Human rhinoviruses including group C are common in stool samples of young Finnish children

Human rhinoviruses (HRVs) are common causes of viral respiratory infections. They have been widely studied in respiratory samples in hospital patient series but only a few studies have been performed to assess their occurrence in other sample types and their circulation in healthy children background population.

To analyze the frequency of HRVs in the background population in Finland by screening HRV RNA from stool samples longitudinally collected in a cohort of young children.

Altogether 4184 stool samples were collected regularly from a cohort of children who were observed from birth. Samples were screened for the presence of RNA of HRVs using RT-PCR. HRV specific sequences were identified by sequencing the VP1 or VP4/VP2 coding region. Virus isolation was performed using four different cell lines and the result was confirmed by real time PCR.

A total of 9% of the stool samples were positive for HRV RNA. Sequence analysis indicated that the most prevalent species was HRV-A, and the most prevalent serotype was HRV61. HRV-B and HRV-C species were also detected. One of the six tested rhinovirus positive samples retained its infectivity and was able to grow in RD and GMK cells.

Our study shows that HRVs are frequently detected in the stool samples from the population of young children. We also show that HRV-C, which can cause severe illnesses in children, is commonly circulating in young children in Finland.