An efficient TILLING platform for cultivated tobacco.

Targeting-induced local lesions in genomes (TILLING) is a powerful reverse-genetics tool that enables high-throughput screening of genomic variations in plants. Although TILLING has been developed for many diploid plants, the technology has been used in very few polyploid species due to their genomic complexity. Here, we established an efficient capillary electrophoresis-based TILLING platform for allotetraploid cultivated tobacco (Nicotiana tabacum L.) using an ethyl methanesulfonate (EMS)-mutagenized population of 1,536 individuals. We optimized the procedures for endonuclease preparation, leaf tissue sampling, DNA extraction, normalization, pooling, PCR amplification, heteroduplex formation, and capillary electrophoresis. In a test screen using seven target genes with eight PCR fragments, we obtained 118 mutants. The mutation density was estimated to be approximately one mutation per 106 kb on average. Phenotypic analyses showed that mutations in two heavy metal transporter genes, HMA2S and HMA4T, led to reduced accumulation of cadmium and zinc, which was confirmed independently using CRISPR/Cas9 to generate knockout mutants. Our results demonstrate that this powerful TILLING platform (available at http://www.croptilling.org) can be used in tobacco to facilitate functional genomics applications.

Integrin αvß1 Modulation Affects Subtype B Avian Metapneumovirus Fusion Protein-mediated Cell-Cell Fusion and Virus Infection.

Avian metapneumovirus (aMPV) fusion (F) protein mediates virus-cell membrane fusion to initiate viral infection, which requires F protein binding to its receptor(s) on the host cell surface. However, the receptor(s) for aMPV F protein is still not identified. All known subtype B aMPV (aMPV/B) F proteins contain a conserved Arg-Asp-Asp (RDD) motif, suggesting that the aMPV/B F protein may mediate membrane fusion via the binding of RDD to integrin. When blocked with integrin-specific peptides, aMPV/B F protein fusogenicity and viral replication were significantly reduced. Specifically we identified integrin αv and/or ß1-mediated F protein fusogenicity and viral replication using antibody blocking, small interfering RNAs (siRNAs) knockdown, and overexpression. Additionally, overexpression of integrin αv and ß1 in aMPV/B non-permissive cells conferred aMPV/B F protein binding and aMPV/B infection. When RDD was altered to RAE (Arg-Ala-Glu), aMPV/B F protein binding and fusogenic activity were profoundly impaired. These results suggest that integrin αvß1 is a functional receptor for aMPV/B F protein-mediated membrane fusion and virus infection, which will provide new insights on the fusogenic mechanism and pathogenesis of aMPV.

Characterization of a Gallid herpesvirus 2 strain with novel reticuloendotheliosis virus long terminal repeat inserts.

A bacterial artificial chromosome clone, designated LCY, was constructed from a Gallid herpesvirus 2 (GaHV-2) isolate from a GaHV-2 and reticuloendotheliosis virus co-infected clinical sample. The LCY GaHV-2 insert was sequenced and found to consist of 175,319 nucleotides. LCY GaHV-2 open reading frames (ORFs) had a high sequence identity to those of reference strains. The major difference was that two REV long terminal repeats (LTRs), in the same direction, were inserted at the internal repeat short (IRs)/unique short (Us) and Us/terminal repeat short (TRs) junctions. In addition, the a-like sequence and UL36 were different from other strains. Phylogenetic analysis revealed that LCY was closely related to pandemic strains in China. A pathogenicity study and a vaccination-challenge test were performed on LCY and the reference strain, GA. The results showed that LCY induced gross Marek's disease (MD) lesions and mortality in 71.4 and 7.1% of chickens, respectively, which are lower rates than those observed for the reference strain GA (85.7 and 35.7%). The commercially available CVI988 vaccine provided complete protection against LCY and GA (100%). These results showed that the isolate exhibited lower pathogenicity in SPF chickens. This study revealed that a novel pattern of LTR inserts was found in the strain LCY and that the strain was of low virulence. The present work expands the available genetic information for GaHV-2 and will be useful for the control of MD in China.

