Safety of Japanese encephalitis vaccines

Prevalence of Japanese encephalitis infection in children below 15 years' age, Bihar

Japanese encephalitis (JE) is the leading cause of acute encephalitis syndromes (AES). Although Bihar has comprehensive data on JE, it ranks third behind Uttar Pradesh and Assam in terms of reported cases. We wanted to determine the incidence of JE cases in Bihar and the endemic districts. In Patna, Muzaffarpur and Gaya, Bihar, this study revealed that JEV is one of the major causes of AES and its epidemiology. We analyzed blood and CSF samples from AES patients delivered to a viral diagnostic laboratory between January 2018 and December 2022 for IgM antibodies against JEV using the enzyme immunoassay recommended by NIV, Pune, India. We detected JEV IgM in 193 (8.79 %) of 2195 individuals. Patient demographics included age, gender and place of residence. Most patients were 6-10 years old and had the disease in June. We need to increase awareness initiatives and cross-sector prevention despite the decline in case fatality rate.

Comparative Analysis of Hemagglutination Inhibition and Plaque Reduction Neutralization Tests for Japanese Encephalitis Virus Antibody Detection

Japanese encephalitis (JE) is a zoonotic disease caused by the Japanese encephalitis virus (JEV), belonging to the Flaviviridae family. Diagnosis of Japanese encephalitis (JE) based on clinical signs alone is challenging due to the high proportion of subclinical cases. The Plaque Reduction Neutralization Test (PRNT) is considered the gold standard for detecting JE-specific antibodies because of its high specificity. However, PRNT is complex, time-consuming, and requires live viruses, limiting its applicability in routine diagnostics. In this study, we compared the sensitivity and correlation of the Hemagglutination Inhibition (HI) assay and PRNT for detecting JE antibodies in avian serum samples. We conducted a comparative analysis of the outcomes obtained from the PRNT and HI using 240 serum samples collected from 30 JEV-immunized avian subjects at various time points. Comparative analysis revealed a significant correlation between the HI and PRNT (R2 = 0.9321, p ≤ 0.0001). The Bland-Altman analysis also exhibited favorable concordance between the two assays. Consequently, HI may function as a viable substitute for PRNT in the screening of a substantial number of serum samples.

Antimicrobial Peptides Against Arboviruses: Mechanisms, Challenges, and Future Directions

This review delves into the potential of antimicrobial peptides (AMPs) as promising candidates for combating arboviruses, focusing on their mechanisms of antiviral activity, challenges, and future directions. AMPs have shown promise in preventing arbovirus attachment to host cells, inducing interferon production, and targeting multiple viral stages, illustrating their multifaceted impact on arbovirus infections. Structural elucidation of AMP-viral complexes is explored to deepen the understanding of molecular determinants governing viral neutralization, paving the way for structure-guided design. Furthermore, this review highlights the potential of AMP-based combination therapies to create synergistic effects that enhance overall treatment outcomes while minimizing the likelihood of resistance development. Challenges such as susceptibility to proteases, toxicity, and scalable production are discussed alongside strategies to address these limitations. Additionally, the expanding applications of AMPs as vaccine adjuvants and antiviral delivery systems are emphasized, underscoring their versatility beyond direct antiviral functions.

Changing epidemic patterns of infectious diseases during and after COVID-19 pandemic in Taiwan

Mitigation measures aimed at curbing the transmission of the severe acute respiratory syndrome coronavirus 2 effectively suppressed the occurrence of many respiratory infections other than coronavirus disease 2019. Several infections experienced a resurgence following the relaxation of non-pharmaceutical interventions, surpassing pre-pandemic levels in Taiwan. This phenomenon, known as immune debt, primarily affected respiratory infections in young children, including respiratory syncytial virus (RSV) infection. Infections transmitted by means other than droplets or contact did not exhibit significant changes in their epidemic patterns, such as varicella and Japanese encephalitis. Alterations in seasonality were noted for RSV infection and influenza, and these changes are also linked to immune debt. The recent emergence of severe pediatric pneumonia in northern China may be associated with immune debt and the rise of macrolide-resistant Mycoplasma pneumoniae associated with severe illness.

Trends in temporal and spatial changes of Japanese encephalitis in Chinese mainland, 2004-2019: A population-based surveillance study

BACKGROUND

Japanese encephalitis (JE) is a serious health concern in China, with approximately 80 % of global infections occurring in China. To develop effective prevention and control strategies, this study explored the epidemiological characteristics of JE in China based on spatiotemporal data, to understand the patterns and trends of JE incidence in different regions and time periods.

METHOD

The incidence and mortality rates of JE were extracted from the Public Health Data Center, the official website of the National Health Commission of the People's Republic of China, and the National Notifiable Infectious Disease Surveillance System from 2004 to 2019. Joinpoint regression was applied to examine the spatiotemporal patterns and annual percentage change in incidence and mortality of the JE.

RESULTS

From 2004 to 2019, a total of 43,569 cases of JE were diagnosed, including 2081 deaths. The annual incidence rate of JE decreased from 0.4171/100,000 in 2004 to 0.0298/100,000 in 2019, with an annual percentage change (APC) of -13.5 % (P < 0.001). The annual mortality rate of JE showed three stages of change, with inflection points in 2006 and 2014. The incidence and mortality rates of JE have declined in all provinces of China, and more cases were reported in 0-14 years of age, accounting for nearly 80 % of all patients.

