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Zaman K, Yunus M, Aziz AB, Feser J, Mooney J, Tang Y, Ellison DW, Thaisomboonsuk B, Zhang L, Neuzil KM, Marfin AA, Letson GW. Antibody persistence and immune memory response following primary vaccination and boosting with live attenuated SA 14-14-2 Japanese encephalitis vaccine (CD-JEV) in Bangladesh: A phase 4 open-label clinical trial. Vaccine X 2022; 10:100143. [PMID: 35243320 PMCID: PMC8857502 DOI: 10.1016/j.jvacx.2022.100143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/22/2021] [Accepted: 01/25/2022] [Indexed: 11/30/2022] Open
Abstract
Despite a lack of measurable antibody four years after primary vaccination, the anamnestic response to a booster dose of live, attenuated SA 14-14-2 Japanese encephalitis vaccine indicates immunity persists. Live, attenuated SA 14-14-2 Japanese encephalitis vaccine is safe and well-tolerated.
Introduction Japanese encephalitis (JE) virus is one of the leading causes of viral encephalitis across temperate and tropical zones of Asia. The live attenuated SA 14-14-2 JE vaccine (CD-JEV) is one of three vaccines prequalified by the World Health Organization (WHO) to prevent JE. WHO currently recommends a single CD-JEV dose for infants in endemic settings. However, in the absence of long-term immunogenicity data, WHO has indicated a need for long-term immunogenicity studies to inform optimal dosing schedules and determine the need for booster doses. Methods This Phase 4, open-label clinical study measured neutralizing antibody (NAb) titers in Bangladeshi children three and four years after primary CD-JEV vaccination and 7 and 28 days after a booster CD-JEV vaccination given four years after primary vaccination. The study also assessed the tolerability and safety of the booster dose. A NAb titer of ≥1:10 was considered seroprotective. Results Of 560 children vaccinated between 10 and 12 months of age with CD-JEV three years earlier and enrolled in this study from 30 July 2015 through 03 January 2016, 52 (9.3%; 95% CI: 7.2–12.0) had a seroprotective titer at enrollment. One year later, of 533 children, 66 (12.4%; 95% CI: 9.9–15.5) had a seroprotective titer before receiving a booster dose. Of 524 children who received a booster CD-JEV dose, 479 (91.4%; 95% CI: 88.7–93.5) and 514 (98.1%; 95% CI: 96.5–99.0) were seroprotected 7 and 28 days later, respectively. The geometric mean titer (GMT) was 6 (95% CI: 6–6) at baseline, 105 (95% CI: 93–119) 7 days post-booster, and 167 (95% CI: 152–183) 28 days post-booster. No vaccine-associated neurologic adverse events or other serious adverse events were noted following the booster dose. Conclusions Although most children did not have measurable antibody titers three and four years after a single primary CD-JEV dose, more than 90% of seronegative children had a strong anamnestic response within one week of a booster dose. This suggests that these children were immune despite the absence of measurable NAb prior to their booster. ClinicalTrials.gov Identifier: NCT02514746.
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Affiliation(s)
- K Zaman
- International Centre for Diarrheal Disease Research, 68, Shaheed Tajuddin Ahmed Sarani, Mohakhali, Dhaka 1212, Bangladesh
| | - Md Yunus
- International Centre for Diarrheal Disease Research, 68, Shaheed Tajuddin Ahmed Sarani, Mohakhali, Dhaka 1212, Bangladesh
| | - Asma B Aziz
- International Centre for Diarrheal Disease Research, 68, Shaheed Tajuddin Ahmed Sarani, Mohakhali, Dhaka 1212, Bangladesh
| | - Jodi Feser
- Center for Vaccine Innovation and Access, PATH, 2201 Westlake Ave, Suite 200, Seattle, Washington 98121, USA
| | - Jessica Mooney
- Center for Vaccine Innovation and Access, PATH, 2201 Westlake Ave, Suite 200, Seattle, Washington 98121, USA
| | - Yuxiao Tang
- Center for Vaccine Innovation and Access, PATH, 2201 Westlake Ave, Suite 200, Seattle, Washington 98121, USA
| | - Damon W Ellison
- Armed Forces Research Institute of Medicine Sciences, 315/6 Rajvithi Rd., Bangkok 10400, Thailand
| | - Butsaya Thaisomboonsuk
- Armed Forces Research Institute of Medicine Sciences, 315/6 Rajvithi Rd., Bangkok 10400, Thailand
| | - Lei Zhang
- Chengdu Institute of Biological Products Co., Ltd., 379, 3rd, Jinhua Road, Jinjiang District, Chengdu 61002, China
| | - Kathleen M Neuzil
- Center for Vaccine Innovation and Access, PATH, 2201 Westlake Ave, Suite 200, Seattle, Washington 98121, USA
| | - Anthony A Marfin
- Center for Vaccine Innovation and Access, PATH, 2201 Westlake Ave, Suite 200, Seattle, Washington 98121, USA
| | - G William Letson
- Center for Vaccine Innovation and Access, PATH, 2201 Westlake Ave, Suite 200, Seattle, Washington 98121, USA
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He J, Chen J, Han X, Gu Q, Liang J, Sun M, Liu S, Yao Y, Shi L. Association of HLA-DM and HLA class II Genes with Antibody Response Induced by Inactivated Japanese Encephalitis Vaccine. HLA 2022; 99:357-367. [PMID: 35118816 DOI: 10.1111/tan.14575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 01/29/2022] [Accepted: 01/31/2022] [Indexed: 11/04/2022]
Abstract
HLA (HLA) class II molecules, HLA-DR, DP, and DQ, together with HLA II-like protein DM, play a dominant role in the processing and presentation of antigens, which may influence vaccine effectiveness. We previously demonstrated that variations in the HLA-DRB1, DPB1, and DQB1 genes may affect the neutralising antibody (NAb) response induced by the inactivated Japanese encephalitis vaccine (IJEV). In the present study, we genotyped HLA-DPA1, DQA1, DMA, and DMB genes and used previous HLA-DRB1, DPB1, and DQB1 data to evaluate the association of these genes with IJEV-induced NAbs, at both the seroconversion and geometric mean titres (GMTs). We confirmed the seropositive association of DQB1*02:01 and NAbs (0.156 vs. 0.075, Padj = 0.018; OR = 2.270; 95% CI = 1.285-3.999) and seronegative association of DQB1*02:02 (0.014 vs. 0.09, Padj = 0.0002; OR = 0.130; 95% CI = 0.047-0.400). Furthermore, the DMB*01:03-DMA*01:01-DPA1*01:03-DPB1*04:01 haplotype was associated with a negative response (0.020 vs. 0.074; Padj = 0.03; OR = 0.250; 95% CI = 0.097-0.649), whereas DRB1*15:02-DMB*01:01-DMA*01:01 was associated with a positive response (0.034 vs. 0; Padj = 0.044). In addition, DRB1*12:02, DRB1*13:02, DPB1*04:01, DPB1*05:01, DPB1*09:01, DQA1*06:01, and DQA1*01:02 were associated with a higher GMT of NAbs, whereas DRB1*11:01, DPB1*13:01, and DQA1*05:05 were associated with a lower GMT of NAbs. In conclusion, the present study suggests that variations in the HLA-DM and HLA class II genes, as well as their combined allotypes, may influence the IJEV NAbs at seroconversion and GMT levels. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Jihong He
- Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China
| | - Jun Chen
- Department of Immunogenetics, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China
| | - Xue Han
- Department of Immunogenetics, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China
| | - Qin Gu
- Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China.,Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Disease, Kunming, China
| | - Jiangli Liang
- Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China.,Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Disease, Kunming, China
| | - Mingbo Sun
- Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China.,Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Disease, Kunming, China
| | - Shuyuan Liu
- Department of Immunogenetics, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China
| | - Yufeng Yao
- Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China
| | - Li Shi
- Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Disease, Kunming, China
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Ngwe Tun MM, Kyaw AK, Nwe KM, Inoue S, Thant KZ, Morita K. Effectiveness of the SA 14-14-2 Live-Attenuated Japanese Encephalitis Vaccine in Myanmar. Vaccines (Basel) 2021; 9:vaccines9060568. [PMID: 34072933 PMCID: PMC8227667 DOI: 10.3390/vaccines9060568] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 11/24/2022] Open
Abstract
Myanmar is an endemic country for the Japanese encephalitis virus (JEV), and the SA-14-14-2 live-attenuated JEV vaccine was first introduced as a catch-up vaccination campaign in 2017. To determine the effectiveness of vaccination by means of neutralizing antibody titers against JEV, a cross-sectional descriptive study was conducted among five to 15-year-old monastic school children in Mandalay, Myanmar. A total of 198 students who had received vaccines were recruited, and single-time investigation of anti-JEV IgG and neutralizing antibodies against wild-type JEV were determined using anti-JEV IgG ELISA and plaque reduction neutralization tests (PRNT50). All students 100% (198/198) showed positive results on the anti-JEV IgG ELISA, and 87% (172/198) of the students had neutralizing antibodies against JEV six months after immunization. The geometric mean titers of both IgG antibodies and neutralizing antibodies increased with the participants’ age groups, and statistically significant differences in anti-JEV IgG titers were noted across age groups. In this study, we could not investigate the persistence of neutralizing antibodies as only single-time blood collection was done. This study, which is the first report of JEV vaccination among children in Myanmar, showed similar neutralizing antibody production rates among vaccinated individuals as did studies in other countries.
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Affiliation(s)
- Mya Myat Ngwe Tun
- Department of Virology, Institute of Tropical Medicine and Leading Program, Nagasaki University, Nagasaki 852-8523, Japan; (K.M.N.); (S.I.); (K.M.)
- Correspondence: ; Tel.: +81-95-819-7829
| | - Aung Kyaw Kyaw
- Department of Medical Research, Pyin Oo Lwin Branch, Pyin Oo Lwin 05082, Myanmar;
| | - Khine Mya Nwe
- Department of Virology, Institute of Tropical Medicine and Leading Program, Nagasaki University, Nagasaki 852-8523, Japan; (K.M.N.); (S.I.); (K.M.)
| | - Shingo Inoue
- Department of Virology, Institute of Tropical Medicine and Leading Program, Nagasaki University, Nagasaki 852-8523, Japan; (K.M.N.); (S.I.); (K.M.)
| | - Kyaw Zin Thant
- Myanmar Academy of Medical Sciences, Yangon 11181, Myanmar;
| | - Kouichi Morita
- Department of Virology, Institute of Tropical Medicine and Leading Program, Nagasaki University, Nagasaki 852-8523, Japan; (K.M.N.); (S.I.); (K.M.)