Molecular and pathogenicity characterization of Gallid herpesvirus 2 newly isolated in China from 2009 to 2013.

During the course of our continuous surveillance of Gallid herpesvirus 2 (GaHV-2), 44 isolates were obtained from GaHV-2-positive chickens of different flocks in China from 2009 to 2013. The meq gene, considered as a major GaHV-2 oncogene, was sequenced and was found to contain an open reading frame of 1020 nucleotides encoding a 339 amino acid (aa) polypeptide in all isolates. Compared with the GaHV-2 GA strain, the meq genes in 15.9 % (7/44) of the isolates analyzed in this study contained an aa substitution mutation at position 88 (A to T) of which is the first report. The main characteristics of Chinese GaHV-2 isolates meq genes included the substitutions K77E, D80Y, V115A, T139A, P176R, and P217A, and the aa substitution frequency at positions 139 and 176 showed an increase. To test the pathogenicity of the isolates, a pathogenicity study and a vaccination-challenge test were performed on three selected isolates (ZY/1203, WC/1203, and WC/1110) and reference strain GA. The results showed that the three isolates induced gross Marek's disease (MD) lesions in 95.0-100 % cases, which was a higher rate than that obtained for strain GA (82.4 %). Three isolates induced mortality in 10-21.1 % of specific-pathogen-free chickens, which was similar to results with strain GA (23.5 %). The commercially available CVI988 vaccine induced lower protective indices (PIs) against ZY/1203 (82.4) and WC/1110 (83.3) as compared to those against WC/1203 (100) and GA (100). These results showed an evolving trend in the meq genes of the isolates; three isolates exhibited higher morbidity as compared to the reference strain and the vaccine induced lower PIs against two isolates as compared to that against the reference strain.

Isolation and full-genome sequence of two reticuloendotheliosis virus strains from mixed infections with Marek's disease virus in China.

Reticuloendotheliosis virus (REV), classified as a gammaretrovirus, has a variety of hosts, including chickens, ducks, geese, turkeys, and wild birds. REV causes a series of pathological syndromes, especially the immunosuppression of the host, which may lead to an increased susceptibility to other pathogens, thus greatly damaging the poultry industry. Mixed infections of REV and Marek's disease virus (MDV) have been reported in many countries, including China. Previous reports revealed that MDV vaccines were not efficacious, and even less-virulent MDV strains would cause some losses due to mixed infections with REV. Additionally, contaminants in the MDV vaccine might be the main source of REV. In this study, two clinical samples were collected from two flocks of chickens that were diagnosed with MDV. Subsequently, two REV isolates were obtained from the clinical samples. The isolates, named CY1111 and SY1209, were further confirmed through an indirect immunofluorescence assay and electron microscopy. Complete genome sequences of the two REV strains were determined to test the relationship between them and other REV strains. Phylogenetic trees showed that the two REV strains were closely related to most REV strains that were isolated from a variety of hosts. Therefore, REVs might spread freely among these hosts under natural conditions. Additionally, most REV strains in China were in the same clade. The present work offers some information regarding REV in China.

Differences in Pathogenicity and Vaccine Resistance Discovered between Two Epidemic Strains of Marek's Disease Virus in China.

Despite highly effective vaccines, Marek's disease (MD) causes great economic loss to the poultry industry annually, largely due to the continuous emergence of new MD virus (MDV) strains. To explore the pathogenic characteristics of newly emerged MDV strains, we selected two strains (AH/1807 and DH/18) with clinically different pathotypes. We studied each strain's infection process and pathogenicity and observed differences in immunosuppression and vaccine resistance. Specific pathogen-free chickens, unvaccinated or vaccinated with CVI988, were challenged with AH/1807 or DH/18. Both infections induced MD damage; however, differences were observed in terms of mortality (AH/1807: 77.8%, DH/18: 50%) and tumor rates (AH/1807: 50%, DH/18: 33.3%). The immune protection indices of the vaccine also differed (AH/1807: 94.1, DH/18: 61.1). Additionally, while both strains caused interferon-ß and interferon-γ expression to decline, DH/18 infection caused stronger immunosuppression than AH/1807. This inhibition persisted even after vaccination, leading to increased replication of DH/18 that ultimately broke through vaccine immune protection. These results indicate that both strains have different characteristics, and that strains such as DH/18, which cause weaker pathogenic damage but can break through vaccine immune protection, require further attention. Our findings increase the understanding of the differences between epidemic strains and factors underlying MD vaccination failure in China.

