Taxonomy proposal for Old World monkey adenoviruses: characterisation of several non-human, non-ape primate adenovirus lineages

Isolation of a recombinant simian adenovirus encoding the human adenovirus G52 hexon suggests a simian origin for human adenovirus G52

Human adenoviruses (HAdVs) are causative agents of morbidity and mortality throughout the world. These double-stranded DNA viruses are phylogenetically classified into seven different species (A-G). HAdV-G52, originally isolated in 2008 from a patient presenting with gastroenteritis, is the sole human-derived member of species G. Phylogenetic analysis previously suggested that HAdV-G52 may have a simian origin, indicating a potential zoonotic spillover into humans. However, evidence of HAdV-G52 in either human or simian populations has not been reported since. Here, we describe the isolation and in vitro characterization of rhesus (rh)AdV-69, a novel simian AdV with clear evidence of recombination with HAdV-G52, from the stool of a rhesus macaque. Specifically, the rhAdV-69 hexon capsid protein is 100% identical to that of HAdV-G52, whereas the remainder of the genome is most similar to rhAdV-55, sharing 95.36% nucleic acid identity. A second recombination event with an unknown adenovirus (AdV) is evident at the short fiber gene. From the same sample, we also isolated a second, highly related recombinant AdV (rhAdV-68) that harbors a distinct hexon gene but nearly identical backbone compared to rhAdV-69. In vitro, rhAdV-68 and rhAdV-69 demonstrate comparable growth kinetics and tropisms in human cell lines, nonhuman cell lines, and human enteroids. Furthermore, we show that coinfection of highly related AdVs is not unique to this sample since we also isolated coinfecting rhAdVs from two additional rhesus macaque stool samples. Our data collectively contribute to elucidating the origins of HAdV-G52 and provide insights into the frequency of coinfections and subsequent recombination in AdV evolution.IMPORTANCEUnderstanding the host origins of adenoviruses (AdVs) is critical for public health as transmission of viruses from animals to humans can lead to emergent viruses. Recombination between animal and human AdVs can also produce emergent viruses. HAdV-G52 is the only human-derived member of the HAdV G species. It has been suggested that HAdV-G52 has a simian origin. Here, we isolated from a rhesus macaque, a novel rhAdV, rhAdV-69, that encodes a hexon protein that is 100% identical to that of HAdV-G52. This observation suggests that HAdV-G52 may indeed have a simian origin. We also isolated a highly related rhAdV, differing only in the hexon gene, from the same rhesus macaque stool sample as rhAdV-69, illustrating the potential for co-infection of closely related AdVs and recombination at the hexon gene. Furthermore, our study highlights the critical role of whole-genome sequencing in understanding AdV evolution and monitoring the emergence of pathogenic AdVs.

Isolation of novel simian adenoviruses from macaques for development of a vector for human gene therapy and vaccines

IMPORTANCE

Adenoviruses are widely used in gene therapy and vaccine delivery. Due to the high prevalence of human adenoviruses (HAdVs), the pre-existing immunity against HAdVs in humans is common, which limits the wide and repetitive use of HAdV vectors. In contrast, the pre-existing immunity against simian adenoviruses (SAdVs) is low in humans. Therefore, we performed epidemiological investigations of SAdVs in simians and found that the SAdV prevalence was as high as 33.9%. The whole-genome sequencing and sequence analysis showed SAdV diversity and possible cross species transmission. One isolate with low level of pre-existing neutralizing antibodies in humans was used to construct replication-deficient SAdV vectors with E4orf6 substitution and E1/E3 deletion. Interestingly, we found that the E3 region plays a critical role in its replication in human cells, but the absence of this region could be compensated for by the E4orf6 from HAdV-5 and the E1 expression intrinsic to HEK293 cells.

