African Horse sickness control through vaccination

Baptiste DUNGU DVM PhD

CEO

Onderstepoort Biological Products Ltd. OBP

Onderstepoort, Pretoria South Africa

Layout

Onderstepoort OBP

AHS history

Vaccine in the control of AHS

Roadmap toward an effective safer DIVA AHS vaccine

FVS OBP OVI

Onderstepoort Biological Products

Onderstepoort Veterinary Institute

Faculty of Veterinary Science

More than 50 different livestock vaccines and other biological products

OBP…in short

State owned company: commercial mandate

200 staff member

More than 50 different biologics:

28 bacterial vaccines,

14 viral vaccines,

4 Protozoal (Blood) vaccines

Autogenous vaccines

6 diagnostic reagents

Therapeutic sera

Culture media

Production Capacity: more than 150 million doses annually

Species covered: Cattle, Sheep, Goat, equine, poultry

6

“What we wish to point out is that, as a scourge which annually causes immense loss to the Colonies, it behoves the authorities to take adequate and scientific means to combat it. As yet absolutely nothing is known about its etiology…it is manifest that until the cause is known we cannot hope to battle with the disease. The discovery of the haematozoon of tsetse-fly disease was a notable feather in the cap of the school of research at Cambridge. Cannot some pathologist from the most progressive of Universities help us in like manner with the paarde-ziekte when peace once more reigns from Cape Town to the Zambezi? (Anon., 1900). “

7 | Onderstepoort Biological Products © | March 9, 2020

…are we running in circles?

www.goldcircle.co.zaSummerveld Training Centre at Shongweni.

9

By 1915

•Virus

•Inoculable but not contagious

•Transmitted by blood sucking insects (mentions

Culicoides but suspects mosquito)

•Has to be a natural reservoir

•Horses, dogs once recovered not viraemic

•Prevention and cure

•Identifies immunity as potentially the best option

•Did first vaccinations using serum of recovered

horse/mule with virus

•Multiple serotypes “antigenic plurality”, some cross

protection between certain types

Vaccine breakthrough, the 60 year project

AHS historical distribution

M Quan, 2014

Egypt (1928, 1943, 1953, 1958,

1971),

Palestine, Jordan, Lebanon, Syria

(1944)

Iran and Persian Gulf (1959-1961)

Libya, Tunisia, Morocco, Algeria

(1965-1967)

Saudi Arabia (1989, 1997)

Spain and southern Iberian

Peninsula (1965-66, 1987-1991)

Cape Verde Islands (1999)

• Vector-borne Orbivirus infection (Reoviridae) of equidae, endemic in large parts of Africa

• 9 different serotypes with some cross-neutralization

• Notifiable disease, OIE Status; worldwide importance

• Exceptional mortality rate in naïve horses

• Up to 95% in horses and 50-70% in mules

• Equus burchelli believed to be primary viral reservoir

• Transmission primarily by biting midges of the genus Culicoides

• Extent of favourable climatic conditions for breeding of Culicoides

• Most serious outbreaks often during March and April

• C. imicola: 98% of all species in trap catches at Onderstepoort and AHSV repeatedly isolated

• C.bolitinos: implicated as vector in a number of outbreaks

AHS – THE DISEASE

AHS - SUSCEPTIBILITY

Equids -

Horses

Mules

Donkeys

Zebra

Canines

Susceptible

50-70%

70-95%

10%

Resistant

1

2

3

4

56

7 8 9

10

10 dsRNA genes VP1

VP2

VP3

VP4

VP5NS1

NS2

VP6

VP7

NS3

African horsesickness virus

10 proteinsOuter capsid pro-teins VP5 & VP2

Core protein VP7 Minor core proteins

Why is AHS still a problem?

• The virus and vectors are endemic in SA & large parts of Africa

• Inadequate immunity

• No sustained vaccination

• Wrong advice and wrong use of vaccine

• Uncontrolled movement of horses

• Weaknesses in surveillance

AHS Control in South AfricaSurveillance, Vaccination and Movement control

Due to nature of current AHS LAV, vaccination restricted to low vector seasonsWith a non-replicating vaccine, the vaccination program could be modified in allowing more flexibility on time and animals to be vaccinated

The virus is endemic in SA

AHSV PCR submissions 2017+18

Total: 776

Positive 2017: 137/3632018: 123/413

Serotypes per season

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9

2016 - 2017 2017 - 2018

AHS-attenuated live virus (ALV) Vaccinesince 1994

• Exclude serotype T5 and T9• T5 was omitted as vaccinated foals suffered severe reactions and

death. Follow-up vaccination studies showed that the combination of T4 and T5 in bottle I was the cause.

