An anti-apoptosis gene of the Bcl-2 family from Marine Birnavirus inhibiting apoptosis of insect cells infected with baculovirus.

VP5 is a 15-kDa nonstructural protein encoded by a small open reading frame in 5'-terminal of segment A of the Marine Birnavirus (MABV) (strainY-6) genome. Comparisons of the amino acid sequence of the VP5 with other Bcl-2 family member proteins indicated that the VP5 protein contains Bcl-2 homology (BH) domains BH1, BH2, BH3, and BH4, but without the transmembrane region. The VP5 gene from MABV was fused to enhancing green fluorescence protein (eGFP) gene and inserted into the baculovirus genome under the control of polyhedrin gene promoter, and then was highly expressed in insect cells. The expressed VP5 was capable of enhancing insect cell viability, prevented membrane blebbing and delayed DNA internucleosomal cleavage when cells were infected with the recombinant virus. The results suggested that the VP5 of MABV is a novel anti-apoptosis gene, which could regulate the cell apoptosis-off system.