[Clinical and coronary angiographic features of young women with acute myocardial infarction].

OBJECTIVE: To observe the clinical and coronary angiographic features of young women (≤ 44 years) with acute myocardial infarction (AMI). METHODS: Clinic and coronary angiographic features were compared among 57 young women with AMI and 60 non-CHD young women, 78 young men with AMI and 80 elderly women with AMI were included, all patients were admitted to hospital from June 2003 to December 2010 and underwent coronary angiography. Body mass index (BMI), smoking history, familial history of early coronary artery disease, essential hypertension, type 2 diabetes mellitus, hyperlipidemia, serum uric acid (UA), menopause, lipids, total bilirubin (TBil), direct bilirubin (DBil), hemoglobin (Hb), red cell distribution width (RDW), fasting blood glucose (FBG) were measured. RESULTS: (1) Prevalence of essential hypertension, hypertriglyceridemia and levels of fasting blood glucose, triglyceride, serum uric acid were significantly higher while high density lipoprotein cholesterol, and hemoglobin were significantly lower in young women with AMI group than in age-matched non-CHD control group (all P < 0.05). (2) Logistic regression analysis showed that essential hypertension (OR = 23.187), lower hemoglobin level (OR = 1.010) and uric acid (OR = 1.040) were independent risk factors for young women with AMI (all P < 0.05). (3) Coronary angiography revealed normal coronary finding in 6 cases, single-vessel disease in 35 cases (26 cases with left anterior descending artery disease) and two-vessel disease in 12 patients. The ratio of single vessel disease involved left anterior descending artery in young women was higher than that of young men and old women with AMI (all P < 0.05). CONCLUSION: Essential hypertension, lower hemoglobin and uric acid are risk factors of young women with AMI. Single vessel coronary disease is the most common coronary angiographic feature of young women with AMI.

Revascularization versus drug therapy for coronary artery disease in patients aged over 80 years: a real-world study.

BACKGROUND: Revascularization for the treatment of coronary artery disease (CAD) is advancing rapidly and is used increasingly in old patients. This study aimed to compare the efficacy and safety of revascularization with drug therapy in CAD patients aged over 80 years at a real-world clinical setting. METHODS: A total of 501 CAD patients aged over 80 years were consecutively enrolled from January 2011 to January 2016 in Anzhen Hospital (Beijing, China), Capital Medical University. The patients were treated with percutaneous coronary intervention (PCI) (n=283), coronary artery bypass grafting (CABG) (n=106), or drug therapy (n=112). All-cause mortality, cardiovascular-related mortality, readmission rate, and Seattle Angina Questionnaire (SAQ) score were compared between the three treatment methods. RESULTS: A total of 411 patients (82.04%) were followed with a median duration of 25 months. All-cause mortality and cardiovascular-related mortality in the drug therapy group were significantly higher than the PCI and CABG groups (both P<0.05). Readmission rate for cardiovascular events in the CABG group was significantly lower than the PCI and drug therapy groups (both P<0.05). Scores of physical limitation, angina frequency, treatment satisfaction, and disease perception of the SAQ in the PCI and CABG groups were significantly higher than the drug therapy group (both P<0.05). Scores of angina stability did not differ significant between the three groups (P=0.127). CONCLUSIONS: Revascularization is superior to drug therapy in efficacy and safety in the treatment of oldest-old patients with CAD.

Clinical efficacy of different treatments and their impacts on the quality of life of octogenarians with coronary artery disease.

