Exploring the virome of diseased horses

Abstract

Metagenomics was used to characterize viral genomes in clinical specimens of horses with various organ-specific diseases of unknown aetiology. A novel parvovirus as well as a previously described hepacivirus closely related to human hepatitis C virus and equid herpesvirus 2 were identified in the cerebrospinal fluid of horses with neurological signs. Four co-infecting picobirnaviruses, including an unusual genome with fused RNA segments, and a divergent anellovirus were found in the plasma of two febrile horses. A novel cyclovirus genome was characterized from the nasal secretion of another febrile animal. Lastly, a small circular DNA genome with a Rep gene, from a virus we called kirkovirus, was identified in the liver and spleen of a horse with fatal idiopathic hepatopathy. This study expands the number of viruses found in horses, and characterizes their genomes to assist future epidemiological studies of their transmission and potential association with various equine diseases.

Revisiting the taxonomy of the family Circoviridae: establishment of the genus Cyclovirus and removal of the genus Gyrovirus

“…Although cycloviruses were discovered in stool samples from primates [34], cyclovirus genomes have now been reported from a diversity of specimens including mammals (bats, cats, cows, goats, horses, squirrels, sheep) [18,34,36,38,43,49,73,91,92], birds (chickens) [34,36], and insects (cockroaches and dragonflies) [11,59,70,71] (Table 1). Additionally, a diversity of cyclovirus genomes have been recovered from human samples other than faeces [17,34,80], including cerebrospinal fluid [80], blood serum [76], and respiratory b Fig.…”

Fungal DNA virus infects a mycophagous insect and utilizes it as a transmission vector

“…For example, the ancient caribou feces-associated virus (aCFV), which was discovered in 700-y-old caribou feces, could infect Nicotiana benthamiana (23). Gemycircularviruses, which were detected in samples of human blood, serum, cerebrospinal fluids, and brain (28,29), as well as horse liver and spleen (31), most likely replicate and are retained in human and animal cells, suggesting that humans and animals are possible hosts of these viruses. The finding that gemycircularviruses were detected in mosquitoes suggests that mosquitoes and other parasitic insects such as fleas as well as parasitic mites and ticks may serve as vectors for transmission of human and animal gemycircularviruses.…”

“…The DNA of SsHADV-1-like viruses was detected in a microbial community from the Sargasso Sea (18) and was found in fecal samples of unexplained human diarrhea (20) and in various animal feces (21)(22)(23), insects (such as mosquitoes, dragonflies, and damselflies) (19,(24)(25)(26), and plants (27). SsHADV-1-like viral DNA was found in human brain and serum samples from multiple sclerosis patients (28), in human HIV-positive blood (29), in the cerebrospinal fluids of Sri Lankan patients with unexplained encephalitis (20), in blood samples of experimental rats (30), and in the liver and spleen of a horse with fatal idiopathic hepatopathy (31). These discoveries suggest that gemycircularviruses represent a group of emerging viruses, which are widespread in nature, and some of them may impact human and animal health.…”

Evolving views on enteric viral infections of equines: an appraisal of key pathogens

“…Based on the RdRp gene segment 2, PBVs are grouped into 2 genogroups (genogroup-I and II). Recent studies also proposed possible new genogroup namely III, IV and V based on the diversity of RdRp sequences (Smits et al, 2014;Li et al, 2015). The proposed new groups include strains from human (group III and V), dromedary (group V) and equine (group IV and V).…”

“…One of the prime causes of equine enteritis is the viral infections. A recent metagenomics study highlighted several new viruses like Cyclovirus, Kirkovirus and Anellovirus along with known enteric viruses such as parvovirus, adenoviruses, coronaviruses, rotaviruses and picobirnaviruses in equines (Li et al, 2015). In last few years, several reviews appeared on various aspects of equine health excluding enteric viral pathogens of equines, except a few that highlighted coronavirus and rotavirus infections in equines (Bailey et al, 2013;Papp et al, 2013;Dhama et al, 2014;Pusterla et al, 2015a).…”