Identification and complete genome analysis of kobuvirus in faecal samples of European roller (Coracias garrulus): for the first time in a bird

Evolutionary dynamics of canine kobuvirus in Vietnam and Thailand reveal the evidence of viral ability to evade host immunity

Canine kobuvirus (CaKoV) is a pathogen associated with canine gastrointestinal disease (GID). This study examined 327 rectal swabs (RS), including 113 from Vietnam (46 healthy, 67 with GID) and 214 from Thailand (107 healthy and 107 with GID). CaKoV was detected in both countries, with prevalences of 28.3% (33/113) in Vietnam and 7.9% (17/214) in Thailand. Additionally, CaKoV was found in both dogs with diarrhea and healthy dogs. CaKoV was mainly found in puppies under six months of age (30.8%). Co-detection with other canine viruses were also observed. The complete coding sequence (CDS) of nine Vietnamese and four Thai CaKoV strains were characterized. Phylogenetic analysis revealed a close genetic relationship between Vietnamese and Thai CaKoV strains, which were related to the Chinese strains. CDS analysis indicated a distinct lineage for two Vietnamese CaKoV strains. Selective pressure analysis on the viral capsid (VP1) region showed negative selection, with potential positive selection sites on B-cell epitopes. This study, the first of its kind in Vietnam, provides insights into CaKoV prevalence in dogs of different ages and healthy statuses, updates CaKoV occurrence in Thailand, and sheds light on its molecular characteristics and immune evasion strategies.

Identification of Multiple Novel Viruses in Fecal Samples of Black-Necked Cranes Using Viral Metagenomic Methods

The black-necked crane is the only species of crane that lives in the high-altitude region of the Tibet Plateau. At present, there is little research on viral diseases of the black-necked crane (Grus nigricollis). In this study, a viral metagenomic approach was employed to investigate the fecal virome of black-necked cranes in Saga County, Shigatse City, Tibet, China. The identified virus families carried by black-necked cranes mainly include Genomoviridae, Parvoviridae, and Picornaviridae. The percentages of sequence reads belonging to these three virus families were 1.6%, 3.1%, and 93.7%, respectively. Among them, one genome was characterized as a novel species in the genus Grusopivirus of the family Picornaviridae, four new parvovirus genomes were obtained and classified into four different novel species within the genus Chaphamaparvovirus of the subfamily Hamaparvovirinae, and four novel genomovirus genomes were also acquired and identified as members of three different species, including Gemykroznavirus haeme1, Gemycircularvirus ptero6, and Gemycircularvirus ptero10. All of these viruses were firstly detected in fecal samples of black-necked cranes. This study provides valuable information for understanding the viral community composition in the digestive tract of black-necked cranes in Tibet, which can be used for monitoring, preventing, and treating potential viral diseases in black-necked cranes.

Isolation and Characteristics of a Novel Aichivirus D from Yak

Aichivirus D (AiV-D) is a newly emerging Kobuvirus detected in bovine and sheep, and information is limited regarding its biological significance and prevalence. This study aimed to explore both the prevalence and characteristics of AiV-D in yaks. From May to August 2021, 117 fecal samples were collected from yaks with diarrhea in three provinces of China's Qinghai-Tibet Plateau, 15 of which were selected and pooled for metagenomic analysis. A high abundance of AiV-D sequences was obtained. Of the 117 diarrhea samples, 29 (24.8%) tested AiV-D-positive, including 33.3% (14/42) from Sichuan, 21.1% (8/38) from Qinghai, and 18.9% (7/37) from Tibet, respectively, suggesting a wide geographical distribution of the AiV-D in yaks in the Qinghai-Tibet Plateau. Furthermore, three AiV-D strains were successfully isolated using Vero cells. Significantly, the AiV-D strain could cause diarrhea, intestinal bleeding, and inflammation in yak calves via oral inoculation. The virus was distributed in the ileum, jejunum, duodenum, colon, cecum, and rectum. Based on phylogenetic analysis of the genome and capsid protein P1 (VP0, VP3, and VP1 genes), the yak AiV-D strains likely represent a novel genotype of AiV-D. On the whole, this study identified a novel genotype of AiV-D from yaks, which was successfully isolated, and confirmed that this virus is a diarrhea pathogen in yaks and has a wide geographical distribution in the Qinghai-Tibet Plateau. Our results expand the host range of AiV-D and the pathogen spectrum of yaks and have significant implications for diagnosing and controlling diarrhea in yaks. IMPORTANCE In this study, we identified and successfully isolated a novel genotype of AiV-D from yaks. Animal infection confirmed that this virus can cause diarrhea, intestinal bleeding, and inflammation in yak calves via oral inoculation. The virus was distributed in the ileum, jejunum, cecum, duodenum, colon, and rectum. All of these results have significant implications for diagnosing and controlling diarrhea in yaks. These novel AiV-D strains have a wide geographical distribution in yaks from the Qinghai-Tibet Plateau in China. In addition to expanding the host range of AiV-D and the pathogen spectrum of yaks, these findings can increase knowledge of the prevalence and diversity of AiV-D.

