In the 19th century, virology emerged as a field of science that studied minuscule agents capable of causing infections in plants and animals.1 It is regarded as a branch of microbiology that specifically focuses on viruses. The discovery of the electron microscope enabled the visualization of viruses, following which this field started growing rapidly.
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What are Viruses?
Viruses are metabolically inert, ultra-microscopic, ubiquitous, infectious agents that replicate only within living cells.2 These microorganisms affect plants, animals, and humans. A virus genome may be composed of either DNA or RNA, and the genetic material can be arranged into double or single strands. These genomes can have a circular or linear arrangement.
In comparison to bacterial genomes, viral genomes are smaller in size. In some viruses, such as paramyxovirus, the nucleoprotein is surrounded by a protein or lipid bilayer called the envelope. The outermost protein of the virus particle determines the correct host cell and, subsequently, enters its cytoplasm.3
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Viral Structure and Functions
Major Scope and Contributions of Virology
Virology provides a tremendous theoretical foundation and guidance to prevent and control infectious diseases. Virologists conduct in-depth studies to understand the structures, life cycles, and transmission pathways of different viruses. The development of effective antivirals and vaccines is a significant achievement of virology.4
For instance, vaccines for yellow fever and polio are considered major contributions of virology as they not only shed light on the importance of antiviral vaccines but also significantly reduce mortality rates due to these diseases.
The availability of effective and affordable vaccines against various diseases has significantly decreased global mortality rates. Besides vaccine developments, gene therapies, diagnostic tools, and antiviral drugs are considered major contributions of medical research linked with viruses.
Virologists continually monitor the emergence of novel viruses to prevent the unfortunate events of regional and global outbreaks. Since viral evolution is a complex and unpredictable event, it is not easy to promptly detect new variants.5
The recent coronavirus disease 2019 (COVID-19) pandemic, caused by the rapid worldwide transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), further emphasized the importance of virology.
Notably, not all viruses are evil. Virology explored how viruses play an important role in maintaining ecological balance; for example, phages are viruses that target bacteria and regulate harmful bacterial populations.6
Furthermore, viruses play a major role in evolution through horizontal gene transfer. This process entails transferring genetic material between organisms leading to genetic diversity and variation.7
Retroviruses have aided gene delivery, which played a significant role in the emergence of genetic modifications and gene therapy.8
Baculovirus is also used as a biocontrol agent, particularly for controlling insect pests and preventing pathogenic infestations in agriculture and forestry without harming beneficial species.9
Evolution of Virology Through Tools and Technological Advancements
The evolution of virology could be divided into four periods, namely, microbiology, biochemistry, genetics, and molecular biology.1 The advancements of tools and techniques have been fundamental to virological progress.
The microbiology period is predominantly based on the availability of high-resolution microscopes. The biochemical period enabled a better understanding of viral proteins and their traits. The genetic phase highlighted viruses' ability to transfer genetic information.
The molecular phase helped scientists understand the roles of viral RNA and DNA. Each period has significantly shaped the scientific landscape, particularly life science, medicine, and public health.
After the discovery of the electron microscope, which enabled the visualization of viruses, the advent of novel biochemical assays and the in vitro propagation of eukaryotic viruses significantly accelerated the pace of virus discovery.1
Subsequently, applications of nucleic acid sequencing methods established phylogenetic relationships among different viruses. This enabled researchers to understand the similarities and dissimilarities between microbes.
The introduction of highly sensitive, cost-effective, high throughput sequencing technologies lead to the discovery of a multitude of novel viruses. Whole-genome sequencing and meta-transcriptomics have offered profound insights into the evolution and function of viruses.10
It is important to understand viral evolution because it sheds light on its adaptive mechanisms, which is critical to predicting its impact on public health. Furthermore, relatively recent strategies, such as cocktail therapy, CRISPR/Cas9, microarray technology, and prion theory, have revolutionized the diagnosis and treatment of viral infection.1
Light microscopy techniques in virology: An overview
Virology: Key Challenges and Future Outlook
A key challenge in virology is associated with the emergence and re-emergence of viruses with potential caused by an epidemic or pandemic.11 A virus may emerge through a vector (e.g., mosquito) or zoonotic spillover into humans. Multiple factors, including changes in the climate, ecological disruption, urbanization, and changes in land use.12 drive the emergence of new viruses
The viral evolution through which they escape vaccine-induced host immunity is a major challenge of virology. Some viruses enable the downregulation of host cell surface proteins to avoid immune surveillance effectively.