Detection and Molecular Characterization of Adenoviruses in Captive and Free-Roaming African Green Monkeys (Chlorocebus sabaeus): Evidence for Possible Recombination and Cross-Species Transmission

In the present study, 31 samples (12 fecal, 9 nasal and 10 rectal swabs) from 28/92 (30.43%, 10 captive and 18 free-roaming African green monkeys (AGMs, Chlorocebus sabaeus)) apparently healthy AGMs in the Caribbean Island of St. Kitts tested positive for adenoviruses (AdVs) by DNA-dependent DNA polymerase (pol)-, or hexon-based screening PCR assays. Based on analysis of partial deduced amino acid sequences of Pol- and hexon- of nine AGM AdVs, at least two AdV genetic variants (group-I: seven AdVs with a Simian mastadenovirus-F (SAdV-F)/SAdV-18-like Pol and hexon, and group-II: two AdVs with a SAdV-F/SAdV-18-like Pol and a Human mastadenovirus-F (HAdV-F)/HAdV-40-like hexon) were identified, which was corroborated by analysis of the nearly complete putative Pol, complete hexon, and partial penton base sequences of a representative group-I (strain KNA-08975), and -II (KNA-S6) AdV. SAdV-F-like AdVs were reported for the first time in free-roaming non-human primates (NHPs) and after ~six decades from captive NHPs. Molecular characterization of KNA-S6 (and the other group-II AdV) indicated possible recombination and cross-species transmission events involving SAdV-F-like and HAdV-F-like viruses, corroborating the hypothesis that the evolutionary pathways of HAdVs and SAdVs are intermingled, complicated by recombination and inter-species transmission events, especially between related AdV species, such as HAdV-F and SAdV-F. To our knowledge, this is the first report on detection and molecular characterization of AdVs in AGMs.

Characterization of monkey adenoviruses with three fiber genes

Although the occurrence of three fiber genes in monkey adenoviruses had already been described, the relatedness of the "extra" fibers have not yet been discussed. Here we report the genome analysis of two simian adenovirus (SAdV) serotypes from Old World monkeys and the phylogenetic analysis of the multiple fiber genes found in these and related AdVs. One of the newly sequenced serotypes (SAdV-2), isolated from a rhesus macaque (Macaca mulatta), was classified into species Human mastadenovirus G (HAdV-G), while the other serotype (SAdV-17), originating from a grivet (Chlorocebus aethiops), classified to Simian mastadenovirus F (SAdV-F). We identified unique features in the gene content of these SAdVs compared to those typical for other members of the genus Mastadenovirus. Namely, in the E1B region of SAdV-2, the 19K gene was replaced by an ITR repetition and a copy of the E4 ORF1 gene. Among the 37 genes in both SAdVs, three genes of different lengths, predicted to code for the cellular attachment proteins (the fibers), were found. These proteins exhibit high diversity. Yet, phylogenetic calculations of their conserved parts could reveal the probable evolutionary steps leading to the multiple-fibered contemporary HAdV and SAdV species. Seemingly, there existed (a) common ancestor(s) with two fiber genes for the lineages of the AdVs in species SAdV-B, -E, -F and HAdV-F, alongside a double-fibered ancestor for today's SAdV-C and HAdV-G, which later diverged into descendants forming today's species. Additionally, some HAdV-G members picked up a third fiber gene either to the left-hand or to the in-between position from the existing two. A SAdV-F progenitor also obtained a third copy to the middle, as observed in SAdV-17. The existence of three fiber genes in these contemporary AdVs brings novel possibilities for the design of optimised AdV-based vectors with potential multiple target binding abilities.

Genome Analyses of Ten New Ape Adenoviruses with Similarity to Human Mastadenovirus C

The adenoviruses (AdVs) isolated from humans are taxonomically grouped in seven different species in the Mastadenovirus genus (HAdV-A through G). AdVs isolated from apes are often included in one of the human AdV species. Here we describe the sequence analyses of ten new AdVs that are related to the HAdV-C species and that were isolated from healthy western lowland gorillas, bonobos, chimpanzees, and orangutans kept in Dutch zoos. We analyzed these viruses and compared their genome sequences to those of human- and ape-derived AdV sequences in the NCBI GenBank database. Our data demonstrated that the ape-derived viruses clustering to HAdV-C are markedly distinct from the human HAdV-C species in the size and nucleotide composition (%GC) of their genome, differ in the amino-acid sequence of AdV proteins, and have longer RGD-loops in their penton-base proteins. The viruses form three well-separated clades (the human, the gorilla, and the combined group of the bonobo and chimpanzee viruses), and we propose that these should each be given species-level ranks. The Ad-lumc005 AdV isolated from orangutans was found to be very similar to the gorilla AdVs, and bootstrap inference provided evidence of recombination between the orangutan AdV and the gorilla AdVs. This suggests that this virus may not be a genuine orangutan AdV but may have been transferred from a gorilla to an orangutan host.

