What Is a Flavivirus?

Flavivirus is a large group of single positive-stranded RNA viruses with an envelope. The virus spreads through blood-sucking arthropods (mosquitoes, ticks, white magpies, etc.) and causes infection. It has been classified as arbovirus in the past. The main prevalent flaviviruses in our country are Japanese encephalitis virus, forest encephalitis virus and dengue virus.

Flavivirus

Flavivirus is a large group of single positive-stranded RNA viruses with an envelope. This type of virus is usually transmitted by blood-sucking arthropods (mosquitoes, ticks, white magpies, etc.), so it was previously classified as arbovirus B group. Because the term "arbovirus" is not accurate enough in taxonomy, it is no longer used. In our country, the main flavivirus members are

Flaviviridae includes three viral genera, namely flavivirus, pestivirus and hepacivirus, with a total of more than 70 viruses. Because flaviviruses are related to the morphological structure,

1. The virus is a small sphere, most of which is 40 ~ 70nm in diameter. The virus has a lipid envelope on the surface, which is inlaid with spikes composed of glycoproteins. The envelope is a 20-hedral symmetrical nucleocapsid protein, which contains Viral RNA.

2. Viral genomic nucleic acid is single-stranded positive-stranded RNA. The viruses all proliferated in the cytoplasm.

3. The virus is sensitive to heat, lipid solvents, and sodium deoxycholate, and is unstable at pH 3 ~ 5.

4. The virus is transmitted by arthropods (mosquitoes, ticks, white maggots, etc.). These arthropods are virus storage hosts, and humans, domestic animals, wild animals, and bird animals are infected by their bites.

Japanese encephalitis virus (JEV) is also known as Japanese encephalitis virus. It is transmitted by mosquito bites and causes Japanese encephalitis.

Dengue virus is the pathogen that causes dengue fever.

Forest encephalitis virus, also known as Russian spring-summer encephalitis virus , is the pathogen of forest encephalitis. The virus was first discovered in the eastern part of the former Soviet Union. Cases have also been reported in Central Europe and Germany. The virus has spread in some forest areas in northeast and northwest China.

Forest encephalitis virus

The morphological structure of forest encephalitis virus is similar to that of JE virus. Animals have a wide range of infections, and mice are the most sensitive, and can be infected by multiple routes of inoculation. The virus grows in primary chicken embryo cells and hamster kidney subculture cells and causes lesions.

Forest encephalitis is an acute infectious disease of the central nervous system, and ticks are the transmission vector. The virus proliferates in the ticks and is passaged by eggs. The ticks can also carry the virus to overwinter, and the ticks are the storage host for the virus. Under natural conditions, the virus infects mammals and birds in the forest with ticks, circulating among the animals. Susceptible people enter the forest area and are infected by tick bites. The virus can also be transmitted through the gastrointestinal tract. Humans have a sudden onset after 7 to 14 days of infection, with symptoms such as high fever, headache, lethargy, and peripheral flaccid paralysis. The mortality rate is 30%. Lasting immunity can be obtained after illness.

The microbiological examination of forest encephalitis virus is similar to that of Japanese encephalitis virus.

Anti-tick and anti-tick bites are the key to preventing forest encephalitis. Workers in forest areas should take personal protection. Inactivated tissue culture vaccines currently used in forest areas in China are safe and effective. Live attenuated vaccines are under development.