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Porcine circovirus-like agents comprise two types of viruses: porcine circovirus-like viruses (P1, P2, P3, and P4) and porcine circovirus-like mini agents (PCVL258, PCVL264, PCVL201, and PCVL347). Of these, P1 has been identified in pigs, cattle, goats, and rabbits in China; P2, P3, P4, PCVL258, and PCVL264 have been identified in pigs; and PCVL201 and PCVL347 have been identified in cattle. The purpose of this study was to determine whether dogs and cats have been exposed to porcine circovirus-like agents. We screened 158 serum samples from diseased dogs and 41 from cats in China by PCR and nucleotide sequencing. In dogs, approximately 18% (n = 28) were positive for P1, 17% (n = 26) for PCVL258, and 9% (n = 14) for PCVL264; in cats, 17.1% (n = 7) were positive for P1, 9.8% (n = 4) for P4, and 14.6% (n = 6) for PCVL258. The P1 genomes in this study consisted of 648 nucleotides (nt) and shared 96.8 to 100% nt identity with other P1 genomes in GenBank. The P4 genome shared 98.3 to 100% nt identity with other reported P4 genomes, and PCVL258 and PCVL264 showed 100% nt identity with previously reported genomes. To our knowledge, this is the first report on molecular characterization of porcine circovirus-like agents in dogs and cats. Further studies are needed to clarify the epidemiology, evolution, and pathogenesis of porcine circovirus-like agents in dogs and cats.

Outbreaks of porcine epidemic diarrhoea virus (PEDV) have caused great economic losses to the global pig industry. PEDV strains with variants in the spike (S) gene have been reported in several countries. To better understand the molecular epidemiology and genetic diversity of PEDV field isolates, in this study, we characterised the complete genome sequence of a novel PEDV variant JSCZ1601 from a outbreak in China in 2016. The PEDV isolate was 28,033 nucleotides (nt) in length without the polyadenylated sequences. Phylogenetic analysis based on the full-length genome sequence of JSCZ1601 grouped it with the pandemic variants determined post-2010 into group 2 (G2). However, the S gene of JSCZ1601 formed a new subgroup separated from the subgroups containing the other G2 strains. Comparative analysis of the amino acids encoded by the S genes revealed the N-terminal of the deduced JSCZ1601 S protein had a novel two-amino-acid deletion (N58 and S59) compared with all identified genogroups. Further, compared with the reference strains, a ‘G’ insertion was detected in the 5′ terminal of the 5′UTR of the JSCZ1601. The animal experiment revealed that this strain was high pathogenic to neonatal pigs. Taken together, a PEDV strain with the new molecular characterizations and phylogenies was found in mainland China. It is necessary to strengthen the monitoring of PEDV variations.

A field porcine epidemic diarrhea virus (PEDV) strain, JS2008, was isolated from stool samples of a piglet with acute diarrhea on a vaccinated farm in eastern China. We sequenced and analyzed the complete genome of strain JS2008, which will help increase our understanding of the molecular characteristics of the epidemic PEDV in China.

Hokoviruses have recently been detected as pathogens belonging to the family Parvoviridae, which comprises porcine hokovirus (PHoV) and bovine hokovirus (BHoV). In this study, we developed a loop-mediated isothermal amplification (LAMP) assay for the rapid, specific and sensitive detection of PHoV. A set of four primers specific for six regions within the PHoV VP1/2 genes was designed using online software. The reaction temperature and time were optimized at 65°C and 60 min, respectively. LAMP products were detected by agarose gel electrophoresis or by visual inspection of a color change caused by a fluorescent dye. The method was highly specific for PHoV, and no cross-reaction was observed with porcine circovirus type 2 (PCV2), porcine parvovirus (PPV), porcine bocavirus (PBoV), pseudorabies virus (PRV), porcine reproductive and respiratory syndrome virus (PRRSV), classic swine fever virus (CSFV), or Japanese encephalitis virus (JEV). The detection limit was approximately 10 copies per reaction, which was 10 times more sensitive than conventional PCR. Furthermore, the efficiency of detection of PHoV in clinical samples was comparable to that of PCR and sequencing. These results show that the LAMP assay is a simple, rapid, sensitive and specific method for detecting PHoV. It does not require specialized equipment and can be used to detect PHoV both in the laboratory and in the field.

Here, we present the first report of a novel rearranged porcine circovirus type 2 (PCV2) strain named BIV, isolated from both in vitro and in vivo sources. The complete circular genome of BIV is 896 nucleotides in length. The data will help us to update current knowledge of the replication of PCV2 viruses in cell culture and of their molecular evolution, as well as their diagnosis.

The recently discovered porcine boca-like virus (Pbo-likeV) is a member of the Parvoviridae family, genus Bocavirus, and it is potentially associated with swine disease. Several studies have associated Pbo-likeV with postweaning multisystemic wasting syndrome in pigs, but the full spectrum of clinical disease and the epidemiology of Pbo-likeV infection remain unclear. The availability of rapid and reliable molecular diagnostics would aid future studies of this novel virus. Thus, we developed a sensitive and specific TaqMan-based real-time PCR assay to target the Pbo-likeV NP1 gene. The assay reproducibly detected 20 copies of a recombinant DNA plasmid containing the NP1 gene, with a dynamic range of six orders of magnitude (102-107 copies). The assay did not cross-react with other animal viruses. Clinical evaluation found that Pbo-likeV was present in Chinese swine herds at a frequency of 44.2% (114/258). Higher infection rates were found in diseased pigs (56.1%, 101/180) compared with healthy pigs (16.7%, 13/78) (P < 0.05). Our assay for the diagnosis and quantification of Pbo-likeV was highly sensitive and specific, and should provide a reliable real-time tool for epidemiological and pathogenetic study of Pbo-likeV infection.

Recently, we identified a novel porcine circovirus type 2-like agent P1 isolate from swine. The present study represents the first survey of P1 prevalence in swine herds from Jiangsu, China, by using PCR targeting the complete genome of P1. Prevalences of 50% and 19% were found among 6 herds and 248 animals, respectively. The results indicate a high prevalence of P1 in China pig populations.

Porcine bocavirus 5 is a novel porcine bocavirus species found in a pig with clinical diarrhea from a farm in China. Here, we report the complete genome sequence of strain PBoV5/JS677, which will help toward understanding the molecular and evolutionary characteristics of the porcine bocavirus.

We report here for the first time the genome sequence of a rearranged porcine circovirus type 2 (PCV2) strain, CH-IVT1, isolated from PCV2-infected PK-15 cells. The complete circular genome of the CH-IVT1 is 605 nucleotides (nt) in length. The finding will help us to understand the molecular evolution of PCV2 and the relationship between PCV2 and PCV-associated diseases.

We first report here the genome sequences of 4 rearranged porcine circovirus type 2 strains, JSTZ, ZJQDH1, ZJQDH2, and JSHM, isolated from porcine sera in China. The complete circular genomes of these isolates are 578, 483, 574, and 772 nucleotides in length, respectively. They are predicted to be defective interfering particles of porcine circovirus type 2. The findings will help us to understand molecular evolution of porcine circovirus type 2 and the relationship between porcine circovirus type 2 and diseases.

We report here the genome sequence of a porcine circovirus-like agent. The sequenced genome of this porcine circovirus-like agent is composed of a 648-nucleotide circular DNA that includes three predicted protein-coding genes, which means the agent should be a novel member of the family Circoviridae .