Novel approaches for vaccine development

Vaccines are critical tools for maintaining global health. Traditional vaccine technologies have been used across a wide range of bacterial and viral pathogens, yet there are a number of examples where they have not been successful, such as for persistent infections, rapidly evolving pathogens with high sequence variability, complex viral antigens, and emerging pathogens. Novel technologies such as nucleic acid and viral vector vaccines offer the potential to revolutionize vaccine development as they are well-suited to address existing technology limitations. In this review, we discuss the current state of RNA vaccines, recombinant adenovirus vector-based vaccines, and advances from biomaterials and engineering that address these important public health challenges.

Complete genome analysis confirms that the pygmy marmoset adenovirus is a variant of the skunk adenovirus 1 - Short communication

The complete genomic sequence along with phylogenetic analyses of an adenovirus (AdV), isolated from a dead captive pygmy marmoset (Callithrix pygmaea) from a Hungarian zoo is reported. Earlier, based on the phylogenetic analysis of the sequence of a PCR-amplified fragment from the DNA polymerase gene, the pygmy marmoset AdV (PMAdV) has been reported to cluster closest to certain chiropteran AdVs. In the following years similar AdVs were discovered in additional mammalian hosts, including a skunk (Mephitis mephitis), African pygmy hedgehogs (Atelerix albiventris), North American porcupines (Erethizon dorsatum) and grey fox (Urocyon cinereoargenteus). After the full genome analysis of the skunk adenovirus (SkAdV-1), a novel species Skunk mastadenovirus A (SkAdV-A) has been established. The AdVs, originating from the African pygmy hedgehogs, have been found to belong to virus species SkAdV-A. Partial gene sequences from the porcupine AdVs have also implied their very close genetic relatedness to SkAdV-A. The complete genomic sequence of PMAdV, examined in this study, was found to share 99.83% nucleotide identity with SkAdV-1, thus unequivocally represents a genomic variant of SkAdV-1. The observation that viruses classifiable as SkAdV-A are able to infect and cause diseases in several, distantly related mammals seems to deserve further studies to elucidate the infection biology of this intriguing AdV.

Epidemiological and molecular characterization of a novel adenovirus of squirrel monkeys after fatal infection during immunosuppression

Adenoviruses are a frequent cause of acute upper respiratory tract infections that can also cause disseminated disease in immunosuppressed patients. We identified a novel adenovirus, squirrel monkey adenovirus 1 (SqMAdV-1), as the cause of fatal infection in an immunocompromised squirrel monkey (Saimiri boliviensis) at the Keeling Center for Comparative Medicine and Research (KCCMR). Sequencing of SqMAdV-1 revealed that it is most closely related (80.4 % pairwise nucleotide identity) to the titi monkey (Plecturocebus cupreus) adenovirus (TMAdV). Although identified in the titi monkey, TMAdV is highly lethal in these monkeys, and they are not thought to be the natural host. While SqMAdV-1 is similar to other primate adenoviruses in size and genomic characteristics, a nucleotide polymorphism at the expected stop codon of the DNA polymerase gene results in a 126 amino acid extension at the carboxy terminus, a feature not previously observed among other primate adenoviruses. PCR testing and partial sequencing of 95 archived faecal samples from other squirrel monkeys (Saimiri boliviensis and Saimiri sciureus) housed at the KCCMR revealed the presence of three distinct, and apparently endemic species of adenoviruses. A grouping of ten squirrel monkey adenovirus variants has high similarity to SqMAdV-1. A single adenovirus variant (designated SqMAdV-3), detected in five monkeys, has similarity to tufted capuchin (Sapajus apella) adenoviruses. The largest group of adenovirus variants detected (designated SqMAdV-2.0-2.16) has very high similarity (93-99 %) to the TMAdV, suggesting that squirrel monkeys may be the natural host of the TMAdV.

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.

