Molecular characterisation of human respiratory adeno viruses in Uganda

Abstract

Background: Human adenoviruses (HAdV) are a diverse group of viruses causing a broad range of infections of the respirator y, urogenital, gastrointestinal tracts, and keratoconjunctivitis. Currently there are over 69 genotypes and 51 serotypes dispersed across the seven species of human adenoviruses (i.e., HAdV A to HAdV G). Infections due to HAdV are usually self-limiting but can be fatal in children and immune-compromised individuals. Objective: The objective for this study was to characterize and determine the prevalence of Human respiratory Adenoviruses and associated factors in samples collected from selected hospitals in Uganda. Methods: A total of 2298 nasopharyngeal samples were analysed by Polymerase Chain Reaction (PCR) to determine the prevalence of HAdV. The positive samples were inoculated on A549 cell lines to isolate Adenovirus. The Hexon gene from the HAdV isolates was amplified, purified, and sequenced to characterize the virus. Results: Of the 2,298 samples tested, 225 (9.8%) were adenovirus positive. Majority 220/2137 (10.3%) were in the children aged between 0 to 5 years followed by 4/106 (3.8%) positives among children between 6 to 15 years and 1/30 (3.3%) among individuals between 16 and 25 years. There were no positives seen in adults above 25 years of age. Age and HAdV infection were significantly associated (p=0.028). The sequenced Isolates’ Hexon gene clustered under species HAdV B and HAdV C with most isolates identifying as genotype B3. The Hexon gene sequence-based phylogenetic tree showed that the HAdV-B and C isolates clustered with HAdV sequences from several parts in and outside Africa. Conclusions: A prevalence of 9.8% was recorded and observed genetic diversity among HAdV in Ugandan population. Children aged between 0 to 5 years were more likely to get infected with HAdV than other age groups. There was a close genetic relationship between Uganda HAdV and those from other parts in and out of Africa. This indicated HAdV capability to spread across a broad geographical region and the implications it would have in causing epidemic and pandemic outbreaks. Recommendations: Deeper genomic characterization based on whole genome sequencing is necessary to further elucidate possible transmission and impact of current adeno-vectored vaccines in Africa.