Limited Replication Research Articles

Restricted replication of xenotropic murine leukemia virus-related virus in pigtailed macaques.

Although xenotropic murine leukemia virus-related virus (XMRV) has been previously linked to prostate cancer and myalgic encephalomyelitis/chronic fatigue syndrome, recent data indicate that results interpreted as evidence of human XMRV infection reflect laboratory contamination rather than authentic in vivo infection. Nevertheless, XMRV is a retrovirus of undefined pathogenic potential that is able to replicate in human cells. Here we describe a comprehensive analysis of two male pigtailed macaques (Macaca nemestrina) experimentally infected with XMRV. Following intravenous inoculation with >10(10) RNA copy equivalents of XMRV, viral replication was limited and transient, peaking at ≤2,200 viral RNA (vRNA) copies/ml plasma and becoming undetectable by 4 weeks postinfection, though viral DNA (vDNA) in peripheral blood mononuclear cells remained detectable through 119 days of follow-up. Similarly, vRNA was not detectable in lymph nodes by in situ hybridization despite detectable vDNA. Sequencing of cell-associated vDNA revealed extensive G-to-A hypermutation, suggestive of APOBEC-mediated viral restriction. Consistent with limited viral replication, we found transient upregulation of type I interferon responses that returned to baseline by 2 weeks postinfection, no detectable cellular immune responses, and limited or no spread to prostate tissue. Antibody responses, including neutralizing antibodies, however, were detectable by 2 weeks postinfection and maintained throughout the study. Both animals were healthy for the duration of follow-up. These findings indicate that XMRV replication and spread were limited in pigtailed macaques, predominantly by APOBEC-mediated hypermutation. Given that human APOBEC proteins restrict XMRV infection in vitro, human XMRV infection, if it occurred, would be expected to be characterized by similarly limited viral replication and spread.

Association of the 5-HTT gene-linked promoter region (5-HTTLPR) polymorphism with psychiatric disorders: review of psychopathology and pharmacotherapy

Serotonin (5-HT) regulates important biological and psychological processes including mood, and may be associated with the development of several psychiatric disorders. An association between psychopathology and genes that regulate 5-HT neurotransmission is a robust area of research. Identification of the genes responsible for the predisposition, development, and pharmacological response of various psychiatric disorders is crucial to the advancement of our understanding of their underlying neurobiology. This review highlights research investigating 5-HT transporter (5-HTTLPR) polymorphism, because studies investigating the impact of the 5-HTTLPR polymorphism have demonstrated significant associations with many psychiatric disorders. Decreased transcriptional activity of the S allele (“risk allele”) may be associated with a heightened amygdala response leading to anxiety-related personality traits, major depressive disorder, suicide attempts, and bipolar disorder. By contrast, increased transcriptional activity of the L allele is considered protective for depression but is also associated with completed suicide, nicotine dependence, and attention deficit hyperactivity disorder. For some disorders, such as post-traumatic stress disorder and major depressive disorder, the research suggests that treatment response may vary by allele (such as an enhanced response to serotonin specific reuptake inhibitors in patients with major depressive disorder and post-traumatic stress disorder with L alleles), and for alcohol dependence, the association and treatment for S or L alleles may vary with alcoholic subtype. While some studies suggest that 5-HTTLPR polymorphism can moderate the response to pharmacotherapy, the association between 5-HTTLPR alleles and therapeutic outcomes is inconsistent. The discovery of triallelic 5-HTTLPR alleles (LA/LG/S) may help to explain some of the conflicting results of many past association studies, while concurrently providing more meaningful data in the future. Studies assessing 5-HTTLPR as the solitary genetic factor contributing to the etiology of psychiatric disorders continue to face the challenges of statistically small effect sizes and limited replication.

Determinants of Spontaneous Surface Antigen Loss in Hepatitis B E Antigen–Negative Patients With A Low Viral Load