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Vadrevu KM, Potula V, Khalatkar V, Mahantshetty NS, Shah A, Ella R. Persistence of Immune Responses With an Inactivated Japanese Encephalitis Single-Dose Vaccine, JENVAC and Interchangeability With a Live-Attenuated Vaccine. J Infect Dis 2021; 222:1478-1487. [PMID: 31858116 PMCID: PMC7529014 DOI: 10.1093/infdis/jiz672] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 12/18/2019] [Indexed: 12/03/2022] Open
Abstract
Background This study reports immunogenicity, safety, and interchangeability of a single-dose, inactivated, Vero-cell derived, JENVAC to the live-attenuated SA 14-14-2 vaccine in healthy children. Methods This phase 4, multicenter, open-label, randomized, control trial enrolled 360 children who were equally randomized to receive a single dose of either JENVAC or SA 14-14-2. Children were followed at various time points, until 2 years (day 720) postvaccination, upon which a subset from each group was divided and allocated to a receive a booster dose or the other vaccine. Results At all time points, immunological measures were statistically higher in the JENVAC group. In the interchangeability study, children receiving 2 doses of JENVAC reported significantly higher response compared with 2 doses of SA 14-14-2. No difference in adverse events was observed. These corroborate with excellent seroprotection after the first dose of an earlier JENVAC study. Conclusions A single-dose vaccination with JENVAC induces protective titers that persist up to 1 year. We report appreciable interchangeability between both vaccines, with JENVAC/JENVAC combination exhibiting the highest immune response. JENVAC is now licensed as a single-dose Japanese encephalitis vaccine.
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Affiliation(s)
| | | | - Vasant Khalatkar
- Colours Children Hospital, Jasleen, Pachsheel Square, Nagpur, India
| | | | | | - Raches Ella
- Bharat Biotech International Limited, Genome Valley, Shameerpet, Hyderabad, India
- Correspondence: Raches Ella, MBBS, MS, Bharat Biotech International Ltd., Genome Valley, Turakapally, Shameerpet, Hyderabad, Telangana 500078, India ()
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Hills S, Van Keulen A, Feser J, Panella A, Letson B, Staples E, Marfin T, Brault A. Persistence of IgM Antibodies after Vaccination with Live Attenuated Japanese Encephalitis Vaccine. Am J Trop Med Hyg 2020; 104:576-579. [PMID: 33236716 PMCID: PMC7866339 DOI: 10.4269/ajtmh.20-1132] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 10/13/2020] [Indexed: 12/27/2022] Open
Abstract
Japanese encephalitis (JE) is a vaccine-preventable, mosquito-borne disease. Substantial progress with JE control in Asia has been made during the past decade, with most endemic countries now having JE vaccination programs, commonly using live attenuated SA14-14-2 JE vaccine (trade name CD-JEV). If a child develops encephalitis during the weeks to months following CD-JEV vaccination and anti-JE virus IgM (JE IgM) antibody is detected in serum, the question arises if this is JE virus infection indicating vaccine failure, or persistent JE IgM antibody postvaccination. To better understand JE IgM seropositivity following vaccination, sera from 268 children from a previous CD-JEV study were tested by two different JE IgM assays to determine JE IgM antibody frequency on days 28, 180, and 365 postvaccination. With the CDC JE IgM antibody capture ELISA (MAC-ELISA), 110 children (41%) had JE IgM positive or equivocal results on their day 28 sample, and eight (3%) and two (1%) had positive or equivocal results on day 180 and day 365 samples, respectively. With the InBios JE Detect™ MAC-ELISA (Seattle, WA), 118 (44%) children had positive or equivocal results on day 28 sample, and three (1%) and one (0.4%) had positive or equivocal results on day 180 and day 365 samples, respectively. Our results indicate that more than 40% children vaccinated with CD-JEV can have JE IgM antibodies in their serum at 1 month postvaccination but JE IgM antibody is rare by 6 months. These data will help healthcare workers assess the likelihood that JE IgM antibodies in the serum of a child with encephalitis after vaccination are vaccine related.
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Affiliation(s)
- Susan Hills
- Arboviral Diseases Branch, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | - Alex Van Keulen
- Arboviral Diseases Branch, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | | | - Amanda Panella
- Arboviral Diseases Branch, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | | | - Erin Staples
- Arboviral Diseases Branch, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | | | - Aaron Brault
- Arboviral Diseases Branch, Centers for Disease Control and Prevention, Fort Collins, Colorado
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Abstract
Japanese encephalitis is a mosquito-borne disease that occurs in Asia and is caused by Japanese encephalitis virus (JEV), a member of the genus Flavivirus. Although many flaviviruses can cause encephalitis, JEV causes particularly severe neurological manifestations. The virus causes loss of more disability-adjusted life years than any other arthropod-borne virus owing to the frequent neurological sequelae of the condition. Despite substantial advances in our understanding of Japanese encephalitis from in vitro studies and animal models, studies of pathogenesis and treatment in humans are lagging behind. Few mechanistic studies have been conducted in humans, and only four clinical trials of therapies for Japanese encephalitis have taken place in the past 10 years despite an estimated incidence of 69,000 cases per year. Previous trials for Japanese encephalitis might have been too small to detect important benefits of potential treatments. Many potential treatment targets exist for Japanese encephalitis, and pathogenesis and virological studies have uncovered mechanisms by which these drugs could work. In this Review, we summarize the epidemiology, clinical features, prevention and treatment of Japanese encephalitis and focus on potential new therapeutic strategies, based on repurposing existing compounds that are already suitable for human use and could be trialled without delay. We use our newly improved understanding of Japanese encephalitis pathogenesis to posit potential treatments and outline some of the many challenges that remain in tackling the disease in humans.
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Liu X, Jia L, Nie K, Zhao D, Na R, Xu H, Cheng G, Wang J, Yu Y, Li Y. Evaluation of environment safety of a Japanese encephalitis live attenuated vaccine. Biologicals 2019; 60:36-41. [PMID: 31178277 DOI: 10.1016/j.biologicals.2019.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/25/2019] [Accepted: 06/01/2019] [Indexed: 02/05/2023] Open
Abstract
JE vaccination is the most effective and economical method of preventing JE. A live attenuated JE vaccine has been widely used in many countries since 1989, playing an important role in controlling JE outbreaks. However, whether the large-scale use of the live attenuated JE vaccine will lead to the dissemination of the vaccine virus in the environment and whether reversion of the neuroattenuation of the virus will occur during the transmission process remain major concerns for some researchers. To evaluate the transmission of a live attenuated JEV vaccine in mosquitoes and hosts, JE SA14-14-2 attenuated vaccine virus was intrathoracically (i.t.) inoculated into Culex tritaeniorhynchus, a native vector. Subsequently, virus harvested from inoculated mosquitoes was inoculated into pigs, a mammalian reservoir. The virus was isolated from the pigs and passaged once again in Culex tritaeniorhynchus. The genome sequences and virulence of the passaged viruses were then investigated. While a few nucleotide substitutions occurred during passaging, there was no change in the encoded amino acids. After intracerebral (i.c.) inoculation of mice with the vaccine, no pathological effects were observed. In addition, virus virulence remained low after inoculation of suckling mouse brains. These results indicate that vaccination of individuals with the live vaccine will not result in transmission of the live SA14-14-2 vaccine virus through mosquito biting and virus amplified in pigs.
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Affiliation(s)
- Xinyu Liu
- National Institutes for Food and Drug Control, Beijing 102629, PR China
| | - Lili Jia
- National Institutes for Food and Drug Control, Beijing 102629, PR China
| | - Kaixiao Nie
- Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, PR China
| | - Danhua Zhao
- National Institutes for Food and Drug Control, Beijing 102629, PR China
| | - Rui Na
- National Institutes for Food and Drug Control, Beijing 102629, PR China
| | - Hongshan Xu
- National Institutes for Food and Drug Control, Beijing 102629, PR China
| | - Gong Cheng
- Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, PR China
| | - Junzhi Wang
- National Institutes for Food and Drug Control, Beijing 102629, PR China.
| | - Yongxin Yu
- National Institutes for Food and Drug Control, Beijing 102629, PR China.
| | - Yuhua Li
- National Institutes for Food and Drug Control, Beijing 102629, PR China; State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu 610041, PR China.
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Yao Y, Yang H, Shi L, Liu S, Li C, Chen J, Zhou Z, Sun M, Shi L. HLA Class II Genes HLA-DRB1, HLA-DPB1, and HLA-DQB1 Are Associated With the Antibody Response to Inactivated Japanese Encephalitis Vaccine. Front Immunol 2019; 10:428. [PMID: 30906300 PMCID: PMC6418001 DOI: 10.3389/fimmu.2019.00428] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 02/18/2019] [Indexed: 01/31/2023] Open
Abstract
Aim: The objective of this study was to evaluate the association of the human leukocyte antigen (HLA) class II genes HLA-DRB1, HLA-DPB1, and HLA-DQB1 with the humoral immune response elicited by inactivated Japanese encephalitis (JE) vaccine (IJEV). Methods: A total of 373 individuals aged 3–12 years in the Inner Mongolia Autonomous Region in China, who received two doses of IJEV at 0 and 7 days, were enrolled in the current study. Based on the individuals' specific JE virus (JEV)-neutralizing antibodies (NAbs), they were divided into a seropositive and a seronegative group. HLA-DRB1, HLA-DPB1, and HLA-DQB1 were genotyped using a sequencing-based typing method. Next, the association of the HLA class II genes and their haplotypes with antibody response was evaluated. Results: Based on NAbs, a total of 161 individuals were classified as seropositive and 212 as seronegative. DQB1*02:01 was significantly associated with JEV seropositivity (P < 0.001, OR = 0.364, 95% CI: 0.221–0.600), while DQB1*02:02 was significantly associated with JEV seronegativity (P = 5.03 × 10−6, OR = 7.341, 95% CI: 2.876–18.736). The haplotypes DRB1*07:01-DPB1*04:01-DQB1*02:01, DRB1*15:01-DPB1*02:01-DQB1*06:02, DRB1*07:01-DQB1*02:01, and DPB1*02:01-DQB1*06:02 were very frequent in the seropositive group, while DRB1*07:01-DPB1*17:01-DQB1*02:02, DRB1*07:01-DQB1*02:02, and DPB1*17:01-DQB1*02:02 were very frequent in the seronegative group. The presence of DRB1*01:01, DRB1*04:05, DRB1*09:01, DRB1*12:02, DRB1*13:02, and DRB1*14:01 was associated with a higher geometric mean titer (GMT) of NAbs than that of DRB1*11:01 at the DRB1 locus (P < 0.05). At the DPB1 locus, the presence of DPB1*05:01 was associated with higher GMTs than that of DPB1*02:01 and DPB1*13:01 (P < 0.05), and the presence of DPB1*04:01 and DPB1*09:01 was associated with higher GMTs than that of DPB1*13:01 (P < 0.05). Conclusions: The present study suggests that HLA class II genes may influence the antibody response to IJEV.
