Molecular Characterization of Human Enteroviruses Detected in Children Under Five Years Old in Kenya 2009 - 2015

Abstract

 Introduction:  Human enterovirus (HEVs) infection is common, with an extensive array of clinical displays ranging from asymptomatic to life-threatening. Presentation include nonspecific febrile illness often accompanied by muscle pain, sore throat, abdominal discomfort, rash, headache, encephalitis, aseptic meningitis and acute flaccid paralysis [2].

Objectives: The study objective was to investigate the natural selection and genetic variability of HEVs and to identify HEV serotypes in circulation among children below 5 years old with diarrhea in an informal settlement(Kibera) in Kenya.

Methodology: Specimens (n=628) from a prospective cohort study assessing the incidence and etiology of diarrhea from 2009-2015 were analyzed. Enteric Taqman array cards (TAC) were used for initial screening where two hundred and nine (78%) tested positive for HEVs. Of these specimens, 72 (42%) had a cycle threshold (Ct) ≤30 and were tested by conventional PCR targeting the 3’ regions of the viral protein 1 (VP1) gene. A total of 48 (67%) underwent sequencing; 11 (23%) of which yielded nucleotide sequences. Phylogenetic analyses clustered the Kenyan serotypes to HEVs groups C, B and A. Evaluation of the VP1 amino acid sequences revealed numerous amino acid substitutions in relation to reference strains, which were confirmed to be due to natural selection by negative or positive selection.

Conclusion: The Heterogeneous nature of stool samples is known to influence disparities in viral nucleic acid yields. TAC detected 209 of which 171 (82%) were confirmed positive for HEVs by real-time reverse transcription polymerase chain reaction (RRT-PCR), targeting the 5’ NTR regions. Therefore, the results may not be a representative of all circulating HEVs in the study area. Since this was a retrospective study of previously collected samples, it is possible that some HEVs strains may have failed to amplify.