Characterization of a novel picornavirus prevalent in experimental rabbits (Oryctolagus cuniculus)

Here, using viral metagenomic method a novel picornavirus (named UJS-2019picorna, GenBank accession number OP821762) was discovered in fecal and blood samples of experimental rabbits (Oryctolagus cuniculus). The complete genome size of UJS-2019picorna is 7832 bp excluding the poly(A)-tail, with GC content of 44.00% and a nucleotide composition of 28.0% A, 28.0% U, 21.5% G, and 22.5% C. The viral genome has a typical picornavirus organization pattern from the 5'-3' direction: VPg-5' UTR-(L)-P1, (VP4-VP2-VP3-VP1)-P2, (2 A-2B-2C)-P3, (3 A-3B-3C-3D)-3' UTR-poly(A). The P1 region of UJS-2019picorna is related to Erbovirus with amino acid identity of 37.31%, while the P2 and P3 regions are the closest to Bopivirus with amino acid identity of 35.66%-39.53%. According to the Picornaviridae Study Group guidelines, UJS-2019picorna should be presumed to be a new genus belonging to the Picornaviridae family. Epidemiologic study revealed that this novel picornavirus was prevalent in a cohort of experimental rabbits, with prevalence rate of 23.68% (9/38) in feces and 18.4% (7/38) in blood samples. Further work is required to elucidate whether this virus is pathogenic to rabbits and whether it has influence on studies using rabbits as experimental animal.

Development of a new TaqMan-based real-time RT-PCR assay for the specific detection of bovine kobuvirus

Bovine kobuvirus (BKV) is a novel kobuvirus considered to be closely related to calf diarrhea and has become a worldwide epidemic. Currently, the BKV lacks an efficient and convenient detection method to assist the research on BKV prevalence. In this study, a new and specific TaqMan-based real-time RT-PCR for the detection of BKV was developed using the conserved region of the 3D gene. The assay was highly specific for BKV, without cross-amplification with other non-targeted pathogens. The limit of detection of this assay was 10² copies. Standard curves showed a strong linear correlation from 10² to 10⁶ copies of BKV standard RNA per reaction, and the parameters revealed as a slope of −3.54, efficiency of 91.64%, and regression coefficients (R²) of 0.998. The assay was also reproducible, with the intra-assay and inter-assay coefficient of variation <1.0%. The newly developed real-time RT-PCR was validated using 243 fecal samples collected from diarrheic or non-diarrheic cattle from nine regions in Hebei province and revealed the positive detection of BKV at a ratio of 19.34% (47/243). Sequencing of partial 3D genes from 13 positive samples and the following phylogenetic analysis demonstrated the reliability of the assay. In conclusion, the newly developed TaqMan-based real-time RT-PCR could be used for the screening and epidemic monitoring of BKV.

Detection of Systemic Canine Kobuvirus Infection in Peripheral Tissues and the Central Nervous System of a Fox Infected with Canine Distemper Virus

Canine kobuvirus (CaKV) is a globally distributed pathogen of dogs and is predominantly associated with infection of the gastrointestinal tract. However, an etiological link to enteric disease has not been established since CaKV has been identified in both asymptomatic dogs and animals with diarrheic symptoms. In this study, an extraintestinal CaKV infection was detected by next-generation sequencing in a fox (Vulpes vulpes) in Germany concomitant with a canine distemper virus (canine morbillivirus; CDV) co-infection. Phylogenetic analysis of the complete coding region sequence showed that this strain was most closely related to a CaKV strain detected in a dog in the United Kingdom in 2008. The tissue and cellular tropism of CaKV was characterized by the detection of viral antigens and RNA. CaKV RNA was detected by in situ hybridization in different tissues, including epithelial cells of the stomach and ependymal cells in the brain. The use of a new RT-qPCR assay for CaKV confirmed the systemic distribution of CaKV with viral RNA also detected in the lymph nodes, bladder, trachea, and brain. The detection of a CDV infection in this fox suggests that immunosuppression should be further investigated as a contributing factor to the enhanced extraintestinal spread of CaKV.

