3. Global Burden of HEV
Genotypes 1 and 2 in 2005
• Methods Annual disease burden of G1 & 2 for 9 of 21 regions
Represent 71% of world’s population
Defined for Global Burden of Diseases, Injuries, and
Risk Factors Study (the GBD 2010 Study)
• Results Incident 20.1 million 95% Cr.I.: 2.8-37.0
Symptomatic3.4 milliom 95% CrI: 0.5-6.5
Death 70.000 95% CrI: 12,400-132,732
Stillbirths 3.000 95% CrI: 1,892 – 4,424
CrI: Credible Interval
Rein DB et al. Hepatology 2012 ; 55 : 988 – 997.
4. • Incubation period 3 – 8 weeks
• Prodromal phase Short
• Symptoms or jaundice Days to several weeks
• Most cases are self-limited
• Case fatality rate 0 – 10%
20% in pregnant women
Hoofnagle JH et al. N Engl J Med 2012 ; 367 : 1237 – 44 .
Clinical features of hepatitis E
Most HEV infections have clinically silent course
5. • Inapparent or asymptomatic infection
• Anicteric hepatitis Biochemical abnormalities – No jaundice
• Icteric hepatitis Similar to other forms of viral hepatitis
• Severe hepatitis Leading to fulminant hepatic failure
• Acute-on-chronic liver disease
Clinical features of hepatitis E
Hepatic manifestations (common)
Aggarwal R & Shahid J. Hepatology 2011 ; 54 : 2218 – 2226.
6. • Acute pancreatitis
• Hematological manifestations Thrombocytopenia, hemolysis
• Autoimmune phenomena Membranous glomerulonephritis
Henoch-Schonlein purpura
• Neurological syndromes Guillian-Barre syndrome
Meningoencephalitis
Pseudotumor cerebri
Cranial nerve palsies
Bilateral pyramidal syndrome
Peripheral neuropathy
Extra-hepatic manifestations (Rare)
Aggarwal R & Shahid J. Hepatology 2011 ; 54 : 2218 – 2226.
Mostly as case reports or small case series
Based usually on detection of anti-HEV IgM rather than HEV RNA
8. Chronic hepatitis E
Previously believed to be always self-limited
• First reported in 2008 in 8 French solid organ transplant recipients
receiving immunosuppressive drugs, & recently developed
transaminase elevation, and had infection with genotype 3
• Also been reported in HIV infection, hematological diseases, or
those receiving anticancer chemotherapy
• Liver histology shows portal hepatitis with lymphocytic infiltrate,
piecemeal necrosis & fibrosis; and in some cases, liver fibrosis
• Persistent infection not reported with genotype 1 or 2 HEV, among
otherwise healthy persons, or from highly endemic regions
Kamar N et al. N Engl J Med 2008 ; 358 : 811 - 817.
9. Course of HEV infection
Wedemeyer H et al. Gastroenterology 2012 ; 142 : 1388 – 1397.
10. Genotypes of HEV
• HEV is classified into four major genotypes
• All four genotypes are believed to represent a single
serotype which has facilitated efforts to develop
hepatitis E vaccines
11. HEV infections according to genotype
Characteristic Genotypes 1 and 2
Epidemic
Genotypes 3 and 4
Autochthonous
Distribution Developing countries Developing & developed countries
Pattern of spread Epidemic & sporadic Sporadic
Species Human Swine, human
Mode of spread Waterborne Foodborne
Icteric illness High Low
Age Adolescents & young older
Sex M = W Higher in men
Mortality High in pregnancy High in older
Extra-hepatic features Few Neurologic
Chronic infection None In immunosuppressed patients
Therapy None known Ribavirin, PEG-IFN
Prevention Vaccine Vaccine
Hoofnagle JH et al. N Engl J Med 2012 ; 367 : 1237 – 44 .
12. Worldwide prevalence of HEV
Endemic regions of hepatitis E
where >25% of acute viral hepatitis is due to HEV
Wedemeyer H et al. Gastroenterology 2012 ; 142 : 1388 – 1397.
13. Geographic distribution of different HEV genotypes
Wedemeyer H et al. Gastroenterology 2012 ; 142 : 1388 – 1397.
15. Genomic organization of HEV
Zakim & Boyer hepatology 2012 – 6th edition.
