Platycodon grandiflorus polysaccharide inhibits the inflammatory response of 3D4/21 cells infected with PCV2.

Porcine circovirus type 2 (PCV2) infection cause multi-systemic inflammation in pigs. Platycodon grandiflorus polysaccharide (PGPSt) has been reported to have the effects of immune regulation and disease resistance. Nevertheless, the role and mechanism of PGPSt in the inflammatory response of 3D4/21 cells induced by PCV2 infection remain unclear. The present study aims to investigate effects of PGPSt on inflammatory response and its possible underlying mechanisms in vitro models. Cells were treated with PCV2 for 36 h to construct a cell inflammation model. The 3D4/21 cell lines were pretreated with or without PGPSt, and the changes of inflammation-related markers and the signaling pathway were detected by CCK-8, ELISA, qPCR and Western blot. The results showed that PGPSt was non-toxic to cells and protected PCV2-infected cells from inflammatory damage. PGPSt could significantly inhibit the high acetylation of histone H3 (AcH3) and histone H4 (AcH4), down-regulate HAT and up-regulate HDAC activity, and reduce the expression of pro-inflammatory enzymes iNOS and COX-2 proteins levels. Then the levels of IL-1ß, IL-6 and TNF-α were significantly inhibited, and the level of IL-10 was promoted. We also observed that PGPSt inhibited the phosphorylation of p65, p38 and Erk1/2, which subsequently inhibited nuclear translocation of NF-κB p65 to express pro-inflammatory factors. In conclusion, PGPSt can reduce the inflammatory response by regulating histone acetylation, reducing the release of inflammatory factors, reducing the expression of pro-inflammatory enzymes, and inhibiting the activation of NF-κB and MAPKs signaling pathways. This suggests that PGPSt had an anti-inflammatory effect on the inflammatory response caused by PCV2 infection, which provided theoretical data support for the research.

The surface morphology of Atractylodes macrocephala polysaccharide and its inhibitory effect on PCV2 replication.

BACKGROUND: Porcine infection with Porcine circovirus type 2 (PCV2) causes immunosuppression, which is easy to cause concurrent or secondary infection, making the disease complicated and difficult to treat, and causing huge economic losses to the pig industry. Total polysaccharide from the rhizoma of Atractylodes macrocephala Koidz. (PAMK) is outstanding in enhancing non-specific immunity and cellular immunity, and effectively improving the body's disease resistance, indicating its potential role in antiviral immunotherapy. RESULTS: PAMK had the characteristics of compact, polyporous and agglomerated morphology, but does not have triple helix conformation. PCV2 infection led to the increase in LC3-II, degradation of p62 and the increase of viral Cap protein expression and viral copy number. PAMK treatment significantly alleviated PCV2-induced autophagy and inhibited PCV2 replication. Moreover, PAMK treatment significantly attenuated the increase of PINK1 protein expression and the decrease of TOMM20 protein expression caused by PCV2 infection, alleviated Parkin recruitment from cytoplasm to mitochondria and intracellular reactive oxygen species accumulation, restored mitochondrial membrane charge, alleviated viral Cap protein expression. CONCLUSION: PAMK alleviates PCV2-induced mitophagy to suppress PCV2 replication by inhibiting the Pink 1/Parkin pathway. These findings may provide new insights into the prevention and treatment of PCV2. © 2023 Society of Chemical Industry.

Diagnosis of a Rabbit Hemorrhagic Disease Virus 2 (RHDV2) and the Humoral Immune Protection Effect of VP60 Vaccine.

Rabbit hemorrhagic disease (RHD) is known as rabbit plague and hemorrhagic pneumonia. It is an acute, septic, and highly fatal infectious disease caused by the Lagovirus rabbit hemorrhagic disease virus (RHDV) in the family Caliciviridae that infects wild and domestic rabbits and hares (lagomorphs). At present, RHDV2 has caused huge economic losses to the commercial rabbit trade and led to a decline in the number of wild lagomorphs worldwide. We performed a necropsy and pathological observations on five dead rabbits on a rabbit farm in Tai'an, China. The results were highly similar to the clinical and pathological changes of typical RHD. RHDV2 strain was isolated and identified by RT-PCR, and partial gene sequencing and genetic evolution analysis were carried out. There were significant differences in genetic characteristics and antigenicity between RHDV2 and classical RHDV strain, and the vaccine prepared with the RHDV strain cannot effectively prevent rabbit infection with RHDV2. Therefore, we evaluated the protective efficacy of a novel rabbit hemorrhagic virus baculovirus vector inactivated vaccine (VP60) in clinical application by animal regression experiment. The result showed that VP60 could effectively induce humoral immunity in rabbits. The vaccine itself had no significant effect on the health status of rabbits. This study suggested that the clinical application of VP60 may provide new ideas for preventing the spread of RHD2.

