OBJECTIVETo quantitatively evaluate the contamination area and risk of a live pathogen during tissue homogenization by either ultrasonic processor or tissue disperser.

METHODSA recombinant Herpes Simplex Virus (rHSV) containing GFP gene was used as the index virus, and fresh liver tissue from healthy mice was used as simulated specimen. After 10% liver homogenate was mixed with rHSV (100 TCID50/0.1 mL) in a 5 mL tube, the stability of rHSV in liver homogenate and influences of an ultrasonic processor and a tissue disperser on viral infectivity were determined by GFP expressions in cell cultures. The contaminating areas of live viruses during homogenization were evaluated by a cell culture-based sedimentary. The contamination radii were counted by measurement of the distance between the operator and the farthest GFP positive well.

RESULTSThe infectivity of rHSV in 10% liver homogenate maintained almost unchanged after it was incubated at room temperature for 30 min. Treatment with an ultrasonic processor clearly dropped down the virus infectivity, while a disperser not. Obvious spills and slashes of live viruses were observed in processes of homogenization with those two apparatuses. The contamination radii are positively related with sample volume, output energy of operator and handling time.

CONCLUSIONHomogenizing infectious samples with an ultrasonic processor and a tissue disperser at commonly used conditions caused obvious spills and splashes of live viruses, which possesses high risk to induce Laboratory acquired infections (LAIs).

Simplexvirus ; pathogenicity ; physiology ; Ultrasonics ; Virulence

Helicobacter pylori (H. pylori) causes chronic gastritis in human stomach, a minority of which progress to peptic ulcer disease, atrophic gastritis, or gastric malignancies. Clinical outcomes of H. pylori infection has been shown to depend on the variability of H. pylori virulence factors, host susceptibility, environmental factors and their interactions. This review provides an update on the molecular pathogenesis of H. pylori infection, focused on H. pylori virulence factors, H. pylori-gastric epithelium interactions, and modulation of host cell signaling. Understanding of H. pylori molecular pathogenic mechanism will facilitate the development of novel treatment strategies for eradication of the bacterium and prevention of H. pylori-induced gastropathy.
Helicobacter Infections/microbiology ; Helicobacter pylori/*pathogenicity ; Humans ; *Virulence Factors

We wished to understand the genetic recombination and phylogenetic characteristics of human en- terovirus A71 (EV-A71) and to explore its potential virulence-related sites. Full-length genomes of three EV-A71 strains isolated from patients in Chenzhou City (China) were sequenced and analyzed. Possible re- combination events and crossover sites were analyzed with Recombination Detection Program v4. 1. 6 by comparison with the complete genome sequences of 231 strains of EV-A71. Similarly, plot and bootscanning analyses were undertaken with SimPlot v3. 5. 1. Phylogenetic trees based on the sequences of VP1 regions were constructed with MEGA v5. 2 using the Kimura two-parameter model and neighbor-joining method. Results suggested that recombination events were detected among the three EV-A71 isolates from Chenzhou City. The common main parent sequence was from JF799986 isolated from samples in Guang- zhou City (China) in 2009, and the minor parent sequence was TW/70516/08. Intertypic recombination e- vents were found in the C4b strain (strain SHZH98 isolated in 1998) and C4a strain (Fuyang strain isola- ted in 2008) with the prototype strains of CVA4 and CVA14 in the 3D region. The chi-square test was used to screen-out potential virulence-related sites with nucleotide substitutions of different types of hand, foot, and mouth disease (HFMD) cases using SPSS v19.0. Results suggested that there were no significant nucleotide substitutions between death cases and severe-HFMD cases. Eighteen significant nucleotide substitutions were found between death/severe-HFMD cases and mild-HFMD cases, and all these 18 substitutions were distributed only in P2 and P3 regions. Intertypic recombination among the predominant circulating EV-A71 strains in the Chinese mainland and other EV-A strains probably dates before 1998, and intratypic recombination might have occurred frequently in the HFMD outbreak from 2008 to 2012. Substitutions in the non-capsid region may be correlated with the changes in virulence of EV-A71. These data suggest that researchers should pay more attention to the relationships between substitutions in the noncapsid region and the virulence of the virus.
Enterovirus A, Human ; genetics ; pathogenicity ; Mutation ; Phylogeny ; Recombination, Genetic ; Virulence

Heparan sulfate (HS) is ubiquitously expressed on the surfaces and in the extracellular matrix of virtually all cell types, making it an ideal receptor for viral infection. Compared with wild-type viruses, cell culture-adapted laboratory strains exhibit more efficient binding to cellular HS receptors. HS-binding viruses are typically cleared faster from the circulation and cause lower viremia than their non-HS-binding counterparts, suggesting that the HS-binding phenotype is a tissue culture adaptation that lowers virus fitness in vivo. However, when inoculated intracranially, efficient cell attachment through HS binding can contribute to viral neurovirulence. The primary aim of this review is to discuss the roles of HS binding in viral pathogenicity, including peripheral virulence and neurovirulence. Understanding how heparan sulfate functions during virus infection in vivo may prove critical for elucidating the molecular mechanism of viral pathogenesis, and may contribute to the development of therapeutics targeting HS.
Heparitin Sulfate ; physiology ; Humans ; Receptors, Virus ; physiology ; Virulence ; Viruses ; pathogenicity

