Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen's Encephalitis

Rasmussen's encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis,intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8?T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8?T cells are involved in the pathogenesis of RE.

Decreases in Both the Seroprevalence of Serum Antibodies and Seroprotection against Japanese Encephalitis Virus among Vaccinated Children

The incidence of Japanese encephalitis(JE)has significantly decreased in China due to JE vaccines.In this study,we investigated the post-JE vaccination seroprevalence and protection provided by vaccinated sera against Japanese encephalitis virus(JEV)to elucidate the persistence and waning of antibodies to JEV among JE-SA14-14-2-vaccinated children.A total of 300 serum samples were collected from vaccinated children aged 3-10 years in Zhaotong,Yunnan,China.The seroprevalence of anti-JEV antibodies was determined by enzyme-linked immune sorbent assay and plaque reduction neutralization test.The highest seropositivity of 82%was observed in vaccinated children during the first 0.5-1.5 years after booster vaccination.Then,the seropositivity began to decline and remained lower than the original level observed in the 0.5-1.5-year group.An association was found between the waning of seroprevalence and elapsed time of the post-booster vaccination.Similarly,the neutralizing antibody(nAb)titres gradually decreased over time,and the levels showed a positive correlation with the protective efficacy in mice.This finding suggests that nAbs play an important role in the antiviral process and that the nAb titre is an adequately credible parameter for evaluating the protective efficacy induced by the JE vaccine.Our results provide data that clarify the persistence and waning of antibodies to JEV,which may help elucidate the pathogenesis of JE.

Elevated expression of EBV and TLRs in the brain is associated with Rasmussen's encephalitis

Rasmussen's encephalitis(RE) is a rare pediatric neurological disorder, the etiology of which remains unclear. It has been speculated that the immunopathogenesis of RE involves damage to neurons, which eventually leads to the occurrence of RE. Viral infection may be a critical factor in triggering RE immunopathogenesis. In this study, we analyzed the expression of Epstein-Barr virus(EBV) antigens as well as of Toll-like receptor 3(TLR3), TLR9, and downstream adapter TIRdomain-containing adapter-inducing interferon-β(TRIF) in the brain tissues of 26 patients with RE and 16 control individuals using immunohistochemistry(IHC). In the RE group, EBV antigens were detected in 53% of individuals at various expression levels. In contrast, there was no detectable EBV antigen expression in control brain tissues. Moreover, we found marked increases in the expression of TLR3, TLR9, and TRIF in the brain tissues of RE patients compared with levels in the control group. Furthermore, among RE cases, EBV expression and high TLR3 expression were associated with more severe brain atrophy. Our results suggest that the elevated expression of EBV and TLRs may be involved in RE occurrence through the activation of downstream molecules.

Small G Rac1 is involved in replication cycle of dengue serotype 2 virus in EAhy926 cells via the regulation of actin cytoskeleton

Bleeding is a clinical characteristic of severe dengue and may be due to increased vascular permeability. However, the pathogenesis of severe dengue remains unclear. In this study, we showed that the Rac1-microfilament signal pathway was involved in the process of DENV serotype 2(DENV2) infection in EAhy926 cells. DENV2 infection induced dynamic changes in actin organization, and treatment with Cytochalasin D or Jasplakinolide disrupted microfilament dynamics, reduced DENV2 entry, and inhibited DENV2 assembly and maturation. Rac1 activities decreased during the early phase and gradually increased by the late phase of infection. Expression of the dominant-negative form of Rac1 promoted DENV2 entry but inhibited viral assembly, maturation and release. Our findings demonstrated that Rac1 plays an important role in the DENV2 life cycle by regulating actin reorganization in EAhy926 cells. This finding provides further insight into the pathogenesis of severe dengue.