Protective effects of agrimonolide on hypoxia-induced H9c2 cell injury by maintaining mitochondrial homeostasis.

Cardiomyocyte death caused by hypoxia is one of the main causes of myocardial infarction or heart failure, and mitochondria play an important role in this process. Agrimonolide (AM) is a monomeric component extracted from Agrimonia pilosa L. and has antioxidant, antitumor, and anti-inflammatory effects. This study aimed to investigate the role and mechanism of AM in improving hypoxia-induced H9c2 cell damage. The results showed that low AM concentrations promote H9c2 cell proliferation and increase cellular ATP content. Transcriptome sequencing showed that AM induces differential expression of genes in H9c2 cells. Gene ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses revealed that these genes were concentrated in mitochondrial function. Subsequent experiments confirmed that AM regulates hypoxia-induced cell cycle arrest. AM inhibited the rate of apoptosis by regulating the expression of apoptosis-related proteins, reducing the level of cleaved Caspase 3 and Bax, and increasing the level of Bcl2, thereby protecting H9c2 cells from hypoxia-induced apoptosis. AM restored the mitochondrial membrane potential, inhibited the generation of ROS, maintained the normal shape of the mitochondria, improved the level of the mitochondrial functional proteins OPA1, MFN1, MFN2, Tom20, and increased the level of ATP. In conclusion, AM protects H9c2 cells from hypoxia-induced cell damage.

Staphylococcus aureus mediates pyroptosis in bovine mammary epithelial cell via activation of NLRP3 inflammasome.

Cell death and inflammation are intimately linked during mastitis due to Staphylococcus aureus (S. aureus). Pyroptosis, a programmed necrosis triggered by gasdermin protein family, often occurs after inflammatory caspase activation. Many pathogens invade host cells and activate cell-intrinsic death mechanisms, including pyroptosis, apoptosis, and necroptosis. We reported that bovine mammary epithelial cells (MAC-T) respond to S. aureus by NOD-like receptor protein 3 (NLRP3) inflammasome activation through K+ efflux, leading to the recruitment of apoptosis-associated speck-like protein (ASC) and the activation of caspase-1. The activated caspase-1 cleaves gasdermin D (GSDMD) and forms a N-terminal pore forming domain that drives swelling and membrane rupture. Membrane rupture results in the release of the pro-inflammatory cytokines IL-18 and IL-1ß, which are activated by caspase-1. Can modulate GSDMD activation by NLRP3-dependent caspase-1 activation and then cause pyroptosis of bovine mammary epithelial cells.

Regulation of Parkin in Cr (VI)-induced mitophagy in chicken hepatocytes.

The large amount of heavy metal chromium emissions from industrial production, ore smelting and sewage treatment plants have made chromium one of the most widespread heavy metal pollutants, with Cr (VI) being the most toxic. In recent years, people have gradually recognized the great harm of heavy metal chromium pollution, but the research on its pathogenic mechanism is still not deep enough. In this study, we treated the Primary cells of chicken liver with Cr (VI) to establish a model of toxicity. The optimal treatment time and Cr (VI) concentration were screened using the CCK-8 test. The intracellular mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were measured qualitatively and quantitatively by laser confocal and flow cytometry, respectively. This result was confirmed by the fact that Cr (VI) could cause mitophagy by causing damage to mitochondria. Subsequently, this study used LMH cells to construct a Parkin silencing model to further investigate that Parkin exerts the function on the Cr (VI)-induced mitophagy in chicken hepatocytes. The results showed that the knockdown of Parkin effectively blocked p62 degradation and LC3 lipidation and that PINK1 expression was significantly inhibited in LMH cells, further suggesting that the knockdown of Parkin effectively inhibited mitophagy. Mitochondrial morphology, MMP, and ROS were observed using laser confocal. The results showed that Parkin knockdown resulted in mitochondrial fission and increased levels of reactive oxygen species, together with increased depolarization of the mitochondrial membrane potential. These changes led to increased mitochondrial damage. In conclusion, this study showed that Cr (VI) could cause the occurrence of mitophagy by damaging mitochondria, and Parkin played a crucial role in Cr (VI)-induced mitophagy in chicken hepatocytes.

