Development and Application of a Novel Attenuated Live Japanese Encephalitis Vaccine SA

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1 Development and Application of a Novel Attenuated Live Japanese Encephalitis Vaccine SA Yu Yongxin (National Institute for the Control of Pharmaceutical and Biological Products, Beijing , China)

2 Japanese encephalitis (JE) is the most important form of viral encephalitis in Asia. It is estimated that the JE virus causes at least cases of clinical disease each year, mostly among children aged <10 years, resulting in about deaths and cases of long-term, neuro-psychiatric sequelae.

3 Before 1989, only inactivated JE vaccine made in hamster kidney cells (HKC) was used in China.

4 In 1989, a novel attenuated live vaccine was licensed in China. Since then, more than 300 million doses have been produced and more than 200 million children have been vaccinated. Currently, more than 50 million doses of this vaccine are produced annually.

5 The attenuated vaccine has also been licensed for use in India, Nepal, Republic of Korea and Sri Lanka.

6 Now this live vaccine is the only vaccine that selected by government for integration into the Expanded Programmes Immunization (EPI) system in all JE endemic provinces in China.

7 The SA PHK strain was recommended to be virus seed for production in the WHO Guidelines for the Production and Control of Japanese encephalitis vaccine (live) for human use. (WHO Technical Report series, No )

8 Attenuation History of Japanese Encephalitis SA Methods Selected virus clones Virulence Mice ic LD50 Attenuation reversion* Immunogenicity ** SA14 parental virus Hamster kidney cells passage Plaque clone Plaque clone Mice non-neural tissue (spleen, sc tissues) passages Plaque clone Hamster spleen passages Plaque clone Suckling mice skin and lymph nodes Plaque clone SA ND ND Low(<10%) Moderate(62%) High(>90%) IC intracerebral SC subcutaneous * virulence increased to 3.5lgicLD50 after 12 mice ic passages Virulence lower than 2.5 lg icld50 after 35 ic passages ** Neutralizing antibody response in children

9 Criteria of selection attenuated and immunogenic virus clone Attenuation Stability (No reversion) Immunogenicity 1 No sign and death of weanling mice after ic inoculation 2 No sign and death of rhesus monkeys (2-3kg) after ic inoculation mice ic virulence (LD50) did not increase to 2.5 lg after 3-5 passages in mice ic. 1. protective effect in mice %~100% protection after 5.0 lgld50 virus ip challenge 2.neutralizing antibody response in humans, 90% seroconversion.

10 Characteristics of Attenuation Animals SA Virulence SA 14 (Parent) Mice(2.5 w) I.C. ( 0 9.5* Hamster I.C Monkey I.C.+SP Nude mice SC 0 >6.0 **Immune inhibited mice SC 0 ND * lgld50/ml ** treated with cytoxan IC intracerebrally SC subcutaneously SP intraspinal Compared with parental SA14

11 Genotypic Characteristics 57 nucleotide substitutions amino acid changes 24 C 1 E* 8 NS1 5 NS2b 2 NS3 4 NS4a 2 NS5 2 Among them the 8 amino-acid substitutions at envelope E protein gene are demonstrated to be the key mutation and responsible for neurovirulence attenuation

12 site E 107 E 138 E 176 E 177 E 264 E 279 E 315 E 439 E8 Eight amino acids substitution in E coding region SA14 Parent L (Leu) E( Glu) I ( Ile) T( Thr) Q( Gln) K(Lys) A(Ala) K(Lys) SA F( Phe) K(Lys) V(Val) A(Ala) H(His) M(Met) V(Val) R(Arg)

13 Attenuation stability after mice/cells passages No. passages sc Virulence (lgld50/ml)* ic 5 (mice ic) 0( 7.0)** 2.0(9.5) ** 17 (PHKC) 0( 5.0) 0( 6.5) 8+1 (HKC+suckling mice ic) 0 ( 7.8) 1.32 ( 9.5) 17+1 (HKC+suckling mice ic) 0 ( 7.8) 2.68 ( 9.5) *tested in 10-12g mice PHKC Primary hamster kidney cells **SA14 parent virus Attenuation characteristics are highly stable after in vivo or in vitro passages

14 Genetic stability of JE live vaccinesa

15 Genetic stability after passages Complete genome sequence comparision Mutation at different genome regions No. PHKC* Passages 5 prm-c (nt ) E (nt ) Nonstructural (nt ) 3 Homology nt/aa 8 (vaccine seed virus) non non non 4/ non non 1/1 5/ /99.88 * primary hamster kidney cells No. nucleotide mutation/no. amino acid mutation Genetic characteristic is highly stable after in vitro passages

16 Attenuation stability after mosquitoes intrathoracical infection Virus* M Virulence Suckling mice 2.5wks mice ic bite ic sc 0/16 0/16 M 1 +BHKC * from infected mosquitoes 0/10 0/10

17 Genetic stability after mosquitoes infection M 1 +BHKC 1 E-gene sequence Homology Aa reversion 99.9%* 0/8** * Compared with SA seed virus ** No. reversion/no. key amino acids /