Molecular Survey on Kobuviruses in Domestic and Wild Ungulates From Northwestern Italian Alps

Since the first identification in 1989 in humans, kobuviruses (KoVs) have been identified from a wide range of animal species including carnivores, rodents, birds, ungulates, rabbits, and bats. Several studies have described the identification of genetically related KoVs in the fecal virome of domestic and wild animals suggesting a mutual exchange of viruses. By screening a total of 231 fecal samples from wild and domestic ungulates, KoVs RNA was detected in wild boars (3.2%; 2/63), chamois (4.6%; 2/43), and goats (2.6%; 2/77). On phylogenetic analysis of the partial RdRp sequence, the wild boar strains clustered within the species Aichivirus C whilst the strains identified in domestic and wild ruminants grouped into the species Aichivirus B. The complete VP1 gene was obtained for chamois and goat KoVs. Interestingly, upon phylogenetic analysis the strains grouped together with a KoV of ovine origin within a distinct genetic type (B3) of the species Aichivirus B.

Novel enteric viruses in fatal enteritis of grey squirrels

Astro- and kobuviruses infect both humans and animals. Here, we report on the disease history, detection and genomic characterization of novel astro- and kobuviruses from fatal diarrhoea of two juvenile grey squirrels. The virus particles had enterovirus-like morphology and a diameter of 28-32 nm. Next-generation sequencing confirmed astro- and kobuviruses and sequence analysis revealed typical astrovirus and picornavirus genome organizations. The astrovirus ORF2 sequence clustered with a clade of unassigned astroviruses, with marmot and rodent mamastroviruses as closest relatives. For the kobuvirus, divergences greater than 49.4 % for P1 and 43.5 % in the non-structural proteins indicated a novel species. However, phylogenetic analysis of the 3D polymerase showed that it clustered with that of the newly classified ludopivirus A1, suggesting a previous recombination event in the evolution of the kobuvirus. Our data provide further insights into the diversity of astro- and kobuviruses and broaden the spectrum of viruses infecting grey squirrels.

A Comprehensive Review on Human Aichi Virus

Although norovirus, rotavirus, adenovirus and Astrovirus are considered the most important viral agents transmitted by food and water, in recent years other viruses, such as Aichi virus (AiV), have emerged as responsible for gastroenteritis outbreaks associated with different foods. AiV belongs to the genus Kobuvirus of the family Picornaviridae. It is a virus with icosahedral morphology that presents a single stranded RNA genome with positive sense (8280 nucleotides) and a poly (A) chain. AiV was first detected from clinical samples and in recent years has been involved in acute gastroenteritis outbreaks from different world regions. Furthermore, several studies conducted in Japan, Germany, France, Tunisia and Spain showed a high prevalence of AiV antibodies in adults (between 80% and 99%), which is indicative of a large exposure to this virus. The aim of this review is to bring together all the discovered information about the emerging pathogen human Aichi virus (AiV), discussing the possibles routes of transmission, new detection techniques and future research. Although AiV is responsible for a low percentage of gastroenteritis outbreaks, the high seroprevalence shown by human populations indicates an evident role as an enteric agent. The low percentage of AiV detection could be explained by the fact that the pathogen is more associated to subclinical infections. Further studies will be needed to clarify the real impact of AiV in human health and its importance as a causative gastroenteritis agent worldwide.

Epidemiology of Aichi virus in fecal samples from outpatients with acute gastroenteritis in Northwestern Spain

BACKGROUND

In recent years, Aichi virus (AiV) has been involved in acute viral gastroenteritis outbreaks. However, the common pathogenesis of AiV releases more in subclinical infections underestimating the impact of AiV in human health.

OBJECTIVES

The present study describes the presence and genetic diversity of AiV in patients with gastroenteritis in Northwestern Spain.

STUDY DESIGN

A total of 2667 stool samples, obtained between July 2010 and June 2011, from diarrheic outpatients were studied for detection and molecular characterization of AiV using PCR techniques followed by sequencing and phylogenetic analyses.

