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.

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.

Molecular detection and genetic diversity of Rickettsia spp. in pet dogs and their infesting ticks in Harbin, northeastern China.

BACKGROUND: Pet dogs are important companion animals that share the environment within households, and play an important role in local community life. In addition, pet dogs also are reservoirs of zoonotic agents, including Rickettsia spp., thus increasing the risk of rickettsial infections in humans. It's meaningful to investigate the epidemiology of rickettsial agents in pet dogs, and make contribute to the surveillance of rickettsioses in human in China. RESULTS: In this study, a total of 496 pet dogs' blood samples and 343 ticks infested in pet dogs were collected, and the presence and prevalence of Rickettsia were determined by amplifying the partial gltA and 17-kDa genes, with an overall positive rate of 8.1 % in blood samples and 14.0 % in tick samples. In addition, the rrs, gltA, groEL, and ompA genes of rickettsial were also recovered to determine the species of Rickettsia detected furtherly. Sequencing blast and phylogenetic analyses revealed the presence of three human pathogenic Rickettsia species (Rickettsia raoultii, Candidatus Rickettsia tarasevichiae and Rickettsia felis) in samples associated with pet dogs. Moreover, all the sequences of Rickettsia that we obtained presented close relationship with others available in GenBank, and Rickettsia raoultii was the most predominant Rickettsia species infected in pet dogs' blood samples or in tick samples. CONCLUSIONS: This study provides the molecular epidemiology data about the Rickettsia spp. infection associated with pet dogs in urban areas of Harbin city. Three rickettisae species pathogenic to humans were identified from pet dogs' blood and the infested ticks in urban areas of Harbin city. Considering the intimate relationship between human and pets, these results indicate the potential transmission risk of human rickettisal infections from pet dogs through ectoparasites, and also highlighting that more attention should be paid to rickettsial infection in pet dogs and the infested ticks from the "One health" perspective.

Prevalence and molecular characterization of Babesia in pet dogs in Shenzhen, China.

Canine babesiosis is an important global tick-borne infectious disease of domestic dogs and wild canids. B. gibsoni and B. vogeli are the most widespread species mainly endemic in dog population in southern and eastern regions of China. In this study, 272 blood samples were collected from pet dogs in five districts of Shenzhen, China. Babesia DNA was detected in 30 samples with an overall prevalence of 11.0 % in pet dogs in Shenzhen. The difference in the positive rate between female and male pet dogs, among different breed, and among the five sampling sites was not significant, while the age and health status of pet dogs significantly influence the positive rate of Babesia spp. infection. Sequencing results showed the presence of only B. vogeli in all of the samples tested. Sequence comparison and phylogenetic analysis revealed that all 30 strains of Babesia identified in this study shared the highest identity with B. vogeli. In sum, all results of this study showed a considerable high infection rate of Babesia spp. in pet dogs, and B. vogeli was the only Babesia species infecting pet dogs in Shenzhen city. Such information is necessary to help to elucidate the epidemiology of canine babesiosis in Shenzhen, and it is necessary to actively monitor this disease in pet dogs.

Molecular detection and characterization of Bartonella spp. in pet cats and dogs in Shenzhen, China.

Bartonella spp. are emerging vector-borne pathogens distributed worldwide that can infect humans and a wide range of mammals including small companion animals (cats and dogs). An increasing number of studies from the worldwide have reported cat and dog Bartonella infections in recently years. Cats and dogs are the primary reservoir or accidental hosts for Bartonella henselae, the main causal agent of human cat scratch disease. Since pet cat and dog sharing human living environment and have the direct and intimate contact with humans, pet cats and dogs may represent excellent epidemiological sentinels for Bartonella infection in humans. In this study, 475 blood samples were collected from pet cats and dogs in local animal hospitals located at five districts of Shenzhen City, and detected the presence of Bartonella. Bartonella DNA was detected in eight samples collected from pet cats, no positive sample was detected from pet dog samples. Sequence comparison and phylogenetic analysis revealed that the eight sequences of Bartonella identified here shared the highest identity with B. henselae. Given the intimate contact between pet animals and humans, many attentions should be paid to prevent the Bartonella infections originate from pet cats or dogs, although the Bartonella infection rate in pet cats and dogs might be rather low.

Molecular characterization of two novel reoviruses isolated from Muscovy ducklings in Guangdong, China.

BACKGROUND: Novel Muscovy duck reovirus (N-MDRV), emerged in southeast China in 2002, which can infect a wide range of waterfowl and induces clinical signs and cytopathic effects that are distinct from those of classical MDRV, and continues to cause high morbidity and 5-50% mortality in ducklings. The present study aimed to investigate the characteristics of two novel reoviruses isolated from Muscovy ducklings in Guangdong, China. RESULTS: Two novel MDRV strains, designated as MDRV-SH12 and MDRV-DH13, were isolated from two diseased Muscovy ducklings in Guangdong province, China in June 2012 and September 2013, respectively. Sequencing of the complete genomes of these two viruses showed that they consisted of 23,418 bp and were divided into 10 segments, ranging from 1191 bp (S4) to 3959 bp (L1) in length, and all segments contained conserved sequences in the 5' non-coding region (GCUUUU) and 3' non-coding region (UCAUC). Pairwise sequence comparisons demonstrated that MDRV-SH12 and MDRV-DH13 showed the highest similarity with novel MDRVs. Phylogenetic analyses of the nucleotide sequences of all 10 segments revealed that MDRV-SH12 and MDRV-DH13 were clustered together with other novel waterfowl-origin reoviruses and were distinct from classical waterfowl-origin and chicken-origin reoviruses. The analyses also showed possible genetic re-assortment events in segment M2 between waterfowl-origin and chicken-origin reoviruses and the segments encoding λA, µA, µNS, σA, and σNS between classical and novel waterfowl-origin reoviruses. Potential recombination events detection in segment S2 suggests that MDRV-SH12 and MDRV-DH13 may be recombinants of classical and novel WRVs. CONCLUSIONS: The results presented in this study, the full genomic data for two novel MDRV strains, will improve our understanding of the evolutionary relationships among the waterfowl-origin reoviruses circulating in China, and may aid in the development of more effective vaccines against various waterfowl-origin reoviruses.

