Influenza
A viruses cause a spectrum of responses, from mild coldlike
symptoms to severe respiratory illness and death. Intrinsic host factors,
such as age, can influence disease severity. Glycosylation plays a
critical role in influenza pathogenesis; however, the molecular drivers
of influenza outcomes remain unknown. In this work, we characterized
the host glycomic response to the H1N1 2009 pandemic influenza A virus
(H1N1pdm09) as a function of age-dependent severity in a ferret model.
Using our dual-color lectin microarray technology, we examined baseline
glycosylation and glycomic response to infection in newly weaned and
aged animals, models for young children and the elderly, respectively.
Compared to adult uninfected ferrets, we observed higher levels of
α-2,6-sialosides, the receptor for H1N1pdm09, in newly weaned
and aged animals. We also observed age-dependent loss of O-linked
α-2,3-sialosides. The loss of these highly charged groups may
impact viral clearance by mucins, which corresponds to the lower clearance
rates observed in aged animals. Upon infection, we observed dramatic
changes in the glycomes of aged animals, a population severely impacted
by the virus. In contrast, no significant alterations were observed
in the newly weaned animals, which show mild to moderate responses
to the H1N1pdm09. High mannose, a glycan recently identified as a
marker of severity in adult animals, increased with severity in the
aged population. However, the response was delayed, in line with the
delayed development of pneumonia observed. Overall, our results may
help explain the differential susceptibility to influenza A infection
and severity observed as a function of age.