RESULTS

The virus was detected in 124 (5.0%) of the samples among all age groups. Coinfections were also detected, from the 124 positive samples, 72 (58.1%) were positive only for AiV, whereas mixed contaminations with Norovirus genogroup I or genogroup II, Sapovirus, or other enteric pathogens were detected in 52 (41.9%) samples. A total of 70 positive samples could be genotyped, being characterized as genotype A (58.6%) or B (41.4%). AiV was detected from August to April, being the highest number of AiV positive samples detected during autumn and winter seasons.

CONCLUSIONS

This survey remarks the importance of emerging enteric viruses in patients who require medical assistance, and offers more information about the real importance of AiV as gastroenteritis agent.

Genetically highly divergent RNA virus with astrovirus-like (5'-end) and hepevirus-like (3'-end) genome organization in carnivorous birds, European roller (Coracias garrulus)

Astroviruses (family Astroviridae) and hepeviruses (family Hepeviridae) are small, non-enveloped viruses with genetically diverse +ssRNA genome thought to be enteric pathogens infecting vertebrates including humans. Recently, many novel astro- and hepatitis E virus-like +ssRNA viruses have been described from lower vertebrate species. The non-structural proteins of astro- and hepeviruses are highly diverse, but the structural/capsid proteins represent a common phylogenetic position shed the light of their common origin by inter-viral recombination. In this study, a novel astrovirus/hepevirus-like virus with +ssRNA genome (Er/SZAL5/HUN/2011, MK450332) was serendipitously identified and characterized from 3 (8.5%) out of 35 European roller (Coracias garrulus) faecal samples by RT-PCR in Hungary. The complete genome of Er/SZAL5/HUN/2011 (MK450332) is 8402 nt-long and potentially composed three non-overlapping open reading frames (ORFs): ORF1a (4449 nt/1482aa), ORF1b (1206 nt/401aa) and ORF2 (1491 nt/496aa). The ORF1ab has an astrovirus-like genome organization containing the non-structural conserved elements (TM, CC, NLS, VPg) and enzyme residues (trypsine-like protease, RNA-dependent RNA-polymerase) with low amino acid sequence identity, 15% (ORF1a) and 44% (ORF1b), to astroviruses. Supposedly the ORF2 is a capsid protein but neither the astrovirus-like subgenomic RNA promoter (sgRNA) nor the astrovirus-like capsid characteristics have been identifiable. However, the predicted capsid protein (ORF2) showed 26% identity to the corresponding protein of hepevirus-like novel Rana hepevirus (MH330682). This novel +ssRNA virus strain Er/SZAL5/HUN/2011 with astrovirus-like genome organization in the non-structural genome regions (ORF1a and ORF1b) and Rana hepevirus-related capsid (ORF2) protein represent a potentially recombinant virus species and supports the common origin hypothesis, although, the taxonomic position of the studied virus is still under discussion.

A novel passerivirus (family Picornaviridae) in an outbreak of enteritis with high mortality in estrildid finches (Uraeginthus sp.)

An enteric outbreak with high mortality (34/52, 65.4%) was recorded in 2014 in home-reared estrildid finches (Estrildidae) in Hungary. A novel passerivirus was identified in a diseased violet-eared waxbill using viral metagenomics and confirmed by RT-(q)PCR. The complete genome of finch picornavirus strain waxbill/DB01/HUN/2014 (MF977321) showed the highest amino acid sequence identity of 38.9%, 61.6%, 69.6% in P1^cap, 2C^hel and 3C^proD^pol, respectively, to passerivirus A1 (GU182406). A high viral load (6.58 × 10¹⁰ genomic copies/ml) was measured in a cloacal specimen and in the tissues (spinal cord, lung, and the intestines) of two additional affected finches. In addition to intestinal symptoms (diarrhoea), the presence of extra-intestinal virus suggests a generalized infection in this fatal disease, for which the passerivirus might be a causative agent.

