AsianScientist (Oct. 10, 2019) – The dengue virus (DENV) can morph its surface structure to avoid being identified by the immune system, say researchers in Singapore. Their findings, which have implications for the design of vaccines, are reported in the journal PLOS Pathogens.
DENV infects about 400 million people annually around the world, with a high prevalence in tropical and sub-tropical regions. There are four subtypes, or serotypes, of the dengue virus (DENV1-4), and they are responsible for causing symptoms ranging from mild fever to severe haemorrhagic fever, sometimes leading to dengue shock syndrome which can be fatal.
In the present study, researchers led by Ms. Lim Xin-Ni at the Duke National University of Singapore (NUS) Medical School in Singapore focused on DENV2 and found that the virus changes its structure under varying temperatures to escape immune detection.
Laboratory-adapted strains of DENV2 typically exist as virus particles with smooth spherical surfaces while growing at the mosquito’s physiological temperature of 29 degrees. The virus particles’ surfaces then become bumpy at human physiological temperature of 37 degrees Celsius. This ability to morph is thought to help the virus evade the immune system of the human host.
However, the team observed the majority of clinical DENV2 samples—those obtained from infected patients—maintained smooth surface structures at 37 degrees Celsius and only morphed into the bumpy surface configuration at 40 degrees Celsius, the temperature of a fever.
The researchers were also able to use computational modelling approaches to predict why particles from different DENV2-infected patient samples are more adept at morphing. By better understanding the interactions between the virus and the host, the researchers hope to develop better therapies and vaccines to treat or prevent infections.
“[Our findings suggest that] for prevention of disease through vaccines that are administered to the patient before dengue infection, we should use those that are effective against the smooth surface virus. When it comes to patients displaying fever symptoms, treatment strategies effective against the bumpy surface particles should be implemented,” said Professor Lok Sheemei at the Duke-NUS Medical school and the corresponding author of the study.
The article can be found at: Lim et al. (2019) Molecular Basis of Dengue Virus Serotype 2 Morphological Switch From 29°C to 37°C.
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Source: Duke-NUS Medical School; Photo: Lim Xin-Ni.
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