barbervax: the first commercially available sub-unit ......haemonchus contortus (barbers pole worm)...
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Barbervax: the first commercially available sub-unit vaccine for a
nematode parasite.
David Smith Moredun Research Institute,
Edinburgh, UK.
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Moredun Research Institute
Mission: “To lead in livestock health solutions for global food
security”
1920 2015
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Haemonchus contortus (Barbers Pole worm)
Globally, the most important nematode parasite of sheep and goats
Blood sucker
Prefers warm climates
Resistance to drugs a serious problem
No vaccine available for this or any other species of gut worm of any host – until Barbervax was launched 6 months ago!
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Vaccine mechanism
Because Haemonchus feeds on blood, molecules on the surface of its intestinal cells are suitable targets for a vaccine
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When surface proteins from the brush border of the worms intestinal cells are injected into a sheep…..
it responds and makes antibodies which circulate. in the blood. If a vaccinated sheep gets infected, the parasites ingest blood so that antibodies bind to the worms intestines …
….leading to greatly reduced egg output and worm numbers……
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H11 and H-gal-GP antigens give best protection for any nematode in any host
• 9 different experiments.
• 82 lambs, aged 2-10 months.
• Challenged 1 x 5,000 Haemonchus.
• Protection (%) eggs worms
mean 95.0 70.4
SD 2.6 8.1
e.g. Moredun’s H-gal-GP in Quil A
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Vaccine to kill blood feeding worm stages and reduce egg laying?
No amplification
during ex-host
period:
Potential to reduce
transmission of
disease
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The gut antigens are mainly digestive proteases
• “H11”, a family of leucine aminopeptidases
(Babraham).
• “H-gal-GP”, a complex of aspartyl and metallo –proteases (Moredun).
• Both highly protective in native form individually and/or in combination.
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H-gal-GP and H11 are “hidden” antigens.
• Advantages: Vaccine works and in all classes of sheep Worms have not evolved to cope Conserved antigens – no “strains” Likely to be sustainable • Disadvantages: Response not boosted by challenge infection Repeated vaccination necessary
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Structure of H-gal-GP complex by EM (J. Trinick and S. Meunsch, Leeds University)
Slightly smaller than FMD virus
Orientation in the membrane?
Albumin and Hb fit Into the cavity. A protease machine?
Could antibodies block substrate access to the protease machine?
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Neither H-gal-GP, nor H11 are protective if unfolded or in recombinant form!
Since no protection with recombinant proteins,
would a low dose of native antigen work?
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1 0 1 0
0
1 0 0 0 0
2 0 0 0 0
3 0 0 0 0
M e an
c u m u la tive
fa e c a l e g g
c o u n t (s e )
D o s e o f n a t iv e a n t ig e n / s h o t (u g )
Low dose vaccine trial in Moredun sheep
This dose is small enough for a native antigen vaccine to be commercially viable
if large numbers of clean adult Haemonchus can be obtained cost-effectively
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Vaccine culture system and bio-fermenter?
Advantages 1. Cost effective
2. Readily scaled-up!
Manufacture of Barbervax in Australia
Ours is unusual,
it can walk and
is edible!
Dept of Agriculture and Food, Albany, W.A
Where?
(must be from Australian Haemonchus)
How?
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Commercial Scale Barbervax Manufacture
Who needs molecular biology when a cement mixer will do?!
Expression system: Haemonchus contortus Large scale fermenter : Ovis aries
(Albany, Western Australia)
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Commercial Scale Vaccine Manufacture
Good Manufacturing Practice Licence 2011
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www.moredun.org.uk
Field trials with lambs in Australia
80% overall reduction in egg count in vaccinates
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www.moredun.org.uk
Replicate plot field trials with lambs in NSW, Australia.
H a e m o n c h u s e g g s p e r g :
p lo ts p o o le d b y t re a tm e n t
0 2 5 5 0 7 5 1 0 0 1 2 5 1 5 0 1 7 5
0
5 0 0 0
1 0 0 0 0
1 5 0 0 0
2 0 0 0 0
2 5 0 0 0
D a y p o s t V 1M
ea
n
SE
N D J F M A
V a c c in e g iv e n
C o n tro ls
V a c c in a te s
T o p lo ts
0 2 5 5 0 7 5 1 0 0 1 2 5 1 5 0 1 7 5
0
1 0 0
2 0 0
3 0 0
4 0 0
0
5 0
1 0 0
1 5 0
2 0 0
P a s tu re in fe c tiv ity a n d
to ta l m o n th ly ra in fa ll
d a y s a fte r V 1
Da
ily
Ha
em
on
ch
us
pic
k-u
p
(me
an
s
e)
mm
ra
in
C o n tro l V a c c in e
N D J F M A
R a in fa ll
Performed independently by CSIRO or VHR Vaccinates and controls grazing separately Tracer lambs
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Vaccinating ewes
Around lambing time and during lactation naturally acquired immunity to nematodes wanes – higher egg counts – the so-called periparturient rise.
This egg output is important epidemiologically as it is the source of infection for the next generation of lambs
Could Barbervax reduce this periparturient rise?
