[Expression and immunogenicity of equine infectious anemia virus membrane protein GP90]

Membrane protein GP90 of China equine infectious anemia virus (EIAV) vaccine strain (DLV) and its parental wild type LN strain were expressed with Bac-to-Bac baculovirus expression system and BALB/c mice were inoculated with purified protein, thereby to explore the availability of protein for differential diagnosis and potential for preparing genetically engineered vaccine.

The authors infected donkey PBMC culture with China EIAV vaccine strain (DLV) and its parental wild type LN strain, extracted its proviral DNA as template, amplified the GP90 of DLV and LN, respectively, and expressed with Bac-to-Bac baculovirus expression system. The sf9 insect cells were infected with the recombinant baculovirus and the expressed proteins were purified by IMAC. BALB/c mice were inoculated with purified protein. The specific binding Abs generated in the immunized mice were determined by ELISA method. The neutralizing assay was set up to determine the neutralizing capability of the antigens generated in immunized animals.

The recombinant virus expressing viral antigens was determined by Western blot. The expressed proteins were purified by IMAC resulting in the protein purity of 87%(DLV) and 82%(LN), respectively. The antibody titer of the groups with and without adjuvant was 1 600 and 800, respectively. Serial 2 fold dilutions of the immunized mice sera were reacted with 100 TCID50 of EIAV. The end point of immunization assay was to protect 50% cells form CPE caused by EIAV in donkey skin cells. The neutralizing antibody titer was in the range 40 to 80 from animal immunized with and without adjuvant.

Membrane proteins of EIAV vaccine strain and wild type strain were successfully expressed in eukaryotic cell expression system according to the scheduled plan. The proteins showed strong immunogenicity and could activate animals to produce anti-EIAV specific antibody including neutralizing antibody to EIAV.