Genetic diversity and cross-species transmission of kobuviruses in Vietnam

Cross-species transmission of viruses poses a sustained threat to public health. Due to increased contact between humans and other animal species the possibility exists for cross-species transmissions and ensuing disease outbreaks. By using conventional PCR amplification and next generation sequencing, we obtained 130 partial or full genome kobuvirus sequences from humans in a sentinel cohort in Vietnam and various mammalian hosts including bats, rodents, pigs, cats, and civets. The evolution of kobuviruses in different hosts was analysed using Bayesian phylogenetic methods. We estimated and compared time of origin of kobuviruses in different host orders; we also examined the cross-species transmission of kobuviruses within the same host order and between different host orders. Our data provide new knowledge of rodent and bat kobuviruses, which are most closely related to human kobuviruses. The novel bat kobuviruses isolated from bat roosts in Southern Vietnam were genetically distinct from previously described bat kobuviruses, but closely related to kobuviruses found in rodents. We additionally found evidence of frequent cross-species transmissions of kobuviruses within rodents. Overall, our phylogenetic analyses reveal multiple cross-species transmissions both within and among mammalian species, which increases our understanding of kobuviruses genetic diversity and the complexity of their evolutionary history.

Complete genome analysis of porcine kobuviruses from the feces of pigs in Japan

Porcine kobuviruses (PoKoVs) are ubiquitously distributed in pig populations worldwide and are thought to be enteric viruses in swine. Although PoKoVs have been detected in pigs in Japan, no complete genome data for Japanese PoKoVs are available. In the present study, 24 nearly complete or complete sequences of the PoKoV genome obtained from 10 diarrheic feces and 14 non-diarrheic feces of Japanese pigs were analyzed using a metagenomics approach. Japanese PoKoVs shared 85.2-100% identity with the complete coding nucleotide (nt) sequences and the closest relationship of 85.1-98.3% with PoKoVs from other countries. Twenty of 24 Japanese PoKoVs carried a deletion of 90 nt in the 2B coding region. Phylogenetic tree analyses revealed that PoKoVs were not grouped according to their geographical region of origin and the phylogenetic trees of the L, P1, P2, and P3 genetic regions showed topologies different from each other. Similarity plot analysis using strains from a single farm revealed partially different similarity patterns among strains from identical farm origins, suggesting that recombination events had occurred. These results indicate that various PoKoV strains are prevalent and not restricted geographically on pig farms worldwide and the coexistence of multiple strains leads to recombination events of PoKoVs and contributes to the genetic diversity and evolution of PoKoVs.

Molecular characterization and genetic diversity of bovine Kobuvirus, Brazil

It is suggested that Bovine kobuvirus (BKV) is involved in the etiology of gastroenteric diseases especially among calves; however, this association remains unknown. This study evaluated 216 fecal samples from cattle with and without diarrhea symptoms obtained from different regions of Brazil. A 216 bp fragment of the BKV 3D gene was amplified by RT-PCR in 14.4 % (31/216) of the studied samples, and 17 samples were subjected to nucleotide sequencing. All positive samples were obtained from animals aged less than 5 months, and most of animals presented diarrhea (p < 0.05). Phylogenetic analyses showed that the obtained sequences were grouped within the genogroup 2 of BKV forming subclades specific for each Brazilian municipality sampled. In addition, the alignment of the sequences revealed differences of nucleotides between sequences from different locations. Our results indicate for the first time that there is a regional genotypic differentiation of BKV in Brazil.

Novel picornavirus in domestic rabbits (Oryctolagus cuniculus var. domestica)

Picornaviruses (family Picornaviridae) are small, non-enveloped viruses with positive sense, single-stranded RNA genomes. The numbers of the novel picornavirus species and genera are continuously increasing. Picornaviruses infect numerous vertebrate species from fish to mammals, but have not been identified in a member of the Lagomorpha order (pikas, hares and rabbits). In this study, a novel picornavirus was identified in 16 (28.6%) out of 56 faecal samples collected from clinically healthy rabbits (Oryctolagus cuniculus var. domestica) in two (one commercial and one family farms) of four rabbit farms in Hungary. The 8364 nucleotide (2486 amino acid) long complete genome sequence of strain Rabbit01/2013/HUN (KT325852) has typical picornavirus genome organization with type-V IRES at the 5'UTR, encodes a leader (L) and a single 2A(H-box/NC) proteins, contains a hepatitis-A-virus-like cis-acting replication element (CRE) in the 2A, but it does not contain the sequence forming a "barbell-like" secondary structure in the 3'UTR. Rabbit01/2013/HUN has 52.9%, 52% and 57.2% amino acid identity to corresponding proteins of species Aichivirus A (genus Kobuvirus): to murine Kobuvirus (JF755427) in P1, to canine Kobuvirus (JN387133) in P2 and to feline Kobuvirus (KF831027) in P3, respectively. The sequence and phylogenetic analysis indicated that Rabbit01/2013/HUN represents a novel picornavirus species possibly in genus Kobuvirus. This is the first report of detection of picornavirus in rabbit. Further study is needed to clarify whether this novel picornavirus plays a part in any diseases in domestic or wild rabbits.