In the long-term interaction between pathogens and host, the pathogens regulate the expression of related viru-lence genes to fit the host environment in response to the changes in the host microenvironment. Gene expression was believed to be controlled mainly at the level of transcription initiation by repressors or activators. Recent studies have revealed that small noncoding RNAs (sRNAs) are key regulators in bacterial pathogenesis. sRNA in bacteria is a noncoding RNA with length ranging from 50 to 500 nucleotides. Pathogens can sense the changes in the host environment and consequently regulate the expression of virulence genes by sRNAs. This condition promotes the ability of pathogens to survive within the host, which is beneficial to the invasion and pathogenicity of pathogens. In contrast to transcriptional factors, sRNA-mediated gene regu-lation makes rapid and sensitive responses to environmental cues. Many sRNAs involved in bacterial virulence and pathogenesis have been identified. These sRNAs are key components of coordinated regulation networks, playing important roles in regulating the expression of virulence genes at post-transcriptional level. This review aims to provide an overview on the molecular mechanisms and roles of sRNAs in the regulation of bacterial virulence.
Bacteria ; pathogenicity ; RNA, Bacterial ; RNA, Small Untranslated ; Virulence

Escherichia coli ; genetics ; pathogenicity ; Humans ; Infant, Newborn ; Virulence ; genetics

Fimbriae Proteins ; genetics ; Genotype ; Humans ; Porphyromonas gingivalis ; genetics ; pathogenicity ; Virulence

OBJEVTIVETo study the effect of spvB/spvC gene on Salmonella virulence and the Host immune.

METHODSSTM.211, STM.211-Delta;spvB, STM.211-Delta;spvC, STM.211-Delta;spvB.spvC and PBS were infected with 0.2 mL 10(5) CFU corresponding strain respectively by intraperitoneal. We observed the mental status, movement, diarrhea, weight, pelage changed hair of the infected mouse. Then the level of IL-10, IL-12, IFN-γ were detected by ELISA. Finally, we observe the pathological changes of liver and spleen with the general view and the microscope.

RESULTSInfection symptoms of STM.211, STM.211-Delta;spvB and STM.211-Delta;spvC were significantly worse than PBS group, but there was no significant difference between STM.211-spvB.spvC group and PBS group. The secretion of IFN-γ and IL-12 of STM.211, STM.211-Delta;spvB, STM.211-Delta;spvC group were significantly lower than those in the STM.211-Delta;spvB.spvC group (P<0.05), but IL-10 secretion was significantly higher than STM.211-Delta;spvB.spvC group (P<0.05). There were no statistical significance among the STM.211, STM.211-Delta;SpvB, STM.211-Delta;spvC groups (P>0.05).

CONCLUSIONSSalmonella virulence can be affected obviously by spvB combined with spvC gene, but not by spvB or spvC. spvB/spvC gene can inhibit the TH1 cytokines (IFN-γ and IL-12) secretion but promote the TH2 cytokines (IL-10) expression, leading immune response trend to TH2 shift. It shows that spvB/spvC gene can help the bacteria evade the host immune defenses, leading to aggravation of infection.

Animals ; Cytokines ; immunology ; Interleukin-12 ; Mice ; Salmonella ; genetics ; pathogenicity ; Salmonella Infections ; immunology ; Virulence ; Virulence Factors ; genetics

One type of important plant disease resistance, gene-for-gene resistance, is resulted from the interactions between products of the pathogen avirulence (Avr) genes and their matching plant resistance (R) genes. Avr genes have been cloned from a variety of pathogens including fungi, bacteria, viruses and oomycetes. No significant homology is found between sequences of the most cloned Avr genes and those of known proteins or between those of themselves. However, significant homology has been found between sequences of the cloned R genes and those of known proteins or between those of themselves. R proteins consist of similar domains. It has been reported that hypersensitive cell death and resistance, which are induced by interactions between products of different Avr/R gene pairs consisting of similar R genes but different Avr genes, are distinct in development speed, strength, and organ and tissue specificity. Avr genes have dual functions: Pathogens containing Avr genes are avirulent to plants carrying the matching R genes, while they are virulent in race, strain, pathovar or species-specific way to plants without carrying the matching R genes.
Bacteria ; genetics ; pathogenicity ; Fungi ; genetics ; pathogenicity ; Gene Expression ; Genes, Bacterial ; physiology ; Genes, Fungal ; physiology ; Genes, Viral ; physiology ; Plant Diseases ; genetics ; microbiology ; virology ; Plant Viruses ; genetics ; pathogenicity ; Virulence

The experimental infection of rats with seven strains of Entamoeba histolytica were carried out according to animal ages, number of inoculated amebae, rat strain differences and rat-culture passages. The rat cecal scoring technique of Neal (1951) was utilized to measure the invasiveness of the parisite. The results are summarized and concluded as follows; 1. In the infection of Sprague-Dawley strain rat with YS9-strain and NAMRU II-stran amebae, which wem confirmed highly invasive to the membrane of cecum of rabbits in the previous reports (Cho,1968; Cross,1968), remarkab1e invasiveness was observed in the 30-day-old rat groups with the average cecal score above 5.0. Although no statistical differences of virulence by the number of inoculations showed in rat groups, the cecal scores were markedly reduced in the 50,000 amebae inoculated rats. 2. The hybrid albino rats were considered unsuitable for virulence study of E. histolytica, since the invasiveness of the amabae was inconsistant. 3. The virulences of YS 14 and YS16-strains from cyst carrier showed no virulence, YS 15 from cyst carrier and YS 24 from liver abscess were moderately invasive, and only YS25 from liver abscess showed highly invasive as with YS 9 and NAMRU II-strain amebae. By rat-culture passage, YS14-strain and YS24-strain amebae showed marked increase of invasiveness. It was presumed that the rat-culture passage should be indispensably supplememed in the studies on the virulence of E. histolytica.
Adult ; Animals ; Cecum/microbiology ; Entamoeba histolytica/*pathogenicity ; Female ; Human ; Korea ; Male ; Middle Aged ; Rats ; Virulence