Loss of hepatitis B surface antigen (HBsAg) usually indicates the cure of hepatitis B virus (HBV) infection. In spontaneous hepatitis B e antigen (HBeAg) seroconverters, lower serum HBsAg and HBV DNA levels have been shown to be associated with HBsAg loss over time. However, little is known about their impacts on HBsAg loss in HBeAg-negative patients with limited viral replication. A total of 688 HBeAg-negative patients with baseline serum HBV DNA levels <2000 IU/mL were enrolled in Taiwan. The relationships of HBsAg and HBV DNA levels with subsequent HBsAg loss were investigated. In a mean follow-up of 11.6 years, the average annual rate of HBsAg loss was 1.6%. Baseline HBsAg and HBV DNA levels were inversely associated with subsequent HBsAg loss. When compared to patients who had HBsAg levels >1000 IU/mL, the rates of HBsAg loss were significantly higher in patients with HBsAg levels of 100-999, 10-99, and <10 IU/mL, with hazard ratios of 2.5 (95% confidence interval [CI], 1.6-4.0), 2.8 (95% CI, 1.6-5.0), and 13.2 (95% CI, 8.1-21.5), respectively. Multivariate analysis showed that HBsAg level, but not HBV DNA, remained as an independent factor. The adjusted hazard ratio of HBsAg loss was 13.2 (95% CI, 7.8-22.1) for HBsAg level <10 versus ≥ 1000 IU/mL. When compared to HBV DNA level by receiver operating characteristic curve analysis, HBsAg level served as a better predictor of both 5-year and 10-year HBsAg loss. In HBeAg-negative patients with HBV genotype B or C infection who have HBV DNA level <2000 IU/mL, HBsAg level <10 IU/mL is the strongest predictor of HBsAg loss.

Monocyte-derived dendritic cells enhance cell proliferation and porcine circovirus type 2 replication in concanavalin A-stimulated swine peripheral blood lymphocytes in vitro

Dendritic cells (DCs) are professional antigen presenting cells cooperating with other immune cells for the activation of innate and adaptive immune responses. The objective of the present study was to investigate the replication activity of porcine circovirus type 2 (PCV2) in DCs and/or lymphocytes during their cross talk and its possible mechanism. Two models were set, herein. Swine blood monocyte (Mo)-derived DCs (MoDCs) or peripheral blood lymphocytes (PBLs) were inoculated with PCV2 prior to their co-cultivation. Bacterial lipopolysaccharide (LPS) and concanavalin A (Con A) were used to stimulate MoDCs and PBLs, respectively. During 6 days of cultivation, a high PCV2 antigen-containing rate without detectable intranuclear signals and a slight but significant increase in the copy number of PCV2 genome were detected in PCV2-inoculated MoDCs. The presence of LPS alone or PCV2-free PBLs, however, had no effect on the location of PCV2 antigens or copy number of PCV2 genome in PCV2-inoculated MoDCs. On the contrary, active PCV2 replication occurred in Con A-stimulated PCV2-inoculated PBLs. When compared with blood Mos, MoDCs induced significantly higher cell proliferation and intensified PCV2 replication in Con A-stimulated PCV2-inoculated PBLs, for which direct contact between MoDCs and lymphocytes was required. Among the cytokines secreted by Con A-activated PBLs, interleukin (IL)-2, but not IL-4 or interferon-γ, could induce cell proliferation and PCV2 replication in PCV2-inoculated PBLs. The findings suggest that although MoDCs support only limited PCV2 replication in themselves, their accessory cell function is required for cell proliferation and PCV2 replication in PCV2-infected lymphocytes.

Permissivity of fish cell lines to threeChlamydia-related bacteria:Waddlia chondrophila,Estrella lausannensisandParachlamydia acanthamoebae

Epitheliocystis is an infectious disease affecting gills and skin of various freshwater and marine fishes, associated with high mortality and reduced growth of survivors. Candidatus Piscichlamydia salmonis and Clavochlamydia salmonicola have recently been identified as aetiological agents of epitheliocystis in Atlantic Salmon. In addition, several other members of the Chlamydiales order have been identified in other fish species. To clarify the pathogenicity of Chlamydia-like organisms towards fishes, we investigated the permissivity of two fish cell lines, EPC-175 (Fathead Minnow) and RTG-2 (rainbow trout) to three Chlamydia-related bacteria: Waddlia chondrophila, Parachlamydia acanthamoebae and Estrella lausannensis. Quantitative PCR and immunofluorescence demonstrated that W. chondrophila and, to a lesser extent, E. lausannensis were able to replicate in the two cell lines tested. Waddlia chondrophila multiplied rapidly in its host cell and a strong cytopathic effect was observed. During E. lausannensis infection, we observed a limited replication of the bacteria not followed by host cell lysis. Very limited replication of P. acanthamoebae was observed in both cell lines tested. Given its high infectivity and cytopathic effect towards fish cell lines, W. chondrophila represents the most interesting Chlamydia-related bacteria to be used to develop an in vivo model of epitheliocystis disease in fishes.

