What is the Herpes Simplex Virus?

Herpes simplex virus ( herpes simplex virus (HSV)) is a typical representative of herpes virus. It is named because herpes simplex occurs in the acute phase of infection ^[1] . Can cause a variety of human diseases, such as gingivostomatitis, keratoconjunctivitis, keratoconjunctivitis, encephalitis, and reproductive system infections and newborn infections.

HSV-1 is a circular virus synthesized by the envelope, capsid, core, and capsule. Double-stranded linear DNA synthesis is the focus of the virus. The filaments are wound in coils, ranging from 125 to 240 kb. The genome of HSV-2 is around 154kb. The G + G component in the genome of HSV-2HG52 strain is about 70%, and the middle part is synthesized by 18% short and 82% long fragments covalently connected at the LS border. Each fragment contains inverted repeats at both ends and a special middle part. Sequences, due to their different forms of connection, HSV-2 genome produces 4 isomeric molecules. HSV has a variety of transcriptional regulation methods, complex genome structure, many genes and overlapping each other. The HSV-2 gene is transcribed and expressed through strict cascade regulation, and is divided into three categories in order according to time: immediate early genes, early genes, and late genes ^[3]

According to the difference in antigenicity, HSV is divided into two serotypes, HSV-1 and HSV-2. The DNA of the two types of viruses is 50% homologous, with common antigens and type-specific antigens ^[4]

The virus is spherical and has

Humans are the natural hosts of herpes simplex virus. Infection is extremely common in the population. 80% -90% of the initial infections are recessive infections, most of which have no obvious symptoms, and a few are dominant infections. Herpes. After the initial infection, it is often turned into a latent infection, which can cause recurrence after external stimuli. The source of infection is patients and carriers. The transmission route is direct contact or sexual contact. The virus can initiate infection by damaging the skin and mucosa ^[5]

In anti-HSV infection immunity, neutralizing antibodies generally appear about 1 week after the primary infection and can last for many years: this antibody can neutralize free viruses and reduce the severity of the disease, but it cannot prevent the virus from moving to ganglion cells Also, it cannot clear the virus that is latent in the cells, and prevent the recurrence of the infection. Specific Tc cells appeared in the second week of HSV infection, destroying host cells infected by the virus and clearing the virus. HSV has partial cross-immunity between the two types ^[5]

HSV-2 virus is the main cause of genital herpes. Once infected, patients will carry the virus for life and periodically develop genital herpes damage. HSV-2 infection also increases the risk of HIV-1 transmission, and is currently not targeted against HSV. -2 effective vaccine launched. Due to the high positive rate of HSV-2 and the common transmission route with HIV-1, more and more attention has been paid to related research on HSV-2.

Previous studies have shown that HSV-2 must inhibit host cells' antiviral type I interferon (IFN / ) signaling pathways to establish persistent infections, but the mechanism is unknown. Research by the Hu Qinxue Group of the Wuhan Institute of Virology, Chinese Academy of Sciences found that HSV-2, through its very early protein US1, inhibits the production of IFN- and evades the host's natural immune control. This discovery provides a new mechanism for how double-stranded DNA virus families block the type I IFN signaling pathway.

It is difficult to establish long-term effective memory immune protection against HSV-2 in the genital tract mucosa, which has become a major bottleneck in the development of herpes virus vaccines. Hu Qinxue's group used the chemokine CCL19 to target and recruit immune cells to secondary lymphoid organs and mucosal tissues. The candidate immunogen HSV-2 gB protein and CCL19 were used to make a chimeric DNA vaccine. . It was found that the "gB-CCL19" chimeric vaccine can induce good protection in mice, thus laying a foundation for the design of vaccines against HSV-2 or other sexually transmitted viruses ^[6]

Prevention should be based on cutting off the transmission route, try to avoid close contact with patients, avoid stimulating the body with harmful factors, and actively exercise the body to improve the body's immunity. If pregnant women have HSV-2 infection during the perinatal birth canal, cesarean section can be performed to avoid neonatal infections ^[4] .

Avoiding contact with patients or injecting specific antibodies into susceptible people can reduce the risk of HSV transmission. Saliva, urethra, or reproductive tract of asymptomatic people are important carriers of HSV-2. Sexual contact should be avoided if damage occurs. In some cases (such as when the amniotic membrane is not broken), a cesarean section can be taken to reduce the newborn's contact with the damaged genitals. Injecting newborns with specific antibodies or gamma globulin after delivery can also be used as an emergency precaution ^[8] .