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The origins of dengue fever: How did this mosquito-borne virus originate?
Dengue fever, also known as bone-breaking fever, is a disease caused by dengue virus (DENV). This virus belongs to a genus in the Flaviviridae family and is mainly transmitted to humans through mosquitoes. As global climate change and urbanization accelerate, the incidence of dengue fever has increased dramatically over the past two decades, and it is estimated that approximately 390 million people worldwide are infected each year. This not only makes dengue virus one of the most serious human pathogens in the tropics, but also caused scientists to conduct in-depth research on its origin and evolution.
The evolution of dengue virus
According to research, dengue virus has four serotypes, of which the third serotype and the fifth serotype under study also show the diversity of their genetic evolution processes. Especially between 1907 and 1949, the history of contact between dengue virus and humans prompted the mutation and adaptation of its genes. This period coincided with the First and Second World Wars, and the migration of mobile populations and environmental changes provided opportunities for the evolution of the virus.
According to statistics, the common ancestor of dengue virus was born around 340 years ago, and it is speculated that it may be related to the spread and epidemic in ancient societies.
The life cycle of dengue virus
The early spread of dengue virus mainly relied on ecological cycles between mosquitoes and non-human apes, but over time, the virus has completely shifted to humans as its main host. Once a mosquito bites a human carrying dengue virus, it begins to multiply in the body and find new hosts for transmission. During the infection process, dengue virus binds to the receptor of the host cell, allowing the virus to enter the host cell and start replicating.
An infected cell can release 1,000 to 10,000 new viral particles, making the spread of the virus even more threatening.
Genomic characteristics of dengue virus
The genome of dengue virus consists of approximately 11,000 bases, encoding three structural proteins and seven non-structural proteins. These structures are critical for the replication and spread of the virus. Among them, the E protein plays an important role in the initial binding of the virus to the host cell, while a variety of non-structural proteins are involved in regulating the replication mechanism of the virus.
Disease manifestations and immune response
The main symptoms of dengue fever include high fever, severe headache, joint and muscle pain, etc. Severe dengue fever, such as dengue hemorrhagic fever and dengue shock syndrome, can lead to fatal consequences. These symptoms mainly result from the impact of dengue virus on the host's immune system. Recent studies suggest that cross-immune reactions may contribute to an increase in severe cases, particularly in people who have been infected with multiple serotypes.
Research points out that multiple non-structural proteins of dengue virus can inhibit the host's innate immune response, which makes the virus more latent and infectious.
Vaccine development and future challenges
The research and development of vaccines against dengue fever has made some progress, and existing vaccines include Deqiba and the newly approved Qdenga. However, the use of vaccines still faces many challenges, such as how to ensure effective protection of susceptible populations in areas with high risk of transmission, especially those individuals who have not been infected with dengue virus.
Where the dengue virus originated is crucial to the future of global public health. Researchers are still exploring the past of this ancestor virus in order to develop more scientific strategies to prevent future epidemics?