Adenovirus Infections in African Humans and Wild Non-Human Primates: Great Diversity and Cross-Species Transmission

Non-human primates (NHPs) are known hosts for adenoviruses (AdVs), so there is the possibility of the zoonotic or cross-species transmission of AdVs. As with humans, AdV infections in animals can cause diseases that range from asymptomatic to fatal. The aim of this study was to investigate the occurrence and diversity of AdVs in: (i) fecal samples of apes and monkeys from different African countries (Republic of Congo, Senegal, Djibouti and Algeria), (ii) stool of humans living near gorillas in the Republic of Congo, in order to explore the potential zoonotic risks. Samples were screened by real-time and standard PCRs, followed by the sequencing of the partial DNA polymerase gene in order to identify the AdV species. The prevalence was 3.3 folds higher in NHPs than in humans. More than 1/3 (35.8%) of the NHPs and 1/10 (10.5%) of the humans excreted AdVs in their feces. The positive rate was high in great apes (46%), with a maximum of 54.2% in chimpanzees (Pan troglodytes) and 35.9% in gorillas (Gorilla gorilla), followed by monkeys (25.6%), with 27.5% in Barbary macaques (Macaca sylvanus) and 23.1% in baboons (seven Papio papio and six Papio hamadryas). No green monkeys (Chlorocebus sabaeus) were found to be positive for AdVs. The AdVs detected in NHPs were members of Human mastadenovirus E (HAdV-E), HAdV-C or HAdV-B, and those in the humans belonged to HAdV-C or HAdV-D. HAdV-C members were detected in both gorillas and humans, with evidence of zoonotic transmission since phylogenetic analysis revealed that gorilla AdVs belonging to HAdV-C were genetically identical to strains detected in humans who had been living around gorillas, and, inversely, a HAdV-C member HAdV type was detected in gorillas. This confirms the gorilla-to-human transmission of adenovirus. which has been reported previously. In addition, HAdV-E members, the most often detected here, are widely distributed among NHP species regardless of their origin, i.e., HAdV-E members seem to lack host specificity. Virus isolation was successful from a human sample and the strain of the Mbo024 genome, of 35 kb, that was identified as belonging to HAdV-D, exhibited close identity to HAdV-D members for all genes. This study provides information on the AdVs that infect African NHPs and the human populations living nearby, with an evident zoonotic transmission. It is likely that AdVs crossed the species barrier between different NHP species (especially HAdV-E members), between NHPs and humans (especially HAdV-C), but also between humans, NHPs and other animal species.

Full genome sequence analysis of a novel adenovirus from a captive polar bear (Ursus maritimus)

The presence of a novel adenovirus (AdV) was detected by PCR and sequencing, in the internal organs of a captive polar bear that had died in the Budapest zoo. The virus content of the samples proved to be high enough to allow for conventional Sanger sequencing on PCR-amplified genomic fragments. With this approach, the sequence of the entire genome of the putative polar bear adenovirus 1 (PBAdV-1) was obtained. Although the genome was found to be short, consisting of 27,952 base pairs merely, with a relatively balanced G + C content of 46.3 %, its organisation corresponded largely to that of a typical mastadenovirus. Every genus-common gene could be identified except that of protein IX. The short E3 region of the PBAdV-1 consisted of two novel, supposedly type-specific ORFs only, whereas no homologue of any of the E3 genes, usually conserved in mastadenoviruses, such as for example that of the 12.5 K protein, were present. In the E4 region, only the highly conserved gene of the 34 K protein was found besides two novel ORFs showing no homology to any known E4 ORFs. In silico sequence analysis revealed putative splicing donor and acceptor sites in the genes of the E1A, IVa2, DNA-dependent DNA polymerase, pTP, 33 K proteins, and also of U exon protein, all being characteristic for mastadenoviruses. Phylogenetic calculations, based on various proteins, further supported that the newly-detected PBAdV is the representative of a new species within the genus Mastadenovirus, and may represent the evolutionary lineage of adenoviruses that coevolved with carnivorans.

Virus-Host Coevolution with a Focus on Animal and Human DNA Viruses

Viruses have been infecting their host cells since the dawn of life, and this extremely long-term coevolution gave rise to some surprising consequences for the entire tree of life. It is hypothesised that viruses might have contributed to the formation of the first cellular life form, or that even the eukaryotic cell nucleus originates from an infection by a coated virus. The continuous struggle between viruses and their hosts to maintain at least a constant fitness level led to the development of an unceasing arms race, where weapons are often shuttled between the participants. In this literature review we try to give a short insight into some general consequences or traits of virus–host coevolution, and after this we zoom in to the viral clades of adenoviruses, herpesviruses, nucleo-cytoplasmic large DNA viruses, polyomaviruses and, finally, circoviruses.

