Transcriptional expression levels of chicken collectins are effected by avian influenza A virus inoculation.

Mammalian collectins have been found to play an important role in the defense against
influenza A virus H9N2 inoculation, but for chicken collectins this has not yet been
clarified. The aim of this study was to determine the effect of avian influenza A virus (AIV)
inoculation on collectin gene expression in the respiratory tract of chickens and whether
this was affected by age. For this purpose 1- and 4-week-old chickens were inoculated
intratracheally with PBS or H9N2 AIV. Chickens were killed at 0, 8, 16 and 24 h postinoculation
and trachea and lung were harvested for analysis. Viral RNA expression and
mRNA expression of chicken collectins 1 and 2 (cCL-1 and cCL-2), chicken lung lectin (cLL)
and chicken surfactant protein A (cSP-A) were determined using real-time quantitative
RT-PCR. In lung, a decrease in mRNA expression of cCL-2, cLL and cSP-A after inoculation
with H9N2 was seen in both 1- and 4-week-old birds, although at different time points,
while in trachea changes were only seen in 4-week-old birds and expression was
increased. Moreover, collectin expression correlated with viral RNA expression in lung of
1-week-old birds. These results suggest that both age and location in the respiratory tract
affect changes in collectin mRNA expression after inoculation with H9N2 and indicate a
possible role for collectins in the host response to AIV in the respiratory tract of chickens.