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The Board of Henderson
Morley, the AIM quoted biotechnology company, is pleased to announce the
results of the Koi Herpes Virus (KHV) Vaccine field studies that have now been
completed in a sub-contract research facility.
Highlights
- Henderson
Morley’s KHV vaccine field study has produced positive results
- In two of the vaccine groups 96% and 93% of
the vaccinated fish survived the study and remained healthy
- Two successful vaccine candidates are now
being developed further with a view to presenting these candidates to
Schering Plough Animal Health
- KHV disease is classed as a ‘Notifiable-Disease’
by the World Organisation of Animal Health. KHV
is therefore a pathogen of growing economic and environmental importance
About the Study
In this study, eight different vaccine candidates were
studied. These candidates were formulated to examine the effects of different
doses of vaccine, addition of purified virus particles, formulation of
candidates with different adjuvants (components of the vaccine that boost
immune responses), and different combinations of adjuvants. Adjuvants, that the
Directors believe, have never been used in fish vaccines before, were also
examined.
Ten groups of Koi carp were
held in isolated tanks each with individual water supplies, of which eight
groups were vaccinated with candidate vaccines. One group received no vaccine
(negative control), and another group were survivors of prior KHV infection, (positive
controls).
Results
The unvaccinated negative
control group died from KHV infection, as did the fish in some of the
unsuccessful low dose vaccine groups. The Board is very pleased that in two of
the vaccine groups, 96% and 93% of the vaccinated fish survived, and remained
healthy following the virus challenge and for the month following the virus
challenge. Other vaccine groups had 76% and 79% survival; however these
candidates are not being selected for further development.
Vaccine Candidates
The candidates
used in this study utilise inactivated virus, so pose no threat of
infection either to the vaccinated fish or other fish in the same tank or pond.
The candidates comprises proprietary methods and techniques developed in-house
at the Birmingham (UK) laboratories and do not have PREPS or
L-particles in their manufacture. New patents are in preparation to protect the
current lead candidates.
KHV
KHV is a serious viral
infection that infects all species of carp, including the high value and
in-bred ornamental fish, Koi carp. The virus was first isolated in 1996, and
has now been detected in over 20 countries. Consequently, in 2006 the World Organisation of Animal Health (OIE) gave KHV
disease ‘Notifiable Disease’ status.
As a Notifiable Disease there is a legal obligation to report any suspicion of
a clinical outbreak of Koi Herpes Virus disease to the Fish Health Inspectorate
(FHI). KHV is therefore a pathogen
of growing economic and environmental importance.
A single fish infected by
KHV may rapidly spread the disease and this often kills between 90% and 100% of
fish in the infected pond or tank, with the potential to devastate entire fish
farms. The virus is temperature sensitive and is mainly active in warm weather
conditions. There is currently no available anti-viral treatment or vaccine
licensed in the EU, US or Japan.
A particular problem with
KHV, which is similar to other herpes viruses in humans and animals, is the
ability to cause latent infection. Once a fish has been infected, or exposed to
the live virus, the infection may recur (usually in response to stressors such
as high water temperature), without further exposure to the virus. Once
infected, fish may also shed the virus into a pond, even in the absence of
symptoms.
Live virus challenge
Approximately two months after
receiving the vaccines (to allow the fish to develop immune responses), fish
were challenged with live Koi Herpes virus that had been characterised by Polymerase Chain Reaction (PCR), a technique
used in molecular biology for creating multiple copies of DNA
from a sample which results in a very accurate diagnosis and typing of virus
infections.
Further
development
The two successful vaccine
candidates are now being developed further with a view to presenting these
candidates to Schering Plough Animal Health under the terms of the development
and option to license agreement as soon as possible.
Chairman Andrew Knight
commented “We are extremely pleased with
the results of this study which demonstrate a level of efficacy for our vaccine
technology and reinforces our decision to transform Henderson Morley into a pure play vaccine
company by 2011. We look forward to
bringing further news on this exciting development in due course. ” |
