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Abstract Background Avian Escherichia coli (E.coli) type 1 fimbriae adhere to avian tracheal epithelial cells through the FimH protein. However, the adhesion-related antigen is still unknown. The purpose of this study was to analyze the antigenicity of the type 1 fimbrial FimH protein of wild-type avian E. coli, screen antigen epitopes, and prepare monoclonal antibodies (mAbs) that can block the adhesion of avian E. coli. Results In this study, the nucleic acid homologies of MG2 (O11), TS12 (O18), and YR5 (O78) with K12 were 97.7%, 99.6%, and 97.7%, respectively, and the amino acid sequence similarity reached 98.7%, 99.3%, and 98.0%, respectively. The epitopes and hydrophilicities of the FimH proteins of these three strains were similar. The more obvious lectin domain epitopes were located at FimH protein positions 111–124 and 154–162. The mAbs 7C2 and 7D8 against these two epitopes were prepared. An adhesion inhibition test showed that 7C2 and 7D8 blocked bacterial adhesion to avian tracheal epithelial cells. The mAb 7C2 against the 111–124 epitope inhibited O78 strain adhesion by 93%, and the mAb 7D8 against the 154–162 epitope inhibited O78 strain adhesion by 49%, indicating that these two epitopes are closely related to the adhesion of type 1 fimbriae. However, only the 111–124 epitope-recognizing mAb 7C2 inhibited bacterial agglutination of erythrocytes, indicating that host cell receptor binding and erythrocyte agglutination are not mediated by the same spatial locations within the FimH protein. Conclusions The results demonstrate that the mAbs 7C2 and 7D8 against FimH protein positions 111–124 and 154–162 could inhibit the adhesion of E.coli to the chicken trachea.

For more than 50% of multiparous cows, it is difficult to adapt to the sudden increase in calcium demand for milk production, which is highly likely to cause hypocalcemia. An electrochemical biosensor is a portable and efficient method to sense Ca2+ concentrations, but biomaterial is easily affected by the pH of the analyte solution. Here, an electrochemical biosensor was fabricated using a glassy carbon electrode (GCE) and single-walled carbon nanotube (SWNT), which amplified the impedance signal by changing the structure and length of the DNAzyme. Aiming at the interference of the pH, the electrochemical biosensor (GCE/SWNT/DNAzyme) was coupled with a pH meter to form an electrochemical device. It was used to collect data at different Ca2+ concentrations and pH values, and then was processed using different mathematical models, of which GPR showed higher detecting accuracy. After optimizing the detecting parameters, the electrochemical device could determine the Ca2+ concentration ranging from 5 μM to 25 mM, with a detection limit of 4.2 μM at pH values ranging from 4.0 to 7.5. Finally, the electrochemical device was used to determine the Ca2+ concentrations in different blood and milk samples, which can overcome the influence of the pH.

Two species of the DNA virus Torque teno sus virus (TTSuV), TTSuV1 and TTSuV2, have become widely distributed in pig-farming countries in recent years. In this study, we performed a comprehensive analysis of synonymous codon usage bias in 41 available TTSuV2 coding sequences (CDS), and compared the codon usage patterns of TTSuV2 and TTSuV1. TTSuV codon usage patterns were found to be phylogenetically conserved. Values for the effective number of codons (ENC) indicated that the overall extent of codon usage bias in both TTSuV2 and TTSuV1 was not significant, the most frequently occurring codons had an A or C at the third codon position. Correspondence analysis (COA) was performed and TTSuV2 and TTSuV1 sequences were located in different quadrants of the first two major axes. A plot of the ENC revealed that compositional constraint was the major factor determining the codon usage bias for TTSuV2. In addition, hierarchical cluster analysis of 41 TTSuV2 isolates based on relative synonymous codon usage (RSCU) values suggested that there was no association between geographic distribution and codon bias of TTSuV2 sequences. Finally, the comparison of RSCU for TTSuV2, TTSuV1 and the corresponding host sequence indicated that the codon usage pattern of TTSuV2 was similar to that of TTSuV1. However the similarity was low for each virus and its host. These conclusions provide important insight into the synonymous codon usage pattern of TTSuV2, as well as better understangding of the molecular evolution of TTSuV2 genomes.

Background: Type 1 pili, as an important virulence factor of E. coli, has certain homology between APEC and UPEC, but the homology degree is not clear enough. Objectives: This study aims to compare the homology between them. Methods: The recombinant bacteria were constructed by homologous recombination. The pili were observed by TEM, and the hemagglutination characteristics were determined by MHSA. The complete gene sequence was determined by sequencing, and the amino acid sequences of the functional proteins of type 1 pili of APEC and UPEC were compared. Results: TEM showed that they could express pili, which were slender, straight, and dense. StablepUC-fimBH has MHSA but stable-pUC-fimBG does not. The amino acid sequence similarity of FimB of NJ05 and UPEC was 98.8%, FimE was 99.4%, and the similarity between them was 51.5%. Compared with UPEC’s type 1 pili FimC and FimD sequences, the similarity was 99.52% and 87.8%, respectively. The amino acid sequence of FimA of NJ05 was 89–96%, similar to UPEC, and the N-terminal and C-terminal amino acid sequences were exactly the same. The gene sequence and amino acid sequence similarity of FimH between them were both above 99%. The similarity of the pilus binding domain of FimH was 52.8%, but only 27.6% in the receptor binding domain. A few of the same amino acid residues were found in the corresponding regions of FimA, FimF, FimG, and FimH. Conclusions: The type 1 pili of APEC and UPEC come from the same origin, which is helpful to further reveal the pathogenic mechanism of E. coli infection in the poultry respiratory tract. [ABSTRACT FROM AUTHOR]

The article investigates the prevalence and genetic characterization of Pigeon circovirus (PiCV) circulating in Chinese flocks. Almost 80 percent of unhealthy pigeons and more than 60 percent of healthy pigeons were noted to have had PiCV sequence. Upon further examination, the researchers concluded that the strains examined were derived from a common strain but had undergone genetic mutations through time.

To investigate the detection rate and distribution of torque teno sus virus 1 (TTSuV1) in porcine reproductive and respiratory syndrome virus (PRRSV) positive/negative pigs, 2384 pathological tissues samples collected from 6 provinces of Eastern China from 2010 to 2013 were amplified using previously published PRRSV and TTSuV1 primers. The presence and viral load of TTSuV1 were investigated in a wide range of samples from 5 PRRSV positive/negative 4-week-old pigs by real-time TaqMan PCR. TTSuV1 was detected in 65.3% of 1115 PRRSV-positive samples, and 47.2% of 1269 negative samples. Viral DNA was most commonly detected in the immune organs, including spleen, lung, pancreas, and mesenteric and inguinal lymph nodes, followed by serum, liver, kidney, trachea, anal swabs, nasal swabs and sex glands of PRRSV-positive or negative pigs. TTSuV1 DNA loads in PRRSV-positive pigs increased from 2 to 5 times in almost all the corresponding parts compared with PRRSV-negative pigs. Statistical analysis showed that PRRSV may have a synergistic effect with TTSuV1, and promote the replication and proliferation of TTSuV1. [ABSTRACT FROM AUTHOR]