• T9 is low-immunogenic and was rare in southern Africa until recently

AHS Bottle I AHS Bottle II Cross reaction

Serotype 1 Serotype 2 1 ↔ 2

Serotype 3 Serotype 6 3 ↔ 7

Serotype 4 Serotype 7 4

Serotype 8 5 ↔ 8

6 ↔ 9

AHS ALV vaccine challenges

AHS free

AHS endemic

AHS vaccine manufacturer

Risk of reassortmentNot in pregnant animalsRestricted for low vector periodsNot recommended in high vector periods or during outbreaksNo DIVAMay not be suitable for epizootic situations or free countriesVaccination may be considered as an “infection” (OIE status)Vaccine produced in Senegal for example comprises all 9 serotypes…

New vaccine? Why?

Attribute Comply

Protection to all serotypes

> 90% animals protected

Duration of immunity ≥ 1 year

Safety ?

Storage, transport temperature 4°C

Enzootic & epizootic use ×

Marker vaccine (DIVA) ×

Current vaccine

AHS vaccine technologies to date

• Live attenuated

• Inactivated vaccinesTraditional vaccine

technologies:

• Live Disabled Single Infection Cycle (DISC) vaccines: (VP6-deficient AHSV strains)

• Live Disabled Single Animal (DISA) vaccines (NS3/NS3a-deficient AHSV strains)

• Inactivated (capsid swap) vaccines

• Sub-unit adjuvanted vaccines

• Canarypox virus expressing AHSV-VP2 and AHSV-VP5

• Modified Vaccinia Ankara (MVA) expressing AHSV-VP2

New technologies (based on

Technology Review report by

J. Castillo):

• Plant expressed AHS-VLP expressed in plant (University of Cape Town, funded by DST)

Other technologies

IHSC driven process for the development of a DIVA AHS vaccine

Glossary of termsExecutive SummaryBackground to the ProcessApproach usedRoadmap toward the development of a DIVA AHS vaccineDesired Characteristics for the DIVA AHS vaccine

Target Product Profile (TPP)AHS vaccine technology reviewVaccination strategy overviewMarket and economic aspects reviewStakeholders inputs & key partnerships for AHS DIVA vaccine developmentCandidate vaccines selection for the medium term

Inactivated AHS vaccinesCanarypox vaccine candidateMVA-VP2 vaccinePlant expressed AHS VLP vaccines

Critical activities for the development of the AHS DIVA vaccineApproved experimental vector-proof horse stablesChallenge model and studies

Timelines for the development of the selected candidateFunding and funding models

Partial funding (pump-priming)Funding of specific candidates

Legal and regulatory needsRecommendations for the Way forwards beyond the present

process

Most important desired characteristics

• Profile of the most desirable characteristics: out of TPP

• Protection to all 9 serotypes

• DIVA

• Flexible for use as monovalent in case of defined outbreaks or epidemics

• Flexible for use in different combinations based on specific epidemiological situation (2 to 3 serotypes in certain regions)

• Effective on all equids and possibly all susceptible animals (e.g. camels)

• Safe for use in horses of all ages and all physiological stages (pregnant, young etc.)

• Adaptable to different vaccination programs: high performance, working horses, movement of horses to and from endemic regions, emergency vaccination etc.

• Affordable to different types of equids

Detailed desired AHS DIVA vaccine

characteristics:

Target Product Profiles

Attribute Minimum Ideal

1 Antigen immunogens protective to AHSV infection Immunogens protective to all 9 serotypes of AHSV

2 Indication for use For active immunisation of horses against

AHSV

For active immunisation of equids (incl. mules and donkeys) of

all ages and physiological conditions against all 9 serotypes of

AHSV. Suitable for immunization of wild equids

Epidemiological relevance Suitable for protection of horses in AHS

enzootic regions

Suitable for protection of equids in enzootic and epizootic

regions, including immunisation of equids being moved between

regions of different AHS status

EFFICACY

Expected efficacy To prevent disease in > 70% of vaccinated

animals

To prevent infection in > 80% of vaccinated animals

Immunity spectrum Protection to all 9 serotypes Equal protection to all 9 serotypes with possibility of individual

serotype protection

5 Onset of immunity Within 3 weeks of complete vaccination Within 10 days following complete vaccination

6 Route of administration Subcutaneous (SC) or Intramuscular (IM) Intramuscular

7 Regimen - vaccination Yearly vaccination to include primo and

booster doses

Yearly vaccination to include primo and booster doses

8 Recommended age at first vaccination As early as possible

9 Duration of immunity Minimum of 12 months Protection to all serotype for at least one year

SAFETY

10 Expected safety Mild and transient injection site reactions

and pyrexia lasting less than 14 days in up to

20% of vaccinated animals.

