Epidemiology and genotypic diversity of canine circovirus identified in pet dogs in Harbin, China.

Canine circovirus (CanineCV) is a single-stranded DNA virus that circulates in dogs and wild carnivores around the world. It has been suggested to be associated with diseases of respiratory and gastrointestinal systems, though its pathogenic potential remains unclear. Currently, CanineCV is divided into six genotypes (genotype 1-6), and genotypes 2, 3, and 4 have been described in China. In this study, 359 blood samples from pet dogs with or without clinical signs were collected in Harbin city. After PCR screening, a total of 34 samples were tested positive for CanineCV, and nine full-length genome sequences were recovered from positive samples. Pairwise sequence comparison showed that they shared 82.4-99.3% genome-wide identity with other CanineCVs available in GenBank. Additionally, recombination events were detected, all of which were determined to be associated with sequences obtained in China. The reconstructed phylogenetic tree based on the recombination-free complete genome sequences revealed that the complete genome sequences generated herein were clustered into genotypes 1 and 3. Furthermore, purifying selection was the dominant evolutionary pressure acting on the genomes of CanineCV. These results expand the knowledge about the genetic diversity of CanineCV circulating in China, and also promote us to better understand the evolution of CanineCV.

Circulation of four species of Anaplasmataceae bacteria in ticks in Harbin, northeastern China.

Ticks play an important role in the evolution and transmission of Anaplasmataceae bacteria which are agents of emerging infectious diseases. In this study, a total of 1286 adult ticks belonging to five species were collected from cattle, goats, horses and vegetation in Harbin area, Heilongjiang province, northeastern China. The tick-borne Anaplasmataceae bacteria were identified by amplifying and sequencing the 16S rRNA (rrs) and heat shock protein-60 encoding (groEL) genes. The results showed that Ixodes persulcatus was dominant (38.8%, 499/1283) among the five tick species, and Anaplasmataceae bacteria were detected in all tick species with an overall prevalence of 7.4%. Four species of Anaplasmataceae bacteria (Anaplasma phagocytophilum, Anaplasma ovis, Anaplasma bovis, and "Candidatus Neoehrlichia mikurensis"), which are pathogenic to humans and/or animals, were identified from tick samples by phylogenetic analyzes of the rrs and groEL gene sequences. Interestingly, the cluster 1 strains were first identified in Asian, and a novel cluster was also detected in this study. These data revealed the genetic diversity of Anaplasmataceae bacteria circulating in ticks in Harbin area, highlighting the need to investigate these tick-borne pathogens and their risks to human and animal health.

Research note: genetic diversity of duck circoviruses circulating in partial areas of Guangdong province, southern China.

Duck circovirus (DuCV) is the smallest known virus in waterfowl that infects both domestic and wild duck. Infected ducks often show stunted growth and immunosuppression, which increases the rate of secondary infection with other pathogens. In this study, 270 liver tissue samples were collected to screen the presence of DuCV in Guangdong province, China, and the complete genome sequences were recovered and systematically analyzed. Genetic analyses revealed that sequences determined in this study shared 81.6% to 100.0% genome-wide pairwise identity with previously identified DuCV genomes. Phylogenetic analyses showed that 2 DuCV genotypes with a high infection rate were co-circulating in duck population in Guangdong province, and extensive recombination events have occurred during the evolution of DuCV. Our results expand upon the knowledge regarding the genetic diversity and evolution of DuCV, and also indicate that extensive genetically divergent DuCV are co-circulating in the duck populations in Guangdong, southern China.

Epidemiology and Genetic Diversity of Bartonella in Rodents in Urban Areas of Guangzhou, Southern China.

Bartonella spp. are gram-negative bacteria that can infect a wide spectrum of mammals. Rodents are considered to be the natural reservoir of many Bartonella species that are transmitted by various blood-sucking arthropods. The close contact between rodents and humans in urban areas increased the chance of transmitting rodent-borne Bartonella to humans. Investigation of the epidemiological characteristics of Bartonella infection in rodents is of great significance for the prevention and control of human Bartonellosis. In this study, rodents were captured to monitor the prevalence of Bartonella in urban areas of Guangzhou city. Six official or candidate species of Bartonella, including two confirmed zoonotic species, were detected with an overall prevalence of 6.4% in rodents captured herein. In addition, Rattus norvegicus was the predominant host species for Bartonella infection, and B. queenslandensis was the dominant species circulating in rodents in these areas. These results provide insights into the prevalence and genetic diversity of Bartonella species circulating in rodents in the urban areas of Guangzhou, and also urged the surveillance of rodent-associated Bartonella species in these areas.

Extensive genetic diversity and recombination events identified in goose circoviruses circulating in partial areas of Guangdong province, Southern China.

Circoviruses represent a group of small viruses with circular single-strand DNA genome that infect a wide range of both domesticated and wild animals. Domesticated geese infected with circovirus have been confirmed in many parts of the world, and is considered to cause immunosuppression and facilitate the secondary infections caused by other pathogens. In the present study, extensive genetically diversified goose circoviruses (GoCVs) were identified in the liver samples of domesticated geese from Guangdong province, southern China. Genetic analysis revealed that the sequences generated in this study shared 81.5 to 99.7% genome-wide pairwise identity with previously identified GoCV genomes. More importantly, nine recombination events were identified among all known complete genomome sequences of GoCV including those obtained herein, and the majority was determined associate with the sequences identified from Guangdong province, suggesting that recombination is the primary driver for the diversification of GoCVs. Additionally, purifying selection was the dominant evolutionary pressure acting on the genomes of GoCVs, and the ORF C1 gene of GoCV showed a higher genetic variation than ORF V1 gene. These results expand the knowledge about the genetic diversity and evolution of GoCV, and also indicate extensive genetically divergent GoCV strains were co-circulating in goose population in partial areas of Guangdong province, southern China.

A Highly Divergent Hepacivirus Identified in Domestic Ducks Further Reveals the Genetic Diversity of Hepaciviruses.

Hepaciviruses represent a group of viruses that pose a significant threat to the health of humans and animals. During the last decade, new members of the genus Hepacivirus have been identified in various host species worldwide, indicating the widespread distribution of genetically diversified hepaciviruses among animals. By applying unbiased high-throughput sequencing, a novel hepacivirus, provisionally designated Hepacivirus Q, was discovered in duck liver samples collected in Guangdong province of China. Genetic analysis revealed that the complete polyprotein of Hepacivirus Q shares 23.9-46.6% amino acid identity with other representatives of the genus Hepacivirus. Considering the species demarcation criteria for hepaciviruses, Hepacivirus Q should be regarded as a novel hepacivirus species of the genus Hepacivirus within the family Flaviviridae. Phylogenetic analyses also indicate the large genetic distance between Hepacivirus Q and other known hepaciviruses. Molecular detection of this novel hepacivirus showed an overall prevalence of 15.9% in duck populations in partial areas of Guangdong province. These results expand knowledge about the genetic diversity and evolution of hepaciviruses and indicate that genetically divergent hepaciviruses are circulating in duck populations in China.