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The hidden truth: How do invisible viruses survive inside cells?
Latency is a dramatic stage in the life cycle of many viruses, allowing the virus to remain hidden within host cells for long periods of time without detection. Specifically, this is a long-lasting type of viral infection that is different from chronic viral infection. During the incubation period, after the initial infection, the reproduction of viral particles stops, but the viral genome is not cleared, which allows it to reactivate and generate new viruses in large quantities without the need to reinfect the host from the outside.
The existence of latent viruses in the host may be why the life of the virus in the host is greatly extended.
There are two main types of latency mechanisms, namely "phenotypic latency" and "proviral latency". In phenotypic latency, viral genes exist as genetic factors within cells. In this case, the latent state of herpes viruses is an obvious example. In this case, viral genes float in the cytoplasm or nucleus in circular or linear structures, although they face surveillance and attack by cellular defense mechanisms.
Herpes viruses, for example, establish latent infections in neurons and reactivate when needed.
The latent ability of viruses exists not only with herpes viruses, but also with human immunodeficiency virus (HIV). HIV uses the enzyme reverse transcriptase to create a DNA copy of the RNA genome and hide it from the host's immune system. The latent phase of HIV is almost impossible to directly target with antiretroviral drugs, making treatment extremely challenging. Therefore, scientists are developing a variety of latency reversal agents in order to effectively activate latent viruses and treat them.
In addition to HIV, another example is HIV and papillomavirus (HPV). An important reason why these viruses lie dormant in host cells is that they can use the host's cell division to replicate their own genes. Such characteristics allow viruses to engage in long-term host dependence and stealth strategies, thereby extending their survival period in the host.
The latent state not only provides concealment, but may also lead to irreversible changes in cells and the risk of cancer.
Cases of cancer are also closely related to latent viruses, such as HPV infection that may lead to cervical cancer. This change in situation stems from the persistence of the virus in cells and the expression of genes during the latency period that may affect cell proliferation and differentiation pathways. In addition, the use of retroviral vectors during gene therapy has also caused patients to develop leukemia-like symptoms.
In summary, the existence of latent viruses makes antiviral treatment a major challenge in how to clear these latent virus reservoirs. In the process of fighting against such invisible viruses, external stimuli such as pressure, ultraviolet rays and other environmental factors often cause the activation of these invisible viruses, further causing acute infections.
Viruses hidden in cells may not cause any symptoms on the surface, but their potential threats cannot be ignored.
Our understanding of the latent capacity of these invisible viruses within cells not only makes us reflect on their impact on health, but also involves the need for treatment and future vaccine development. Is it true that the latent virus hidden in our bodies is just waiting for the opportunity to explode?
