Introduction
Exposure to respiratory viruses is a significant cause of morbidity
worldwide both in children and adults. Among children, respiratory
syncytial virus (RSV) causes bronchiolitis and is the most common cause
of respiratory hospitalization and the second biggest cause of lower
respiratory infection mortality worldwide (1). Other respiratory
viruses, especially rhinovirus (RV) strains, are also major risk factors
of respiratory morbidity because they are known to trigger severe asthma
exacerbations in children (2). Longitudinal studies showed that RSV and
RV-induced bronchiolitis and wheezing illness in early childhood are
associated with subsequent development of asthma (3–8). In healthy
adults, RSV and RV are responsible of common colds, with frequent
reinfections; and in frail elderly persons, they cause insidious
deteriorations of respiratory health with high mortality (2).
Additionally, RV can trigger symptoms of asthma and asthma exacerbations
in allergic patients and individuals susceptible to viral-induced
attacks (9).
Infections of RSV and RV viruses are more common during childhood.
Virulence and persistence of specific immune responses to these
respiratory viruses differ between individuals. To date, the studies
identifying determinants, in particular personal factors (age, sex, body
mass index (BMI), tobacco smoking) and season of blood sampling, of RSV
and RV-specific antibody response remains scarce and often conflicting
results are reported, especially related to passive and active tobacco
exposure (10–12). Moreover, none of these studies focused on population
including both children and adults.
Using the novel micro-array technology, it is possible to measure
RSV-specific antibody response as well as RV-specific antibody responses
to different RV species (13). Accordingly, cumulative levels of
RV-specific antibody levels may be considered as an immunological
imprint of previous RV infections and their severity. However, there may
be also differences regarding the severity of RV infections depending on
the RV-species involved. For example, among the three RV species, RV-A
and RV-C were associated with more severe illness and RV-B with mild
symptoms or asymptomatic infections, especially in children (14,15).
In the present study, we performed a comprehensive analysis to assess
RSV and RV-specific IgG responses in a large cohort of well
characterized children and adults by using a micro-array technology to
identify factors associated with RSV and RV-specific antibody responses.