Posted on 2024年 11月 6日
Some viruses can be incorporated into human genes when infected. In particular, a type of virus called a “retrovirus” has the property of incorporating genetic information into the host’s (human) DNA.
How Retroviruses Work
Retroviruses are RNA viruses, a typical example of which is HIV (human immunodeficiency virus). Retroviruses are incorporated into host genes through the following processes
- Reverse transcription: After infection, retroviruses use a special enzyme called reverse transcriptase to convert their RNA into DNA. This process is called reverse transcription.
- Incorporation: The viral DNA produced enters the nucleus of the host cell and is incorporated into the host’s DNA. This incorporates the genetic information of the virus as part of the human DNA.
- Replication: Once the viral DNA is incorporated, the host cell uses the viral genetic information to produce new viral RNA and proteins, resulting in viral replication. In this process, new viruses are produced and released outside the cell to infect other cells again.
Viral Traces Embedded in the Human Genome
The human genome contains traces of “endogenous retroviruses (ERVs),” viruses that have incorporated genes from viruses they have infected during evolution and remained for long periods of time. These virus-derived genes have become part of human genes through evolution and account for approximately 8% of all human DNA. Today, many of these viral genes have either lost their function or some have been diverted to important roles in human cells.
Other Viruses and DNA Incorporation
Many non-retroviruses are not incorporated into human DNA. However, certain DNA viruses and herpes viruses can also remain in the nucleus of a cell and infect it for long periods of time. Although these viruses do not incorporate directly into the host’s DNA, they can remain in the body for long periods of time through repeated infections.
Gene Therapy and the Use of Viruses
In the field of gene therapy, technologies are being developed that take advantage of the DNA incorporation properties of viruses to use viruses to compensate for defective genes or to provide effective treatment for specific diseases. This involves modifying viruses as vectors (gene carriers) to incorporate genes into host cells that are useful in treating diseases.
Conclusion
Among viruses, retroviruses in particular can be incorporated into human genes, and many viral traces have been left in the human genome during the course of evolution. These viral characteristics have been used in gene therapy and in the study of viral evolution, making the relationship between viruses and genes a complex and interesting field.
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