Mild and transient injection site reactions and pyrexia lasting

less than 7 days in up to 10% of vaccinated animals.

11 Reproductive safety No for milk, 4 weeks for meat Suitable for all stages of pregnancy

Suitable for stallions at any stage

12 Environmental safety No vaccine derived infectious material detectable…

14 Reassortment risk Demonstrated inability to reassort with

wildtype AHSV

Structurally incapable of reassorting with other viruses

DIVA

15 Detection of infection Detection of infection in vaccinated animals

by PCR or serology

Detection of infection in vaccinated animals by PCR or serology

OTHER VACCINE CHARACTERISTICS

16 Package size 1 to 10 doses 1 and 10 doses

17 Cost to end users Not more than current vaccines Not more than double current vaccine price

18 Storage requirements Stable at 4°C Stable at 30°C for 48 hours

19 Shelf-life as packaged for sale 12 months 24 months

Selection of AHS vaccine technology

Inactivated AHS vaccine

• More appropriate for medium term solution

• Proven efficacy & safety

• Proven polyvalency

• DIVA possible: PCR & ELISA (including purified vaccine)

• No risk of virus maintenance

• Industrial processes available

• Interest expressed by manufacturers

• If used largely, may contribute to reducing endemicity

• Suitable for use during outbreaks in all age and physiological groups

Inactivated AHS vaccine development currently ongoing

Development of the inactivated AHS vaccine at OBP

• Vaccine development

• Establishment of a Vector protected facility for clinical studies

• Development and validation of DIVA diagnostic assays

• Interaction with partners (scientific, technical, stakeholders, funders)

Progress with inactivated AHS vaccine development

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

Ma

r-1

9

Ap

r-1

9

Ma

y-1

9

Jun

-19

Jul-

19

Au

g-1

9

Se

p-1

9

Oct-

19

No

v-1

9

De

c-1

9

Jan

-20

Fe

b-2

0

Ma

r-2

0

Ap

r-2

0

Ma

y-2

0

Jun

-20

Jul-

20

Au

g-2

0

Se

p-2

0

Oct-

20

No

v-2

0

De

c-2

0

Jan

-21

Fe

b-2

1

Ma

r-2

1

Ap

r-2

1

Ma

y-2

1

Jun

-21

Jul-

21

Au

g-2

1

Se

p-2

1

Oct-

21

No

v-2

1

Refurbishment of OBP vector protected stables √ √ √ √ √ √ √

Proof of concept (PoC)

9 AHSV serotypes ID confirmation √ √

Agreements between partners finalised √ √ √

Production of MS √ √ √

Production of 9 virus antigens √ √ √ √

Assessment of Inactivation & concentration √ √

Formulation of mono- & multivalent vaccines

Immunogenicity study in horses

PoC for multivalent immunogenicity

Challenge studies in horses

PoC for multivalent protection

Full development

Production of GMP seed material √

Prodution of pilot batches

Dose titration studies in horses

Development & validation of QC procedures √

Production of industrial batches

Product Shelflife

Full regulatory safety study in horses

Regulatory efficacy studies in horses

Duration of immunity

Field safety and Efficacy

Registration

Dossier preparation & submission

Refurbishment of vector-proof stables in compliance with Vet services requirements

Multivalent Inactivated AHS vaccine project plan

Agreement OBP-HKJC

HKJC has granted OBP GBP100,000 as contribution toward the development of the inact AHS vaccine

Funding to be used toward the Immunogenicity in horses Proof of Concept clinical study

Vector-protected animal facility

Facility required by DAFF for vector-born animal diseases clinical studies

Required for immunogenicity, challenge and other regulatory clinical studies

Currently being established at OBP

DIVA Diagnostics

• ELISA format• Based on ratio of anti-NS3 vs anti-VP7 antibodies

• NS3 varies between serotypes• Determine minimum NS3 antigens to react with anti-

NS3 antibodies of all serotypes

• Validation• Determine analytical sensitivity and specificity

• Establish diagnostic specificity

• RT-PCR• Targeting any serogroup specific gene

• e.g. Segment 7

Way forward…

• South African African horse sickness vaccine working group (SA AHS VWG) established since 28th June 2019

• Some of the major activities:• Review of the TPP for AHS vaccines

• Draft guidelines for selection of seed strains for AHS vaccines

• Draft guidelines for multivalent immunogenicity studies in horses

• Standards for the design and operation of vector protected facilities for the keeping of animals for experimental infections with vector-borne animal pathogens

• Fundraising…

THANK YOU