Antiviral Activity of Antimicrobial Lipopeptide from Bacillus subtilis fmbj Against Pseudorabies Virus, Porcine Parvovirus, Newcastle Disease Virus and Infectious Bursal Disease Virus in Vitro

Bacillus subtilis fmbj can produce lipopeptide antimicrobial substance, whose main components were surfactin and fengycin. In the study, the antiviral activity of antimicrobial lipopeptides (AMLs) from B. subtilis fmbj (CGMCC No. 0934) against Pseudorabies Virus (PRV), Porcine Parvovirus (PPV), Newcastle Disease Virus (NDV) and Infectious Bursal Disease Virus (IBDV) was evaluated in vitro. The AMLs represented a direct inactivation effect on cell-free virus stocks of PRV, PPV, NDV and IBDV, and it could effectively inhibit infection and replication of the NDV and IBDV, but failed to affect PRV and PPV. The AMLs were represented higher toxicity for the Porcine Kidney (PK-15) cells (50% cytotoxic concentration (CC₅₀) value was 32.87 μM) and lower for the Chicken Embryo Fibroblasts (CEF) cells (CC₅₀ value was 89.16 μM). The Selectivity index of AMLs on PRV, PPV, NDV and IBDV was 1.44, 2.23, 8.40 and 12.19, respectively.     

宠物和实验动物

宠物在我国已经成为一个日渐壮大的产业和庞大的群体。宠物与人类朝夕相处,最容易成为动物源性疾病的传染源,对人类健康造成潜在威胁。为了人类自身和宠物健康,我们必须对宠物投入更多的关注。宠物和实验动物作为两种不同用途的动物,存在众多的相似点。我国已经建立了相对完善的实验动物生产、使用、质量保障和福利的管理体系。实验动物的管理体系也许可以为宠物的生产、饲养、质量保证和福利的管理体系提供借鉴。     

2009年全国其他感染性腹泻报告病例分析

目的了解我国2009年其他感染性腹泻的流行特点和病原学信息,提出改善建议,为更好的控制其他感染性腹泻病的流行提供数据支持。方法收集中国疾病控制信息系统"疾病监测信息报告管理系统"中2009年其他感染性腹泻的病例报告,对其流行病学及病原学信息进行描述性统计分析。结果 2009年全国共报告655 965例其他感染性腹泻病例,其中≤5岁儿童分别占报告总病例的50.38%和死亡病例的70.0%。实验室确诊病例占报告病例数的5.04%,其中病毒性感染占92.79%,细菌性感染占6.92%。结论≤5岁的散居儿童应为其他感染性腹泻的重点监测人群。其他感染性腹泻报告病例中约有95%为临床诊断病例。我国其他感染性腹泻的病原学诊断率及病原学诊断结果的报告率亟待提高。     

Adaptation of signature-tagged mutagenesis to Escherichia coli K1 and the infant-rat model of invasive disease

With the exception of the polysialic acid capsule (K1 antigen), little is known about other virulence factors needed for systemic infection by Escherichia coli K1, the leading cause of Gram-negative neonatal meningitis in humans. In this work, the functional genomics method of signature-tagged mutagenesis (STM) was adapted to E. coli K1 and the infant-rat model to identify non-capsule virulence genes. Validation of the method was demonstrated by the failure to recover a reconstructed acapsular mutant from bacterial pools used to systemically infect 5-day-old rats. Three new genes required for systemic disease were identified from a total of 192 mutants screened by STM (1.56% hit rate). Gut colonization, Southern blot hybridization, mixed-challenge infection, and DNA sequence analyses showed that the attenuating defects in the mutants were associated with transposon insertions in rfaL (O antigen ligase), dsbA (thiol:disulfide oxidoreductase), and a new gene, puvA (previously unidentified virulence gene A), with no known homologues. The results indicate the ability of STM to identify novel systemic virulence factors in E. coli K1.     

Targeted Protein Engineering Provides Insights into Binding Mechanism and Affinities of Bacterial Collagen Adhesins

The collagen-binding bacterial proteins, Ace and Cna, are well characterized on the biochemical and structural level. Despite overall structural similarity, recombinant forms of the Ace and Cna ligand-binding domains exhibit significantly different affinities and binding kinetics for collagen type I (CI) in vitro. In this study, we sought to understand, in submolecular detail, the bases for these differences. Using a structure-based approach, we engineered Cna and Ace variants by altering specific structural elements within the ligand-binding domains. Surface plasmon resonance-based binding analysis demonstrated that mutations that are predicted to alter the orientation of the Ace and Cna N₁ and N₂ subdomains significantly affect the interaction between the MSCRAMM (microbial surface components recognizing adhesive matrix molecule) and CI in vitro, including affinity, association/dissociation rates and binding ratio. Moreover, we utilized this information to engineer an Ace variant with an 11,000-fold higher CI affinity than the parent protein. Finally, we noted that several engineered proteins that exhibited a weak interaction with CI recognized more sites on CI, suggesting an inverse correlation between affinity and specificity.     