Meta-transcriptomic analysis reveals a new subtype of genotype 3 avian hepatitis E virus in chicken flocks with high mortality in Guangdong, China.

BACKGROUND: Hepatitis E virus (HEV) is one of most important zoonotic viruses, and it can infect a wide range of host species. Avian HEV has been identified as the aetiological agent of big liver and spleen disease or hepatitis-splenomegaly syndrome in chickens. HEV infection is common among chicken flocks in China, and there are currently no practical measures for preventing the spread of the disease. The predominant avian HEV genotype circulating in China have been identified as genotype 3 strains, although some novel genotypes have also been identified from chicken flocks in China. RESULTS: In this study, we used a meta-transcriptomics approach to identify a new subtype of genotype 3 avian HEV in broiler chickens at a poultry farm located in Shenzhen, Guangdong Province, China. The complete genome sequence of the avian HEV, designated CaHEV-GDSZ01, is 6655-nt long, including a 5' UTR of 24 nt and a 3' UTR of 125 nt (excluding the poly(A) tail), and contains three open reading frames (ORFs). Sequence analysis indicated that the complete ORF1 (4599 nt/1532 aa), ORF2 (1821 nt/606 aa) and ORF3 (264 nt/87 aa) of CaHEV-GDSZ01 share the highest nucleotide sequence identity (85.8, 86.7 and 95.8%, respectively) with the corresponding ORFs of genotype 3 avian HEV. Phylogenetic analyses further demonstrated that the avian HEV identified in this study is a new subtype of genotype 3 avian HEV. CONCLUSIONS: Our results demonstrate that a new subtype of genotype 3 avian HEV is endemic in Guangdong, China, and could cause high mortality in infected chickens. This study also provides full genomic data for better understanding the evolutionary relationships of avian HEV circulating in China. Altogether, the results presented in this study suggest that more attention should be paid to avian HEV and its potential disease manifestation.

A New Segmented Virus Associated with Human Febrile Illness in China.

BACKGROUND: In 2017, surveillance for tickborne diseases in China led to the identification of a patient who presented to a hospital in Inner Mongolia with a febrile illness that had an unknown cause. The clinical manifestation of the illness was similar to that of tickborne encephalitis virus (TBEV) infection, but neither TBEV RNA nor antibodies against the virus were detected. METHODS: We obtained a blood specimen from the index patient and attempted to isolate and identify a causative pathogen, using genome sequence analysis and electron microscopy. We also initiated a heightened surveillance program in the same hospital to screen for other patients who presented with fever, headache, and a history of tick bites. We used reverse-transcriptase-polymerase-chain-reaction (RT-PCR) and cell-culture assays to detect the pathogen and immunofluorescence and neutralization assays to determine the levels of virus-specific antibodies in serum specimens from the patients. RESULTS: We found that the index patient was infected with a previously unknown segmented RNA virus, which we designated Alongshan virus (ALSV) and which belongs to the jingmenvirus group of the family Flaviviridae. ALSV infection was confirmed by RT-PCR assay in 86 patients from Inner Mongolia and Heilongjiang who presented with fever, headache, and a history of tick bites. Serologic assays showed that seroconversion had occurred in all 19 patients for whom specimens were available from the acute phase and the convalescent phase of the illness. CONCLUSIONS: A newly discovered segmented virus was found to be associated with a febrile illness in northeastern China. (Funded by the National Key Research and Development Program of China and the National Natural Science Foundation of China.).

Molecular evidence of Babesia in pet cats in mainland China.

BACKGROUND: Babesia spp. are important emerging tick-borne protozoan hemoparasites, and pose a great impact on companion animals. Canine babesiosis has been well described worldwide, while felis babesiosis has primarily been reported from South Africa. To the best of our knowledge, Babesia spp. infections in dogs have been well elucidated in pet dog population in China, no report about Babesia spp. infection in cat population in mainland China. RESULTS: In this study, a total of 203 blood samples were collected from pet cats in Shenzhen city, and detected the presence of Babesia spp. with nested-PCR. Sequence comparison based on the 18S rRNA gene and ITS region revealed that three cats (1.48%) were infected with Babesia. vogeli. Notably, the sequences of ITS region obtained in this study shared the highest nucleotide identity with the sequence of B. vogeli strain isolated in cat from Taiwan. CONCLUSIONS: This study is the first report about babesiosis in domestic cats, and also provides molecular evidence of Babesia spp. infection in cat in mainland China. The data present in this study suggest B. vogeli may be circulating in cat population in mainland China. Further study to investigate the epidemiology of Babesia infection in cat nationwide is warranted.