Abstract:
This paper describes the expression of a cloned African horsesickness virus (AHSV) serotype 5 VP2-
gene by a baculovirus recombinant that was generated by the BAC-TO-BAC™ system. Immunization
of horses with crude cell lysates containing recombinant baculovirus-expressed AHSV5 VP2 did induce
neutralizing antibodies, but afforded only partial protection against virulent virus challenge. Further
analysis of partially protective crude cell lysates revealed that baculovirus-expressed AHSV5 VP2
was predominantly present in the form of insoluble aggregates. Only approximately 10% of VP2 was
present in a soluble form. Immunization of guinea-pigs with aggregated and soluble forms of AHSV5
VP2 established that only soluble VP2 was capable of inducing neutralizing antibodies. This finding
adds a new dimension to the development of AHSV VP2s as subunit vaccines. Further investigation
is needed to limit formation of insoluble aggregates and optimize conditions for producing VP2 in a
form capable of inducing protective immunity.