CONCLUSIONS

The morbidity and mortality rates of JE in China are generally on a downward trend, and emphasis should be placed on strengthening disease surveillance in special areas and populations, popularizing vaccination, and increasing publicity.

AB5-Type Toxin as a Pentameric Scaffold in Recombinant Vaccines against the Japanese Encephalitis Virus

Japanese encephalitis virus (JEV) is an enveloped icosahedral capsid virus with a prime neutralizing epitope present in E protein domain III (EDIII). E dimers are rearranged into a five-fold symmetry of icosahedrons. Cholera toxin B (CTB) and heat-labile enterotoxin B (LTB) of AB5-type toxin was used as the structural scaffold for emulating the pentameric axis of EDIII. We produced homo-pentameric EDIII through the genetic fusion of LTB or CTB in E. coli without recourse to additional refolding steps. Harnessing an RNA-mediated chaperone further enhanced the soluble expression and pentameric assembly of the chimeric antigen. The pentameric assembly was validated by size exclusion chromatography (SEC), non-reduced gel analysis, and a GM1 binding assay. CTB/LTB-EDIII chimeric antigen triggered high neutralizing antibodies against the JEV Nakayama strain after immunization in mice. Altogether, our proof-of-principle study creating a JEV-protective antigen via fusion with an AB5-type toxin as both a pentameric scaffold and a built-in adjuvant posits the bacterially produced recombinant chimeric antigen as a cost-effective alternative to conventional inactivated vaccines against JEV.

The spatial-temporal pattern of Japanese encephalitis and its influencing factors in Guangxi, China

Japanese encephalitis (JE) is a major global public health threat. Using Japanese encephalitis incidence data from 2004 to 2010 in Guangxi Province, China, this study comprehensively explored the driving forces and the interactive effects between environmental and social factors of Japanese encephalitis using the Geo-detector method. The results indicated that the incidence of Japanese encephalitis showed a fluctuating downward trend from 2004 to 2010. The onset of JE was seasonal, mainly concentrated in June-July, and highly aggregated in northwestern Guangxi. Among the factors associated with Japanese encephalitis, days with temperatures >30 °C, accumulated temperatures >25 °C, slope, the normalized difference vegetation index, the gross domestic product of tertiary industries, the gross domestic product of primary industries and the number of pigs slaughtered showed higher contributions to Japanese encephalitis incidence. An enhanced interactive effect was found between environmental and social factors, and the interaction between days with humidity levels >80% and the gross domestic product of tertiary industries had the greatest combined effect on JE. These findings enhanced the understanding of the combined effect of social and environmental factors on the incidence of Japanese encephalitis and could help improve Japanese encephalitis transmission control and prevention strategies.

Recent advances to overcome the burden of Japanese encephalitis: A zoonotic infection with problematic early detection

Japanese encephalitis (JE) is a vector-borne neurotropic disease caused by Japanese encephalitis virus (JEV) associated with high mortality rate distributed from Eastern and Southern Asia to Northern Queensland (Australia). The challenges in early detection and lack of point-of-care biomarkers make it the most important Flavivirus causing encephalitis. There is no specific treatment for the disease, although vaccines are licenced. In this review, we focussed on point-of-care biomarkers as early detection tools and developing the effective therapeutic agents that could halt JE. We have also provided molecular details of JEV, disease progression, and its pathogenesis with recent findings which might bring insights to overcome the disease burden.

Molecular pathogenesis of Japanese encephalitis and possible therapeutic strategies

Japanese encephalitis virus (JEV), a single-stranded, enveloped RNA virus, is a health concern across Asian countries, associated with severe neurological disorders, especially in children. Primarily, pigs, bats, and birds are the natural hosts for JEV, but humans are infected incidentally. JEV requires a few host proteins for its entry and replication inside the mammalian host cell. The endoplasmic reticulum (ER) plays a significant role in JEV genome replication and assembly. During this process, the ER undergoes stress due to its remodelling and accumulation of viral particles and unfolded proteins, leading to an unfolded protein response (UPR). Here, we review the overall strategy used by JEV to infect the host cell and various cytopathic effects caused by JEV infection. We also highlight the role of JEV structural proteins (SPs) and non-structural proteins (NSPs) at various stages of the JEV life cycle that are involved in up- and downregulation of different host proteins and are potentially relevant for developing efficient therapeutic drugs.

Protective Immune Responses Induced by an mRNA-LNP Vaccine Encoding prM-E Proteins against Japanese Encephalitis Virus Infection

Japanese encephalitis virus (JEV) is an important zoonotic pathogen, which causes central nervous system symptoms in humans and reproductive disorders in swine. It has led to severe impacts on human health and the swine industry; however, there is no medicine available for treating yet. Therefore, vaccination is the best preventive measure for this disease. In the study, a modified mRNA vaccine expressing the prM and E proteins of the JEV P3 strain was manufactured, and a mouse model was used to assess its efficacy. The mRNA encoding prM and E proteins showed a high level of protein expression in vitro and were encapsulated into a lipid nanoparticle (LNP). Effective neutralizing antibodies and CD8+ T-lymphocytes-mediated immune responses were observed in vaccinated mice. Furthermore, the modified mRNA can protect mice from a lethal challenge with JEV and reduce neuroinflammation caused by JEV. This study provides a new option for the JE vaccine and lays a foundation for the subsequent development of a more efficient and safer JEV mRNA vaccine.