More efficient surveillance of both animals and humans is critical to protecting the global population from infectious viral infection. More research is needed to understand better viral evolution, genomics, ecology, and host interactions to determine virus origins and predict potential transmission dynamics. This information would help prevent future viral outbreaks and formulate novel treatment strategies.
Application of artificial intelligence (AI) in virology through computational analysis of virus genome sequences would enable quick detection of viruses with high transmission dynamics and pathogenicity. AI might also eventually predict the biological and phenotypic characteristics of a virus, how it interacts with a host and triggers the host's immune system.13
Advanced genomic approaches (e.g., deep sequencing of nucleic acids) could be combined with other powerful technologies, such as proteomics, short hairpin RNAs (shRNAs), optical imaging, mass spectrometry, and high-throughput screening to discover novel viruses and their antagonists. Genetic analyses, including whole-genome sequencing, will identify genes required for infection, transmission in various hosts, and pathogenesis. In the future, the identification of host genes that confer protection or susceptibility to viral infection could lead to the development of novel preventive strategies.
References
- Zuo K, et al. Evolution of Virology: Science History through Milestones and Technological Advancements. Viruses. 2024;16(3):374. doi: 10.3390/v16030374.
- Fenner F, et al. Structure and Composition of Viruses. Veterinary Virology. 1987:3–19. doi: 10.1016/B978-0-12-253055-5.50005-0.
- Casasnovas JM. Virus-receptor interactions and receptor-mediated virus entry into host cells. Subcell Biochem. 2013;68:441-66. doi: 10.1007/978-94-007-6552-8_15.
- Ellebedy AH, Ahmed R. Antiviral Vaccines: Challenges and Advances. The Vaccine Book. 2016:283–310. doi: 10.1016/B978-0-12-802174-3.00015-1.
- LaTourrette K, Garcia-Ruiz H. Determinants of Virus Variation, Evolution, and Host Adaptation. Pathogens. 2022;11(9):1039. doi: 10.3390/pathogens11091039.
- Naureen Z, et al. Bacteriophages presence in nature and their role in the natural selection of bacterial populations. Acta Biomed. 2020;91(13-S):e2020024. doi: 10.23750/abm.v91i13-S.10819.
- Buck CB, et al. Widespread Horizontal Gene Transfer Among Animal Viruses. bioRxiv [Preprint]. 2024. doi: 10.1101/2024.03.25.586562.
- Bin UM, et al. Viruses as tools in gene therapy, vaccine development, and cancer treatment. Arch Virol. 2022;167(6):1387-1404. doi: 10.1007/s00705-022-05432-8.
- Ferrelli ML, Salvador R. Effects of Mixed Baculovirus Infections in Biological Control: A Comprehensive Historical and Technical Analysis. Viruses. 2023;15(9):1838. doi: 10.3390/v15091838.
- Shi M, et al. Meta-transcriptomics and the evolutionary biology of RNA viruses. Virus Res. 2018;243:83-90. doi: 10.1016/j.virusres.2017.10.016.
- Sanyal S. Crossroads in virology: current challenges and future perspectives in the age of emerging viruses. Dis Model Mech. 2023;16(10):dmm050476. doi: 10.1242/dmm.050476.
- Church DL. Major factors affecting the emergence and re-emergence of infectious diseases. Clin Lab Med. 2004;24(3):559-86. doi: 10.1016/j.cll.2004.05.008.
- Elste J, et al. Significance of Artificial Intelligence in the Study of Virus–Host Cell Interactions. Biomolecules. 2024; 14(8):911. doi.org/10.3390/biom14080911
Further Reading
Scientists Capture Viral Infection Process Using Light Microscope