Ref. No.:
IAH July 2012/4
Title: Recombinant vaccines for African horse sickness based on baculovirus pseudotyping
and transduction
Anticipated start date: 1st January 2013 (flexible)
Duration: 4 years full-time
Eligibility:
 This studentship is open to both science graduates (with, or who anticipate obtaining, at least a
2.1, or equivalent, in a relevant biological or mathematics-based subject in their
undergraduate degrees, or a Masters degree in an appropriate subject) and veterinary
graduates. Other first degrees may be considered. You should be looking for a challenging,
interdisciplinary research training environment and have an active interest in the control of
infectious diseases.

Fully-funded studentships are available to home students and eligible EU students, in line with
BBSRC criteria http://www.bbsrc.ac.uk/web/FILES/Guidelines/studentship_eligibility.pdf.

EU students must also provide evidence that they meet the English language requirement, e.g.
with an IELTS score of 6.5 and no less that 6.0 in any of the subsections.
Supervision:
Principal Supervisor: Dr Javier Castillo-Olivares (IAH)
Co Supervisor: Professor Peter Mertens (IAH)
University Supervisor: Professor Linda King (Oxford Brookes University)
Abstract
African horse sickness (AHS), caused by the African horse sickness virus (AHSV), is a severe disease
of horses, with fatality rates that can exceed 90% in infected animals. Recent outbreaks of Bluetongue
disease in ruminants across the whole of Europe, including the UK (caused by the related bluetongue
virus) that have been linked to climate change and increased global trade, indicate increased risks
posed by these insect transmitted viruses.
The horse industry is a major component of the UK economy, with a value comparable to that of the
cattle industry. An outbreak of AHS would therefore represent not only a significant direct threat to
animal health and welfare; it would also trigger restrictions on animal movements that would have a
devastating effect on both trade and sporting events.
Control of AHSV involves effective surveillance, regulations to prevent their initial introduction and
vaccination. However, the current 'live-virus' vaccines against AHSV can be transmitted in the field
and are considered unsuitable / unsafe for use in Europe. During the last two decades, these
drawbacks have therefore stimulated the development of recombinant DNA vaccines; baculovirus
expressed protein sub-unit vaccines have shown their protective efficacy against AHSV. However, the
expressed proteins are not stable and these vaccines have limited shelf-life. Recombinant pox-viruses
or plasmid DNA carrying AHSV protein genes express the protective antigens within host cells
avoiding the need for protein purification or re-folding. These viruses have been used successfully as
vaccines for AHSV.
Baculoviruses can also be used to insert foreign peptides or proteins in their envelope (pseudotyped
baculovirus) or to carry foreign genes that are expressed from a mammalian promoter inside
mammalian cells (baculovirus transduction). These types of recombinant baculoviruses have been
used successfully as experimental vaccines for a variety of viruses.
The objective of this project is to determine whether protective immunity against AHSV can be
achieved by baculovirus transduction and / or pseudotyping. These vaccination strategies will be
based mainly on the protective antigen of AHSV, VP2, but other AHSV proteins will be explored as
well. Both baculovirus approaches will be used separately or in combination. The recombinant
vaccines will be tested in an appropriate mouse model for AHSV.
Registration, Training and Funding:
The student will be expected to spend time at Oxford Expression Technologies, a biotechnology
company specialised in baculovirus expression systems, and at IAH Pirbright; he/she will therefore
acquire a broad range of technical skills and scientific knowledge.
The student will be registered at Oxford Brookes University, providing access to a wide range of
student facilities and training courses on both sites.
This project is funded by the IAH and Oxford Expression Technologies. Eligible students will receive
a minimum annual stipend of £13,590 and University registration fees will be paid. Students may be
eligible for additional funding based on location and prior qualifications, e.g. veterinary graduates.
Full Description of Project
African Horse Sickness virus (AHSV) is an arbovirus that causes a severe systemic disease in horses.
