Objective. To determine whether the level of apoptosis induced by infectious pancreatic necrosis
virus (IPNV) is related to the amino acid sequence of the BH2 domain of the VP5 protein and the
level of infectivity. Materials and methods. Three IPNV strains were used, the VP2 protein gene was
amplified for genotyping and the VP5 sequence was also obtained. The infectivity of the strains was
calculated using the viral titer obtained at 12, 24, 36 and 45 hpi in CHSE-214 cells. The percentage
of apoptosis in infected cells was visualized by TUNEL assay and immunohistochemistry (caspase 3
detection). Results. The V70/06 and V33/98 strains corresponded to genotype Sp, while V112/06 to
VR-299; the amino acid analysis of the V70/06 strain allows its classification as middle virulent strain
and V33/98 and V112/06 strains as low virulent ones; infection with the V112/06 strain produced a
lower viral titer (p<0.05). The VP5 gene of the 3 strains showed four homologous domains to Bcl-2,
however, the BH2 domain was truncated in V70/06 and V33/98 (12 kDa), being complete (15kDa) in
V112/06, which also showed the Trp155 residue, equivalent to Trp188 considered as a critical factor
for the function of Bcl-2. The average apoptosis was below 12%, showing no differences between
strains (p>0.05). Conclusions. The results showed that the differences in the BH2 sequence of the
VP5 protein, infectivity and the VP2 sequence are not associated with the modulation of apoptosis
