To investigate molecular epidemiology of DuCV in Cherry Valley ducks in China,the complete genomes of six DuCV strains,which were detected from Cherry Valley ducks in China between 2007 and 2008,were sequenced.Sequence and phylogenetic analysis were carried out to compare these six strains with another 27DuCV strains from Mulard duck,Muscovy duck,Pekin ducks and Mule duck.The analysis showed that the six DuCV strains exhibited typical genetic features of the family of DuCV,such as a stem-loop structure,three major open reading frames (Rep,Cap and ORF3),four intergenic repeats and the conserved motifs for rolling circle replication and for the dNTP binding domain located in the Rep protein.Phylogenetic analysis of the nucleotide sequences of the complete genome and Cap gene of these strains together with those that have been previously published demonstrated two distinct DuCV genotypes.The DuCV strains with complete genomes containing 1988and 1989 nucleotides clustered in genotype A,whereas the strains with complete genomes containing 1991,1992,1995 and 1996 nucleotides lay in genotype B.The six DuCV strains from Cherry Valley ducks were divided into the two groups.The results of the study provides some insight into the variation of DuCVs in Cherry Valley ducks.

The duck circovirus (DuCV) infection in sick ducks from Fujian Province was investigated. The liver samples of 43 sick Muscovy ducks with infectious serositis were collected from 12 duck farms in Fujian Province.Based on the published sequences of DuCV, two primers were designed for the detection of DuCV and four pairs of primers were designed to amplify four overlapping fragments that cover the complete genome of DuCV. The specific PCR products were amplified from positive samples. The fragments were then cloned into pMD18-T vector and sequenced, and the full length genomic sequence of the FJ0601 isolate of DuCV was obtained. PCR analysis showed that the proportion of ducks which were positive for circovirus was 79% and 10 out of the 12 farms were positive. Sequence analysis showed that the complete genome of DuCV-FJ0601 was 1988 bp and possessed features common to the family Circoviridae which included a stem-loop structure and the Rep protein motifs. Homology analysis showed that FJ0601 isolate of DuCV had 97.3%～97.5% nucleotide sequence identity to all the four Taiwan isolates (TC1/2002, TC2/2002, TC3/2002, TC4/2002), 82.9% identity to the America (33753-52) isolate and 82.3% identity to the Germany isolate. Phylogenetic analysis with Clustal W, however,showed that FJ0601 isolate of DuCV was on a common branch with Taiwan isolates, and Germany and America isolates belonged to the other branch.

Objective:To establish a mouse model of gastric cancer by inoculating MKN45 cells into mice with normal immune function utilizing microcarrier technology. Methods:A total of 60 male C57BL/6 mice were randomly divided into three groups, namely, 2D, con-trol, and 3D groups, according to the coculture system of MKN45 and microcarrier. The mouse models of gastric carcinoma were estab-lished by hypodermic injection. The time of tumorigenesis, rate of tumor formation, and pathological features were observed in each group. Results:In the 3D group, the time of tumor formation was short, whereas the rate of tumor formation was high (80%). No de-tectable tumor formations were observed in the 2D and control groups. HE and immunohistochemical staining of the transplantation tumor model showed evident characteristics of human gastric cancer. Conclusion:A human gastric cancer model in normal immune mice was successfully established. The onset and development mechanism of gastric cancer could be more effectively investigated in mice with normal immune function through this model. Moreover, a more valuable and new animal model for the research and devel-opment of anticancer drug was established.

Objective:To establish a nomogram model based on elastic imaging parameters and ultrasound image features, and evaluate its predictive value in central lymph node metastasis (CLNM) in papillary thyroid carcinoma (PTC) .Methods:The clinical data of 168 patients (the research group) with papillary thyroid carcinoma who underwent thyroid surgery in our hospital from Jan. 2019 to Dec. 2021 were retrospectively collected, including gender, age, ultrasound elastography parameters (elasticity ratio, blue area ratio), and ultrasound examination indicators (nodule diameter, nodule number, internal echo, border, edge, aspect ratio, microcalcification, capsule invasion). Another 150 patients who underwent thyroid surgery in our hospital during the same period were selected as the validation group.According to the results of postoperative pathological examination, the the research group were divided into two groups: 64 cases (38.10%) of CLNM and 104 cases (61.90%) of non-CLNM. Binary logistic regression analysis was used to explore the influencing factors of CLNM in PTC patients, and a nomogram model based on elastic imaging parameters and ultrasound image features was established. The nomogram model was drawn to predict the receiver operating characteristic (ROC) curve of CLNM in PTC patients.Results:There were statistically significant differences in nodule diameter, edge, microcalcification, capsule invasion, blue area ratio, and elasticity ratio ( P<0.05). Most of the nodules in the CLNM group were ≥10 mm in diameter, with uneven margins, an aspect ratio of <1, microcalcifications and capsular invasion. Logistic regression analysis showed that nodule diameter, capsule invasion, blue area ratio and elastic ratio were risk factors for CLNM ( P<0.05). The AUC of the combined detection was 0.857 (0.777-0.937), and the sensitivity and specificity were 78.1% and 86.5%, respectively, and the AUC and sensitivity were significantly higher than the individual detection of each index ( P<0.05). In the research group, the sensitivity and specificity of the ultrasound parameter prediction model in predicting CLNM were 81.25% (52/64) and 84.62% (88/104), respectively. In the validation group, the sensitivity and specificity of the ultrasound parameter prediction model in predicting CLNM were 79.17% (38/48) and 85.29% (87/102), respectively. Conclusion:Elastography parameters (blue area ratio, elasticity ratio) and ultrasound image features (nodule diameter, capsular invasion) are the influencing factors of CLNM in PTC patients, and the combined prediction based on the above four indicators has good application value.