Adenovirus infection is associated with altered gut microbial communities in a non-human primate

Adenovirus (AdV) infections are one of the main causes of diarrhea in young children. Enteric AdVs probably disrupt gut microbial defences, which can result in diarrhea. To understand the role of the gut microbiome in AdV-induced pathologies, we investigated the gut microbiome of a naturally AdV-infected non-human primate species, the Malagasy mouse lemur (Microcebus griseorufus), which represents an important model in understanding the evolution of diseases. We observed that AdV infection is associated with disruption of the gut microbial community composition. In AdV+ lemurs, several commensal taxa essential for a healthy gut microbiome decreased, whereas genera containing potential pathogens, such as Neisseria, increased in abundance. Microbial co-occurrence networks revealed a loss of important microbial community interactions in AdV+ lemurs and an overrepresentation of Prevotellaceae. The observation of enteric virus-associated loss of commensal bacteria and associated shifts towards pathobionts may represent the missing link for a better understanding of AdV-induced effects in humans, and also for their potential as drivers of co-infections, an area of research that has been largely neglected so far.

Adenoviruses of the most ancient primate lineages support the theory on virus-host co-evolution

The scarcity or complete lack of information on the adenoviruses (AdVs) occurring in the most ancient non-human primates resulted in the initiation of a study for exploring their abundance and diversity in prosimians and New World monkeys (NWMs). In order to assess the variability of these AdVs and the possible signs of the hypothesised virus-host co-evolution, samples from almost every family of NWMs and prosimians were screened for the presence of AdVs. A PCRscreening of 171 faecal or organ samples from live or dead, captive or wild-living prosimians and NWMs was performed. The PCR products from the gene of the IVa2 protein were sequenced and used in phylogeny calculations. The presence of 10 and 15 new AdVs in seven and ten different species of prosimians and NWMs was revealed, respectively. Phylogenetic analysis indicated that the tentative novel AdVs cluster into two separate groups, which form the most basal branches among the primate AdVs, and therefore support the theory on the co-evolution of primate AdVs with their hosts. This is the first report that provides a comprehensive overview of the AdVs occurring in prosimians and NWMs, and the first insight into the evolutionary relationships among AdVs from all major primate groups.

Rapid Cloning of Novel Rhesus Adenoviral Vaccine Vectors

Human and chimpanzee adenovirus vectors are being developed to circumvent preexisting antibodies against common adenovirus vectors such as Ad5. However, baseline immunity to these vectors still exists in human populations. Traditional cloning of new adenovirus vaccine vectors is a long and cumbersome process that takes 2 months or more and that requires rare unique restriction enzyme sites. Here we describe a novel, restriction enzyme-independent method for rapid cloning of new adenovirus vaccine vectors that reduces the total cloning procedure to 1 week. We developed 14 novel adenovirus vectors from rhesus monkeys that can be grown to high titers and that are immunogenic in mice. All vectors grouped with the unusual adenovirus species G and show extremely low seroprevalence in humans. Rapid cloning of novel adenovirus vectors is a promising approach for the development of new vector platforms. Rhesus adenovirus vectors may prove useful for clinical development.IMPORTANCE To overcome baseline immunity to human and chimpanzee adenovirus vectors, we developed 14 novel adenovirus vectors from rhesus monkeys. These vectors are immunogenic in mice and show extremely low seroprevalence in humans. Rhesus adenovirus vectors may prove useful for clinical development.

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.

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

The knowledge of the closest human relatives of human adenoviruses (AdVs) such as adenoviruses found in nonhuman primates is still limited, despite the growing importance of adenoviruses in vaccine development, gene and cancer therapy. We examined 153 stool samples of 17 non-human primate species and detected adenoviral DNA sequences of DNA polymerase (DPOL) gene in 54 samples (35%), originating from 12 out of 17 primate species. We further sequenced 15 hexon gene fragments and based on the phylogenetic analysis we propose two new provisional species SAdV-H and SAdV-I. Our study shows extensive diversity of adenoviral strains forming separate clades often from closely related host species from old world monkeys suggesting the existence of new species of AdVs and shows the necessity for clear ICTV guidelines for final establishment of so far provisional AdV species.