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Affiliation(s)
- Yufeng Yao
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
| | - Huijuan Yang
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China.,Yunnan Key Laboratory of Vaccine Research and Development on Severe Infectious Disease, Kunming, China
| | - Lei Shi
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China.,Yunnan Key Laboratory of Vaccine Research and Development on Severe Infectious Disease, Kunming, China
| | - Shuyuan Liu
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
| | - Chuanying Li
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
| | - Jun Chen
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
| | - Ziyun Zhou
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
| | - Mingbo Sun
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China.,Yunnan Key Laboratory of Vaccine Research and Development on Severe Infectious Disease, Kunming, China
| | - Li Shi
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
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Barzon L, Palù G. Recent developments in vaccines and biological therapies against Japanese encephalitis virus. Expert Opin Biol Ther 2018; 18:851-864. [DOI: 10.1080/14712598.2018.1499721] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Luisa Barzon
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Giorgio Palù
- Department of Molecular Medicine, University of Padova, Padova, Italy
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10
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Ginsburg AS, Meghani A, Halstead SB, Yaich M. Use of the live attenuated Japanese Encephalitis vaccine SA 14-14-2 in children: A review of safety and tolerability studies. Hum Vaccin Immunother 2017; 13:2222-2231. [PMID: 28841362 DOI: 10.1080/21645515.2017.1356496] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Japanese encephalitis (JE) is the leading cause of viral neurological disease and disability in Asia. Some 50-80% of children with clinical JE die or have long-term neurologic sequelae. Since there is no cure, human vaccination is the only effective long-term control measure, and the World Health Organization recommends that at-risk populations receive a safe and effective vaccine. Four different types of JE vaccines are currently available: inactivated mouse brain-derived vaccines, inactivated Vero cell vaccines, live attenuated SA 14-14-2 vaccines and a live recombinant (chimeric) vaccine. With the rapidly increasing demand for and availability and use of JE vaccines, countries face an important decision in the selection of a JE vaccine. This article provides a comprehensive review of the available safety literature for the live attenuated SA 14-14-2 JE vaccine (LAJEV), the most widely used new generation JE vaccine. With well-established effectiveness data, a single dose of LAJEV protects against clinical JE disease for at least 5 years, providing a long duration of protection compared with inactivated mouse brain-derived vaccines. Since 1988, about 700 million doses of the LAJEV have been distributed globally. Our review found that LAJEV is well tolerated across a wide age range and can safely be given to children as young as 8 months of age. While serious adverse events attributable to LAJEV have been reported, independent experts have not found sufficient evidence for causality based on the available data.
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Affiliation(s)
| | - Ankita Meghani
- b Department of International Health , Johns Hopkins Bloomberg School of Public Health , Baltimore , MD , USA
| | - Scott B Halstead
- c Department of Preventive Medicine and Biometrics , Uniformed Services University of the Health Sciences , Bethesda , MD , USA
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11
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Hegde NR, Gore MM. Japanese encephalitis vaccines: Immunogenicity, protective efficacy, effectiveness, and impact on the burden of disease. Hum Vaccin Immunother 2017; 13:1-18. [PMID: 28301270 DOI: 10.1080/21645515.2017.1285472] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Japanese encephalitis (JE) is a serious public health concern in most of Asia. The disease is caused by JE virus (JEV), a flavivirus transmitted by Culex mosquitoes. Several vaccines have been developed to control JE in endemic areas as well as to protect travelers and military personnel who visit or are commissioned from non-endemic to endemic areas. The vaccines include inactivated vaccines produced in mouse brain or cell cultures, live attenuated vaccines, and a chimeric vaccine based on the live attenuated yellow fever virus 17D vaccine strain. All the marketed vaccines belong to the JEV genotype III, but have been shown to be efficacious against other genotypes and strains, with varying degrees of cross-neutralization, albeit at levels deemed to be protective. The protective responses have been shown to last three or more years, depending on the type of vaccine and the number of doses. This review presents a brief account of the different JE vaccines, their immunogenicity and protective ability, and the impact of JE vaccines in reducing the burden of disease in endemic countries.
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Affiliation(s)
- Nagendra R Hegde
- a Ella Foundation, Genome Valley , Turkapally, Shameerpet Mandal , Hyderabad , India
| | - Milind M Gore
- b National Institute of Virology, Indian Council of Medical Research , Pune , India
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12
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Turtle L, Tatullo F, Bali T, Ravi V, Soni M, Chan S, Chib S, Venkataswamy MM, Fadnis P, Yaïch M, Fernandez S, Klenerman P, Satchidanandam V, Solomon T. Cellular Immune Responses to Live Attenuated Japanese Encephalitis (JE) Vaccine SA14-14-2 in Adults in a JE/Dengue Co-Endemic Area. PLoS Negl Trop Dis 2017; 11:e0005263. [PMID: 28135273 PMCID: PMC5279729 DOI: 10.1371/journal.pntd.0005263] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 12/15/2016] [Indexed: 11/21/2022] Open
Abstract
Background Japanese encephalitis (JE) virus (JEV) causes severe epidemic encephalitis across Asia, for which the live attenuated vaccine SA14-14-2 is being used increasingly. JEV is a flavivirus, and is closely related to dengue virus (DENV), which is co-endemic in many parts of Asia, with clinically relevant interactions. There is no information on the human T cell response to SA14-14-2, or whether responses to SA14-14-2 cross-react with DENV. We used live attenuated JE vaccine SA14-14-2 as a model for studying T cell responses to JEV infection in adults, and to determine whether these T cell responses are cross-reactive with DENV, and other flaviviruses. Methods We conducted a single arm, open label clinical trial (registration: clinicaltrials.gov NCT01656200) to study T cell responses to SA14-14-2 in adults in South India, an area endemic for JE and dengue. Results Ten out of 16 (62.5%) participants seroconverted to JEV SA14-14-2, and geometric mean neutralising antibody (NAb) titre was 18.5. Proliferation responses were commonly present before vaccination in the absence of NAb, indicating a likely high degree of previous flavivirus exposure. Thirteen of 15 (87%) participants made T cell interferon-gamma (IFNγ) responses against JEV proteins. In four subjects tested, at least some T cell epitopes mapped cross-reacted with DENV and other flaviviruses. Conclusions JEV SA14-14-2 was more immunogenic for T cell IFNγ than for NAb in adults in this JE/DENV co-endemic area. The proliferation positive, NAb negative combination may represent a new marker of long term immunity/exposure to JE. T cell responses can cross-react between JE vaccine and DENV in a co-endemic area, illustrating a need for greater knowledge on such responses to inform the development of next-generation vaccines effective against both diseases. Trial Registration clinicaltrials.gov (NCT01656200) The Flavivirus genus member Japanese encephalitis (JE) virus (JEV), causes severe brain disease in tens of thousands of children across Asia every year. JE is vaccine preventable, and the immune response to JEV plays a major role in disease outcome. However, the response to JEV is hard to study as JE affects young children in rural areas. Related flaviviruses, such as dengue virus (which has no good vaccine), can influence the outcome of JE, probably due to cross-reactive immune responses. T cells (a subset of white blood cells) respond to virus infections, but we know little about the timing and nature of T cell responses to JEV after infection and whether T cells are protective against JEV. We used the live JE vaccine SA14-14-2 as a model to study the immune response to JEV. We found T cell responses frequently after JE vaccination. In this small group of volunteers, many of whom were exposed to dengue virus, most of the T cell responses tested cross-reacted between JEV and dengue virus. However, only about two thirds of people made antibody responses to the vaccine. Studying these responses could help design new vaccines for use against JE and dengue in Asia.
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Affiliation(s)
- Lance Turtle
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
- NIHR Health Protection Research Unit for Emerging and Zoonotic Infections, University of Liverpool, Liverpool, United Kingdom
- Tropical & Infectious Disease Unit, Royal Liverpool University Hospital, Liverpool, United Kingdom
- * E-mail: (LT); (VS)
| | - Filippo Tatullo
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
- Dept of Neurovirology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
| | - Tanushka Bali
- Dept of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Vasanthapuram Ravi
- Dept of Neurovirology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
| | - Mohammed Soni
- Dept of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Sajesh Chan
- Dept of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Savita Chib
- Dept of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Manjunatha M. Venkataswamy
- Dept of Neurovirology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
| | - Prachi Fadnis
- Dept of Neurovirology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
| | | | - Stefan Fernandez
- Dept of Virology, Armed Forces Research Institute of Medical Science (AFRIMS), Bangkok, Thailand
| | - Paul Klenerman
- Translational Gastroenterology Unit, Nuffield Dept. of Medicine, University of Oxford, Peter Medawar Building for Pathogen Research, Oxford, United Kingdom
| | - Vijaya Satchidanandam
- Dept of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
- * E-mail: (LT); (VS)
| | - Tom Solomon
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
- NIHR Health Protection Research Unit for Emerging and Zoonotic Infections, University of Liverpool, Liverpool, United Kingdom
- Walton Centre NHS Foundation Trust, Liverpool, United Kingdom
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13
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Wijesinghe PR, Abeysinghe MRN, Yoksan S, Yao Y, Zhou B, Zhang L, Fleming JA, Marfin AA, Victor JC. Immunogenicity of live attenuated Japanese encephalitis SA 14-14-2 vaccine among Sri Lankan children with previous receipt of inactivated JE vaccine. Vaccine 2016; 34:5923-5928. [PMID: 27773472 PMCID: PMC5104688 DOI: 10.1016/j.vaccine.2016.10.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 10/05/2016] [Accepted: 10/06/2016] [Indexed: 11/20/2022]
Abstract
BACKGROUND The performance of live attenuated Japanese Encephalitis SA 14-14-2 vaccine (CD-JEV) among children previously given inactivated mouse brain-derived JE vaccine (IMBV) is unknown. We evaluated the safety and immunogenicity of CD-JEV administered to 2- and 5-year-old children in Sri Lanka. METHODS In this open-label, single arm trial in the Colombo District of Sri Lanka, generally healthy children 2 and 5years of age who had previously received two and three doses of IMBV, respectively, were administered one dose of CD-JEV subcutaneously. Participants were monitored for adverse events for one year post-vaccination. Serum neutralizing antibody responses were evaluated pre and 28 and 365days post-vaccination using JE plaque reduction neutralization test and characterized as the proportion of participants seroconverting. Seroconversion was defined as either reaching a titer considered seroprotective (⩾1:10) among participants with a baseline titer <1:10 or achieving at least a 4-fold rise in titer among participants with a baseline titer ⩾1:10. RESULTS Of 305 children given CD-JEV, 294 were included in the primary analysis of immunogenicity. Prior to vaccination, 144/147 (98.0%) 2-year-olds and 146/147 (99.3%) 5-year-olds had seroprotective levels. 28days post-vaccination, 79/147 [53.7% (95% CI, 45.3-62.0)] 2-year olds and of 60/147 [40.8% (95% CI, 32.8-49.2)] 5-year olds achieved seroconversion. Among 2-year-olds, geometric mean titers (GMTs) rose from 697 to 3175 28days post-vaccination. Among 5-year-olds, GMTs rose from 926 to 2776. Most adverse reactions were mild, and no serious adverse events were related to study vaccination. CONCLUSION Administration of CD-JEV to these children with pre-existing neutralizing JE antibody titers was safe and resulted in substantial boosting of antibody levels. These results may inform other countries in Asia considering switching from IMBV to now WHO-prequalified CD-JEV vaccine to combat this disease of public health importance.
