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Molecular-Genetic Period in Microbiology

For medical students2 min readUpdated 2026-10-10

The molecular-genetic period marks the transition from studying whole cells to investigating microorganisms at the subcellular and molecular levels. During this era, pathogen genomes were sequenced, and breakthrough genetic engineering technologies were developed, including PCR, recombinant vaccines, and monoclonal antibody-based therapeutics.

Core TechnologyCreation of recombinant DNA and producer strains

Immunology BreakthroughDetailed mapping of T- and B-lymphocyte and phagocyte receptor apparatus

DiagnosticsImplementation of the polymerase chain reaction (PCR)

HLA SystemStudy of the major histocompatibility complex

Fundamental Discoveries and Immunity

A key feature of this historical stage was the shift of researchers to the subcellular and molecular levels. Scientists were able to study in detail the molecular organization of bacteria and viruses, determining the chemical composition and structure of their genomes. The precise spatial structure of microbial antigens, virulence factors, and human protective antibodies was finally established.

A colossal leap occurred in fundamental immunology:

The mechanisms of humoral defense factors—the complement system, interferons, and various cytokines—were detailed.
The receptor apparatus of immunocompetent cells (T- and B-lymphocytes, phagocytes) was studied, revealing the subtle mechanisms of their intercellular interaction.
Molecular cascades of cell death processes, such as apoptosis and pyroptosis, were described in detail.

Genetic Engineering and Biopharmaceuticals

Accumulated knowledge regarding gene structure became the foundation for biotechnology. The key technology was the creation of recombinant DNA, which allowed for the engineering of recombinant producer strains—microorganisms programmed to synthesize compounds needed by humans. This enabled the mass production of biologically active substances: hormones, dietary proteins, interleukins, and therapeutic agents (including antitumor drugs).

The approach to vaccine prophylaxis changed cardinally. A new generation of immunization products emerged:

Recombinant vaccines (a classic example being the hepatitis B vaccine).
Synthetic vaccines, representing combinations of isolated antigenic determinants with polymeric carriers and adjuvants.
Live vector vaccines.

Genetic Diagnostics and Immunogenetics

New diagnostic and therapeutic methods actively penetrated clinical medicine. A true revolution was the use of products based on highly specific monoclonal antibodies, as well as the application of the polymerase chain reaction (PCR) for ultra-precise genetic diagnosis of infections.

In parallel, the field of immunogenetics took shape. Methods of gene prevention were developed, and the foundations of gene therapy for severe immunodeficiency states were laid. The use of immunomodulators in treating both infectious and non-infectious pathologies gained scientific backing.

Transplantation and Antimicrobial Therapy

Molecular biology uncovered tissue genetic markers, providing a powerful impetus to the development of transplantation and reproductive immunology. The Human Leukocyte Antigens (HLA) system—the major histocompatibility complex—was studied in depth. This successfully resolved tissue incompatibility issues during donor organ transplantation and provided an understanding of the causes of immunological conflict in the maternal-fetal system.

Biotechnological progress also influenced the evolution of antimicrobial therapy. Chemo- and antibiotic prophylaxis methods were significantly refined, and laboratories began synthesizing fundamentally new classes of antiviral and antibacterial drugs targeting specific molecular structures of pathogens.

Mnemonic

To remember the applied achievements of this period, use the mnemonic VADIM: V — Vaccines (recombinant), A — Antibodies (monoclonal), D — Diagnostics (PCR), I — Immunogenetics (HLA system), M — Modulators (interferons and cytokines).

Frequently asked questions

What types of cell death are studied in modern immunology?

Modern science studies accidental necrosis and regulated (programmed) types of cell death. The main types include:

Necrosis — unregulated death in response to adverse factors.
Appoptosis — a genetically controlled process occurring without the release of cellular contents or inflammation.
Necroptosis — a genetically controlled process morphologically resembling necrosis.
Ferroptosis — iron- and glutathione-dependent death associated with lipid peroxidation.
Pyroptosis — cell death accompanied by pronounced inflammation.

What genetic diagnostic methods for infections are used in modern microbiology?

Modern microbiology utilizes nucleic acid analysis methods for infection genetic diagnostics. The primary methods include:

Polymerase chain reaction (PCR) — used for screening and detecting viral and bacterial genetic material.
Nucleic acid molecular hybridization — detecting complementarity using radiolabeled single-stranded probes.
Gene sequencing — determining DNA nucleotide sequences (including 16S and 23S rRNA sequencing).
Plasmid analysis and ribotyping.
RFLP — restriction fragment length polymorphism analysis.
Polymorphic DNA amplification.

What molecular structures of bacteria and viruses serve as targets for modern antimicrobial drugs?

Transport systems and processes synthesizing structural components of microorganisms act as targets for modern antimicrobials. Key targets include:

Transport steps — membrane transport of substances (e.g., N-acetylglucosamine transport blocked by vancomycin).
Peptidoglycan synthesis process — disruption of bacterial cell wall construction.
Viral protein synthesis and proliferation — blocked by type I interferons.

Targets may also include structures modified during the development of antibiotic resistance.

For the treatment of which specific diseases are gene therapy methods developed in immunogenetics?

Gene therapy methods are developed primarily to treat primary immunodeficiency states and oncological diseases. Specific conditions include:

Severe Combined Immunodeficiency (SCID) — correcting adenosine deaminase deficiency via ADA gene transfection into autologous bone marrow cells.
X-linked SCID — transfer of the γ(c)-chain gene.
Malignant tumors — transferring cytokine gene-transfected cells into the body for targeted delivery to tumor cells.

At what level did research shift during this period?

The research focus shifted from the cellular and tissue levels to the subcellular and molecular levels. The main objects of study became microorganism genomes, antigen molecules, and immune system cell receptors.

What vaccines were developed during this stage?

Thanks to genetic engineering, next-generation vaccines emerged: recombinant (genetic engineering-based, e.g., for hepatitis B), live vector vaccines, and synthetic vaccines utilizing polymeric carriers.

What is the HLA system and why was it discovered?

The HLA (Human Leukocyte Antigens) system is the human major histocompatibility complex. Studying it is essential for matching donors, resolving transplant rejection issues, and understanding maternal-fetal immune conflicts.

What role did the creation of recombinant DNA play?

The engineering of recombinant DNA enabled the creation of producer strains—bacteria that synthesize medically necessary proteins, hormones, interferons, and other therapeutic drugs.

Go deeper

Structure and functions of the complement system and cytokines.
Mechanisms of programmed cell death: apoptosis and pyroptosis.
Principles of the polymerase chain reaction (PCR) method.
Differences between recombinant, vector, and synthetic vaccines.
Technology for producing monoclonal antibodies.
Genetic basis of maternal-fetal immunological conflict.