Isolation and characterization of adenoviruses infecting endangered golden snub-nosed monkeys (Rhinopithecus roxellana)

BACKGROUND

Adenoviruses are important pathogens with the potential for interspecies transmission between humans and non-human primates. Although many adenoviruses have been identified in monkeys, the knowledge of these viruses from the Colobinae members is quite limited.

FINDINGS

We conducted a surveillance of viral infection in endangered golden snub-nosed monkeys (Rhinopithecus roxellana) in the subfamily Colobinae in China, and found that 5.1% of sampled individuals were positive for adenovirus. One of the adenoviruses (SAdV-WIV19) was successfully isolated and its full-length genome was sequenced. The full-length genome of WIV19 is 33,562 bp in size, has a G + C content of 56.2%, and encodes 35 putative genes. Sequence analysis revealed that this virus represents a novel species in the genus Mastadenovirus. Diverse cell lines, including those of human origin, were susceptible to WIV19.

CONCLUSION

We report the first time the isolation and full-length genomic characterization of an adenovirus from the subfamily Colobinae.

Molecular epidemiological study of adenovirus infecting western lowland gorillas and humans in and around Moukalaba-Doudou National Park (Gabon)

Adenoviruses are widespread in human population as well as in great apes, although the data about the naturally occurring adenovirus infections remain rare. We conducted the surveillance of adenovirus infection in wild western lowland gorillas in Moukalaba-Doudou National Park (Gabon), in order to investigate naturally occurring adenovirus in target gorillas and tested specifically a possible zoonotic transmission with local people inhabiting the vicinity of the park. Fecal samples were collected from western lowland gorillas and humans, and analyzed by PCR. We detected adenoviral genes in samples from both gorillas and the local people living around the national park, respectively: the overall prevalence rates of adenovirus were 24.1 and 35.0 % in gorillas and humans, respectively. Sequencing revealed that the adenoviruses detected in the gorillas were members of Human mastadenovirus B (HAdV-B), HAdV-C, or HAdV-E, and those in the humans belonged to HAdV-C or HAdV-D. Although HAdV-C members were detected in both gorillas and humans, phylogenetic analysis revealed that the virus detected in gorillas are genetically distinct from those detected in humans. The HAdV-C constitutes a single host lineage which is compatible with the host-pathogen divergence. However, HAdV-B and HAdV-E are constituted by multiple host lineages. Moreover, there is no evidence of zoonotic transmission thus far. Since the gorilla-to-human transmission of adenovirus has been shown before, the current monitoring should be continued in a broader scale for getting more insights in the natural history of naturally occurring adenoviruses and for the safe management of gorillas' populations.

Genome analysis of four Old World monkey adenoviruses supports the proposed species classification of primate adenoviruses and reveals signs of possible homologous recombination

Within the family Adenoviridae, presently Simian mastadenovirus A is the single species approved officially for monkey adenoviruses (AdVs), whilst the establishment of six further species (Simian mastadenovirus B to Simian mastadenovirus G) has been proposed in the last few years. We examined the genetic content and phylogenetic relationships of four Old World monkey (OWM) AdV types [namely simian AdV (SAdV)-8, -11, -16 and -19] for which it had been proposed that they should be classified into different AdV species: SAdV-11 to Human mastadenovirus G, and the other three viruses into three novel species. By full genome sequencing, we identified gene contents characteristic for the genus Mastadenovirus. Among the 36 ORFs, 2 genes of different lengths, predicted to encode the adenoviral cellular attachment protein (the fibre), were found. The E3 regions contained six genes, present in every OWM AdV, but lacked the E3 19K gene, which has seemingly appeared only in the ape (hominid) AdV lineages during evolution. For the first time in SAdVs, two other exons belonging to the gene of the so-called U exon protein were also predicted. Phylogenetic calculations, based on the fibre-1 and the major capsid protein, the hexon, implied that recombination events might have happened between different AdV species. Phylogeny inference, based on the viral DNA-dependent DNA polymerase and the penton base protein, further supported the species classification proposed earlier.