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MESH Headings
- Antibodies, Neutralizing/blood
- Antibodies, Viral/blood
- Child, Preschool
- Encephalitis Virus, Japanese/immunology
- Encephalitis, Japanese/epidemiology
- Encephalitis, Japanese/prevention & control
- Female
- Humans
- Immunization, Secondary
- Immunogenicity, Vaccine
- Japanese Encephalitis Vaccines/administration & dosage
- Japanese Encephalitis Vaccines/adverse effects
- Japanese Encephalitis Vaccines/immunology
- Male
- Sri Lanka/epidemiology
- Subcutaneous Absorption
- Vaccination
- Vaccines, Attenuated/administration & dosage
- Vaccines, Attenuated/adverse effects
- Vaccines, Attenuated/immunology
- Vaccines, Inactivated/administration & dosage
- Vaccines, Inactivated/adverse effects
- Vaccines, Inactivated/immunology
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Affiliation(s)
| | | | | | - Yafu Yao
- Chengdu Institute of Biological Products, Chengdu, China
| | - Benli Zhou
- Chengdu Institute of Biological Products, Chengdu, China
| | - Lei Zhang
- Chengdu Institute of Biological Products, Chengdu, China
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14
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Erra EO, Kantele A. The Vero cell-derived, inactivated, SA14-14-2 strain-based vaccine (Ixiaro) for prevention of Japanese encephalitis. Expert Rev Vaccines 2015; 14:1167-79. [PMID: 26162529 DOI: 10.1586/14760584.2015.1061939] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
With an estimated 68,000 cases each year, Japanese encephalitis (JE) is the leading cause of viral encephalitis in Asia. Vaccination against the disease is recommended for endemic populations and also for travelers at risk. Recently, a Vero cell-derived, inactivated, SA14-14-2 strain-based JE vaccine (JE-VC) became available for travelers from non-endemic regions, replacing the traditional mouse brain-derived vaccines. First licensed in 2009, JE-VC is currently available in Europe, the USA, Canada, Australia and several other countries. In 2013, the vaccine was approved by the European Medicines Agency and the US Food and Drug Administration for use in children. This review summarizes current data on the immunogenicity, safety and clinical use of JE-VC.
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Affiliation(s)
- Elina O Erra
- Haartman Institute, University of Helsinki, Helsinki, Finland
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15
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Kwon HJ, Lee SY, Kim KH, Kim DS, Cha SH, Jo DS, Kang JH. The Immunogenicity and Safety of the Live-attenuated SA 14-14-2 Japanese Encephalitis Vaccine Given with a Two-dose Primary Schedule in Children. J Korean Med Sci 2015; 30:612-6. [PMID: 25931793 PMCID: PMC4414646 DOI: 10.3346/jkms.2015.30.5.612] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 12/10/2014] [Indexed: 11/25/2022] Open
Abstract
Effective and tolerable vaccination is an essential strategy to prevent Japanese encephalitis (JE) in endemic areas. Although the live attenuated SA 14-14-2 JE vaccine (LAJEV) has been widely used since its introduction, the systemic data of LAJEV was very rarely available in Korea. We conducted the open-label, prospective cohort study to assess the immunogenicity and safety of this vaccine. Ninety subjects were enrolled, and LAJEV in a 2-dose primary series was given with a 12-month interval. Neutralizing antibody titers were measured before and after each vaccination, and active monitoring for adverse events was performed. After the first dose, 91.1% of subjects had seroprotection with a geometric mean titer (GMT) of 40.9. Seroprotection rate after the second dose was 97%, and GMT showed an increase of 6.5-fold. Most adverse events following immunization were self-limited, and no serious adverse events were reported until 42 days after each dose. The 2-dose administration of LAJEV in the primary immunization schedule appeared to be highly immunogenic and safe.
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Affiliation(s)
- Hyo Jin Kwon
- Department of Pediatrics, The Catholic University of Korea College of Medicine, Seoul, Korea
| | - Soo Young Lee
- Department of Pediatrics, The Catholic University of Korea College of Medicine, Seoul, Korea
| | - Ki Hwan Kim
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
| | - Dong Soo Kim
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
| | - Sung Ho Cha
- Department of Pediatrics, Kyunghee University College of Medicine, Seoul, Korea
| | - Dae Sun Jo
- Department of Pediatrics, Chonbuk National University College of Medicine, Jeonju, Korea
| | - Jin Han Kang
- Department of Pediatrics, The Catholic University of Korea College of Medicine, Seoul, Korea
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16
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Xu M, Liang Z, Xu Y, Wang J. Chinese vaccine products go global: vaccine development and quality control. Expert Rev Vaccines 2015; 14:763-73. [PMID: 25697690 DOI: 10.1586/14760584.2015.1012503] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Through the continuous efforts of several generations, China has become one of the few countries in the world that is capable of independently addressing all the requirements by the Expanded Program on Immunization. Regulatory science is applied to continuously improve the vaccine regulatory system. Passing the prequalification by WHO has allowed Chinese vaccine products to go global. Chinese vaccine products not only secure disease prevention and control domestically but also serve the needs for international public health. This article describes the history of Chinese vaccine development, the current situation of Chinese vaccine industry and its contribution to the prevention and control of infectious diseases. We also share our experience of national quality control and vaccine regulation during the past decades. China's experience in vaccine development and quality control can benefit other countries and regions worldwide, including the developing countries.
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Affiliation(s)
- Miao Xu
- Key Laboratory of the Ministry of Health for Research on Quality and Standardization of Biotech Products, National Institutes for Food and Drug Control, No.2, Tiantan Xili, Dongcheng District, Beijing 100050, People's Republic of China
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17
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Zaman K, Naser AM, Power M, Yaich M, Zhang L, Ginsburg AS, Luby SP, Rahman M, Hills S, Bhardwaj M, Flores J. Lot-to-lot consistency of live attenuated SA 14-14-2 Japanese encephalitis vaccine manufactured in a good manufacturing practice facility and non-inferiority with respect to an earlier product. Vaccine 2014; 32:6061-6. [PMID: 25239483 DOI: 10.1016/j.vaccine.2014.09.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 08/30/2014] [Accepted: 09/03/2014] [Indexed: 11/15/2022]
Abstract
We conducted a four-arm, double-blind, randomized controlled trial among 818 Bangladeshi infants between 10 and 12 months of age to establish equivalence among three lots of live attenuated SA 14-14-2 JE vaccine manufactured by the China National Biotec Group's Chengdu Institute of Biological Products (CDIBP) in a new Good Manufacturing Practice (GMP) facility and to evaluate non-inferiority of the product with a lot of the same vaccine manufactured in CDIBP's original facility. The study took place in two sites in Bangladesh, rural Matlab and Mirpur in urban Dhaka. We collected pre-vaccination (Day 0) and post-vaccination Day 28 (-4 to +14 days) blood samples to assess neutralizing anti-JE virus antibody titers in serum by plaque reduction neutralization tests (PRNT). Seroprotection following vaccination was defined as a PRNT titer ≥1:10 at Day 28 in participants non-immune at baseline. Follow-up for reactogenicity and safety was conducted through home visits at Day 7 and monitoring for serious adverse events through Day 28. Seroprotection rates ranged from 80.2% to 86.3% for all four lots of vaccine. Equivalence of the seroprotection rates between pairs of vaccine lots produced in the new GMP facility was satisfied at the pre-specified 10% margin of the 95% confidence interval (CI) for two of the three pairwise comparisons, but not for the third (-4.3% observed difference with 95% CI of -11.9 to 3.3%). Nevertheless, the aggregate seroprotection rate for all three vaccine lots manufactured in the GMP facility was calculated and found to be within the non-inferiority margin (within 10%) to the vaccine lot produced in the original facility. All four lots of vaccine were safe and well tolerated. These study results should facilitate the use of SA 14-14-2 JE vaccine as a routine component of immunization programs in Asian countries.
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Affiliation(s)
- K Zaman
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
| | - Abu Mohd Naser
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | | | | | - Lei Zhang
- Chengdu Institute of Biological Products, Co., Ltd., Chengdu, China
| | | | - Stephen P Luby
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh; Stanford University, Palo Alto, CA, USA
| | - Mahmudur Rahman
- Institute of Epidemiology Disease Control and Research (IEDCR), Dhaka, Bangladesh
| | - Susan Hills
- Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA
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18
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Wijesinghe PR, Abeysinghe MN, Yoksan S, Yao Y, Zhou B, Zhang L, Yaich M, Neuzil KM, Victor JC. Safety and immunogenicity of live-attenuated Japanese encephalitis SA 14-14-2 vaccine co-administered with measles vaccine in 9-month-old infants in Sri Lanka. Vaccine 2014; 32:4751-7. [DOI: 10.1016/j.vaccine.2014.06.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 05/19/2014] [Accepted: 06/06/2014] [Indexed: 10/25/2022]
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19
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Abstract
Japanese encephalitis (JE) is the most common form of viral encephalitis that appears in the form of frequent epidemics of brain fever throughout Southeast Asia, China and India. The disease is caused by a Flavivirus named Japanese encephalitis virus that is spread to humans by mosquitoes. An internationally approved mouse brain-derived inactivated vaccine has been available that is relatively expensive, gives immunity of uncertain duration and is not completely safe. Cell culture-derived inactivated and attenuated JE vaccines are in use in China, but these are not produced as per the norms acceptable in most countries. Several new promising JE vaccine candidates have been developed, some of which are under different stages of clinical evaluation. These new candidate JE vaccines have the potential to generate long-lasting immunity at low cost.
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Affiliation(s)
- Kaushik Bharati
- Virology laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110 067, India.
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20
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Li X, Ma SJ, Liu X, Jiang LN, Zhou JH, Xiong YQ, Ding H, Chen Q. Immunogenicity and safety of currently available Japanese encephalitis vaccines: a systematic review. Hum Vaccin Immunother 2014; 10:3579-93. [PMID: 25668666 PMCID: PMC4514081 DOI: 10.4161/21645515.2014.980197] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/26/2014] [Accepted: 09/05/2014] [Indexed: 11/19/2022] Open
Abstract
A number of Japanese encephalitis (JE) vaccines have been used for preventing Japanese encephalitis around the world. We here reviewed the immunogenicity and safety of the currently available Japanese encephalitis vaccines. We searched Pubmed, Embase, Web of Science, the Cochrane Library and other online databases up to March 25, 2014 for studies focusing on currently used JE vaccines in any language. The primary outcomes were the seroconversion rate against JEV and adverse events. Meta-analysis was performed for the primary outcome when available. A total of 51 articles were included. Studies were grouped on the basic types of vaccines. This systematic review led to 2 aspects of the conclusions. On one hand, all the currently available JE vaccines are safe and effective. On the other hand, the overall of JE vaccine evaluation is disorganized, the large variation in study designs, vaccine types, schedules, doses, population and few hand-to-hand trails, make direct comparisons difficult. In order to make a more evidence-based decision on optimizing the JE vaccine, it is warranted to standardize the JE vaccine evaluation research.