Streptococcus agalactiae-induced autophagy of bovine mammary epithelial cell via PI3K/AKT/mTOR pathway.

Streptococcus agalactiae (S. agalactiae) infection is a significant cause of mastitis, resulting in loss of cellular homeostasis and tissue damage. Autophagy plays an essential function in cell survival, defense, and the preservation of cellular homeostasis, and is often part of the response to pathogenic challenge. However, the effect of autophagy induced by S. agalactiae in bovine mammary epithelial cells (bMECs) is mainly unknown. So in this study, an intracellular S. agalactiae infection model was established. Through evaluating the autophagy-related indicators, we observed that after S. agalactiae infection, a significant quantity of LC3-I was converted to LC3-II, p62 was degraded, and levels of Beclin1 and Bcl2 increased significantly in bMECs, indicating that S. agalactiae induced autophagy. The increase in levels of LAMP2 and LysoTracker Deep Red fluorescent spots indicated that lysosomes had participated in the degradation of autophagic contents. After autophagy was activated by rapamycin (Rapa), the amount of p-Akt and p-mTOR decreased significantly, whilst the amount of intracellular S. agalactiae increased significantly. Whereas the autophagy was inhibited by 3-methyladenine (3MA), the number of intracellular pathogens decreased. In conclusion, the results demonstrated that S. agalactiae could induce autophagy through PI3K/Akt/mTOR pathway and utilize autophagy to survive in bMECs.

Identification and genotyping of a new subtype of bovine viral diarrhea virus 1 isolated from cattle with diarrhea.

In 2019, diarrhea cases occurred on cattle farms in Qionglai and Guang'an, Sichuan Province. Two out of 20 (10%) serum and nasal swab samples were positive when tested using a bovine viral diarrhea virus (BVDV) antigen-capture ELISA kit. Two non-cytopathic strains of BVDV were isolated and named QL1903 and GA190608, respectively. The nucleotide sequences of the genomes of the two isolates were 89.52% identical. Phylogenetic analysis based on the 5'-UTR sequence revealed that the BVDV isolate QL1903 belonged to BVDV subtype 1b, whereas isolate GA190608 clustered with strains HN1814, EN-19, and BJ09_26 in a separate branch, which has tentatively been classified as a new genetic subtype, "1v".

Intracellular Staphylococcus aureus inhibits autophagy of bovine mammary epithelial cells through activating p38α.

Staphylococcus aureus is a common pathogen of bovine mastitis which can induce autophagy and inhibit autophagy flux, resulting in intracellular survival and persistent infection. The aim of the current study was to investigate the role of p38α in the autophagy induced by intracellular S. aureus in bovine mammary epithelial cells. An intracellular infection model of MAC-T cells was constructed, and activation of p38α was examined after S. aureus invasion. Through activating/inhibiting p38α by anisomycin/SB203580, the autophagosomes, LC3 and p62 level were analyzed by immunofluorescence and western blot. To further study the detailed mechanism of p38α, phosphorylation of ULK1ser757 was also detected. The results showed that intracellular S. aureus activated p38α, and the activation developed in a time-dependent manner. Inhibition of p38α promoted intracellular S. aureus-induced autophagy flow, up-regulated the ratio of LC3 II/I, reduced the level of p62 and inhibited the phosphorylation of ULK1ser757, whereas the above results were reversed after activation of p38α. The current study indicated that intracellular S. aureus can inhibit autophagy flow by activating p38α in bovine mammary epithelial cells.

Mitophagy is involved in chromium (VI)-induced mitochondria damage in DF-1 cells.

