High frequency of Polio-like Enterovirus C strains with differential clustering of CVA-13 and EV-C99 subgenotypes in a cohort of Malawian children

Abstract

Enteroviruses (EVs) are among the most commonly detected viruses infecting humans worldwide. Although the prevalence of EVs is widely studied, the status of EV prevalence in sub-Saharan Africa remains largely unknown. The objective of our present study was therefore to increase our knowledge on EV circulation in sub-Saharan Africa. We obtained 749 fecal samples from a cross-sectional study conducted on Malawian children aged 6 to 60 months. We tested the samples for the presence of EVs using real time PCR, and typed the positive samples based on partial viral protein 1 (VP1) sequences. A large proportion of the samples was EV positive (89.9%). 12.9% of the typed samples belonged to EV species A (EV-A), 48.6% to species B (EV-B) and 38.5% to species C (EV-C). More than half of the EV-C strains (53%) belonged to subgroup C containing, among others, Poliovirus (PV) 1-3. The serotype most frequently isolated in our study was CVA-13, followed by EV-C99. The strains of CVA-13 showed a vast genetic diversity, possibly representing a new cluster, 'F'. The majority of the EV-C99 strains grouped together as cluster B. In conclusion, this study showed a vast circulation of EVs among Malawian children, with an EV prevalence of 89.9%. Identification of prevalences for species EV-C comparable to our study (38.5%) have only previously been reported in sub-Saharan Africa, and EV-C is rarely found outside of this region. The data found in this study are an important contribution to our current knowledge of EV epidemiology within sub-Saharan Africa.