18 -20 Stability after -20 long storage Time storage Virus titer ( logpfu/ml) Neurovirulence ( mice ic) Aa Aa reversion 0(seed virus) 5.5~6.5 0/10-10 years /10 0/8 15 years /10 0/8

19 Neuroattenuation and genetic characteristics are highly stable after mice IC, cell culture passages, mosquitoes infection and longterm storage

20 Immunogenicity studies in animal models

21 P3 Comparision with killed vaccines Vaccines NTAb Pre-challenge Protection IP Vaccines IC SA (1 dose) % 80% PHKV (2 dose) 70% 40% PMBV (2 dose) 20 80% 30% Unvaccinated 20% 10% PHKV: Primary hamster kidney cells vaccine, PMBV: Purified mouse brain killed vaccine (Biken )

22 Although the neutralizing antibody levels developed similarly between the live and Biken mouse brain vaccines prechallenge, mice vaccinated (one dose) with the live vaccine produced higher protection by i.p. challenge and much stronger protection by i.c. challenge than the MBV(2 doses, 80% vs 30%).

23 Cellular Immunity Response Enzyme-linked Immunospot (ELISPOT) for detecting IFN-r SFC in mice I FN-γ SFC per 10 6 MNC Vaccine LAV Dilutions vaccine IFN-r SFC Positive (%)* N LAV LAV- 3 LAV- 4 LAV- 5 I PV IPV Control IFN-r SFC production in mice * each group 10 mice LAV: live attenuated vaccine; IPV inactivated purified vaccine LAV-3~LAV-5: different dilutions of live attenuated vaccine

24 LAV-10 0 LAV-10-3 LAV-10-4 LAV-10-5 IPV-10 0 control IFN-γ SFC Production LAV Live attenuated vaccine IPV Inactivated purified vaccine

25 ELISPOT assay for detecting IL-2 SFC in mice I L- 2 SFC per 10 6 MNC Vaccines LAV Dilutions vaccine 10-4 IL-2 SFC positive*(% ) N LAV LAV- 3 LAV- 4 LAV- 5 I PV IPV Control IFN-r SFC production in mice * each group 10 mice LAV: live attenuated vaccine; IPV inactivated purified vaccine LAV-3~LAV-5: different dilutions of live attenuated vaccine

26 LAV-10 0 LAV-10-3 LAV-10-4 LAV-10-5 IPV-10 0 control IL-2 SFC Production LAV Live attenuated vaccine IPV Inactivated purified vaccine

27 Duration of cellular immunity 120 I FN-γ SFC per 10 6 MNC N LAV mont h Dynamic levels of IFN-r SFC

28 Control LAV 14d 1m 3m 6m 1y Dynamic level of IFN-r SFC

29 Summary of Immunogenicity and its duration induced by JE live vaccine in mice Times after vaccination Protective effect (%) Antibody response (Nab titer) Cellular immunity (% positive rate) IFN-r IL-2 14d 100(10/10)* (5/5) 100(5/5) 1m 100(10/10) (5/5) 100(5/5) 3m 100(10/10) 80 80(4/5) 100(5/5) 6m 90(9/10) 40 80(4/5) 80(4/5) 1y 100(10/10) 40 80(4/5) 80(4/5) * No. survivor/no. tested No. positive/no. tested Cellular immunity induced by the live vaccine was evidently and persisted long time (at least one year).

30 Protection against JE isolates outside China Virus Isolation * strains years countries Protection B Thailand 100%(10/10) VN Vietnam 90%(9/10) JKT Indonesia 100%(10/10) India 100%(10/10) Phan Philippines 100%(10/10) Nakayama 1935 Japan 90%(9/10) * ip challenge with JE virus.

31 Strains SH-53 Protections against different genotype JE genotype strains /10 * PFU Virus dose /10 Control 2/10 lgld50 Challenge dose 3.58 SH /10 10/10 2/ LN /10 8/10 1/ SH /10 8/10 1/ SH /10 9/10 1/ SC /10 9/10 2/ HN /10 10/10 2/ * No. survivor/no. tested

32 Strains HLJ HLJ DL04-06 P3 SA14 SA4 KT Protections against different JE genotype strains genotype 2340 PFU Virus dose 10/10 10/10 9/9 10/10 10/10 9/10 9/10 10/10 10/ /10 10/10 10/10 8/10 9/10 9/10 9/10 10/10 9/10 Control 2/10 2/10 2/10 0/10 2/10 1/10 1/10 2/10 1/10 lgld50 Challenge dose * No. survivor/no. tested

33 The live vaccine (1 dose) was capable of inducing broad immunity against heterologous JE virus strains.

34 Safety studies in Humans

35 Years Safety studies in children No.Children (1~15 ages) Adverse event(1/10000) / Encephalitis Meningitis * *Low fever 4.59, Rash 0.78, Nausea, Vomiting 0.31,fatigue 0.56/ No serious adverse events or vaccine associated encephalitis