Detection of novel kobu-like viruses in Japanese black cattle in Japan

During surveillance for bovine diarrhea of unknown causes in Japanese black cattle in Kagoshima Prefecture, Japan, we found two types of novel kobu-like viruses in fecal samples of calves. Sequence analyses revealed that they had L protein and 2A protein with H-box/NC sequence motif, which are present in kobuviruses. Phylogenetic analysis revealed that they were related to kobuviruses; however, they clustered apart from other kobuviruses. In the prevalence study of two types of novel kobu-like viruses, 16.9% and 10.4% prevalence of these viruses were observed in the feces of diarrheal calves in this area.

Genomic characterization of a US porcine kobuvirus strain

Porcine kobuvirus has been detected from pig fecal samples in the USA, but there is still no information on the full-length genomes. In this study, we characterized the first complete genomic sequence of a US porcine kobuvirus strain OH/RV50/2011. The viral genome is 8123 nucleotides (nt) long, including a 576-nt 5'-untranslated region (UTR), a 7380-nt polyprotein encoding sequence, and a 167-nt 3'-UTR. A complete genome sequence alignment suggested that two types of porcine kobuviruses were found based on whether a 30-aa deletion existed in the 2B encoding region. Furthermore, several conserved motifs that can be used for the design of universal kobuvirus or porcine kobuvirus-specific primers were verified in non-structural protein genes. Phylogenetic analysis based on the complete genome sequence showed that RV50 was grouped with other porcine kobuviruses and more closely related to Chinese strains. Secondary structure analysis of the 5'-UTR showed that RV50 has three stem-loop domains in the first 108 nt and has a potential hepacivirus-/pestivirus-like type IV group-B-like internal ribosomal entry site, like the porcine kobuvirus prototype strain S-1. Codon usage analysis showed that the most preferred usage tends to be C or U at the end of a codon in a porcine kobuvirus genome. These results will be useful in understanding the evolution of porcine kobuviruses .

Molecular characterization of canine kobuvirus in wild carnivores and the domestic dog in Africa

Knowledge of Kobuvirus (Family Picornaviridae) infection in carnivores is limited and has not been described in domestic or wild carnivores in Africa. To fill this gap in knowledge we used RT-PCR to screen fresh feces from several African carnivores. We detected kobuvirus RNA in samples from domestic dog, golden jackal, side-striped jackal and spotted hyena. Using next generation sequencing we obtained one complete Kobuvirus genome sequence from each of these species. Our phylogenetic analyses revealed canine kobuvirus (CaKV) infection in all four species and placed CaKVs from Africa together and separately from CaKVs from elsewhere. Wild carnivore strains were more closely related to each other than to those from domestic dogs. We found that the secondary structure model of the IRES was similar to the Aichivirus-like IRES subclass and was conserved among African strains. We describe the first CaKVs from Africa and extend the known host range of CaKV.

Cross-species transmission and emergence of novel viruses from birds

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The role of birds in cross-species transmission and emergence of novel viruses such as avian influenza A viruses are discussed.

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The novel avian viruses identified between 2012 and 2014 are summarized.

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The concept of ‘pathogen augmentation’ is introduced.

Birds, the only living member of the Dinosauria clade, are flying warm-blooded vertebrates displaying high species biodiversity, roosting and migratory behavior, and a unique adaptive immune system. Birds provide the natural reservoir for numerous viral species and therefore gene source for evolution, emergence and dissemination of novel viruses. The intrusions of human into natural habitats of wild birds, the domestication of wild birds as pets or racing birds, and the increasing poultry consumption by human have facilitated avian viruses to cross species barriers to cause zoonosis. Recently, a novel adenovirus was exclusively found in birds causing an outbreak of Chlamydophila psittaci infection among birds and humans. Instead of being the primary cause of an outbreak by jumping directly from bird to human, a novel avian virus can be an augmenter of another zoonotic agent causing the outbreak. A comprehensive avian virome will improve our understanding of birds’ evolutionary dynamics.