BACKGROUND: Coronary artery disease (CAD) in octogenarians (age of ≥80 years) has a high risk of mortality and high medical expenses. Research shows that the prevalence of CAD is higher among octogenarians than that among younger people, but few such patients undergo percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). This study aimed to evaluate different treatments with respect to their clinical effects and impacts on quality of life of octogenarians with CAD. METHODS: Data of 519 octogenarians with CAD consecutively treated at Beijing Anzhen Hospital, Capital Medical University (Beijing, China) from January 2010 to January 2016 were collected in this study. The patients were categorized into three groups based on the treatments they received: the PCI group (n = 292), CABG group (n = 110), and medical treatment group (n = 117). The followings were recorded during follow-up: clinical data, death (all-cause and cardiovascular-related), re-hospitalization time, Seattle Angina Questionnaire (SAQ) score, and occurrence of hemorrhagic events (cerebral bleeding, gastrointestinal bleeding, and dermal ecchymosis). RESULTS: The median follow-up duration was 25.0 (25th, 75th percentile: 17.0, 55.5) months among 417 patients. The all-cause death rates (28.2% vs. 12.0% and 14.6%, respectively) and cardiovascular-related death rates (15.4% vs. 3.8% and 6.4%, respectively) were significantly higher in the medical treatment group than those in the PCI group and CABG group (all P < 0.05). The re-hospitalization rate for cardiovascular events was significantly lower in the CABG group than those in the PCI group and medical treatment group (3.8% vs. 12.8% and 14.9%, respectively) (χ = 8.238, P = 0.018). The SAQ scores of physical limitation, angina frequency, treatment satisfaction, and disease perception were significantly higher in the PCI group and CABG group than those in the medical treatment group (all P < 0.05). No significant difference in the angina stability score was observed among the three groups (F = 3.179, P = 0.204). CONCLUSION: PCI and CABG result in reduced mortality and better quality of life in octogenarians with CAD.

Differential expression of type I interferon mRNA and protein levels induced by virulent Marek's disease virus infection in chickens.

Marek's disease virus (MDV), an α-herpesvirus targeting avian species, causes fatal Marek's disease (MD) in chickens. The host interferon (IFN) responses play a key role in resisting viral infection. However, host IFN responses following MDV infection in the chicken central immune organs (thymus and bursa of Fabricius), which contain numerous MDV target cells, is poorly understood. In this study, we performed animal experiments in specific pathogen-free chickens infected with two virulent MDV strains (BS/15 and Md5) or without infection as negative controls. Specifically, the type I IFN (IFN-α and IFN-ß) transcriptional and proteomic expression levels at 7, 10, 14, 17, and 21 days post infection (dpi) were detected and analyzed. Our results indicated that the mRNA and protein expression levels of IFN-α and IFN-ß in the thymus and bursa of Fabricius were mainly downregulated in cytolytic infection (such as 10 dpi) and reactivation (such as 17 dpi) stages, but not the latent (such as 14 dpi) stage of MDV infection, which was determined by comprehensively analyzing the MDV viral load and immune organ damage caused by MDV infection. These data suggest that MDV could inhibit the expression of host type I IFNs, which may be involved in the MDV-induced host immunosuppression and contribute to the immune escape of MDV from host immunity. Furthermore, we found that the downregulated expression of the host type I IFNs induced by BS/15 and Md5 infection was significantly different, which we speculated may be related to the diverse virulence and pathogenicity of MDV strains. In conclusion, our study demonstrated that MDV mostly inhibited the expression of type I IFNs in infected hosts, which may be associated to its pathogenesis.

Exploiting the combined effects of high pressure and moderate heat with nisin on inactivation of Clostridium botulinum spores.

In the present work, we studied the combined effects of pressure (300.0-700.0 MPa), temperature (30-70 degrees C) and the presence of nisin (0-333 IU/ml) on the inactivation of Clostridium botulinum 33A spores at various pressure holding times (7.5-17.5 min). Moreover, response surface methodology (RSM) was employed and a quadratic equation for HPP and nisin-induced inactivation was built with RSM. By analyzing the response surface plots and their corresponding contour plots as well as solving the quadratic equation, the experimental values were shown to be significantly in good agreement with predicted values because the adjusted determination coefficient (R(Adj)(2)) was 0.9261 and the level of significance was P<0.0001. The optimum process parameters for a six-log cycle reduction of C. botulinum spores were obtained as: pressure, 545.0 MPa; temperature, 51 degrees C; pressure holding time, 13.3 min; and nisin concentration, 129 IU/ml. The adequacy of the model equation for predicting the optimum response values was verified effectively for 10 test points. Compared to conventional high pressure processing (HPP) techniques, the main process advantages of HPP-nisin combination sterilization in the UHT milk are, lower pressure, natural preservative (nisin), and temperature in a shorter treatment time.