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Key Words
- ACIP, The Advisory Committee on Immunization Practices
- AEs, Adverse events
- CENTRAL, Cochrane Central Register of Controlled Trials
- CIs, Confidence intervals
- DARE, Database of Abstracts of Reviews of Effects
- GMTs, Geometric mean titers
- HAART, Highly active antiretroviral therapy
- JE, Japanese encephalitis
- JE-CV, Chimeric live-attenuated JE vaccine
- JEV, Japanese encephalitis virus
- Japanese encephalitis vaccine
- LILACS, Latin American and Caribbean Health Sciences Literature
- MBJEV, Mouse brain–derived inactivated vaccines
- MMR, Measles mumps rubella vaccine
- NIP, National Immunization Program
- NOS, Newcastle–Ottawa scale
- ORs, Odd ratios
- PHK, Primary hamster kidney cells
- PRNT50, Plaque-reduction neutralization tests
- RCTs, Randomized controlled trials
- TBE, Tick-borne encephalitis vaccine
- TGPO, Thai Governmental Pharmaceutical Organization
- WHO, World Health Organization
- YF-VAX, Yellow fever vaccine
- YFV, Yellow fever virus
- YFV17D, Yellow fever virus 17D vaccine strain
- immunogenicity
- meta-analysis
- safety
- systematic review
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Affiliation(s)
- Xing Li
- Department of Epidemiology; School of Public Health and Tropical Medicine; Southern Medical University; Guangzhou, China
| | - Shu-Juan Ma
- Department of Epidemiology; School of Public Health and Tropical Medicine; Southern Medical University; Guangzhou, China
| | - Xie Liu
- Department of Epidemiology; School of Public Health and Tropical Medicine; Southern Medical University; Guangzhou, China
| | - Li-Na Jiang
- Department of Epidemiology; School of Public Health and Tropical Medicine; Southern Medical University; Guangzhou, China
| | - Jun-Hua Zhou
- Department of Epidemiology; School of Public Health and Tropical Medicine; Southern Medical University; Guangzhou, China
| | - Yi-Quan Xiong
- Department of Epidemiology; School of Public Health and Tropical Medicine; Southern Medical University; Guangzhou, China
| | - Hong Ding
- Department of Epidemiology; School of Public Health and Tropical Medicine; Southern Medical University; Guangzhou, China
| | - Qing Chen
- Department of Epidemiology; School of Public Health and Tropical Medicine; Southern Medical University; Guangzhou, China
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21
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Yun SI, Lee YM. Japanese encephalitis: the virus and vaccines. Hum Vaccin Immunother 2013; 10:263-79. [PMID: 24161909 PMCID: PMC4185882 DOI: 10.4161/hv.26902] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 10/14/2013] [Accepted: 10/22/2013] [Indexed: 12/11/2022] Open
Abstract
Japanese encephalitis (JE) is an infectious disease of the central nervous system caused by Japanese encephalitis virus (JEV), a zoonotic mosquito-borne flavivirus. JEV is prevalent in much of Asia and the Western Pacific, with over 4 billion people living at risk of infection. In the absence of antiviral intervention, vaccination is the only strategy to develop long-term sustainable protection against JEV infection. Over the past half-century, a mouse brain-derived inactivated vaccine has been used internationally for active immunization. To date, however, JEV is still a clinically important, emerging, and re-emerging human pathogen of global significance. In recent years, production of the mouse brain-derived vaccine has been discontinued, but 3 new cell culture-derived vaccines are available in various parts of the world. Here we review current aspects of JEV biology, summarize the 4 types of JEV vaccine, and discuss the potential of an infectious JEV cDNA technology for future vaccine development.
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Affiliation(s)
- Sang-Im Yun
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research; College of Agriculture and Applied Sciences; Utah State University; Logan, UT USA
| | - Young-Min Lee
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research; College of Agriculture and Applied Sciences; Utah State University; Logan, UT USA
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22
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Choi UY, Lee SY, Kim KH, Kim DS, Choi KM, Cha SH, Kang JH. Is a booster dose necessary in children after immunization with live attenuated Japanese encephalitis vaccine? J Trop Pediatr 2013; 59:423-5. [PMID: 23764540 DOI: 10.1093/tropej/fmt043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Japanese encephalitis virus is a common cause of encephalitis in Asian children; therefore, maintenance of immunity against Japanese encephalitis virus is essential. Although many countries recommend booster vaccination, some trials have concluded that administration of one or two vaccinations is sufficient. The current study was conducted to evaluate immunogenicity and safety after a booster vaccination with live attenuated vaccine. For 68 study subjects, measurement of antibody titer was performed before and at 4-6 weeks after administration of a booster dose. Adverse reactions occurring at the injection site and systemic adverse reactions were documented. The percentages of subjects with seroprotective neutralizing antibody titers was 100% before and after booster vaccination, and the geometric mean titer increased after booster vaccination. Thus, we predict that immunity will be maintained for a long time by an amnestic response. Low percentages of adverse reactions indicated the safety of the immunizations.
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Affiliation(s)
- Ui Yoon Choi
- Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Korea
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23
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Li J, Chen H, Wu N, Fan D, Liang G, Gao N, An J. Characterization of immune responses induced by inactivated, live attenuated and DNA vaccines against Japanese encephalitis virus in mice. Vaccine 2013; 31:4136-42. [PMID: 23845821 DOI: 10.1016/j.vaccine.2013.06.099] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/20/2013] [Accepted: 06/25/2013] [Indexed: 10/26/2022]
Abstract
Vaccination is the most effective countermeasure for protecting individuals from Japanese encephalitis virus (JEV) infection. There are two types of JEV vaccines currently used in China: the Vero cell-derived inactivated vaccine and the live attenuated vaccine. In this study, we characterized the immune response and protective efficacy induced in mice by the inactivated vaccine, live attenuated vaccine and the DNA vaccine candidate pCAG-JME, which expresses JEV prM-E proteins. We found that the live attenuated vaccine conferred 100% protection and resulted in the generation of high levels of specific anti-JEV antibodies and cytokines. The pCAG-JME vaccine induced protective immunity as well as the live attenuated vaccine. Unexpectedly, immunization with the inactivated vaccine only induced a limited immune response and partial protection, which may be due to the decreased activity of dendritic cells and the expansion of CD4+CD25+Foxp3+ regulatory T cells observed in these mice. Altogether, our results suggest that the live attenuated vaccine is more effective in providing protection against JEV infection than the inactivated vaccine and that pCAG-JME will be a potential JEV vaccine candidate.
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Affiliation(s)
- Jieqiong Li
- Department of Microbiology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, PR China
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24
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25
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Immunogenicity and Protective Effectiveness of Japanese Encephalitis Vaccine: A Prospective Multicenter Cohort Study. ACTA ACUST UNITED AC 2013. [DOI: 10.14776/kjpid.2013.20.3.131] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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26
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Marks F, Nguyen TTY, Tran ND, Nguyen MH, Vu HH, Meyer CG, You YA, Konings F, Liu W, Wierzba TF, Xu ZY. Effectiveness of the Viet Nam produced, mouse brain-derived, inactivated Japanese encephalitis vaccine in Northern Viet Nam. PLoS Negl Trop Dis 2012; 6:e1952. [PMID: 23272262 PMCID: PMC3521705 DOI: 10.1371/journal.pntd.0001952] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 10/26/2012] [Indexed: 11/26/2022] Open
Abstract
Background Japanese encephalitis (JE) is a flaviviral disease of public health concern in many parts of Asia. JE often occurs in large epidemics, has a high case-fatality ratio and, among survivors, frequently causes persistent neurological sequelae and mental disabilities. In 1997, the Vietnamese government initiated immunization campaigns targeting all children aged 1–5 years. Three doses of a locally-produced, mouse brain-derived, inactivated JE vaccine (MBV) were given. This study aims at evaluating the effectiveness of Viet Nam's MBV. Methodology A matched case-control study was conducted in Northern Viet Nam. Cases were identified through an ongoing hospital-based surveillance. Each case was matched to four healthy controls for age, gender, and neighborhood. The vaccination history was ascertained through JE immunization logbooks maintained at local health centers. Principal Findings Thirty cases and 120 controls were enrolled. The effectiveness of the JE vaccine was 92.9% [95% CI: 66.6–98.5]. Confounding effects of other risk variables were not observed. Conclusions Our results strongly suggest that the locally-produced JE-MBV given to 1–5 years old Vietnamese children was efficacious. Japanese encephalitis (JE) is a disease caused by a flavivirus transmitted by mosquitoes. Although pigs and wild birds are main reservoirs of the disease, it is occasionally transmitted to humans. The majority of infections in humans are asymptomatic. In persons developing encephalitis, JE has a high case-fatality rate and, among survivors, JE frequently causes persistent neurological sequelae and mental disabilities. Therefore, it is a public health concern in many parts of Asia and many countries vaccinate against JE. Since 1997, children in Vietnam are vaccinated in high risk areas and receive a locally-produced vaccine. This study is aimed at evaluating the effectiveness of the Vietnamese JE vaccine through a case-control study, in which 30 cases and 120 controls were enrolled. The effectiveness of the JE vaccine was 92.9% [95% CI: 66.6–98.5], which suggests that the locally-produced JE vaccine given to 1–5 year old Vietnamese children was efficacious.
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Affiliation(s)
- Florian Marks
- International Vaccine Institute, Seoul, South Korea.
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Teng M, Luo J, Xing GX, Cheng N, Yang YY, Deng RG, Zhang GP. Main Factors Influencing the Efficient Propagation of Virulent or Attenuated Strains of Japanese encephalitis virus in BHK-21 Cells. INDIAN JOURNAL OF VIROLOGY : AN OFFICIAL ORGAN OF INDIAN VIROLOGICAL SOCIETY 2012; 23:344-8. [PMID: 24293822 DOI: 10.1007/s13337-012-0094-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 07/09/2012] [Indexed: 11/24/2022]
Abstract
Japanese encephalitis virus (JEV) causes severe viral encephalitis in humans and some other mammalian animals. Highly efficient culture of the virus is critical for antigen preparation, vaccine production and other basic researches. We have investigated the influence of a number of variables such as the strain virulence, the state of the host cells, medium composition, infection method and others on the proliferation of distinct JEV strains in BHK-21 cells. The results showed that two distinct strategies are needed for the propagation of virulent or attenuated JEV strains. The most critical variables were the method of infection, and especially the density of the host cell. Our studies indicate the general approaches to the in vitro culture of other JEV strains using BHK-21 cell line.
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Affiliation(s)
- Man Teng
- Key Laboratory of Animal Immunology of the Ministry of Agriculture, Henan Provincial Key Laboratory of Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou, 450002 People's Republic of China
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Teng M, Luo J, Fan JM, Chen L, Wang XT, Yao W, Wang CQ, Zhang GP. Molecular characterization of Japanese encephalitis viruses circulating in pigs and mosquitoes on pig farms in the Chinese province of Henan. Virus Genes 2012; 46:170-4. [PMID: 22945473 DOI: 10.1007/s11262-012-0813-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2012] [Accepted: 08/25/2012] [Indexed: 12/01/2022]
Abstract
Since the first Chinese case report of Japanese encephalitis, Japanese encephalitis virus (JEV) has circulated in China for at least 60 years. Even though pigs play a critical role in the JEV transmission cycle information on the prevalence of JEV in pigs has not been investigated in China. As the central Chinese province of Henan has the largest human population in China, a history of serious JEV and is the largest pig producing province it was chosen for this study. We have found that currently natural infection with JEV in pigs and mosquitoes is prevalent and both genotypes 1 and 3 co-circulate in pigs and mosquitoes in central China. Phylogenetic analysis showed that all of the newly obtained pig-derived JEV isolates are more closely related to isolates from the 1950s to 1960s than to those recently isolated from humans and mosquitoes. Further analyses based on all the previous reported Chinese isolates indicates that presently genotype 3 JEV is the predominant genotype in pigs but genotype 1 JEV is emerging and spreading rapidly in recent years. Our study provides information for understanding the current epidemiology of JEV in China and suggests possible measures applicable to the further control of JEV.