Electroporation-Mediated Immunization of a Candidate DNA Vaccine Expressing Dengue Virus Serotype 4 prM-E Antigen Confers Long-Term Protection in Mice

Dengue fever, caused by dengue viruses(DENVs), is a widespread mosquito-borne zoonotic disease; however, there is no available anti-dengue vaccine for worldwide use. In the current study, a DNA vaccine candidate(pV-D4 ME) expressing prM-E protein of DENV serotype 4(DENV-4) was constructed, and its immunogenicity and protection were evaluated in immunocompetent BALB/c mice. The pV-D4 ME candidate vaccine induced effective humoral and cellular immunity of mice against DENV-4 in vivo when administered both at 50 μg and 5 μg through electroporation. Two weeks after receiving three immunizations, both doses of pV-D4 ME DNA were shown to confer effective protection against lethal DENV-4 challenge. Notably, at 6 months after the three immunizations, 50 μg, but not 5 μg, of pV-D4 ME could provide stable protection(100% survival rate) against DENV-4 lethal challenge without any obvious clinical signs. These results suggest that immunization with 50 μg pV-D4 ME through electroporation could confer effective and long-term protection against DENV-4, offering a promising approach for development of a novel DNA vaccine against DENVs.

Seroepidemiologic study on convalescent sera from dengue fever patients in Jinghong,Yunnan

After dengue virus(DENV)infection,antibody-dependent enhancement(ADE)is easy to occur when the neutralizing antibody(NAb)gradually decreases to a sub-neutralizing concentration.In this cohort surveillance,we utilized sera samples collected from dengue fever patients at different convalescent phases in Jinghong City,to investigate the dynamic change rule of DENV-specific antibodies,and to analyze the risk of ADE caused by secondary infection with heterologous serotypes DENVs.For baseline serosurvey,191 four-year and 99 six-year sera samples during convalescence were collected in 2017 and 2019,respectively.The positive rate of DENVspecific immunoglobulin G was 98.4%in 2017,which significantly decreased to 82.8%in 2019.The geometric mean titer(GMT)of NAb decreased from 1:155.35 to 1:46.66.Among 290 overall samples,73 paired consecutive samples were used for follow-up serosurvey.In four-year sera,the GMTs of NAb against DENV-3 and cross-reactive antibodies against DENV-1,DENV-2 and DENV-4 were 1:167.70,1:13.80,1:18.54 and 1:45.26,respectively,which decreased to 1:53.18,1:10.30,1:14.60 and 1:8.17 in six-year sera.In age-stratified analysis,due to the increasing number of ADE positive samples from 2017 to 2019 in 31–40 and 51–60 years groups,the risk of ADE in DENV-4 infection was positively associated with the extension of convalescent phase,and the odd ratio was higher than other groups.With the recovery period lengthened,the risk of secondary infection with DENV-1 and DENV-2 was reduced.Our results offer essential experimental data for risk prediction of severe dengue in hyper-endemic dengue areas,and provide crucial scientific insight for the development of effective dengue vaccines.

Seroprevalence of Dengue Virus among Young Adults in Beijing,China, 2019

Dear editor,Dengue is one of the major mosquito-borne diseases and prevalent across tropical and subtropical regions(CarodArtal et al.2013;Ferguson 2018).Infection with four serotypes of dengue virus(DENV1–4)individually or multiply may cause severe clinical manifestations and complications.In the mainland of China,dengue had been usually characterized as an imported epidemic disease in the past.

Prion Protein Expression is Correlated with Glioma Grades

Dear Editor,Glioma is the most common primary central nervous system(CNS)tumors in human.Gliomas are classified into low-grade glioma(LGG,grades I–II)and high-grade glioma(HGG,grades III–IV)according to the World Health Organization classification guidelines(Louis et al.2007).Comparing to the LGG,the HGG becomes more aggressive and has a poorer median overall survival.At present,glioma is mainly treated by radiotherapy,chemotherapy and surgical resection,but the effect is not ideal,especially for the glioblastoma(GBM),which is the most malignant type of gliomas and is resistant to current therapy protocols.There are several theories about the pathogenesis of glioma,such as radiation(Ohgaki and Kleihues 2005)。