Unfractionated Heparin with Sequential Enoxaparin in Patients with Complex Coronary Artery Lesions during Percutaneous Coronary Intervention.

BACKGROUND: Unfractionated heparin (UFH), despite its limitations, has been used as the primary anticoagulant alternative during the percutaneous coronary intervention (PCI). Some studies indicated that intravenous enoxaparin could be an effective and safe option. Our team used enoxaparin alone at one time according to the guidelines (Class IIA) and found a little catheter thrombosis during PCI. We recommend a new anticoagulation strategy using enoxaparin in combination with UFH. Enoxaparin has a more predictable anticoagulant response with no need of repeatedly monitoring anticoagulation during PCI. This retrospective study aimed to evaluate the efficacy and safety of using enoxaparin in combination with UFH in PCI patients with complex coronary artery disease. METHODS: Between January 2015 and April 2017, 600 PCI patients who received intravenous UFH at an initial dose of 3000 U plus intravenous enoxaparin at a dose of 0.75 mg/kg (observation group) and 600 PCI patients who received UFH at a dose of 100 U/kg (control group) were consecutively included in this retrospective study. The endpoints were postoperative 48-h thrombolysis in myocardial infarction (TIMI) bleeding and transfusion and 30-day and 1-year major adverse cardio-cerebrovascular events (MACCE). RESULTS: Baseline clinical, angiographic, and procedural characteristics were similar between groups, except there was less stent implantation per patient in the observation group (2.13 vs. 2.25 in the control group, P = 0.002). TIMI bleeding (3.3% vs. 4.7%) showed no significant difference between the observation group and control group. During the 30-day follow-up, the rate of MACCE was 0.9% in the observation group and 1.5% in the control group. There was no significant difference in the rates of MACCE, death, myocardial infarction, target vessel revascularization, cerebrovascular event, and angina within 30 days and 1 year after PCI between groups as well as in the subgroup analysis of transfemoral approach. CONCLUSIONS: UFH with sequential enoxaparin has similar anticoagulant effect and safety as UFH in PCI of complex coronary artery disease.

A predictive model for the influence of food components on survival of Listeria monocytogenes LM 54004 under high hydrostatic pressure and mild heat conditions.

The combination of high hydrostatic pressure with mild temperature was explored to achieve a predictive model of microbial inactivation in food matrix processing. The pressure processing conditions were fixed at 448 MPa for 11 min at the treatment temperature of 41 degrees C, which have been determined as the optimum processing conditions considering six log-cycle reductions of Listeria monocytogenes. Based on the results, response surface methodology (RSM) was performed in the present work, the influence of food components like soybean protein (0-5.00%), sucrose (0.25-13.25%), bean oil (0-10.00%), and pH (4-10) of the food matrix on survival of L. monocytogenes by high pressure and mild heat was studied, and a quadratic predictive model for the influence of food components and pH of food matrix on L. monocytogenes reduction by high pressure and mild heat was built with RSM accurately. The experimental results showed that the efficiency of L. monocytogenes reduction in milk buffer and food matrix designed in the present work, under the HPP treatment process parameters described above, were different. The soybean protein (P=0.0086), sucrose (P<0.0001), and pH (P=0.0136) significantly affected reduction of L. monocytogenes, but the effect of bean oil on reduction of L. monocytogenes was not significant (P=0.1028). The predictive model is significant since the level of significance was P<0.0001 and the calculated F value (11.53) is much greater than the tabulated F value (F(0.01 (14, 5))=9.77). Moreover, the adequacy of the predictive model equation for predicting the level of L. monocytogenes reduction was verified effectively by the validation data.