AHSV immunity is thought to be mediated mainly by virus neutralising (VN) antibodies, which target
primarily, although not exclusively, the outer capsid protein VP2. Although neutralising antibodies
are considered to protect by preventing initial infection of the equine host, little is known about
cellular immunity against AHSV. However, it is expected, as with the related bluetongue virus, that it
plays an important role in protection against severe clinical signs of disease and clearance of viral
infection in the host.
Live vaccines are used for the control of AHS in Africa but they present a series of drawbacks and are
not considered suitable for use in Europe. Killed vaccines are efficacious but have not been used
extensively in the field, their production represents a bio-risk and they are not currently available.
Recombinant baculovirus, pox-virus and plasmid DNA expressing AHSV proteins have all shown
their potential as expression or delivery systems for AHS antigens as vaccine candidates.
Although bluetongue virus and AHSV proteins have been expressed by recombinant baculoviruses in
insect cells, and have previously been tested as sub-unit vaccine candidates, two novel baculovirusvaccines have recently been developed for other viruses. One of these consists of recombinant
baculoviruses containing the genes for protective antigens, which are expressed from a mammalian
promoter, such as the cytomegalovirus promoter. These baculoviruses can enter mammalian cells (a
process coined baculovirus transduction), delivering the relevant gene for a protective antigen. The
transduced host cells then express the antigen, leading to the induction of an appropriate immune
response. Alternatively, genes of protective antigens or epitopes can be fused to the baculovirus
envelope glycoprotein GP64. When the new recombinant GP64 is expressed, these protective antigens
form part of the virion envelope and are displayed on the surface of the recombinant (pseudotyped)
baculovirus particle, which can potentially be used as sub-unit vaccine.
Neither of these novel approaches have as yet been used to deliver BTV or AHSV genes as vaccine
candidates. In this project, the student will therefore develop novel recombinant vaccines for AHSV
using pseudotyped baculoviruses displaying AHSV outer capsid protein VP2 in the baculovirus
envelope. The same protein, AHSV VP2, will also be cloned into the baculovirus genome under the
control of a CMV promoter for expression in host mammalian cells upon transduction. There will be
much scope for the student to improve or modify the expression of these antigens by deciding which
domains of VP2 should be expressed and whether or not other AHSV proteins should be incorporated
in the constructs to improve the immunogenicity of the vaccines.
The student will then explore the possibility of using these recombinant viruses (using transduction or
pseudotyping or both) as novel vaccines. He/she will analyse the immune responses that follow
vaccination of mice with these recombinant constructs, by developing the immunological assays
appropriate for these studies. These vaccines are expected to induce different effector mechanisms of
immunity and the student will test whether a combination of both approaches (transduction and
pseudotyping) is superior to either approach alone. By working with Oxford Expression
Technologies, any effective vaccine candidates that are generated can be rapidly developed as
commercial products, helping to ensure their wider availability.
References for background reading:
1. Mellor PS, Hamblin C. African horse sickness. Vet Res 2004 Jul-Aug;35(4):445-66.
2. Castillo-Olivares J, Calvo-Pinilla E, Casanova I, Bachanek-Bankowska K, Chiam R, Maan S, et al.
A modified vaccinia Ankara virus (MVA) vaccine expressing African horse sickness virus (AHSV)
VP2 protects against AHSV challenge in an IFNAR -/- mouse model. PLoS One 2011;6(1):e16503-8.
3. Chen CY, Lin CY, Chen GY, Hu YC. Baculovirus as a gene delivery vector: recent understandings
of molecular alterations in transduced cells and latest applications. Biotechnol Adv 2011 NovDec;29(6):618-31.
4. Madhan S, Prabakaran M, Kwang J. Baculovirus as vaccine vectors. Curr Gene Ther 2010
Jun;10(3):201-13.
Further information regarding the partner institutions can be found at:
www.iah.ac.uk/
http://oetltd.com//
http://www.brookes.ac.uk/
Informal enquiries can be sent to: javier.castillo-olivares@iah.ac.uk