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The secret of four serotypes: How complex is dengue virus?
With the impact of global change and climate change, dengue virus (DENV) has increased dramatically in the past two decades, becoming one of the most worrying mosquito-borne diseases in tropical regions. According to estimates in 2013, there may be up to 390 million cases of infection reported each year, but many infected people do not show obvious symptoms, which poses a huge challenge to public health prevention and control.
There are four major dengue virus serotypes, which not only have different antigenicity but can also co-infect in the same host, leading to more complex disease manifestations.
Dengue virus is a positive-sense single-stranded RNA virus belonging to the Flaviviridae family, and its complexity is beyond the understanding of many people. Past studies have shown that there are actually 46 different strains of dengue virus, not just four serotypes.
Evolution and changes of viruses
Based on previous analyses, researchers have identified three genotypes of dengue virus, with a fourth type reported in 2013 and a suspected fifth type, DEN-5, reported in 2015 but not yet confirmed. The evolution of these genotypes is closely related to global climate change and human activities, especially World War II and the movement of people after the war.
Dengue virus life cycle
The dengue virus first spread through the wilderness cycle in Africa, and over time, the virus has completely switched to human-mosquito transmission. Typically, an infected mosquito transmits the virus to a human after biting it. Once the virus enters the host, it accumulates and replicates in multiple cell types, including skin cells and dendritic cells.
Future studies are needed to analyze this process in depth, especially how it responds to the human immune system, which in turn affects viral replication.
Signs and symptoms of dengue fever
Epidemics of dengue fever are particularly common during the wet season in tropical regions. Symptoms of infection usually include severe headache, muscle and joint pain, rash and minor bleeding. For some people, dengue fever can develop into more severe forms such as dengue hemorrhagic fever or dengue shock syndrome.
Immune Response Challenges
The complexity of dengue lies not only in the diversity of the virus itself, but also in the host's immune system response. The scientists found that dengue virus suppresses the host's innate immune response, including interferon signaling, which significantly improves the virus's survival during infection.
"DENV's E envelope protein is the key to binding to host cell receptors and can affect the entire infection process."
Progress in vaccine development
In the past few years, several vaccines have entered the market as an important means of preventing dengue fever. In 2022, the European Medicines Agency approved the Qdenga vaccine, a live vaccine that targets all four serotypes, while the Dengvaxia vaccine is only recommended for those who have been infected before.
Conclusion
As the complexity of dengue virus continues to be revealed, future research needs to explore more deeply, especially on how to prevent and treat this virus that threatens human health. When faced with the challenge of dengue fever, how should humans respond to this highly variable pathogen?
