Incorporation of quantum dots on virus in polycationic solution

Developing methods to label viruses with fluorescent moieties has its merits in elucidating viral infection mechanisms and exploring novel antiviral therapeutics. Fluorescent quantum dots (QDs), an emerging probe for biological imaging and medical diagnostics, were employed in this study to tag retrovirus encoding enhanced green fluorescent protein (EGFP) genes. Electrostatic repulsion forces generated from both negatively charged retrovirus and QDs were neutralized by cationic Polybrene, forming colloidal complexes of QDs-virus. By examining the level of EGFP expression in 3T3 fibroblast cells treated with QDs-tagged retroviruses for 24 hours, the infectivity of retrovirus incorporated with QDs was shown to be only slightly decreased. Moreover, the imaging of QDs can be detected in the cellular milieu. In summary, the mild method developed here makes QDs-tagged virus a potential imaging probe for direct tracking the infection process and monitoring distribution of viral particles in infected cells.     

Experimental evidence for parasite‐induced over‐winter mortality in juvenile Rhodeus amarus

In this study, the effects of the eye fluke Diplostomum pseudospathaceum (Trematoda) infection on over‐winter survival of young‐of‐the‐year (YOY) European bitterling Rhodeus amarus (Cyprinidae) were examined between September 2010 and April 2011. The fish were reared in semi‐natural conditions to ensure that results were not confounded by other parasite infections. The cumulative mortality of R. amarus from November until April was significantly higher in D. pseudospathaceum‐infected fish (57·3%) compared to controls (42·1%). Infection of the parental generation did not have any effect on the mortality of juveniles. The results indicate that D. pseudospathaceum infection increases over‐winter mortality of YOY R. amarus. The possible mechanisms causing mortality are discussed.     

Sneathia属细菌与宫颈人乳头瘤病毒感染及宫颈病变的关系

高危型人乳头瘤病毒（human papilloma,HPV）的持续感染可导致宫颈癌前病变和宫颈癌。阴道微生物群在HPV感染和宫颈病变的发生中起主要作用。近年来,利用分子生物学测序技术揭示了Sneathia属细菌与HPV感染和宫颈病变密切相关,阴道菌群中Sneathia属细菌的富集可能促进了HPV感染及宫颈病变的发生,作用机制尚不清楚,但可能与破坏宫颈上皮和影响宿主免疫系统有关。Sneathia属细菌可能成为预防和治疗宫颈病变的潜在靶点。

     

沙眼衣原体感染诱导小鼠生殖道局部促炎性细胞因子的表达情况

建立小鼠生殖道沙眼衣原体感染模型,观察小鼠生殖道局部促炎性细胞因子的表达。将小鼠生物型沙眼衣原体C. muridarum 1＆#215;104 IFU阴道接种于C57B6背景雌性小鼠,取感染后阴道拭子做沙眼衣原体培养,计算IFU,监测小鼠感染和病原体清除情况;80 d后处死小鼠,检测子宫输卵管病理改变;ELISA检测感染过程中小鼠生殖道促炎性细胞因子IL-1α、IL-6、MIP-2和TNF-α产生情况。小鼠感染在第3至第15天维持较高水平,然后病原体被逐渐清除,整个病程约3~5周;病理检测显示子宫输卵有严重炎症、管腔扩张积水,狭窄等;于感染后第3天检测到局部IL-1α、IL-6、MIP-2分泌,第7天达高峰,然后逐渐下降至正常水平（ IL-6于11 d恢复正常,IL-1α和 MIP-2于15 d恢复正常）。 TNF-α仅在第7天检测到高水平表达。相对于TNF-α和IL-6,IL-1α和MIP-2维持时间较长。成功建立沙眼衣原体感染小鼠生殖道模型,沙眼衣原体急性感染可诱导小鼠生殖道局部分泌IL-1α、IL-6、MIP-2和TNF-α。     

Mitochondrial oxidative metabolism during respiratory infection in riboflavin deficient mice

