latin term virus, meaning "poison", was introduced to designate them.
Following the discovery of the plant pathogen, viruses affecting humans, animals, and even bacteria were uncovered. By the first half of the 20th century, the accumulated body of knowledge led to the formation of an entirely new and independent scientific discipline—virology.
Emergent infections and the evolution of the microbial world
Over the past thirty to forty years, the global epidemiological landscape has undergone significant changes. Scientists are constantly identifying new pathogens. This is driven by two main factors: the rapid advancement of laboratory detection and identification methods, and the natural evolution of the microbial world (mutations and genetic changes).
As a result, the concept of emergent infections has emerged—a group of highly dangerous and unpredictable diseases. In recent decades alone, about thirty new or significantly altered variants of microorganisms have been discovered:
- Viruses: HIV, causative agents of severe hemorrhagic fevers (Ebola, Marburg, and Lassa), and coronaviruses (the culprits behind SARS).
- Bacteria: causative agents of Legionnaires' disease and Lyme disease.
Concurrently, a frightening alteration in the properties of long-known microbes is taking place. Through genetic transformations, they can acquire pathogenicity for humans, as occurred with the monkeypox virus or the bacterium Helicobacter pylori (which causes peptic ulcer disease). Additionally, there is a widespread epidemic spread of "old" infections, such as chlamydia, tuberculosis, and parenteral hepatitides.
Global victories and future outlook
Despite formidable evolutionary processes in the microbial world, medicine has achieved impressive results in combating infections. The principal triumph of global vaccination programs has been the complete eradication of smallpox on the planet. Currently, global healthcare faces the ambitious task of final eradication of poliomyelitis.
Nevertheless, expert projections remain realistic: the natural variability of microorganisms does not stop. Humanity will inevitably continue to face the emergence of entirely new infectious agents and dangerous modifications of already known old pathogens in the future.
Briefly: answers to topical questions
What is the structure and chemical composition of the viral capsid?
The capsid is the protein shell of a virus.
- Chemical composition — proteins; capsid proteins are called capsomeres. In simple viruses, the nucleic acid together with the capsid forms a nucleoprotein.
- Structure — the capsid can have various types of symmetry, for example, cubic.
In some viruses, the capsid has an icosahedral shape and consists of two types of capsomeres:
- Hexons — form the faces and are connected to neighboring particles.
- Pentons — are located at the vertices of the icosahedron, consisting of a base and a glycoprotein fiber (fibril) extending from it.
What types of virus-host cell interactions exist?
Based on the outcome of the interaction between the virus and the host cell, two types of infection are distinguished.
- Productive infection — occurs in permissive (susceptible) cells, characterized by a complete reproduction cycle and culminating in the formation of infectious progeny. Acute infection corresponds to the productive type of interaction at the cellular level.
- Abortive infection — the process is interrupted and does not conclude with the formation of infectious viral particles.
Abortive infection arises due to genetic non-permissiveness of cells, infection with defective viruses, or the formation of defective interfering particles.
To remember emergent hemorrhagic fevers: MEL (Marburg, Ebola, Lassa).
Class and exam questions
Who discovered viruses and when?
The Russian botanist D.I. Ivanovsky in 1892 while studying the causative agent of tobacco mosaic disease.
What are emergent infections?
This is a group of dangerous and unpredictable infectious diseases whose causative agents were recently discovered or have changed their properties (e.g., HIV, Ebola and Marburg viruses).
Give examples of physician self-infection in the history of microbiology.
G.N. Minkh and O.O. Mochutkovsky studied epidemic typhus on themselves, V.P. Smirnov investigated plague, and M.N. Chumakov worked with the poliovirus.
Which microbes have acquired pathogenicity for humans during evolution?
According to studies from recent decades, the monkeypox virus and the bacterium Helicobacter pylori, which causes peptic ulcer disease, have acquired pathogenicity.
What else to study on this topic
- Deontology in medicine: historical development of the concept.
- Methods of detection and identification of new viruses.
- Genetic transformation and mutations of microorganisms.
- History of smallpox eradication worldwide.
- Parenteral hepatitides and tuberculosis: reasons for the return of old infections.
Study the full topic in the «Microbiology» course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Discovery of viruses and evolution of infections" and 4,383 other pages of the subject
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- 141 video lectures on the subject
Other topics in the section "Introduction to microbiology and immunology"
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