36 Event Vaccinated Group (n=13,266) Safety studies in children Unvaccinated Group (n=12,951) Risk ratio (95% confidence interval) Encephalitis 0(0.0) 0(0.0) undefined Meningitis Hospital admission Fever lasting 3days 0(0.0) 82(0.6) 357(2.7) 0(0.0) 114(0.9) 442(3.4) undefined 0.70( ) 0.79( ) No increased risk of serious adverse events

37 Immunogenicity in Humans

38 Districts Neutralizing antibody response Seroconversion % GMT Heilongjiang Hebei Jilin Anhui Beijing 92.0(12/13)* 100(33/ (26/27) 95.0 (18/19) 91.3(63/69) * No. positive /No. tested One dose of vaccination will induce 90% seroconversion

39 Efficacy in JE endemic areas Study districts Years Total No Vaccinated JE case Morbidity Unvaccinated Total No JE case Morbidity Guizhou Jiangxi Yunan Anhui GY Anhui MC 1992 ~ * 6* * 24* *Confirmed by IgM test or IgG 4 fold increased 18 dead JE cases were all in the unvaccinated group. Two doses induced significant reduction of JE morbidity.

40 Efficacy Persistence 11 Years in Jiangxi Province Years Cases Vaccinated Unvaccinated Before Vac. 1979~ After Vac. 1989~ ~ ~ : 93.4% 1~10 ages (68573) vaccinated 1990~1999: each year 1 dose for 1 age, 2nd dose for 2 ages Produced high protection and persisted at least 11 years

41 JE morbidity in China (1990~2005) Mor bi di t y( 1/ ) Mor bi di t y of JE i n Chi na ( ) 2~10million 20~30million >40million Year s Morbidity decreased with the more doses of live vaccine used

42 Vaccine used outside China

43 Korea 2002 to 2007 year ~ doses used annually Neutralizing antibody seroconversion 98% No serious adverse event or encephalitis related with the vaccine 30~70 98%

44 Nepal 1999~2007 year A total of 5 million doses used 500

45 Efficacy in Nepal (Background) Study area: JE endemic area in Nepal - Banke, Bardiya, Karlali Vaccination: Single dose of live JE vaccine given in 1999 Study population: 1~15 years old children, (born between 1984 to 1998) 160,000 subjects vaccinated Study design: Case control study with age-sex matched, neighborhood controls

46 Nepal 1999 Efficacy of single-dose vaccination Districts Rate vaccination JE No. JE cases Kailali Bardiya Banke

47 Nepal 1999 Efficacy of single-dose vaccination Districts Kailali Banke Rate vaccination JE No. JE cases ( Bardiya

48 Result: 1999 Efficacy in Nepal(1999) Doses of vaccine received 0 1 Cases (N=20) 20 0 Controls (N=557) 231 (41.5%) 326 (58.5%) Efficacy (%) (95% CI) 99.3% (99.3 ~ 100.0%) Single dose of SA was 99.3% effective Immediate after vaccination. Lancet 2001; 358: 791-5

49 Result: 2000 Efficacy in Nepal(2000) Doses of vaccine received 0 1 Cases (N=35) 34 1 Controls (N=430) 196 (45.6%) 234 (54.4%) Efficacy (%) (95% CI) 98.5% (90.14 ~ 99.86%) Single dose of SA was 98.5% effective 12~15 months after vaccination. Lancet 2005; 366 (9494):

50 20045 Efficacy in Nepal(2004) Doses of vaccine received Cases (N=20) Controls (N=219) Efficacy (%) (95% CI) % (73.1~99.9%) Single dose of SA was 96.2% effective 5 years after vaccination

51 Efficacy persistence Years 1st year nd year th year 2004 Efficacy(%) 99.3(CI 94.9~100%) 98.5(CI 90.1~99.2%) 96.2(CI 73.1~99.9%)

52 India 1998~ % In 2006 : 9.3 Million children vaccinated 930 In 2007 : 15.3 Million children vaccinated 1530

53 Saving lives Cases of viral encephalitis are still reported from the program districts in The only difference is that JE is no more the leading cause of viral encephalitis and the number of viral encephalitis cases are much lesser than previous years 2006~2007

54 Safety study No serious adverse events reported within 30 minutes post vaccination in both centers No vaccine-related serious adverse event reported within 28 days post vaccination Vaccine is well-tolerated across a wide age range 30 28

55 Scientific Committee appointed by Government reviewed all data related to AEFI and concluded No direct causality has been established between reported illness and the SA JE vaccine. Therefore no stricture on further use of the vaccine is warranted SA

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63 Conclusion SA The SA virus is highly attenuated with good immunogenicity. The neuroattenuation and genetic characteristics of SA are stable after in vitro and in vivo passages or mosquitoes infections.

64 Conclusion 5-11 Decline in JE morbidity and long-term immunity (5-11 years) were evidently, and no serious adverse events related to vaccination was recorded.

65 Conclusion SA The results confirm that SA live vaccine is safe and effective for prevention of JE disease in humans

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