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Affiliation(s)
- Man Teng
- Key Laboratory of Animal Immunology of the Ministry of Agriculture, Henan Provincial Key Laboratory of Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou, People's Republic of China
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Song BH, Yun GN, Kim JK, Yun SI, Lee YM. Biological and genetic properties of SA₁₄-14-2, a live-attenuated Japanese encephalitis vaccine that is currently available for humans. J Microbiol 2012; 50:698-706. [PMID: 22923123 DOI: 10.1007/s12275-012-2336-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 07/13/2012] [Indexed: 11/29/2022]
Abstract
Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, is a major cause of acute encephalitis, a disease of significance for global public health. In the absence of antiviral therapy to treat JEV infection, vaccination is the most effective method of preventing the disease. In JE-endemic areas, the most widely used vaccine to date is SA(14)-14-2, a live-attenuated virus derived from its virulent parent SA(14). In this study, we describe the biological properties of SA(14)-14-2, both in vitro and in vivo, and report the genetic characteristics of its genomic RNA. In BHK-21 (hamster kidney) cells, SA(14)-14-2 displayed a slight delay in plaque formation and growth kinetics when compared to a virulent JEV strain, CNU/LP2, with no decrease in maximum virus production. The delay in viral growth was also observed in two other cell lines, SH-SY5Y (human neuroblastoma) and C6/36 (mosquito larva), which are potentially relevant to JEV pathogenesis and transmission. In 3-week-old ICR mice, SA(14)-14-2 did not cause any symptoms or death after either intracerebral or peripheral inoculation with a maximum dose of up to 1.5×10(3) plaque-forming units (PFU) per mouse. The SA(14)-14-2 genome consisted of 10977 nucleotides, one nucleotide longer than all the previously reported genomes of SA(14)-14-2, SA(14) and two other SA(14)-derived attenuated viruses. This difference was due to an insertion of one G nucleotide at position 10701 in the 3 noncoding region. Also, we noted a significant number of nucleotide and/or amino acid substitutions throughout the genome of SA(14)-14-2, except for the prM protein-coding region, that differed from SA(14) and/or the other two attenuated viruses. Our results, together with others', provide a foundation not only for the study of JEV virulence but also for the development of new and improved vaccines for JEV.
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Affiliation(s)
- Byung-Hak Song
- Department of Microbiology, College of Medicine, Chungbuk National University, Cheongju 361-763, Republic of Korea
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Zhang JS, Zhao QM, Zuo SQ, Jia N, Guo XF. Cytokine and chemokine responses to Japanese encephalitis live attenuated vaccine in a human population. Int J Infect Dis 2012; 16:e285-8. [DOI: 10.1016/j.ijid.2011.12.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 12/13/2011] [Indexed: 10/14/2022] Open
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Jia N, Zhao QM, Guo XF, Cheng JX, Wu C, Zuo SQ, Dai PF, Zhao JY, Zhang JS. Encephalitis temporally associated with live attenuated Japanese encephalitis vaccine: four case reports. BMC Infect Dis 2011; 11:344. [PMID: 22168358 PMCID: PMC3282669 DOI: 10.1186/1471-2334-11-344] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 12/14/2011] [Indexed: 11/10/2022] Open
Abstract
Background Japanese encephalitis (JE) vaccination is the most effective measure for preventing JE disease. The live attenuated JE vaccine, which has shown good efficacy and safety, has been widely used in China. Case presentations We report four laboratory-confirmed JE cases detected in JE-endemic areas during the JE virus (JEV) transmission season, who all received a first dose of live attenuated JE vaccine within 2 weeks prior to the onset of illness. All cases presented with acute encephalitis and rapidly reduced consciousness. All cerebrospinal fluid (CSF) samples from the patients were positive for JEV-specific immunoglobulin M (IgM) antibodies, but viral isolation and polymerase chain reaction (PCR) detection of JEV were both negative. Conclusions It is difficult to identify a causal link between the disease and the vaccination, as the source of positive CSF JEV IgM antibodies might be natural JEV infection or possibly due to a traumatic lumbar puncture. Our observations highlight the need for public health officers and doctors to consider reasonable vaccination policies during the JE season. In addition, continued surveillance as well as thorough investigation of any events that occur after JE vaccination is necessary.
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Affiliation(s)
- Na Jia
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 20 Dong Da-Street, Fengtai District, Beijing 100071, People's Republic of China
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Paul RC, Rahman M, Gurley ES, Hossain MJ, Diorditsa S, Hasan AM, Banu SS, Alamgir A, Rahman MA, Sandhu H, Fischer M, Luby SP. A novel low-cost approach to estimate the incidence of Japanese encephalitis in the catchment area of three hospitals in Bangladesh. Am J Trop Med Hyg 2011; 85:379-85. [PMID: 21813862 DOI: 10.4269/ajtmh.2011.10-0706] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Acute meningoencephalitis syndrome surveillance was initiated in three medical college hospitals in Bangladesh in October 2007 to identify Japanese encephalitis (JE) cases. We estimated the population-based incidence of JE in the three hospitals' catchment areas by adjusting the hospital-based crude incidence of JE by the proportion of catchment area meningoencephalitis cases who were admitted to surveillance hospitals. Instead of a traditional house-to-house survey, which is expensive for a disease with low frequency, we attempted a novel approach to identify meningoencephalitis cases in the hospital catchment area through social networks among the community residents. The estimated JE incidence was 2.7/100,000 population in Rajshahi (95% confidence interval [CI] = 1.8-4.9), 1.4 in Khulna (95% CI = 0.9-4.1), and 0.6 in Chittagong (95% CI = 0.4-0.9). Bangladesh should consider a pilot project to introduce JE vaccine in high-incidence areas.
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Affiliation(s)
- Repon C Paul
- International Centre for Diarrheal Disease Research, Bangladesh, Government of the People's Republic of Bangladesh.
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Phenotypic and genotypic characteristics of Japanese encephalitis attenuated live vaccine virus SA14-14-2 and their stabilities. Vaccine 2010; 28:3635-41. [PMID: 20226891 DOI: 10.1016/j.vaccine.2010.02.105] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 02/05/2010] [Accepted: 02/24/2010] [Indexed: 10/19/2022]
Abstract
A novel Japanese encephalitis (JE) attenuated live vaccine virus SA14-14-2 was licensed for commercial application in China in 1989. Since then this vaccine has been widely used in China and other countries in Asia, and no vaccine associated encephalitis case was reported. The neurovirulence of the SA14-14-2 was tested in JE susceptible laboratory animals, such as mice, monkeys, hamsters and athymic nude mice. The results showed that the attenuated virus strain was avirulent to these animals by intracerebral inoculation (i.c.) or intraperitoneal inoculation (i.p.). Studies on the neuroattenuation stability revealed that no reversion after 17 times tissue culture passages or one i.c. sucking mice passage. Mosquito infection studies indicated that after one mosquito intrathoracical passage, the progeny viruses in the infected mosquitoes were unable to cause sucking mice or weanling mice disease. Molecules characteristics' studies of the SA14-14-2 virus strain showed that there are 57-61 nucleotide changes and 24-31 amino acid substitutions, eight substitutions in the E protein gene are the critical amino acid related to the virus attenuation. The E gene sequence studies have showed that the 8 critical amino acids were not changed after 22 passages in tissue cultures or one passage in mosquitoes. Comparison of the full-length sequence to the parental SA14 virus has revealed that after 22 passages in the tissue cultures, only 8 nucleotides changed leading to 4 amino acid substitutions. However they were not the reverse mutation and none of the 8 critical residues changed. The homology of the nucleotide and amino acid between the virus of passage 22 and the primary seed virus in Genbank was 99.93% and 99.88% respectively. The above results demonstrated that the SA14-14-2 virus is highly attenuated for the various JE susceptible animals. The attenuated phenotypes and the genetic characteristics of the SA14-14-2 strain are highly stable after multiple in vitro passages or mosquitoes infection. Therefore the safety of the live JE vaccine is due to a high degree of neuroattenuation and a number of stable phenotypically and genetically characteristics, suggesting that reversion to neurovirulence of the vaccine strain would be highly unlikely.
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Hills S, Dabbagh A, Jacobson J, Marfin A, Featherstone D, Hombach J, Namgyal P, Rani M, Solomon T. Evidence and rationale for the World Health Organization recommended standards for Japanese encephalitis surveillance. BMC Infect Dis 2009; 9:214. [PMID: 20038298 PMCID: PMC2809064 DOI: 10.1186/1471-2334-9-214] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 12/29/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Japanese encephalitis (JE) is the most important form of viral encephalitis in Asia. Surveillance for the disease in many countries has been limited. To improve collection of accurate surveillance data in order to increase understanding of the full impact of JE and monitor control programs, World Health Organization (WHO) Recommended Standards for JE Surveillance have been developed. To aid acceptance of the Standards, we describe the process of development, provide the supporting evidence, and explain the rationale for the recommendations made in the document. METHODS A JE Core Working Group was formed in 2002 and worked on development of JE surveillance standards. A series of questions on specific topics was initially developed. A literature review was undertaken and the findings were discussed and documented. The group then prepared a draft document, with emphasis placed on the feasibility of implementation in Asian countries. A field test version of the Standards was published by WHO in January 2006. Feedback was then sought from countries that piloted the Standards and from public health professionals in forums and individual meetings to modify the Standards accordingly. RESULTS After revisions, a final version of the JE surveillance standards was published in August 2008. The supporting information is presented here together with explanations of the rationale and levels of evidence for specific recommendations. CONCLUSION Provision of the supporting evidence and rationale should help to facilitate successful implementation of the JE surveillance standards in JE-endemic countries which will in turn enable better understanding of disease burden and the impact of control programs.
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Widman DG, Frolov I, Mason PW. Third-generation flavivirus vaccines based on single-cycle, encapsidation-defective viruses. Adv Virus Res 2009; 72:77-126. [PMID: 19081489 DOI: 10.1016/s0065-3527(08)00402-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Flaviviruses are arthropod-borne pathogens that cause significant disease on all continents of the world except Antarctica. Flavivirus diseases are particularly important in tropical regions where arthropod vectors are abundant. Live-attenuated virus vaccines (LAVs) and inactivated virus vaccines (INVs) exist for some of these diseases. LAVs are economical to produce and potent, but are not suitable for use in the immunocompromised. INVs are safer, but are more expensive to produce and less potent. Despite the success of both classes of these first-generation flavivirus vaccines, problems associated with their use indicate a need for improved products. Furthermore, there are no suitable vaccines available for important emerging flavivirus diseases, notably dengue and West Nile encephalitis (WNE). To address these needs, new products, including LAVs, INVs, viral-vectored, genetically engineered LAVs, naked DNA, and subunit vaccines are in various stages of development. Here we describe the current state of these first- and second-generation vaccine candidates, and compare these products to our recently described single-cycle, encapsidation defective flavivirus vaccine: RepliVAX. RepliVAX can be propagated in C-expressing cells (or as a unique two-component virus) using methods similar to those used to produce today's economical and potent LAVs. However, due to deletion of most of the gene for the C protein, RepliVAX cannot spread between normal cells, and is unable to cause disease in vaccinated animals. Nevertheless, RepliVAX is potent and efficacious in animal models for WNE and Japanese encephalitis, demonstrating its utility as a third-generation flavivirus vaccine that should be potent, economical to produce, and safe in the immunocompromised.