Cr (VI), which is a common heavy metal pollutant with strong oxidizing property, exists widely in nature. Organisms can be exposed to Cr (VI) through various means. Cr (VI) causes mitochondrial dysfunction after being absorbed by cells. Whether Cr (VI) induces the selective autophagic degradation of mitochondria, which is a biological process called mitophagy, remains unclear. Mitophagy not only recycles intracellularly damaged mitochondria to compensate for nutrient deprivation but also is involved in mitochondria quality control. Thus, this study investigated whether Cr (VI) could induce mitophagy in DF-1 cells. Carbonyl cyanide m-chlorophenylhydrazone, which is a mitochondrial-uncoupling reagent that induces mitophagy, was used. DF-1 cells were incubated with different doses of Cr (VI) for varying durations. The autophagy-related proteins LC3-II and p62 levels decreased after 6 h of Cr (VI) treatment but recovered within 24 h. The mitochondrial membrane potential, which is an indicator of mitochondrial damage, was detected by flow cytometry. We found that different durations of Cr (VI) treatment induced mitochondrial mass decrease and depolarization. Furthermore, the expression of the protein translocase of outer mitochondrial membrane 20 (TOMM20), which is a mitochondrial outer membrane protein, was decreased significantly in the presence of Cr (VI). Our findings indicate that Cr (VI) may contribute to the mitochondrial morphology and function damage and may therefore lead to the autophagic clearance of mitochondria.

Platycodon grandifloras polysaccharides inhibit mitophagy injury induced by Cr (VI) in DF-1 cells.

This study aimed to investigate the role of Platycodon grandiflorus polysaccharide (PGPS) in chromium (VI)-induced autophagy in a chicken embryo fibroblast cell lines (DF-1 cells). DF-1 cells were exposed to Cr (VI), PGPSt, and Cr (VI) + PGPSt, and their effects on cell viability, reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and autophagy-related proteins were examined. The results showed that the cell viability was reduced after Cr (VI) treatment, and 3-MA, CsA or PGPSt suppressed this decrease. Cr (VI) treatment increased the ROS levels and decreased the MMP, thereby enhancing the expression of mitochondrial autophagy marker proteins (PINK1, Parkin, and LC3-II), inhibiting mitophagy autophagy protein TOMM20 expression, and promoting the degradation of autophagy-related marker p62. These changes led to exceeding mitochondrial autophagy and cell trauma and could be mitigated by PGPSt. Overall, our research showed that Cr (VI) can induce exceeding mitochondrial autophagy in DF-1 cells, whereas PGPSt can improve Cr (VI)-induced mitochondrial autophagy by inhibiting ROS and restoring MMP.

Protective effects of anthocyanin against apoptosis and oxidative stress induced by arsanilic acid in DF-1 cells.

Anthocyanin is a natural plant pigment that acts as an antioxidant and scavenges free radicals. This study aimed to investigate the potential protective role of nightshade anthocyanin (NA), a natural flavonoid compound, against the arsanilic acid (ASA)-induced cell death of DF-1 cells. DF-1 cells were initially exposed to ASA, and then NA was applied to the treated cells. Cell viability, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and apoptosis were examined. Results showed that NA inhibited the ASA-induced decrease in cell viability, increase in ROS, and loss of MMP in DF-1 cells. Moreover, caspase-3 activation was inhibited by ASA supplementation and NA attenuated the ASA-induced increase in the percentage of apoptotic cells. In summary, our study suggested that NA can enhance ASA-induced cytotoxicity and apoptosis, thereby providing a basis for the molecular mechanisms of NA-mediated protection.

Effects of Cr(VI)-induced calcium-sensing receptor activation on DF-1 cell pyroptosis.

This study aims to investigate the effects of Cr(VI)-induced calcium-sensing receptor (CaSR) activation on DF-1 cell pyroptosis. Previous studies show that Cr(VI) could accumulate in the body of chickens and change Ca levels. Hence, a Ca-related pathway may be an important mechanism participating in some pathological processes. Pyroptosis level, which is meditated by CaSR, increases under Cr(VI) accumulation. In the present study, pyroptosis was determined by flow cytometry to detect SYTOX blue and caspase-1 staining followed by morphological observation. Interleukin (IL)-1ß and IL-18 levels were detected by ELISA, while CaSR protein and [Ca2+]i contents were detected by Western blot and fluorescence microplate spectrophotometry, respectively. The results showed that Cr(VI) causes DF-1 cell pyroptosis in a time- and dose-dependent manner and that this effect is caspase-1 dependent. Further experiments indicated that pyroptosis could be induced by Cr(VI) and is accompanied by up-regulated [Ca2+]i content. CaSR inhibition led to decreases in pyroptosis level. Some mechanisms may be involved in Cr(VI)-triggered CaSR activation and enhance DF-1 cell pyroptosis. Taken together, the results of this study support future investigations on Cr(VI)-induced pyroptosis in DF-1 cells.

The regulatory role of COX-2 in the interaction between Cr(VI)-induced endoplasmic reticulum stress and autophagy in DF-1 cells.