Direct evidence of reassortment and mutant spectrum analysis of a very virulent infectious bursal disease virus.

The complete genomic sequence of very virulent infectious bursal disease virus (vvIBDV) Gx strain was determined, including the sequences of segment A, encoding the precursor polyprotein, and segment B, encoding the viral RNA polymerase (VP1) and 5'- and 3'-untranslating regions. Alignment of segment A of Gx with the sequences of 12 other vvIBDV strains showed 97.5% to 99.0% amino acid identity, whereas alignment of segment B of Gx with nine other vvIBDV strains revealed high sequence divergence, ranging from 10.3% to 11%. Phylogenetic analysis of segments A and B showed that they were in different branches, indicating that the reassortment occurred in this strain and that segment A and segment B derived from different pathotype strains. The mutant spectrum analysis of quasispecies virus demonstrated that the mean minimum mutation frequency in VP1 was 8.78-fold higher than in the polyprotein. The most frequent mutations were in the first 1986 nucleotides (nonsynonymous mutations) and the last 660 nucleotides (synonymous mutations), indicating that the 219 amino acid residues in the C-terminal of the VP1 form a functional region.

[Construction of chicken embryo fibroblasts cDNA expression library].

Chicken embryo fibroblast (CEF) is a primary cellular material to research the infectious bursal disease virus (IBDV). Constructing the cDNA expression library of CEF is the foundation to research cell tropism and find cell receptors of IBDV from CEF. In order to achieve that purpose, a high-quality cDNA expression library of CEF was constructed by Gateway technology, which could avoid using the restriction enzyme for cloning to solve technical limitation of roution method. The mRNA was extracted from chicken embryonic fibroblast. Moreover, single-strand cDNA and double-strand cDNA were synthesized by using biotin-conjugated Oligo (dT) primer in turn. The double-strand cDNA was ligated Adapter and then purified by the cDNA Size Fractionation Columns. After BP recombination reaction, a cDNA entry library was constructed with a titer of 1 x 10(6) cfu/mL, total clones of 1.2 x 10(7) cfu and an average insertion size of about 2243 bp. After LR recombination reaction, the cDNA entry library was transformed into expression library which took on a titer of 5 x 10(5) cfu/mL, total clones of 5.5 x 10(6) cfu and an average insertion size of about 2411bp. The results indicate that the constructed cDNA expression library performs a remarkable high value in both recombination rate and library coverage. As a result, the cDNA expression library, with its good quality, may facilitate to identify the receptors associated with the resistance against IBDV in chicken embryonic fibroblast and to cast new light on the mechanism of cellular tropism. Moreover, it may also provide data of chicken embryonic fibroblast in transcription level and may be helpful to study its biological functions.

A Chinese Variant Marek's Disease Virus Strain with Divergence between Virulence and Vaccine Resistance.

Marek's disease (MD) virus (MDV) has been evolving continuously, leading to increasing vaccination failure. Here, the MDV field strain BS/15 was isolated from a severely diseased Chinese chicken flock previously vaccinated with CVI988. To explore the causes of vaccination failure, specific-pathogen free (SPF) chickens vaccinated with CVI988 or 814 and unvaccinated controls were challenged with either BS/15 or the reference strain Md5. Both strains induced MD lesions in unvaccinated chickens with similar mortality rates of 85.7% and 80.0% during the experimental period, respectively. However, unvaccinated chickens inoculated with BS/15 exhibited a higher tumor development rate (64.3% vs. 40.0%), but prolonged survival and diminished immune defects compared to Md5-challenged counterparts. These results suggest that BS/15 and Md5 show a similar virulence but manifest with different pathogenic characteristics. Moreover, the protective indices of CVI988 and 814 were 33.3 and 66.7 for BS/15, and 92.9 and 100 for Md5, respectively, indicating that neither vaccine could provide efficient protection against BS/15. Taken together, these data suggest that MD vaccination failure is probably due to the existence of variant MDV strains with known virulence and unexpected vaccine resistance. Our findings should be helpful for understanding the pathogenicity and evolution of MDV strains prevalent in China.

