Serology-enabled discovery of genetically diverse hepaciviruses in a new host.

Genetic and biological characterization of new hepaciviruses infecting animals contributes to our understanding of the ultimate origins of hepatitis C virus (HCV) infection in humans and dramatically enhances our ability to study its pathogenesis using tractable animal models. Animal homologs of HCV include a recently discovered canine hepacivirus (CHV) and GB virus B (GBV-B), both viruses with largely undetermined natural host ranges. Here we used a versatile serology-based approach to determine the natural host of the only known nonprimate hepacivirus (NPHV), CHV, which is also the closest phylogenetic relative of HCV. Recombinant protein expressed from the helicase domain of CHV NS3 was used as antigen in the luciferase immunoprecipitation system (LIPS) assay to screen several nonprimate animal species. Thirty-six samples from 103 horses were immunoreactive, and viral genomic RNA was present in 8 of the 36 seropositive animals and none of the seronegative animals. Complete genome sequences of these 8 genetically diverse NPHVs showed 14% (range, 6.4% to 17.2%) nucleotide sequence divergence, with most changes occurring at synonymous sites. RNA secondary structure prediction of the 383-base 5' untranslated region of NPHV was refined and extended through mapping of polymorphic sites to unpaired regions or (semi)covariant pairings. Similar approaches were adopted to delineate extensive RNA secondary structures in the coding region of the genome, predicted to form 27 regularly spaced, thermodynamically stable stem-loops. Together, these findings suggest a promising new nonprimate animal model and provide a database that will aid creation of functional NPHV cDNA clones and other novel tools for hepacivirus studies.

Characterization of a canine homolog of human Aichivirus.

Many of our fatal "civilization" infectious diseases have arisen from domesticated animals. Although picornaviruses infect most mammals, infection of a companion animal is not known. Here we describe the identification and genomic characterization of the first canine picornavirus. Canine kobuvirus (CKoV), identified in stool samples from dogs with diarrhea, has a genomic organization typical of a picornavirus and encodes a 2,469-amino-acid polyprotein flanked by 5' and 3' untranslated regions. Comparative phylogenetic analysis using various structural and nonstructural proteins of CKoV confirmed it as the animal virus homolog most closely related to human Aichivirus (AiV). Bayesian Markov chain Monte Carlo analysis suggests a mean recent divergence time of CKoV and AiV within the past 20 to 50 years, well after the domestication of canines. The discovery of CKoV provides new insights into the origin and evolution of AiV and the species specificity and pathogenesis of kobuviruses.

Bocavirus episome in infected human tissue contains non-identical termini.

UNLABELLED: Human bocaviruses (HBoV) are highly prevalent human infections whose pathogenic potential remains unknown. Recent identification of the first non-human primate bocavirus [1] in captive gorillas raised the possibility of the persistent nature of bocavirus infection. To characterize bocavirus infection in humans, we tested intestinal biopsies from 22 children with gastrointestinal disease for the presence of HBoV DNA. Four HBoV-positive tissue samples were analyzed to determine whether viral DNA was present in the linear genomic, the episomal closed circular or the host genome-integrated form. Whereas one tissue sample positive for HBoV3 contained the episomal form (HBoV3-E1), none had the genome-integrated form. The complete genome sequence of HBoV3-E1 contains 5319 nucleotides of which 513 represent the non-coding terminal sequence. The secondary structure of HBoV3-E1 termini suggests several conserved and variable features among human and animal bocaviruses. Our observation that HBoV genome exists as head-to-tail monomer in infected tissue either reflects the likely evolution of alternative replication mechanism in primate bocaviruses or a mechanism of viral persistence in their host. Moreover, we identified the HBoV genomic terminal sequences that will be helpful in developing reverse genetic systems for these widely prevalent parvoviruses. SIGNIFICANCE: HBoV have been found in healthy human controls as well as individuals with respiratory or gastrointestinal disease. Our findings suggest that HBoV DNA can exist as episomes in infected human tissues and therefore can likely establish persistent infection in the host. Previous efforts to grow HBoV in cell culture and to develop reverse genetic systems have been unsuccessful. Complete genomic sequence of the HBoV3 episome and its genomic termini will improve our understanding of HBoV replication mechanism and its pathogenesis.

Characterization of a canine homolog of hepatitis C virus.

An estimated 3% of the world's population is chronically infected with hepatitis C virus (HCV). Although HCV was discovered more than 20 y ago, its origin remains obscure largely because no closely related animal virus homolog has been identified; furthermore, efforts to understand HCV pathogenesis have been hampered by the absence of animal models other than chimpanzees for human disease. Here we report the identification in domestic dogs of a nonprimate hepacivirus. Comparative phylogenetic analysis of the canine hepacivirus (CHV) confirmed it to be the most genetically similar animal virus homolog of HCV. Bayesian Markov chains Monte Carlo and associated time to most recent common ancestor analyses suggest a mean recent divergence time of CHV and HCV clades within the past 500-1,000 y, well after the domestication of canines. The discovery of CHV may provide new insights into the origin and evolution of HCV and a tractable model system with which to probe the pathogenesis, prevention, and treatment of diseases caused by hepacivirus infection.

Identification of a severe acute respiratory syndrome coronavirus-like virus in a leaf-nosed bat in Nigeria.

Bats are reservoirs for emerging zoonotic viruses that can have a profound impact on human and animal health, including lyssaviruses, filoviruses, paramyxoviruses, and severe acute respiratory syndrome coronaviruses (SARS-CoVs). In the course of a project focused on pathogen discovery in contexts where human-bat contact might facilitate more efficient interspecies transmission of viruses, we surveyed gastrointestinal tissue obtained from bats collected in caves in Nigeria that are frequented by humans. Coronavirus consensus PCR and unbiased high-throughput pyrosequencing revealed the presence of coronavirus sequences related to those of SARS-CoV in a Commerson's leaf-nosed bat (Hipposideros commersoni). Additional genomic sequencing indicated that this virus, unlike subgroup 2b CoVs, which includes SARS-CoV, is unique, comprising three overlapping open reading frames between the M and N genes and two conserved stem-loop II motifs. Phylogenetic analyses in conjunction with these features suggest that this virus represents a new subgroup within group 2 CoVs.

Nonvisible insufficient subcutaneous reticular venous plexus can be observed through the skin using a new illumination method.

BACKGROUND: Insufficient subcutaneous reticular venous plexus (ISRVP) is an overlooked disease because the human eye cannot see many of the insufficient veins. OBJECTIVE: To present a total reticular vision (TRV) method that exposes nonvisible ISRVP to normal vision. METHOD & MATERIALS: TRV used visual-spectrum white and red light of 700 nm and infrared light of 15 to 850 nm from an ultradigital viewer camera. We studied 124 asymptomatic subjects from the general population without visible ISRVP. Another six patients with ISRVP without other venous pathology were compared with six healthy controls, Very low pressure was applied to the proximal thigh, and minimal volume increments on the medial malleolus were photoplethysmographically registered to validate subcutaneous venous reflux. RESULTS: Total reticular vision exposed ISRVP on the lower extremities in 72 of 124 subjects (58%), with observed damaged veins corresponding to more than 90% of nonvisible and 5% of visible portions of ISRVP. Subcutaneous reflux was registered only in patients with ISRVP. CONCLUSION: Total reticular vision exposed more than 90% of nonvisible ISRVP, a new pathology, allowing for the study of its relationship with other superficial venous insufficiencies. The authors have indicated no significant interest with commercial supporters.