Induction of antibody responses to African horse sickness virus (AHSV) in ponies after vaccination with recombinant modified vaccinia Ankara (MVA).
BACKGROUND
African horse sickness virus (AHSV) causes a non-contagious, infectious disease in equids, with mortality rates that can exceed 90% in susceptible horse populations. AHSV vaccines play a crucial role in the control of the disease; however, there are concerns over the use of polyvalent live attenuated vaccines particularly in areas where AHSV is not endemic. Therefore, it is important to consider alternative approaches for AHSV vaccine development. We have carried out a pilot study to investigate the ability of recombinant modified vaccinia Ankara (MVA) vaccines expressing VP2, VP7 or NS3 genes of AHSV to stimulate immune responses against AHSV antigens in the horse.


RESULTS
VP2, VP7 and NS3 genes from AHSV-4/Madrid87 were cloned into the vaccinia transfer vector pSC11 and recombinant MVA viruses generated. Antigen expression or transcription of the AHSV genes from cells infected with the recombinant viruses was confirmed. Pairs of ponies were vaccinated with MVAVP2, MVAVP7 or MVANS3 and both MVA vector and AHSV antigen-specific antibody responses were analysed. Vaccination with MVAVP2 induced a strong AHSV neutralising antibody response (VN titre up to a value of 2). MVAVP7 also induced AHSV antigen-specific responses, detected by western blotting. NS3 specific antibody responses were not detected.


CONCLUSIONS
This pilot study demonstrates the immunogenicity of recombinant MVA vectored AHSV vaccines, in particular MVAVP2, and indicates that further work to investigate whether these vaccines would confer protection from lethal AHSV challenge in the horse is justifiable.
Chiam
Rachael
R
Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom.
Sharp
Emma
E
Maan
Sushila
S
Rao
Shujing
S
Mertens
Peter
P
Blacklaws
Barbara
B
Davis-Poynter
Nick
N
Wood
James
J
Castillo-Olivares
Javier
J
D000356:African Horse Sickness Virus / Q000276:immunology*; D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D000956:Antigens, Viral / Q000737:chemistry; D036022:Capsid Proteins / Q000737:chemistry; D005786:Gene Expression Regulation; D006736:Horses; D009500:Neutralization Tests; D014611:Vaccination; D014613:Vaccines, Attenuated; D014614:Vaccines, Synthetic / Q000627:therapeutic use*; D014758:Viral Core Proteins / Q000737:chemistry; D017361:Viral Nonstructural Proteins / Q000737:chemistry; D014765:Viral Vaccines / Q000627:therapeutic use*
D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; C115108:NS3 protein, African horse sickness virus; C442519:VP2 protein, African horse sickness virus; D014613:Vaccines, Attenuated; D014614:Vaccines, Synthetic; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins; D014765:Viral Vaccines; C069264:VP7 major core antigen, African horsesickness virus