Phagosomes induced by cytokines function as anti-Listeria vaccines: novel role for functional compartmentalization of STAT-1 protein and cathepsin-D

Phagosomes are critical compartments for innate immunity. However, their role in the protection against murine listeriosis has not been examined. We describe here that listericidal phago-receptosomes are induced by the function of IFN-γ or IL-6 as centralized compartments for innate and adaptive immunity because they are able to confer protection against murine listeriosis. These phago-receptosomes elicited LLO(91-99)/CD8(+)- and LLO(189-201)/CD4(+)-specific immune responses and recruited mature dendritic cells to the vaccination sites controlled by T cells. Moreover, they present exceptional features as efficient vaccine vectors. First, they compartmentalize a novel listericidal STAT-1-mediated signaling pathway that confines multiple innate immune components to the same environment. Second, they show features of MHC class II antigen-loading competent compartments for cathepsin-D-mediated LLO processing. Third, murine cathepsin-D deficiencies fail to develop protective immunity after vaccination with listericidal phago-receptosomes induced by IFN-γ or IL-6. Therefore, it appears that the connection of STAT-1 and cathepsin-D in a single compartment is relevant for protection against listeriosis.     

Human and Pneumococcal Cell Surface Glyceraldehyde-3-phosphate Dehydrogenase (GAPDH) Proteins Are Both Ligands of Human C1q Protein

C1q, a key component of the classical complement pathway, is a major player in the response to microbial infection and has been shown to detect noxious altered-self substances such as apoptotic cells. In this work, using complementary experimental approaches, we identified the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a C1q partner when exposed at the surface of human pathogenic bacteria Streptococcus pneumoniae and human apoptotic cells. The membrane-associated GAPDH on HeLa cells bound the globular regions of C1q as demonstrated by pulldown and cell surface co-localization experiments. Pneumococcal strains deficient in surface-exposed GAPDH harbored a decreased level of C1q recognition when compared with the wild-type strains. Both recombinant human and pneumococcal GAPDHs interacted avidly with C1q as measured by surface plasmon resonance experiments (K_D = 0.34–2.17 nm). In addition, GAPDH-C1q complexes were observed by transmission electron microscopy after cross-linking. The purified pneumococcal GAPDH protein activated C1 in an in vitro assay unlike the human form. Deposition of C1q, C3b, and C4b from human serum at the surface of pneumococcal cells was dependent on the presence of surface-exposed GAPDH. This ability of C1q to sense both human and bacterial GAPDHs sheds new insights on the role of this important defense collagen molecule in modulating the immune response.     

Highly potent inhibitors of proprotein convertase furin as potential drugs for treatment of infectious diseases

Optimization of our previously described peptidomimetic furin inhibitors was performed and yielded several analogs with a significantly improved activity. The most potent compounds containing an N-terminal 4- or 3-(guanidinomethyl)phenylacetyl residue inhibit furin with K(i) values of 16 and 8 pM, respectively. These analogs inhibit other proprotein convertases, such as PC1/3, PC4, PACE4, and PC5/6, with similar potency, whereas PC2, PC7, and trypsin-like serine proteases are poorly affected. Incubation of selected compounds with Madin-Darby canine kidney cells over a period of 96 h revealed that they exhibit great stability, making them suitable candidates for further studies in cell culture. Two of the most potent derivatives were used to inhibit the hemagglutinin cleavage and viral propagation of a highly pathogenic avian H7N1 influenza virus strain. The treatment with inhibitor 24 (4-(guanidinomethyl)phenylacetyl-Arg-Val-Arg-4-amidinobenzylamide) resulted in significantly delayed virus propagation compared with an inhibitor-free control. The same analog was also effective in inhibiting Shiga toxin activation in HEp-2 cells. This antiviral effect, as well as the protective effect against a bacterial toxin, suggests that inhibitors of furin or furin-like proprotein convertases could represent promising lead structures for future drug development, in particular for the treatment of infectious diseases.