The high genetic similarity between rhinoviruses and enteroviruses remains as a pitfall for molecular diagnostic tools: A three-year overview

Background: Enteroviruses (EVs) and rhinoviruses (RVs) belong to the Enterovirus genus within the Picornaviridae family, and show genetic similarities. These viruses are related to mild diseases, but EVs infections can sometimes lead to more severe complications. Current diagnostic molecular techniques should discriminate between the four EV and the three RV species that infect humans. The aim was to revise the EV and RV PCR-confirmed specimens by sequencing for genetic characterisation. Material and methods: Respiratory tract specimens were collected from patients with suspicion of respiratory infection. Respiratory viruses' laboratory-confirmation was performed by commercial multiplex real-time RTPCR assays. Genetic characterisation of all EV and in a selection of RV was performed based on the phylogenetic analyses of partial VP1 and VP4/2 sequences, respectively. Results: From 19,957 tested specimens, 309 (1.5%) were EV-positive, 2546 (12%) were RV-positive, and 233 (1%) were EV/RV co-detections. The phylogenetic analyses revealed that: among single EV detections, 177/309 (57%) were characterised as EV, 2/309 (1%) as RV, and 130/309 (42%) could not be typed; among single 1771 RV detections (Ct < 35), 1651/1771 (93%) were characterised as RV, 3/1771 (0.3%) as EV and 117/1771 (6.7%) could not be typed. Among EV/RV co-detections, 62/233 (27%) were characterised as EV, 130/233 (56%) as RV and 41/233 (18%) could not be typed. Conclusions: A diagnostic method well considered for routine laboratory-confirmation of respiratory viruses should discriminate EV and RV targets. RVs are usually associated with mild respiratory disease, but the potential relatedness of EVs to neurological complications makes their monitoring mandatory. Therefore, an accurate detection and differentiation should be required in commercial diagnostic solutions.