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Affiliation(s)
- Douglas G Widman
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555, USA
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Tauber E, Kollaritsch H, von Sonnenburg F, Lademann M, Jilma B, Firbas C, Jelinek T, Beckett C, Knobloch J, McBride W, Schuller E, Kaltenböck A, Sun W, Lyons A. Randomized, Double‐Blind, Placebo‐Controlled Phase 3 Trial of the Safety and Tolerability of IC51, an Inactivated Japanese Encephalitis Vaccine. J Infect Dis 2008; 198:493-9. [DOI: 10.1086/590116] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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Comparison of the immunogenicity and safety of measles vaccine administered alone or with live, attenuated Japanese encephalitis SA 14-14-2 vaccine in Philippine infants. Vaccine 2008; 26:2234-41. [PMID: 18394765 DOI: 10.1016/j.vaccine.2008.02.042] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Revised: 02/12/2008] [Accepted: 02/21/2008] [Indexed: 11/20/2022]
Abstract
Japanese encephalitis (JE) virus is a major cause of disease, disability, and death in Asia. An effective, live, attenuated JE vaccine (LJEV) is available; however, its use in routine immunization schedules is hampered by lack of data on concomitant administration with measles vaccine (MV). This study evaluated the immunogenicity and reactogenicity of LJEV and MV when administered at the same or separate study visits in infants younger than 1 year of age. Three groups of healthy infants were randomized to receive LJEV at age of 8 months and MV at 9 months (Group 1; n=100); MV and LJEV together at 9 months (Group 2; n=236); or MV and LJEV at 9 and 10 months, respectively (Group 3; n=235). Blood was obtained 4 weeks after each vaccine administration to determine antibody levels for measles and JE. Reactogenicity was assessed by parental diaries and clinic visits. Four weeks after immunization, measles seroprotection rates (defined as > or =340 mIU/ml) were high and comparable in all three groups and specifically, rates in the combined MV-LJEV (Group 2) were not statistically inferior to those in Group 3 receiving MV separately (96% versus 100%, respectively). Likewise, the LJEV seroprotection rates were high and similar between the three groups. The reactogenicity profiles of the three vaccine schedules were also analogous. LJEV and MV administered together are well tolerated and immunogenic in infants younger than 1 year. These results should facilitate incorporation of LJEV into routine immunization schedules with MV.
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Beasley DWC, Lewthwaite P, Solomon T. Current use and development of vaccines for Japanese encephalitis. Expert Opin Biol Ther 2008; 8:95-106. [PMID: 18081539 DOI: 10.1517/14712598.8.1.95] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Japanese encephalitis (JE) is a significant cause of human morbidity and mortality throughout Asia. Vaccines for JE have been available for many years and their use has been effective in reducing the incidence of JE disease in several countries but, as disease incidence has decreased, concerns regarding adverse events following immunisation have increased. OBJECTIVE To review existing JE vaccines and new candidates in advanced preclinical or clinical evaluation. METHODS The review primarily covers published and some unpublished literature from the past decade describing current use of approved JE vaccines in various parts of the world, and advanced development and clinical testing of alternative vaccine candidates. RESULTS/CONCLUSION There is a clear need for additional licensing of existing or new JE vaccines. Several promising candidates are currently in use or completing clinical trials.
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Affiliation(s)
- David W C Beasley
- University of Texas Medical Branch, Department of Microbiology and Immunology, Galveston, TX 77555-0609, USA
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Sohn YM, Tandan JB, Yoksan S, Ji M, Ohrr H. A 5-year follow-up of antibody response in children vaccinated with single dose of live attenuated SA14-14-2 Japanese encephalitis vaccine: immunogenicity and anamnestic responses. Vaccine 2008; 26:1638-43. [PMID: 18294743 DOI: 10.1016/j.vaccine.2008.01.021] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 01/07/2008] [Accepted: 01/14/2008] [Indexed: 11/24/2022]
Abstract
Out of 98 subjects who had participated in the 2000 JE vaccination campaign, 69 people were enrolled in the tests of 2004 and 2005 for the evaluation of long term immune response of a single dose of live attenuated SA14-14-2 JE vaccine. 89.9% of study subjects (62/69) had maintained a high level of neutralizing antibody until 2004 as their GMT was measured as 133 (Min 11, Max 2991). Forty-four subjects were still positive in 2005, 5 years after JE vaccination, and their neutralizing antibody positive rate was significantly higher than that of 69 age-sex matched unvaccinated control subjects: 63.8% (44/69) vs. 14.5% (10/69) (P<0.05). Twenty-four subjects (Group 1) who were seronegative for neutralizing antibody at the 2005 test were given a second dose for revaccination in 2006. Also 49 seronegative (Group 2) subjects who were enrolled as a control group in 2005 were given one dose of primary JE vaccine in 2006. Seven days after vaccination, seropositive rate was discovered to be 76.5% (13/17) and 168.52 (Min 38, Max 2173) in Group 1, while no seroconversion in Group 2. On the 30th day, seropositive rate and GMT were 82.4% (14/17) and 392.01 (Min 22, Max 2197) in Group 1, while 75.7% (28/37) and 45.72 (Min 12, Max 505) in Group 2, respectively. We observed the persistence of neutralizing antibody of single dose of live attenuated SA14-14-2 JE vaccine, 89.9% after 4 years and 63.8% after 5 years, and a rapid secondary immune response on the seventh day after booster dose among those who had been seronegative in spite of the first dose of vaccine. Single dose of live JE vaccine could be effective to provide a long-term protection in JE endemic area, where natural boosting is quite probable in the vaccinees. However, further studies should be carried out to support whether one dose of live JE vaccine is sufficient for people in JE non-endemic area.
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Affiliation(s)
- Young Mo Sohn
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, Republic of Korea
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Abstract
BACKGROUND Vaccination is recognized as the only practical measure for preventing Japanese encephalitis. Production shortage, costs, and issues of licensure impair vaccination programmes in many affected countries. Concerns over vaccine effectiveness and safety also have a negative impact on acceptance and uptake. OBJECTIVES To evaluate vaccines for preventing Japanese encephalitis in terms of effectiveness, adverse events, and immunogenicity. SEARCH STRATEGY In March 2007, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2007, Issue 1), MEDLINE, EMBASE, LILACS, BIOSIS, and reference lists. We also attempted to contact corresponding authors and vaccine companies. SELECTION CRITERIA Randomized controlled trials (RCTs), including cluster-RCTs, comparing Japanese encephalitis vaccines with placebo (inert agent or unrelated vaccine), no intervention, or alternative Japanese encephalitis vaccine. DATA COLLECTION AND ANALYSIS Authors independently extracted data and assessed methodological quality. Dichotomous data were compared with relative risks and a 95% confidence interval (CI), and converted into percentage vaccine efficacy. MAIN RESULTS Eight RCTs involving 358,750 participants were included. These trials investigated two available and three pre-licensure vaccines. Two RCTs assessing efficacy of the commercially available inactivated Nakayama vaccine were identified. A two-dose schedule of the licensed vaccine provided significant protection of 95% (95% CI 10% to 100%) for one year only, while two doses of an unpurified precursor vaccine protected children by 81% (95% CI 45% to 94%) in year one and by 59% (95% CI 2% to 83%) in year two. Serious adverse events were not observed. Mild and moderate episodes of injection site soreness, fever, headache, and nausea were reported in less than 6% of children receiving inactivated vaccine compared to 0.6% of unvaccinated controls. One cluster-RCT compared the live-attenuated SA14-14-2 vaccine (widely used in China) with no intervention measuring adverse events. Fever was reported in 2.7% of vaccinees compared to 3.1% of controls, while 0.1% of both groups suffered diarrhoea or seizures. Four small pre-licensure RCTs assessing a genetically engineered vaccine and two cell culture-derived inactivated vaccines revealed high immunogenicity and relative safety. AUTHORS' CONCLUSIONS Only one of the three currently used vaccines has been assessed for efficacy in a RCT. Other RCTs have assessed their safety, however, and they appear to cause only occasional mild or moderate adverse events. Further trials of effectiveness and safety are needed for the currently used vaccines, especially concerning dose levels and schedules. Trials investigating several new vaccines are planned or in progress.
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Key Words
- humans
- encephalitis, japanese
- encephalitis, japanese/prevention & control
- japanese encephalitis vaccines
- japanese encephalitis vaccines/adverse effects
- japanese encephalitis vaccines/immunology
- japanese encephalitis vaccines/therapeutic use
- randomized controlled trials as topic
- vaccines, attenuated
- vaccines, attenuated/adverse effects
- vaccines, attenuated/immunology
- vaccines, attenuated/therapeutic use
- vaccines, inactivated
- vaccines, inactivated/adverse effects
- vaccines, inactivated/immunology
- vaccines, inactivated/therapeutic use
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Affiliation(s)
- K L Schiøler
- Liverpool School of Tropical Medicine, C/O Cochrane Infectious Diseases Group, Pembroke Place, Liverpool, UK, L3 5QA.
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Abstract
Japanese encephalitis (JE) is an inflammatory disease in the central nervous system caused by infection with Japanese encephalitis virus (JEV). JE is a disease with a high fatality rate and endemic and epidemic in East, Southeast, and South Asia. High morbidity is noted in children living in the endemic area. JEV is maintained mainly between vector mosquitoes and pigs in nature. The risk of JE increases as the number of vector mosquitoes increases. The expansion of JEV-endemic area depends on irrigated rice field and pig farming. These environments that are suitable for infectious cycle of JEV exist widely in Asia today. The effective and safe vaccine is available in endemic countries and for international travelers. JE vaccination is strongly recommended to those who visit the JEV-endemic regions, especially in the rainy season.
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Affiliation(s)
- Akira Oya
- National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
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Chiou SS, Tsai KH, Huang CG, Liao YK, Chen WJ. High antibody prevalence in an unconventional ecosystem is related to circulation of a low-virulent strain of Japanese encephalitis virus. Vaccine 2006; 25:1437-43. [PMID: 17113688 DOI: 10.1016/j.vaccine.2006.10.044] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2006] [Revised: 10/05/2006] [Accepted: 10/23/2006] [Indexed: 11/17/2022]
Abstract
Liu-Chiu islet, a relatively isolated ecosystem that is free of rice cultivation, has long considered free of Japanese encephalitis (JE). However, a new strain (T1P1) of JE virus was isolated from the mosquito, Armigeres subalbatus, and a rather broad distribution of neutralizing antibody has been reported on the islet, suggesting that the circulating virus could be an attenuated strain. In an assessment on 219 blood samples obtained from residents of Liu-Chiu islet, the positive rate of JEV-specific IgM antibodies decreased with age while that of neutralizing antibodies increased with age. Both antibodies were mainly responsive to the T1P1 strain since higher positive rates and titers of specific neutralizing antibodies are shown in this investigation. Importantly, the T1P1 strain is herein characterized as being broader in neutralizing virus strains, stable in genetic traits, and productive in Vero cells. Taken together, the JE virus strain endemically circulating on Liu-Chiu islet may have served as a natural form of a live-attenuated vaccine. As a result, it possibly can be utilized as a new and effective vaccine candidate in the future.
