Use of an improved quantitative polymerase chain reaction assay to determine differences in human rhinovirus viral loads in different populations

Human rhinoviruses (HRV) frequently cause acute respiratory infections and chronic respiratory disease exacerbations. However, testing is not generally offered. We developed a modified HRV quantitative polymerase chain reaction (qPCR) assay to assess viral loads in the community and hospital patients. The assay had a lower limit of detection of 2 log10 viral copies/mL and displayed linearity over 5 log10 viral copies, with a lower limit of quantitation of 4 log10 viral copies/mL. Mean viral loads (95% confidence interval) for hospitalized children, university students, and institutionalized elderly, were 7.08 log10 viral copies/mL (6.7-7.5), 6.87 log10 viral copies/mL (6.5-7.2), and 7.09 log10 viral copies/mL (6.9-7.3), respectively (P = 0.67). Serial specimens of 14 university students showed a decrease of mean viral loads from 6.36 log10 viral copies/mL on day 1 to 2.32 log10 viral copies/mL 7 days past symptom onset (P < 0.001). Using an HRV qPCR, we showed that viral loads did not differ between the community and hospitalized populations and significantly decreased following symptoms onset in healthy individuals.