Humanized mice as a useful model to study HIV-1 induced immune activation, its mechanisms and potential therapeutic approaches

Recent understanding of HIV-1 pathogenesis mechanism has changed our views about possible mechanisms of CD4T-cell depletion during infection. Apart from HIV-1-mediated killing a more comprehensive explanation has appeared that includes T cell exhaustion and chronic immune activation as a central feature in HIV-1 pathogenesis. While highly active antiretroviral therapy (HAART) markedly reduces viral load, T cell activation levels and soluble markers of inflammation remain abnormally high. Markers of chronic activation, such as CD38, PD-1 or HLA-DR on T cells, appear to be better predictors for clinical progression during HIV infection than HIV RNA levels and CD4Tcell counts alone. Therefore, a better understanding of HIV-induced immune activation and the design of new immunomodulatory approches in combination with HAART are needed. We have generated an efficient model of human stem cells (HSCs) engraftment in NOD/LtsZ-scidlL-2Rnull (NSG) mice that supports chronic HIV infection with high plasma viral loads. HIV-1 infection in these humanized mice is characterized by widespread immune activation with increased expression of PD-1, HLA-DR, CD38, CD69, CD25 and other immune activation markers. These humanized mice provide an effective in vivo system for the assessing novel approaches for their potential in suppressing chronic immune activation during HIV-1 infection, in absence of interference of antiretroviral therapy. In this study, we evaluated in vivo the benefits of two novel approaches aimed at reducing HIV-induced immune activation. Minocycline is an antibiotic of the tetracycline family with anti-inflammatory and immunomodulatory properties affecting CD4 T cells activation by a mechanism involving the inhibition of the NF-AT1 transcription factor activity. We hypothesized that this antibiotic could suppress the HIV-1-induced chronic immune activation and thus, limit the HIV pathogenesis when combined to HAART. Therefore, we treated HIV-1 (JRCSF) infected-humanized NSG mice with minocycline (100mg/kg/day) for 60 days. We next evaluated the expression, by flow cytometry, of several T cells activation markers together with CD4+T cells counts. Our data suggest that minocycline is effective in suppressing HIV-1 induced immune activation in peripheral blood and lymphoid organs (spleen, lymph nodes and bone marrow). Levels of cellular immune activation markers such as PD-1, HLA-DR, CD38, CD69, CD25, CD28 and CTLA-4 were significantly lower in minocycline treated group. These immunological benefits of minocycline were correlated with higher CD4+T cell counts in the treated group. The immune activation which is associated with retroviral infection is also associated with increased levels of intracytoplasmic cyclic AMP which could act as a positive feedback loop in the infection since several reports have suggested that cAMP and downstream signaling pathways play an important role in the permissivity of susceptible cells to HIV infection and replication. We have used a peptide which prevents the binding of the catalytic subunit of PKA type I to its anchoring protein and therefore blocks most effects of cyclic AMP within lymphocytes and monocytes (RIAD peptide). Mice were treated with 3.5 mg/kg of RIAD peptide weekly. Treatment of humanized mice with RIAD peptide limited viral replication after high dose of HIV intraperitoneal challenge and reduced the intracytoplasmic levels of cyclic AMP. Further experiments are needed to better appreciate the therapeutic potential of these novel therapies in the suppression of HIV-induced chronic immune activation.

Interaction of porcine conventional dendritic cells with swine influenza virus

Swine influenza virus (SwIV) causes sub-acute or acute respiratory infections on swine farms and pigs can act as “mixing vessels” for new influenza strains. Knowledge of the immune response of SwIV in its natural host, pigs, is very limited. Dendritic cells (DCs) mediate the induction of immunity to pathogens, but their interaction with SwIV has not been fully characterized. Thus, porcine bone marrow derived DCs (poBMDCs) were exposed to a circulating strain of H3N2 SwIV in vitro. Infection of poBMDCs resulted in structures resembling influenza virus inside poBMDCs in vesicles and also free in cytoplasm. Viral progeny was undetectable in supernatant but limited replication was detected in the first 8 h after infection. However, viral particles from infected-poBMDCs were able to induce cytopathic effect in susceptible cells only when cell-to-cell interaction was favoured. The data generated in our studies reveal the particular interaction of H3N2 SwIV with conventional DCs.

What do matrix population models reveal about the sustainability of non-timber forest product harvest?