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Affiliation(s)
- Shyan-Song Chiou
- Graduate Institute of Veterinary Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung 40227, Taiwan
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Mackenzie JS, Williams DT, Smith DW. Japanese Encephalitis Virus: The Geographic Distribution, Incidence, and Spread of a Virus with a Propensity to Emerge in New Areas. PERSPECTIVES IN MEDICAL VIROLOGY 2006. [DOI: 10.1016/s0168-7069(06)16010-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Ohrr H, Tandan JB, Sohn YM, Shin SH, Pradhan DP, Halstead SB. Effect of single dose of SA 14-14-2 vaccine 1 year after immunisation in Nepalese children with Japanese encephalitis: a case-control study. Lancet 2005; 366:1375-8. [PMID: 16226615 DOI: 10.1016/s0140-6736(05)67567-8] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND In July, 1999, a single dose of live-attenuated SA 14-14-2 Japanese encephalitis vaccine was given to children aged 1-15 years in the Terai region of Nepal. Cases of natural infection occurred almost immediately. Our aim was to assess the long-term protective effect of this vaccination. METHODS In 2000, this same population had a second seasonal exposure to the virus. We therefore did a case-control study to measure the prevalence of vaccination against Japanese encephalitis in 35 patients hospitalised for the disease 1 year after immunisation, and in age-sex matched village controls. FINDINGS Of 35 children resident in Bardiya and Banke districts admitted to the Bheri Zonal Hospital with serologically confirmed Japanese encephalitis, only one had been vaccinated in 1999. In 430 age-sex matched village controls, 234 (54.4%) were vaccinated. We calculated a median unbiased estimate of the odds ratio of 0.0155, with lower and upper confidence limits of 0.0004 and 0.0986. The protective effect of vaccine after 12-15 months was 98.5% (CI 90.1-99.2%). INTERPRETATION Our study provides evidence of sustained high protection afforded by one dose of live attenuated SA 14-14-2 vaccine in Nepalese children.
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Affiliation(s)
- Heechoul Ohrr
- Department of Preventive Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea.
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Hombach J, Solomon T, Kurane I, Jacobson J, Wood D. Report on a WHO consultation on immunological endpoints for evaluation of new Japanese encephalitis vaccines, WHO, Geneva, 2-3 September, 2004. Vaccine 2005; 23:5205-11. [PMID: 16055233 DOI: 10.1016/j.vaccine.2005.07.002] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2005] [Accepted: 07/01/2005] [Indexed: 11/22/2022]
Abstract
The World Health Organization (WHO) is undertaking consultations on immunological responses as parameters for evaluation and licensure of new Japanese encephalitis (JE) vaccines. Immunological markers could be used by vaccine developers and regulatory authorities to assess vaccine efficacy in absence of clinical efficacy data. The consultation which is reported here reviewed current data on mechanisms of protective immunity gathered from animal experimentation, clinical data from licensed vaccines and from vaccine candidates still in clinical development. Immunological assays and readouts for use in evaluation of candidate vaccines were also discussed. The consultation made a series of recommendations for specifications on immunological criteria to assess JE vaccine efficacy. More detailed recommendations will be drafted following further consultations to serve as WHO guidelines for evaluation and licensure for new JE vaccines.
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Affiliation(s)
- Joachim Hombach
- Immunization, Vaccines and Biologicals, World Health Organization, 20, Geneva 27, Switzerland.
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Fletcher MA, Fabre P, Debois H, Saliou P. Vaccines administered simultaneously: directions for new combination vaccines based on an historical review of the literature. Int J Infect Dis 2004; 8:328-38. [PMID: 15494254 DOI: 10.1016/j.ijid.2004.03.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2003] [Revised: 03/03/2004] [Accepted: 03/09/2004] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVES The recognized benefits of administering vaccines simultaneously has encouraged vaccine producers to develop combination vaccines. If contemporary research and development can realize vaccines that achieve the current standards for safety, immunogenicity, and efficacy, other specific vaccine associations may also merit reconsideration as combination vaccines. METHODS An historical review of the vaccine association literature reveals two important themes: first, the programs of mass vaccination, in particular, the eradication of smallpox, sessions where multiple vaccines (other than the smallpox vaccine) were given concurrently, and the Expanded Programme on Immunization (EPI); and, second, the domain of travel vaccines, including travellers to a disease-endemic country (such as migrants, tourists, military personnel, or expatriates) and WHO requirements for international travellers. RESULTS/CONCLUSIONS Based on this historical review, combination vaccines worth reconsideration could fill epidemiologic niches in the EPI with, for instance, a measles--yellow fever, a measles--Japanese encephalitis or a pertussis-based paediatric combination rabies vaccine. Furthermore, other combinations could broaden protection against the pathogens responsible for meningitis, pneumonia, or enteric diseases. Nevertheless, complex issues such as necessity, feasibility, or affordability will ultimately determine if any one of these becomes a combination vaccine.
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Affiliation(s)
- Mark A Fletcher
- Wyeth Vaccines Research, Coeur Défense-Tour A, 110 esplanade du Général de Gaulle, 92931 Paris la Défense, Cedex, France.
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Affiliation(s)
- Goro Kuno
- Arbovirus Diseases Branch, Division of Vector-Borne Infectious Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado 80522, USA
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Abstract
The JEV widely is used in Asian countries each year and is an important vaccine for travelers to the East from other parts of the world. JE virus is a zoonotic disease with natural reservoirs and cannot be eliminated. Although a declining incidence of JE has been observed in Asia because of reduced transmission by agricultural approaches and vaccination, the most important control measure now, and in the future, is vaccination of humans against JE. The inactivated vaccine, produced from infected mouse-brain-derived tissue, is the only commercially available vaccine. There are several concerns with the use of this vaccine. It is expensive, requires two or three doses to achieve protective efficacy, and, in practice, requires further booster doses to maintain immunity. The apparent increase in allergic reactions in the first part of the 1990s has set focus on the safety of the JEV. A cheap, live attenuated SA 14-14-2 vaccine is used almost exclusively in China and parts of Korea, but there have been no trials of SA 14-14-2 vaccine outside JE endemic countries. The vaccine seems to be highly efficient, and few adverse events have been observed; however, PHK cells are used for the production of this vaccine, and these cells are not approved by the WHO. A satisfactory cell substrate is needed. A committee under the WHO has proposed that for the live JEV, there should be validity of the assays for retrovirus when applied to PHK cell substrate and validity of the mouse assays for neurovirulence. Further information should be reviewed on the long-term follow-up of recipients of the vaccine. Several new types of vaccines have reached the phase of clinical trials; however, studies remain to be completed. Until a new vaccine is available, the priority of surveillance of adverse events and the continuous reporting of such events to the users of the vaccines must be of importance. This fact is highlighted by the possibility of the varying frequency of adverse events with different batches over the years. The WHO offers information and recommendations for vaccines in the EPI and issues a series of updated papers on other vaccines that are of international public health importance (eg, JEV). The development of alternative efficient, safe, and appropriately priced JEVs is recommended, as is intensified surveillance of adverse events. Prospective vaccine studies of safety may be limited because of sample size and because rare adverse events may not be detected. Several new initiatives have been taken to improve surveillance of adverse events to vaccines within the past 10 years. In Japan, there is an increasing awareness of the importance of efforts taken to improve vaccine safety, and surveillance of adverse events and possibilities of compensation for vaccine-related injuries are in place. In Vietnam, a database to detect adverse events after vaccination has been established; the project involves active visits to data collectors at the vaccination sites. Comparative studies of adverse events, such as one recent study from Japan and the United States, are important for the evaluation of the reporting systems. The reporting rate for JEV adverse events from Japan was approximately one order of magnitude lower than that in the United States. Japan had strict predefined reporting criteria and time limits for observations. If time limits for the observation are too strict (eg, defining a possible neurologic reaction to occur within 1 week after vaccination), later reactions will not be included (eg, if ADEM is elicited by a vaccine, the symptoms cannot be expected to occur until weeks after the vaccination). The passive surveillance systems have limitations with an underreporting of adverse events, depending on clinical seriousness, temporal proximity to vaccination, awareness of healthcare workers, and tradition of reporting particular events. In developed countries, surveillance of adverse events is formalized, although not necessarily optimal. An increase in reporting would be expected when the reporting of adverse events is mandatory. Reports have been sent to VAERS, the Vaccine Safety Datalink Project, and the European Union Pharmacovigilance System. A Brighton collaboration has been implemented to enhance comparability of vaccine safety data. Public health authorities in specific countries, such as the CDC in the United States and the National Advisory Committee in Canada, regularly have published information on the JE situation in Asia and the preventive measures to be taken, including information on the vaccines and adverse reactions. The conventional recommendation is that travelers should be vaccinated if they will spend more than 1 month in a JE endemic area or in areas with epidemic transmission with even shorter periods. Although the risk for JE for short-term travelers is considered small (1 case per 1 million travelers per year), sporadic cases, including deaths, have been reported among tourists traveling to endemic areas. Risk for travelers in rural districts in the season of risk is considerably higher (range, 1 case per 5000 travelers to 1 case per 20,000 travelers per week). Doctors who advise travelers should be updated on the latest JE occurrences in Asia. Updates on the JE situation can be found on bulletins at http://www.promedmail.org or are available from the WHO or CDC. The allergic reactions primarily described after vaccination with the inactivated mouse-brain-derived JEV have been observed in several countries during the 1900s. Allergic reactions, including the mucocutaneous and neurologic reactions reported after JE vaccination, may vary in frequency, and these reactions should be evaluated meticulously yearly. This step enables recommendations, including information on possible side effects, to be given in an optimal way.
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Affiliation(s)
- Anne-Marie Plesner
- Department of Medical Officers of Health, Copenhagen County, Islands Brygge 67 DK-2300 Copenhagen S, Denmark.
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Saluzzo JF. Empirically Derived Live-Attenuated Vaccines Against Dengue and Japanese Encephalitis. Adv Virus Res 2003; 61:419-43. [PMID: 14714439 DOI: 10.1016/s0065-3527(03)61011-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Abstract
Vaccination against JE ideally should be practiced in all areas of Asia where the virus is responsible for human disease. The WHO has placed a high priority on the development of a new vaccine for prevention of JE. Some countries in Asia (Japan, South Korea, North Korea, Taiwan, Vietnam, Thailand, and the PRC) manufacture JE vaccines and practice childhood immunization, while other countries suffering endemic or epidemic disease (India, Nepal, Laos, Cambodia, Bangladesh, Myanmar, Malaysia, Indonesia and the Philippines) have no JE vaccine manufacturing or policy for use. With the exception of the PRC, all countries practicing JE vaccination use formalin inactivated mouse brain vaccines, which are relatively expensive and are associated with rare but clinically significant allergic and neurological adverse events. New inactivated JE vaccines manufactured in Vero cells are in advanced preclinical or early clinical development in Japan, South Korea, Taiwan, and the PRC. An empirically derived, live attenuated vaccine (SA14-14-2) is widely used in the PRC. Trials in the PRC have shown SA14-14-2 to be safe and effective when administered in a two-dose regimen, but regulatory concerns over manufacturing and control have restricted international distribution. The genetic basis of attenuation of SA14-14-2 has been partially defined. A new live attenuated vaccine (ChimeriVax-JE) that uses a reliable flavivirus vaccine--yellow fever 17D--as a live vector for the envelope genes of SA14-14-2 virus is in early clinical trials and appears to be well tolerated and immunogenic after a single dose. Vaccinia and avipox vectored vaccines have also been tested clinically, but are no longer being pursued due to restricted effectiveness mediated by anti-vector immunity. Other approaches to JE vaccines--including naked DNA, oral vaccination, and recombinant subunit vaccines--have been reviewed.
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Affiliation(s)
- T P Monath
- Acambis Inc., 38 Sidney Street, Cambridge, MA 02139, USA
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