Short untranslated regions (UTR) at both ends
Three open reading frames (ORFs)
ORF1: encodes nonstructural polyprotein (nsp)
ORF2: encodes the viral capsid protein
ORF3: encodes small regulatory phosphoprotein
16. Assembly of HEV virions
Hoofnagle JH et al. N Engl J Med 2012 ; 367 : 1237 – 44 .
17. Open Reading Frame 2 (ORF-2)
Encodes viral capsid protein
N-terminal signal sequence (SS)
Domain 1: RNA encapsidation
Domain 2: form core of viral capsid
Domain 3: exposed on virus particle
Neutralization epitope (aa 458 – 607) in domain 3
Binding of HEV to its cellular receptor
Aggarwal R & Jameel S. Hepatol Int 2008 ; 2 : 308 – 315.
18. ORF-2 & HEV vaccine
• Antibody elicited in humans & animals against ORF2
is long lived, cross-reactive among diverse HEV
genotypes & neutralizes HEV in vitro
• ORF2 protein of HEV has been the antigen used for all
vaccine studies thus far
• Full-length or truncated forms of the protein expressed
in bacterial cells, insect cells, yeast, animal & plant cells
have emerged as potential vaccine candidates
Kamili S. Virus Research 2011 ; 161: 93 – 100.
19. Vaccine candidates for HEV
Kamili S. Virus Research 2011 ; 161: 93 – 100.
Light colored vertical bar indicates location of neutralizing epitope
Blue bars indicate proteins undergoing clinical evaluation
21. Pre-clinical evaluation of HEV vaccine candidates
ORF-2 protein Amino acids Source Remarks
Expressed in E. coli TrpE-C2 221 – 660 Burma
pE2 394 – 607 China
HEV 239 368 – 606 China Human CT
Expressed in insect
Baculovirus-mediated
Spodoptera litura larvae
56-kDa protein
53-kDa protein
62-kDa
50 kDa (VLPs)
62-kDa
112 – 607
112 – 577
112 – 660
112 – 534
112 – 660
Pakistan
Burma
Burma
Burma
India
Human CT
Oral route
Expressed in other system
Yeast Pichia pastoris
Transgenic tomato plants
HBV/HEV
pE2
551 – 607
394 – 607
China
China
DNA vaccines
Naked
DNA plus protein
pJHEV
pcHEVORF2
+26 kDa
1 – 660
1 – 660
Burma
Burma
India
Stability
Easy preparation
VLPs: Virus Like Particles
22. 56 kDa vaccine
Phase II – Double-blinded placebo-controlled RCT
ShresthaMP et al. N Engl J Med 2007 ; 356 : 895 – 903.
• 1 794 healthy subjects mostly male (99%) & young (mean 25y)
• Compagny: GlaxoSmithKline Biologicals with the US army – Nepal
• Randomization: HEV vaccine versus placebo
• Primary end-point: prevention of clinically overt HEV infection
• Predominantly if not exclusively genotype 1
• 20 μg IM at 0, 1, 6 months
• Follow-up period: 2 years post-vaccination
• Efficacy after third dose: 95,5%
• Side effects: increased injection-site pain
23. Limitation of 56 kDa vaccine
• Study subjects mostly men (>99%) & young (mean
age 25 years)
• Primary end point was clinically overt HEV infection
authors and did not study the HEV infection rate
• anti-HEV antibody titers declined significantly by
end of the study, so that nearly 44% of subjects had
antibody titers below the level considered as protective
24. 56 kDa vaccine
• GlaxoSmithKline did not pursue the manufacture of
this vaccine despite its efficacy
• The firm estimates that there is little commercial
potential for the vaccine
25. Regulatory milestones of HEV 239 vaccine
• 2001 Researchers at Xiamen University modified a E. coli
strain to produce protein stimulating immune system
in humans, to make protective antibodies against HEV
• 2000 Yangshengtang Group joint biotech laboratory with
the university & preclinical/clinical development began
• 2006 Laboratory given national status by Chinese Ministry
of Science and Technology & relaunched as NIDVD*
• 2007 Yangshengtang set up subsidiary company (Innovax)
to take potential vaccines from CT to manufacturing
• 2010 Publication of phase III trial of HEV 239 in Lancet
• 2011 Vaccine approved by China FDA
* NIDVD: National Institute of Diagnostics and Vaccine Development in Infectious Diseases
Human Vaccines Immunotherapeutics 2012 ; 8 : 1743 – 1744.
