Evolution and diversity of human adenoviruses isolated from patients with keratoconjunctivitis

Human adenovirus type 8 is a highly contagious eye disease and is considered as the most common epidemic keratoconjunctivitis worldwide. The virus may alter the course of detection as mutations and recombination in surface antigens are associated with binding and pathogenesis in human adenovirus. The recognition of new recombinant human adenovirus has been based on sequencing of three genes, penton base, hexon and fiber.

50 suspected samples of ocular keratoconjunctivitis were selected over 6 months. Following DNA extraction from isolates positive for cytopathic effect in each well, the complete sequences of hexon, fiber, and penton regions were performed on the genome of human adenovirus isolates using PCR. The sequences of capsid genes, including hexon, fiber, and penton were assessed to observe the evidence of recombination at the molecular level using genetic tools.

The results of nucleotide and amino acid sequence of 5/50 patients with epidemic keratoconjunctivitis positive for hypervariable region of hexon (132_aa -449), hypervariable of knob fiber (183_aa -362) and hypervariable penton (106_aa -466) isolates showed nucleotide and amino acid identity of 98% and 99.41%, 99% and 100%, 95% and 99.72% with hexon, fiber and penton of human adenovirus 8 subtypes. The results of phylogenetic tree and Simplot of the entire sequences and hypervariable regions of isolated hexon, fiber and penton showed all the isolates of human adenovirus from Ahvaz, Iran, were clustered with human adenovirus 8A, B, E, P and J, subtypes isolated strains from different regions of the world.

The results of this study revealed that the human adenovirus isolates from patients with epidemic keratoconjunctivitis were closed to human adenovirus 8A, B, E, P and J subtypes. To determine the emergence of new human adenovirus D8 subtypes strain, analysis of complete genome sequence of human adenovirus was required.