Hexavalent chromium (Cr(VI)) is a common environmental pollutant. Exposure of Cr(VI) can lead to cell autophagy, but the preventive measures for diminishing Cr(VI)-induced autophagy need further study. COX-2 can be induced by several heavy metals and can lead to endoplasmic reticulum (ER) stress and autophagy; thus, COX-2, ER stress, and autophagy may be related. This study mainly investigated the role of COX-2 in the eIF2α-ATF4 pathway, which is a major pathway in cell autophagy. In this study, Cr(VI) was used as a xenobiotic to determine changes in the parameters of ER stress, autophagy, and COX-2 levels. At the same time, a clear contrast was obtained by assigning positive and negative controls of ER stress and autophagy. The results showed that during Cr(VI) invasion, the parameters of ER stress and autophagy (such as BiP, PERK, p62, LC3-II, and mTOR) were enhanced, similarly to the positive control of ER stress and/or the autophagy controls. Such enhancement is a protective mechanism for cell survival. Additionally, the COX-2 levels increased. Moreover, when COX-2 was inhibited, the PERK level remained high, whereas the LC3-II level decreased. This finding suggests that COX-2 specifically affects the interaction between ER stress and autophagy. Notably, this study reveals that Cr(VI) can induce ER stress and autophagy in DF-1 cells and that COX-2 plays an essential role in the interaction between ER stress and autophagy.

Moderate selenium dosing inhibited chromium (VI) toxicity in chicken liver.

This study aimed to clarify the effect of selenium (Se) on chromium (VI) [Cr(VI)]-induced damage in chicken liver. A total of 105 chickens were randomly divided into seven groups of 15. Group I received deionized water; group II received Cr(VI) (7.83 mg/kg/d) alone; and other groups orally received both Cr(VI) (7.83 mg/kg/d) and Se of different doses (0.14, 0.29, 0.57, 1.14, and 2.28 mg/kg/d). The levels of superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), Ca2+ -ATPase, and mitochondrial membrane potential (MMP) were measured. Results showed that Cr(VI) increased MDA content and decreased GSH content, T-SOD activity, Ca2+ -ATPase activity, and MMP level. Meanwhile, Se co-treatment (0.14, 0.29, and 0.57 mg/kg/d) increased the viability of the above indicators compared with Cr(VI)-treatment alone. In addition, histopathologic examination revealed that Cr(VI) can cause liver damage, whereas Se supplementation of moderate dose inhibited this damage. This study confirmed that Se exerted protective effect against Cr(VI)-induced liver damage.

Effects of Polysaccharides from Platycodon grandiflorum on Immunity-Enhancing Activity In Vitro.

The study is aimed at investigating the immunoenhancement activity of polysaccharides from Platycodon grandiflorum polysaccharides (PGPSs) in vitro. In this study, some research on lymphocyte proliferation, cell cycle, and the levels of CD4⁺ and CD8⁺ T cells were performed. Four different concentrations of PGPSs (PGPStc, PGPS60c, PGPS80c, and PGPStp) were harvested and added to peripheral blood T lymphocytes. We observed significant increases in T lymphocyte proliferation at PGPStc groups individually or synergistically with phytohemagglutinin (PHA) at most concentrations, and their lymphocyte proliferation rates were the highest. The active sites of PGPStc and PGPS60c were subsequently chosen. Then, we utilized flow cytometry to determine lymphocyte cell cycle distribution and levels of CD4⁺ and CD8⁺ T cells. At most time points, PGPStc could facilitate lymphocyte cell cycle progression from the G0/G1 phase to the S and G2/M phases and, simultaneously, increase the levels of CD4⁺ and CD8⁺ T cells. These results indicate that PGPStc enhances the immune functions, suggesting that PGPStc could be a potential immunopotentiator for further in vivo and clinical trial experiments.

Synergistic inhibition of avian leukosis virus subgroup J replication by miRNA-embedded siRNA interference of double-target.