26. Clinical milestones of HEV 239 vaccine
All studies conducted in China during 2005 – 2009
Phase I
2005
Safety – Guangxi province – 44 volunteers of ages 21-55
20 μg HEV vaccine at 0 – 1 month
Phase IIa Dose schedule & dose escalation – 457 subjects
2 schedules: 0 – 6 & 0 – 1 – 6 mo
anti-HEV IgG seroconversion higher in 3-dose group
Difference not statistically significant (100% vs. 98%)
GMC of anti-HEV IgG significantly higher in 3-dose group
Phase IIb 155 subjects – 4 groups – 3 doses of 10, 20, 30, 40 μg
100% seroconversion in all four groups
High-dosage groups (20, 30 & 40 μg) showed higher
anti-HEV IgG GMC levels than 10-μg dosage group
AE similar among four dosage groups
Phase III
2007 – 2009
Large scale double blind placebo-controlled RCT
Zhang J et al. Vaccine 2009 ; 27 : 1869 – 74.
27. HEV 239 vaccine – Hecolin®
Phase III – Double blind placebo-controlled RCT
• 112 604 healthy subjects, men & women, 16 – 65 years
• Compagny: Xiamen Innovax Biotech – China
• Randomization: HEV vaccine versus HBV vaccine
• Primary end-point: prevention of clinically overt HEV infection
• Genotype 1 & 4 prevalent – Predominant genotype 4
• 30 μg IM at 0, 1, 6 months
• Follow-up period: 13 month post-vaccination
• Efficacy after third dose: 100%
• No side effects
Zhu FC et al. Lancet 2010 ; 376 : 895 – 902.
28. In December 2011,
the China Food & Drug Administration
approved the hepatitis E vaccine Hecolin®
for use in subjects ≥ 16 year old
29. Who should get the vaccine?
• Travelers to endemic areas
• Pregnant women in endemic areas
• Food industry workers
• Aged persons
• During HEV outbreaks (100% efficacy after 2 doses/1mo)
• Organ transplantation receptors
• Patients with underlying chronic liver disease
High risk groups
Wu T et al. Human Vaccines & Immunotherapeutics 2012 ; 8 : 823 – 827.
30. Questions remain to be answered
• HEV infection rate (focus was on clinical disease rate)
• Titer of protective antibodies
• Duration of protection afforded by the vaccine
• Used for post-exposure prophylaxis
• Safety in Pregnant women
People younger than 15 y or older than 65 y
Chronic liver disease
Immunosuppressed patients
31. Safety of Hecolin® in pregnant women
Post-hoc analysis
• Safety of the vaccine for pregnant women was
demonstrated by preliminary analysis in 37 pregnant
women who inadvertently received 1, 2 or 3 doses of
HE vaccine during pregnancy
• The vaccine was well tolerated
The babies born in the vaccine group were as healthy
as those born in the control group
Wu T et al. Hepatology 2012 ; 55 : 2038.
32. Financial aspects of Hecolin®
• Development of Hecolin® cost about 500 million renminbi
or $80 million, much of which came from Chinese
government through the university
• The vaccine will be sold to distributors in China
at cost of 110 renminbi ($17.60) per dose
• Innovax expects sales to reach 62 million renminbi in 2013
Human Vaccines Immunotherapeutics 2012 ; 8 : 1743 – 1744.
33. Xiamen University and Innovax are in talks with the
World Health Organization (WHO) to register Hecolin
with the organization’s Prequalification Programme,
which makes medicines available to agencies such as:
• the United Nations Children’s Fund
• the Joint UN Programme on HIV/AIDS
Park SB. Nature 2012 ; 491 : 21 – 22.
34. Jeremy Farrar
Director of Oxford University Clinical Research Unit
“New companies operating with different funding models
offer a great opportunity, & one which could have a
profound impact.”
“We have to be sure that these vaccines can be used
anywhere”
“It would be a great shame if these products were not
available outside China”
Park SB. Nature 2012 ; 491 : 21 – 22.
35. Conclusion
Though several questions remain to be answered,
the successful clinical testing of this vaccine is a
major step forward in the future control of HEV
Assembly of virions begins with the production of capsid monomers (with or without an N-terminal region), which self-assemble into dimers and subsequently decamers. Decamers lacking the capsid N-terminal assemble into small virus like particles that are the source of HEV vaccines and serologic reagents. Decamers of full-length capsid monomers encapsidate the viral RNA to form full-size virions.
