RECOMBINANT MVA EXPRESSING VP2 PROTEIN OF IBDV INDUCES SERONEUTRALIZING ANTIBODIES IN CHICKENS

ZANETTI F. A.; DEL MÉDICO ZAJAC M. P.; FERRER M. F.; CALAMANTE G.

Gramado

Encuentro; XXI Encontro Nacional de Virologia. V Encontro de Virologia do Mercosul.; 2010

Infectious bursal disease virus (IBDV) is the causative agent of an immunosuppressive disease that affects young domestic chicken and causes major economic losses to the poultry industry worldwide. The viral protein 2 (VP2) component of the icosahedral capsid is known as the only host-protective antigen; it is highly conformation-dependent with at least three independent epitopes responsible for the induction of neutralizing antibodies. Modified Vaccinia virus Ankara (MVA) is used as a non-replicative viral vector for the development of vaccines against infectious diseases. Its inability to replicate in most of mammalian cells provides an excellent safety barrier. Despite this abortive infection, the antigens encoded by the foreign genes inserted into the recombinant vectors are expressed and become presented to the host immune system. The aim of this work was to develop, characterize and evaluate the immunogenicity of a recombinant MVA expressing VP2 protein of an Argentinean IBDV isolate. First, recombinant MVA-VP2 was obtained and molecularly characterized. The expression of foreign protein in MVA-VP2-infected-cells was confirmed by Western blot using a rabbit polyclonal anti-VP2 serum. Then, the immunogenicity of this recombinant poxvirus was assessed in SPF White Leghorn chickens. The birds were inoculated by intramuscular route with three doses of a homogenate of cells infected with MVA-VP2 or wt MVA. Antibodies specific to IBDV were analyzed by ELISA and by in vitro virus neutralization test. Presence of specific and IBDV-neutralizing antibodies was only observed in chickens immunized with MVA-VP2. Taken together, these results indicate that VP2 protein expressed from MVA-VP2 has the correct conformational structure for inducing seroneutralizing antibodies. The recombinant MVA-VP2 virus is a good candidate to be evaluated as a vaccine (alone or combined with other immunogens) to prevent IBDV infection in chickens.