As viruses are well known triggers of wheeze and a potential confounder of the association between bacteria and wheeze, we controlled for viruses in bacteria samples and bacteria in virus samples by including both in the multivariate analyses.
The other two ducks (M7 and M8) were used as controls for virus infectivity during a 7-day-period.
All ducks were caged in the same room, except the controls for virus infectivity which were kept separately until the day they were challenged: M7 was introduced in the room on day 21 (and euthanized on day 28) whereas M8 was introduced in the room on day 35 (and euthanized on day 42).
Samples from 7 additional patients who had had HCPS in the same geographic region in previous years were used as controls for virus sequence analysis.
When we controlled for virus activity, vaccination (>85% uptake) was associated with a significant decline in RCAP incidence of −31%95%5% CI −51%to−1515%, −411%95%5% CI −52 to –32%), and −34%95%5% CI −42%to−25%5%) among <6-month-old, 6 18-month-old, and 18–35-month-old children, respectively.
No universal mechanism of control for all viruses or viral transgenes has proven successful.
We used dynasore, a dynamin inhibitor known to block influenza virus entry in the absence of serum, as a positive control for influenza virus entry inhibition.
It accumulates light intermediate particles and was used as a control for intermediate virus assembly.
To date, a small number of proteins, namely the chloramphenicol transferase (CAT), the green fluorescent protein (GFP), and the firefly luciferase have been expressed from influenza replicons for matters of transfection control for influenza virus reverse genetics and better understanding of the influenza replication machinery [12], [13], [14].
Each study also included a pathogenicity control for the virus inoculum.