Studies in children and mice have shown that respiratory infection alters riboflavin metabolism, resulting in increased urinary loss of this vitamin. This could be due to mobilization of riboflavin from the liver to blood because liver Flavin adenine dinucleotide (FAD) levels were lowered in the mice during infection. To understand the functional implications of lowered hepatic FAD levels during respiratory infection, flavoprotein functions such as oxidative phosphorylation and β-oxidation of the liver mitochondria were examined during infection in mice. Weanling mice were fed either riboflavin-restricted or control diet for 18 days and then injected with a sublethal dose of Klebsiella pneumoniae. During infection, the state 3 respiratory rate with palmitoyl-L-carnitine and glutamate were significantly lowered (27–29%) in the riboflavin-restricted group, whereas in the control group 10% reduction was observed with palmitoyl-L-carnitine as substrate. A 22% reduction in the respiratory control ratio with palmitoyl-L-carnitine as substrate was observed during infection in the riboflavin-restricted group. The β-oxidation of palmitoyl-L-carnitine was significantly lowered (29%) in the riboflavin-restricted infected group. The results of the study suggest that the effects of infection on vital physiologic functions were more pronounced in the riboflavin-restricted mice than in the control mice. © Elsevier Science Inc. 1999     

Detection of Ralstonia solanacearum in Soil and Weeds from Commercial Tomato Fields Using Immunocapture and the Polymerase Chain Reaction

A detection assay for Ralstonia solanacearum in soil and weeds was developed by combining immunocapture and the polymerase chain reaction (IC‐PCR). Anti‐R. solanacearum polyclonal antibodies were produced in a white female rabbit and Dynal^® super‐paramagnetic beads were coated with purified immunoglobulinG (IgG). Using IC‐PCR, the 718 bp target DNA was amplified at a detection threshold of approximately 10⁴ colony‐forming units (CFU) bacteria per millilitre of suspension. DNA was not amplified in soil suspensions derived from autoclaved and non‐autoclaved soils, which contained R. solanacearum at 1–10⁵ CFU/g soil. However, a positive PCR result was obtained when bacteria in the soil suspensions were first enriched in nutrient broth. IC‐PCR detected R. solanacearum in tomato stems 24 h after inoculation by stem puncture with a suspension containing approximately 10⁵ CFU/ml. IC‐PCR detected the bacterium in 28 of 55 (51%) weeds and 10 of 32 (31%) soil samples. Of the weeds, Physalis minima, Amaranthus spinosus and Euphorbia hirta had the highest incidence of infection. R. solanacearum was not detected in soil taken from fallow fields, but it was discovered in some weed species. Symptomless tomato and pepper plants collected from the fields in which tomato bacterial wilt had previously occurred were found to contain R. solanacearum. These discoveries suggest that weeds and latent hosts may play a role in the survival of R. solanacearum between cropping cycles.     

An independent validation study of loci associated with nematode resistance in sheep

Gastrointestinal nematode infection is a constraint on sheep production worldwide. Selective breeding programmes to enhance resistance to nematode infection are currently being implemented in a number of countries. Identification of loci associated with resistance to infection or causative mutations for resistance would enable more effective selection. Loci associated with indicator traits for nematode resistance has been identified in previous studies. In this study, Scottish Blackface, Texel and Suffolk lambs were used to validate the effects at eight genomic regions previously associated with nematode resistance (OAR3, 4, 5, 7, 12, 13, 14, 21). No SNP was significantly associated with nematode resistance at the region‐wide level but seven SNPs in three of the regions (OAR4, 12, 14) were nominally associated with trichostrongyle egg count in this study and six of these were also significant when fitted as single SNP effects. Nematodirus egg count was nominally associated with SNPs on OAR3, 4, 7 and 12.     

Leucocyte recruitment and molecular fortification of keratinocytes triggered by streptococcal M1 protein

Streptococcus pyogenes of the M1 serotype is commonly associated with invasive streptococcal infections and development of streptococcal toxic shock syndrome. The M1 protein is a powerful inducer of inflammatory responses for several human cell types, but the reason why M1 protein‐related strains is over‐represented in invasive streptococcal diseases is still not understood. This study was undertaken to investigate if soluble M1 protein can aggravate the severity of streptococcal skin infections in respect to inflammation, leucocyte recruitment, and tissue remodelling as seen in patients with cellulitis and necrotizing fasciitis. We found that HaCaT cells are able to recruit activated leucocytes when encountering M1 protein. Neither the bacterial protein nor activated leucocytes caused cell damage on HaCaT cells, instead HaCaT cells responded to the bacterial virulence factor by releasing several proteins protective against bacterial infection and leucocyte responses. However, although not cytotoxic, M1 protein completely abolished wound healing abilities of HaCaT cells. Taken together, our results demonstrate that M1 protein is a critical virulence factor that can augment streptococcal skin infection suggesting that the protein is an interesting target for drug development.