BACKGROUND: The diseases caused by avian leukosis virus subgroup J (ALV-J) has become a serious problem in the poultry. Due to largely ineffective vaccines, new control measures are needed to be developed. RNA interference (RNAi) has been developed a promising measure for antivirus in poultry. METHODS: In this study, miRNA-embedded siRNA interference was designed and used to inhibit ALV-J replication in vitro and in vivo. Each sequence of target siRNA derived from the gag (p15), pol (p32), env (gp85) and LTR (U3) gene of ALV-J was embedded into mouse miR-155 backbone as a pre-miRNA hairpin oligonucleotide sequence. After annealing, they were cloned into pcDNA6.2-GW/EmGFP-miR vector, respectively. For detecting the interference effect, recombinant vectors were introduced into DF-1 cells and day-old SPF chickens that infected with ALV-J. RESULTS: In vitro, single target interference showed effective inhibition of reducing 74% ~ 85% mRNA of ALV-J. Double targets showed more efficient inhibition of reducing 96% ~ 98% mRNA of ALV-J. In vivo, chicks were inoculated with each recombinant plasmid in peritoneal cavity at day of hatch, and monitored infection status at interval 1 day postinfection for 4 weeks. Delivery of single target or double targets miRNA significantly reduced viremia and pathogenicity caused by ALV-J in vivo, especially the double targets. CONCLUSIONS: These data demonstrated that the miRNA-embedded siRNA interference is an efficient method for inhibition of ALV-J replication, especially double targets.

Oxidative stress and hepatocellular injury induced by oral administration of Cr(3+) in chicken.

This study aims to investigate the oxidative stress and hepatocellular injury induced by Cr(3+) in chicken. Different doses of CrCl3 solutions (50% LD50 , 25% LD50 , and 12.5% LD50) and equivalent water were orally administered to chicken. Chicken liver samples were measured for the activities of antioxidant enzymes, the contents of glutathione, total antioxidant capacity (T-AOC), malondialdehyde (MDA), and hydrogen peroxide to indirectly evaluate the oxidative stress in chicken liver. Results indicated that the oral administration of Cr(3+) at high dose significantly increased (P < 0.05) the MDA levels after 28 days of exposure, with decreased T-AOC, glutathione, and antioxidant enzymes activities. Low and medium doses groups show that T-AOC, glutathione, and antioxidant enzymes activities increased after 14 days, then decreased gradually, but low and medium groups higher than control group, only high group lower than control group finally. These statistics and histopathological analysis suggest that high dose and long-term exposure of Cr(3+) induce oxidative stress and hepatocellular injury.

First detection of severe fever with thrombocytopenia syndrome virus in the tick species Haemaphysalis concinna in Shandong Province, China.

The aim of this study was to detect severe fever with thrombocytopenia syndrome virus (SFTSV) infection using polymerase chain reaction (PCR) amplification in adult Haemaphysalis concinna ticks. A total of 72 adult H. concinna ticks were obtained from 35 goats, three adult H. concinna ticks (4.17 %) collected from two goats were found to be infected with SFTSV via PCR assay. Sequence analysis showed that the partial segment M glycoprotein gene of SFTSV was about 500 bases long by polymerase chain reaction (PCR) amplification and that the PCR products from the samples had an identical sequence (KP714259). With regard to the phylogenetic analysis, the Nei-Gojobri (Kimura 2-parameter) method was used to construct the phylogenetic trees. Phylogenetic analysis indicated that the obtained sequence closely resembled SFTSV strain from Zhejiang Province (KC189856) and belonged to the same clade. The similarity of these strains was up to 96.62 % (only differing by 17 bases). In addition, phylogenetic analysis also indicated that the sequence obtained from adult H. concinna ticks was most closely related to the sequence isolated from Haemaphysalis longicornis (KF781498) with 97.22 % similarity (differing only by 4 bases) and belonged to the same clade.

Prevalence and risk factors of Giardia doudenalis in dogs from China.

The aim of this study was to carry out a survey for the presence of Giardia duodenalis infection in canine using ELISA and PCR and to identify risk factors for infection. Samples from 318 dogs' feces living in nine cities in China were used in the present study. Each sample was tested for the presence of G. duodenalis-specific antigens using ELISA and 197 out of 318 samples were further examined for the presence of G. duodenalis using PCR. The overall rate of canines infected with giardiasis in the present study was 16.04% and 15.22% using ELISA and PCR, respectively. No significant difference was found between sex and Giardia positivity. Young dogs (up to one year) and living in communities were identified as risk factors for infection by multivariate logistic regression analysis. In conclusion, giardiasis in dogs was present in nine cities in China; as risk factors, young dogs (up to one year) and living in communities were of great significance. Giardia-infected canine should be treated for hygienic management to prevent transmission of the infection from dog to human.