Infection history in a human with recurrent respiratory tract infections. (A) Timeline of pathogens recovered from the respiratory tract. These were classified as positive single-stranded RNA virus, negative single-stranded RNA virus, double-stranded DNA virus, or bacteria as indicated in the adjacent symbol key. (B) RT-PCR molecular typing of RNA isolated from nasopharyngeal samples, using primer sets that preferentially amplify the indicated HRV species. Patient’s samples a to h, as indicated in A, were collected between 2 and 4 yr of age. Sample a was negative for respiratory pathogens and h positive for influenza A. Purified HRV-B14 and -A16 virus stocks, and a sample from a different subject having respiratory symptoms but negative for HRV/enterovirus, were also tested. Results are representative of three repeats. (C) Phylogenetic tree based on nucleotide sequences of 5′UTR of HRV isolates showing evolutionary relationship of the patient’s samples to closest serotypes and representative HRV species.