Recombinant bacterial vector vaccines have been widely used as carriers for the delivery of protective antigens and nucleic acid vaccines to prevent certain infectious diseases because of their ability to induce mucosal immunity, humoral immunity and cellular immunity. However, protective antigens and nucleic acids recombined into bacterial vector vaccines are difficult to be released into host cells because of the presence of bacterial cell wall. Vaccine strains that are residual in animals or livestock products may also cause environmental contamination and spread of the vaccine strains. The effective solution for these problems is to construct an auto-lysis system that can regulate the vaccine strains to grow normally in vitro while lysis in vivo. The lysis systems that have been applied in germs mainly include: the lysis system based on regulated delayed peptidoglycan synthesis, the lysis system based on the regulation of bacteriophage lysis protein and the lysis system based on the toxin-antitoxin system. In addition, a potential lysis system based on bacterial Type Ⅵ Secretion System (T6SS) is also expected to be a new method for the construction of auto-lysis strains. This review will focus on the regulatory mechanisms of these bacterial lysis systems.
Animals ; Antigens, Bacterial ; Bacterial Vaccines ; Vaccines, Attenuated ; Vaccines, DNA

Objective: To investigate the protective effect of intraperitoneal transplantation of human liver-derived stem cells at different times against concanavalin A (ConA)-induced acute liver injury in mice. Methods: A total of 88 male C57BL/6 mice were randomly divided into normal control group (group C), ConA model group (group M), and human liver-derived stem cells (HYX1)+ConA group (group E); according to the interval between phosphate buffer/HYX1 injection and ConA injection, Groups M and E were further divided into 3-hour groups (M1 and E1 groups), 6-hour groups (M2 and E2 groups), 12-hour groups (M3 and E3 groups), 24-hour groups (M4 and E4 groups), and 48-hour groups (M5 and E5 groups). The levels of alanine aminotransferase (ALT), aspartate transaminase (AST), and total bilirubin (TBil) in peripheral blood were measured, liver tissue sections were used to observe pathological changes, and the Ishak score for liver inflammation was determined. The independent samples t-test was used for comparison between groups, and P < 0.05 was considered statistically significant. Results: The levels of ALT, AST, and TBil in group C were (36.25±1.16) U/L, (120.20±5.77) U/L, and (2.20±0.23) μmol/L, respectively; the levels of ALT, AST, and TBil and Ishak score were (8 721.23±837.39) U/L, (8 110.31±290.10) U/L, (8.41±0.10) μmol/L, and (13.32±1.30), respectively, in group M1, (8 334.31±666.50) U/L, (7 560.20±760.34) U/L, (10.40±0.80) μmol/L, and (12.67±0.81), respectively, in group M2, (8 960.75±551.93) U/L, (8 535.62±675.14) U/L, (10.95±1.43) μmol/L, and (14.57±0.65), respectively, in group M3, (8 618.57±886.40) U/L, (11 440.54 ± 1 327.86) U/L, (13.30±1.86) μmol/L, and (13.21±1.06), respectively, in group M4, and (10 170.13±1 112.37) U/L, (11 470.56±1 108.40) U/L, (12.75±1.55) μmol/L, and (15.07±1.58), respectively, in group M5. The levels of ALT, AST, and TBil and Ishak score were (1 016.35±163.47) U/L, (952.30±103.91) U/L, (7.77±0.62) μmol/L, and (3.50±0.21), respectively, in group E1, (42.10±6.20) U/L, (126.72±13.33) U/L, (3.41±0.53) μmol/L, and (2.01±0.40), respectively, in group E2, (44.21±4.30) U/L, (216.71±35.88) U/L, (3.47±0.44) μmol/L, and (2.13±0.25), respectively, in group E3, (2 909.69±212.14) U/L, (2 988.43±333.70) U/L, (7.03±0.93) μmol/L, and (4.70±0.50), respectively, in group E4, and (7 874.26±799.60) U/L, (10 940.54±947.35) U/L, (10.53±1.09) μmol/L, and (8.60±0.83), respectively, in group E5. Groups M1-M5 had significantly higher levels of ALT, AST, and TBil than group C (all P < 0.01), and groups M1-M4 had significantly higher levels of AST and ALT than groups E1-E4 (all P < 0.01), while there were no significant differences in the levels of AST and ALT between groups M5 and E5 (both P > 0.05). The pathological sections of liver tissue showed that compared with group M, group E had significant reductions in the degree of necrosis and Ishak score (both P < 0.05). Conclusion Intraperitoneal transplantation of human liver-derived stem cells has a protective effect against ConA-induced acute liver injury in mice, and the injection at 6 and 12 hours in advance has the best protective effect.