ILDR1 promotes H1N1 SIV infection in cultured cells
In order to explore the role of ILDR1 in influenza virus infection, we
first determined the level of ILDR1 in C57BL/6J mice after H1N1 SIV
infection. Western blot results show that ILDR1 level is significantly
increased by more than 15-fold on the first day after infection and then
decreases as the viral load decreases (Figures 1D and 1F). ILDR1
expression was also examined by performing immunohistology. ILDR1 is
weakly expressed in the lungs of mice before infection, while a
substantial increase of ILDR1-positive cells was observed at 3 dpi
(Figure 5A and 5B). The quantitative analysis shows a 3–6-fold
(P<0.05) increase in the percentage area stained in the lungs
at 3 dpi. ILDR1 levels was restored to a normal level on 14 dpi (Figure
5A and 5B). In addition, ILDR1 levels inPlscr1 -/- mice were examined after SIV
infection at 3 dpi. The results show that ILDR1 expression is
up-regulated after viral infection in Plscr1-/- mice, suggesting
that ILDR1 might play a role in Influenza virus infection (Figure 3D).
We next analyzed the effect of ILDR1 on SIV infection in HEK 293T cells.
qRT-PCR results reveal that the expression of ILDR1 mRNA is
significantly increased after SIV infection in a dosage- and
time-dependent way (Figures 5B and 5C). To examine the effect of ILDR1
overexpression, HEK293T cells were transfected with ILDR1-expressing
vector or empty vector, followed by infection with SIV at an MOI of 0.1.
The results show that SIV TCID50 and viral RNA are
significantly increased in ILDR1-overexpressing cells (Figures 5D and
5F). Meanwhile, the viability of virus-infected cells is significantly
decreased in ILDR1-overexpressing cells (Figure 5E). Taken together, our
present data suggest that ILDR1 promotes H1N1 SIV infection.