Co-Infection with Marek's Disease Virus and Reticuloendotheliosis Virus Increases Illness Severity and Reduces Marek's Disease Vaccine Efficacy.

Marek's disease virus (MDV) and reticuloendotheliosis virus (REV) cause Marek's disease (MD) and reticuloendotheliosis (RE), respectively. Co-infection with MDV and REV is common in chickens, causing serious losses to the poultry industry. However, experimental studies of such co-infection are lacking. In this study, Chinese field strains of MDV (ZW/15) and REV (JLR1501) were used as challenge viruses to evaluate the pathogenicity of co-infection and the influence of MD vaccination in chickens. Compared to the MDV-challenged group, the mortality and tumor rates increased significantly by 20.0% (76.7 to 96.7%) and 26.7% (53.3 to 80.0%), in the co-challenged group, respectively. The protective index of the MD vaccines CVI988 and 814 decreased by 33.3 (80.0 to 47.7) and 13.3 (90.0 to 76.7), respectively. These results indicated that MDV and REV co-infection significantly increased disease severity and reduced the vaccine efficacy. The MDV genome load showed no difference in the feather pulps and spleen, and pathogenicity-related MDV gene expression (meq, pp38, vIL-8, and ICP4) in the spleen significantly increased at some time points in the co-challenged group. Clearly, synergistic pathogenicity occurred between MDV and REV, and the protective efficacy of existing MD vaccines was attenuated by co-infection with Chinese field MDV and REV strains.

Analysis of reduction of Geobacillus stearothermophilus spores treated with high hydrostatic pressure and mild heat in milk buffer.

Our unpublished experimental results of fractional factorial experiments showed that the significant external factors affecting high pressure processing (HPP) inactivation were pressure, temperature and pressure holding time. Based on these results, response surface methodology (RSM) was employed in the present work and a quadratic equation for HPP inactivation was built. By analyzing the response surface plots and their corresponding contour plots as well as solving the quadratic equation, the experimental values were shown to be significantly in good agreement with predicted values since the adjusted determination coefficient (R(Adj)(2)) was 0.9747. The optimum process parameters for six log-cycles reduction of Geobacillus stearothermophilus spores were obtained as: temperature, 86 degrees C; pressure, 625.0 MPa and pressure holding time, 14.0 min. The adequacy of the model equation for predicting the optimum response values was verified effectively by the validation data.

[Effects of high hydrostatic pressure on energy metabolism of Lactobacillus plantarum].

Effects of high hydrostatic pressure on energy metabolism were investigated with Lactobacillus plantarum ATCC8014 as the test microorganism in this work. An INT colorimetric method of oxidation-reduction was established to measure INT metabolic activity of deoxidization of L. plantarum ATCC8014 cells. The utilization of glucose and INT metabolic activity of deoxidization of the cells after HPP treatment were determined using colorimetric methods. The experimental results showed that survival counts of ATCC8014 cells on MRS agar medium and INT metabolic activity of deoxidization decreased significantly, and little changes of utilization of glucose took place with increasing pressure ranging from 150 to 250 MPa for 15 min. Utilization of glucose also reduced evidently at high pressure ( > 300 MPa) for 15 min. Whereas survival cell counts on MRS agar medium were below the detection limit and INT metabolic activity of deoxidization of ATCC8014 was 0% after a 15-min pressure holding time at 400MPa, utilization of glucose of the cells retained 56.1% compared with that of untreated cells. In summary, it can be concluded that enzymes absorbing and transporting glucose in cellular membrane appear to have a high resistance to pressure, enzymes and biological regulating systems involved in glycolysis are more resistant to pressure than those in TCA (tricarboxylic acid cycle) system, TCA of ATCC8014 is more sensitive to pressure than glycolysis, and the decrease of INT metabolic activity of deoxidization is highly related to cell reduction during HHP, which provide some theoretical evidences for mechanisms of HHP sterilization. Inhibition of TCA metabolism is a very important cause of ATCC8014 inactivation by HHP. High hydrostatic pressure can be used as an effective tool to explore pathways of biological metabolism.