Limited success of efficient PEDV propagation in traditional
cell lines is one of the key hurdles in PEDV research.
The best result so far was described in a study in which
different derivatives of Vero cell lines were tested for their
ability to recover US PEDV isolates. However, out of the
88 PEDV-positive samples tested, only nine (10.22 %)
exhibited cytopathic effects in cells and positive RT-PCR
results in supernatants (Oka et al., 2014). Here, we have
developed a platform to facilitate the in vitro culture of
PEDV by engineering Vero E6 cells to permanently express
pAPN as a substrate for PEDV propagation. This modified
cell line can augment PEDV replication, based on the observation
that the majority of PEDV-positive intestinal samples
used in our study gave rise to progressive syncytium formation
in VeroE6–APN but not in parental VeroE6 cells
(data not shown). As Vero cells are of monkey origin and
do not express pAPN, it is possible that PEDV may use an
alternative pathway to initiate replication in Vero cells.
Interestingly, we demonstrated that ectopic expression of
pAPN in Vero E6 cells could enhance the replication effi-
ciency of PEDV in this modified cell line. In addition, the
fact that PEDV freshly isolated from the intestines of
infected piglets grew better in VeroE6–APN than in
VeroE6 cells suggests that PEDV may prefer pAPN to available
alternative receptors for Vero E6 cell entry. Recently, a
number of studies have shown that cells of porcine origin,
such as small intestinal epithelial cells and alveolar macrophages,
are susceptible to PEDV infection. However, it has