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Group
(all grazing together) Vaccination schedule
6-8 weeks
before
lambing
1-2 weeks
before
lambing
At lamb
marking,
then at 6
week
intervals
First vaccinated + + +
Previously vaccinated
as lambs and hoggets - + +
Control - - -
Ewe trial design
• egg counts and anaemia every two weeks • precautionary drench if PCV<22% or epg>10,000 • 3 trials
Would the vaccine reduce the periparturient rise?
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0
2 0 0 0
4 0 0 0
6 0 0 0
Me
an
9
5%
CI
CSIRO
Dundee
Kingstown
Individual ewe Haemonchus egg counts averaged over lactation
0
1 0 0 0
2 0 0 0
3 0 0 0
4 0 0 0
Me
an
(
95
%C
I)
0
1 0 0 0
2 0 0 0
3 0 0 0
4 0 0 0
Me
an
9
5%
CI
PV FV Control
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How protective does a Haemonchus vaccine need to be?
No amplification
during ex-host
period:
Modelling the
epidemiological
benefit relative to
a conventional
anthelmintic
control programme
Dobson RJ, et al 2011. A multi-species model to assess the effect of refugia on worm control and anthelmintic resistance in sheep grazing systems. Aust Vet J., 2011 89:200–208.
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Vaccine % mean yr. Haemonchosis*
protection Deaths to AR years
90% 0.2 16.5 1/20
85% 0.5 16.7 1/20
80% 0.6 17.3 1/20
75% 0.9 17.3 1/20
70% 1.6 18.7 2/20
65% 4.5 19.8 5/20
60% 9.3 20.0 9/20
55% 15.6 20.7 9/20
50% 19.3 20.8 9/20
Unvaccinated 27.7 11.5 8/20
How good does a Haemonchus vaccine have to be in lambs?
*Haemonchosis = the number of years out of 20 in which lamb deaths, caused by H. contortus, were 3% or more.
Vaccinated lambs received one anthelmintic treatment and theoretical vaccines with protection ranging from 90-50%. Unvaccinated lambs received four anthelmintic treatments.
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BENEFIT TO LAMBS
Level of protection* induced by the
vaccine
%Deaths
Mean H.c.
epg
Haemonchosis
years/20
Ewe Lamb
50-80% 70% 5.9 310 4.0
0% 0% 32.3 955 10.0
Vaccinating ewes benefits their lambs
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BENEFIT TO LAMBS
Level of protection* induced by the
vaccine
%Deaths
Mean H.c.
epg
Haemonchosis
years/20
Ewe Lamb
50-80% 70% 5.9 310 4.0
0% 0% 32.3 955 10.0
BENEFIT TO EWES
50-80% 70% 1.2 86 2.3
0% 0% 18.5 270 8.0
Vaccinating ewes benefits their lambs as well as themselves
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Barbervax profile
• 5ug native antigen + 1mg saponin adjuvant /dose
• 1ml injection under the skin. 250ml packs.
• Shelf life at least 2.5 years at 2-8C.
• 5 doses for lambs during the summer Haemonchus risk period
• 4/5 doses for older sheep if vaccinated in previous summers.
• Reduces the periparturient rise – epidemiological benefit to flock
• Works versus all Haemonchus including drench resistant worms.
• Sustainable - vaccine resistance unlikely to develop.
• Non toxic. “Green”.
• Slows the development of anthelmintic resistance in all species
• No effect against scour worms.
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Armidale, New South Wales, Australia
APVMA Registered
October 1st , 2014
All 300,000
doses of vaccine sold by word of mouth within
10 days
No large pharma involved
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Haemonchus vaccine field trials (33)
EMBRAPA, Sobral (2)
UNESP Botucatu (3)
DAFWA, Albany (2)
OVI, Pretoria (3)
Afrivet, Joburg (2)
Zurich, Switzerland (2)
SUL, INIA Uruguay (6)
CSIRO, VHR Armidale (10)
EMBRAPA, Bage (1)
Merida, Mexico (1)
Morogoro, Tanzania (1)
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www.moredun.org.uk
Potential Global Impact on Livestock
Nelore cattle In Brazil
Boer Goats, South Africa Bergamasco ewes, Brazil Sheep and goats, Tanzania
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Barbervax is an unusual vaccine
1. Sub-unit native antigen vaccine for a metazoan parasite
2. A “hidden” antigen vaccine 4. Manufactured by a research institute - no pharmas involved. 5. No share holders – profits re-invested in research
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Acknowledgements
Scotland Moredun G. Newlands, S. Smith, M.Oliver, R. Mole and J. Fitzpatrick Australia DAFWA B. Besier, J. Lyon, D. Michael VHR B. Chick, R. Neilson CSIRO M. Knox, P. Hunt Murdoch Uni R. Dobson Brazil UNESP A. Amarante, C. Bassetto EMBRAPA C. Souza, M. Benavides, M. Texiera S. Africa OVI A. Spickett, T. Musoke Afrivet H. Bredenkamp, P. Oberem Switzerland Zurich Uni H. Herzberg, L. Meier Uruguay SUL D. Castells INIA A. Mederos, G. Banchero