New adenovirus species found in a patient presenting with gastroenteritis

Abstract

An unidentified agent was cultured in primary monkey cells at the Los Angeles County Public Health Department from each of five stool specimens submitted from an outbreak of gastroenteritis. Electron microscopy and an adenovirus-specific monoclonal antibody confirmed this agent to be an adenovirus. Since viral titers were too low, complete serotyping was not possible. Using the DNase-sequence-independent viral nucleic acid amplification method, we identified several nucleotide sequences with a high homology to human adenovirus 41 (HAdV-41) and simian adenovirus 1 (SAdV-1). However, using anti-SAdV-1 sera, it was determined that this virus was serologically different than SAdV-1. Genomic sequencing and phylogenetic analysis confirmed that this new adenovirus was so divergent from the known human adenoviruses that it was not only a new type but also represented a new species (human adenovirus G). In a retrospective clinical study, this new virus was detected by PCR in one additional patient from a separate gastroenteritis outbreak. This study suggests that HAdV-52 may be one of many agents causing gastroenteritis of unknown etiology.

FIG. 1.

Transmission electron micrograph of isolated HAdV-52. Note that the virus has a typical icosahedral shape and is roughly 70 nm, which is typical of adenoviruses (29). Bar, 100 nm.

FIG. 2.

DNase-SISPA of HAdV-52 from DNA-extracted tissue culture sample 2244. PCR products were analyzed on a 6.5% acrylamide gel. Lane L, molecular weight markers.

FIG. 3.

Gene organization in HAdV-52 (A) and HAdV-40 (B). Each genome is represented by a central black horizontal line marked at 5-kbp intervals. Protein-encoding regions are shown as boxes. Dark gray boxes above the black line represent open reading frames (ORFs) that are encoded on the positive strand. Light gray boxes underneath the black line represent ORFs that are encoded on the negative strand. Note that HAdV-40 does not have a 12.5K homolog, and the first ORF (dUTPase) present in HAdV-52 is missing, too.

FIG. 4.

Phylogenetic analysis of HAdV-52 is based on the predicted amino acid sequences of pTP (A), pIIIa (B), and penton base (C) from selected adenoviruses. Numbers denote human adenovirus serotypes. HAdV-52 (in bold) shows the new isolate. Simian adenoviruses are designated by the word simian and their serotype number. Note that simian adenoviruses 1 and 3 are from Old World monkeys, while SAdV-21 to -25 were isolated from chimpanzees. All of these trees are unrooted. SAdV-3 was chosen as an outgroup, as earlier studies suggested it to be the most ancient from the fully sequenced primate adenoviruses (21, 22). Official human adenovirus species are designated by the letter used for their subsequent lettering, e.g., F for human adenovirus F. Simian adenovirus A is shown by its abbreviated name, SAdV-A. The newly proposed HAdV species (containing a monkey and a human AdV type) is designated “proposed G” (in bold). Bootstrap values (for 100 data sets) are shown for the accepted and the presently proposed species.

FIG. 5.

Alignment of a selected region of HAdV-52 and adenovirus hexon sequences. Letters in parentheses denote the human species. Porcine AdV-3 is porcine adenovirus 3, and BrushTail-Pos AdV is brush tail possum adenovirus. Tyrosine at position 831 is highlighted in boldface and yellow.