New adenoviruses from new primate hosts - growing diversity reveals taxonomic weak points

Genomics-based re-examination of the taxonomy and phylogeny of human and simian Mastadenoviruses: an evolving whole genomes approach, revealing putative zoonosis, anthroponosis, and amphizoonosis

With the advent of high-resolution and cost-effective genomics and bioinformatics tools and methods contributing to a large database of both human (HAdV) and simian (SAdV) adenoviruses, a genomics-based re-evaluation of their taxonomy is warranted. Interest in these particular adenoviruses is growing in part due to the applications of both in gene transfer protocols, including gene therapy and vaccines, as well in oncolytic protocols. In particular, the re-evaluation of SAdVs as appropriate vectors in humans is important as zoonosis precludes the assumption that human immune system may be naïve to these vectors. Additionally, as important pathogens, adenoviruses are a model organism system for understanding viral pathogen emergence through zoonosis and anthroponosis, particularly among the primate species, along with recombination, host adaptation, and selection, as evidenced by one long-standing human respiratory pathogen HAdV-4 and a recent re-evaluation of another, HAdV-76. The latter reflects the insights on amphizoonosis, defined as infections in both directions among host species including "other than human", that are possible with the growing database of nonhuman adenovirus genomes. HAdV-76 is a recombinant that has been isolated from human, chimpanzee, and bonobo hosts. On-going and potential impacts of adenoviruses on public health and translational medicine drive this evaluation of 174 whole genome sequences from HAdVs and SAdVs archived in GenBank. The conclusion is that rather than separate HAdV and SAdV phylogenetic lineages, a single, intertwined tree is observed with all HAdVs and SAdVs forming mixed clades. Therefore, a single designation of "primate adenovirus" (PrAdV) superseding either HAdV and SAdV is proposed, or alternatively, keeping HAdV for human adenovirus but expanding the SAdV nomenclature officially to include host species identification as in ChAdV for chimpanzee adenovirus, GoAdV for gorilla adenovirus, BoAdV for bonobo adenovirus, and ad libitum.

Non-Human Primate-Derived Adenoviruses for Future Use as Oncolytic Agents?

Non-human primate (NHP)-derived adenoviruses have formed a valuable alternative for the use of human adenoviruses in vaccine development and gene therapy strategies by virtue of the low seroprevalence of neutralizing immunity in the human population. The more recent use of several human adenoviruses as oncolytic agents has exhibited excellent safety profiles and firm evidence of clinical efficacy. This proffers the question whether NHP-derived adenoviruses could also be employed for viral oncolysis in human patients. While vaccine vectors are conventionally made as replication-defective vectors, in oncolytic applications replication-competent viruses are used. The data on NHP-derived adenoviral vectors obtained from vaccination studies can only partially support the suitability of NHP-derived adenoviruses for use in oncolytic virus therapy. In addition, the use of NHP-derived adenoviruses in humans might be received warily given the recent zoonotic infections with influenza viruses and coronaviruses. In this review, we discuss the similarities and differences between human- and NHP-derived adenoviruses in view of their use as oncolytic agents. These include their genome organization, receptor use, replication and cell lysis, modulation of the host’s immune responses, as well as their pathogenicity in humans. Together, the data should facilitate a rational and data-supported decision on the suitability of NHP-derived adenoviruses for prospective use in oncolytic virus therapy.

Development of a TaqMan-based real-time PCR for detecting duck adenovirus 3

Recently, a novel duck adenovirus (designated as duck adenovirus 3, DAdV-3) was discovered in Muscovy ducks, China. Here, we developed a TaqMan-based real-time PCR assay (qPCR) for the detection of DAdV-3 infection. After the optimization of the qPCR conditions, the lower limit of detection for DAdV-3 infection was 40.9 copies/μl. No cross-reactivity was observed with other duck-derived pathogens. Intra- and inter-assay variability was less than 2.30%. DAdV-3 was detected in embryos and newly hatched ducklings by qPCR assay, the findings provided evidence of possible vertical transmission of DAdV-3. The developed qPCR analysis showed high specificity, sensitivity, and reproducibility, thereby indicating that it can be used in future investigations on the pathogenesis and epidemiology of DAdV-3.

Detection of novel adenovirus in sick pigeons

This study reports a novel adenovirus that was found circulating in pigeons in China. Nucleotide homology analysis of the hexon gene showed a nucleotide similarity of 79.0 and 70.9% with PiAd-2 variant A and PiAd-1, respectively. Phylogenetic analysis suggested that the identified virus, together with PiAd-2 variant, constitutes a monophyletic group (proposed as Pigeon Aviadenovirus B) in the genus Aviadenovirus. The present study contributes to the understanding of the epidemiology, ecology, and taxonomy of adenoviruses in pigeons.

Adenovirus infection in savanna chimpanzees (Pan troglodytes schweinfurthii) in the Issa Valley, Tanzania

Adenoviruses are a widespread cause of diverse human infections with recently confirmed zoonotic roots in African great apes. We focused on savanna-dwelling chimpanzees in the Issa Valley (Tanzania), which differ from those from forested sites in many aspects of behavior and ecology. PCR targeting the DNA polymerase gene detected AdV in 36.7% (69/188) of fecal samples. We detected five groups of strains belonging to the species Human mastadenovirus E and two distinct groups within the species Human mastadenovirus C based on partial hexon sequence. All detected AdVs from the Issa Valley are related to those from nearby Mahale and Gombe National Parks, suggesting chimpanzee movements and pathogen transmission.