Summary 1. Understanding how management activities impact plant population dynamics is necessary to conserve at-risk species, control invasive species and sustainably harvest non-timber forest products (NTFP). For NTFP, knowledge about how the sustainability of harvest varies by plant life-form and part harvested is limited and needed to inform management of the thousands of species providing income to millions of people world-wide. 2. Matrix population models are commonly used to generate management recommendations. We reviewed studies of 46 NTFP species that used matrix models and synthesize the current knowledge on harvest effects. For 19 species with harvested and control populations, we assessed the impacts of harvest on projected population growth rates (k) using meta-analysis and analysed trends in population responses to harvest across species, life-forms and plant part harvested using elasticity and life table response experiment (LTRE) analyses, and the combination of both, to assess vulnerability to harvest. 3. NTFP harvest significantly reduced k across species. On the scale of individual studies, however, k provided little information about harvest sustainability unless replication was sufficiently high. Most studies had low levels of replication over space or time and did not include contrasting levels of harvest. 4. Whole-plant harvest of herbs and bark harvest from trees were not sustainable largely because of decreases in survival. Palm leaf or fruit harvest and rattan stem harvest were potentially sustainable. Combined elasticity–LTRE analysis was especially valuable in assessing the sustainability of harvest when differences in k between harvested and control populations were small, for studies with limited replicates, and where harvest effects varied regionally. 5. Synthesis and applications. The use of matrix models to assess the impacts of NTFP harvest is still rare in regions where trade of wild plants is heaviest and for several commonly harvested life-forms. Given the high variance in estimates for most NTFP species,k does not provide a precise assessment of harvest impacts. We recommend that managers consider the combined elasticity–LTRE analysis in addition tok in making management decisions for NTFP. NTFP research that accounts for environmental drivers of population dynamics in addition to harvest should be prioritized.

Hyperactivation of anandamide synthesis and regulation of cell-cycle progression via cannabinoid type 1 (CB 1 ) receptors in the regenerating liver

The mammalian liver regenerates upon tissue loss, which induces quiescent hepatocytes to enter the cell cycle and undergo limited replication under the control of multiple hormones, growth factors, and cytokines. Endocannabinoids acting via cannabinoid type 1 receptors (CB(1)R) promote neural progenitor cell proliferation, and in the liver they promote lipogenesis. These findings suggest the involvement of CB(1)R in the control of liver regeneration. Here we report that mice lacking CB(1)R globally or in hepatocytes only and wild-type mice treated with a CB(1)R antagonist have a delayed proliferative response to two-thirds partial hepatectomy (PHX). In wild-type mice, PHX leads to increased hepatic expression of CB(1)R and hyperactivation of the biosynthesis of the endocannabinoid anandamide in the liver via an in vivo pathway involving conjugation of arachidonic acid and ethanolamine by fatty-acid amide hydrolase. In wild-type but not CB(1)R(-/-) mice, PHX induces robust up-regulation of key cell-cycle proteins involved in mitotic progression, including cyclin-dependent kinase 1 (Cdk1), cyclin B2, and their transcriptional regulator forkhead box protein M1 (FoxM1), as revealed by ultrahigh-throughput RNA sequencing and pathway analysis and confirmed by real-time PCR and Western blot analyses. Treatment of wild-type mice with anandamide induces similar changes mediated via activation of the PI3K/Akt pathway. We conclude that activation of hepatic CB(1)R by newly synthesized anandamide promotes liver regeneration by controlling the expression of cell-cycle regulators that drive M phase progression.

Influence of Grazing Management on Plant Diversity of Highland Sourveld Grassland, KwaZulu-Natal, South Africa

Commercial livestock production offers one of the main opportunities for mainstreaming of biodiversity conservation in the grassland biome of South Africa. Grazing management is expected to influence success. With the uses of three long-term grazing trials, effects of stocking rate and cattle-to-sheep ratio on the plant composition and diversity of Highland Sourveld grassland in KwaZulu-Natal were examined. Plant diversity was sampled with the use of modified Whittaker plots. Canonical correspondence analysis was used to test the effects of treatments on compositional variation, and general linear models were used to test individual species’ responses. In a biennial rotation, burned/grazed plots supported lower species richness of forbs and all plants than unburned/ungrazed plots, attributed to the impact of grazing during the season of occupation. A high stocking rate resulted in a long-term decrease of forb richness in one experiment, but an increase in another. An increasing proportion of sheep to cattle resulted in a long-term decrease of the richness of forbs and of total species richness. The three trials identified nongrass species that behaved as increasers or decreasers in response to an increase in stocking rate, and a set of species that behaved as decreasers in response to an increasing proportion of sheep to cattle. Constraints on using long-term trials for identifying the effects of livestock management on plant diversity include lack of baseline data, limited replication, pre-experimental impacts on the study site, and the difficulty of assessing uncommon species. La producción ganadera comercial ofrece una de las principales oportunidades para canalizar la conservación de la biodiversidad en los pastizales de Sudáfrica. Se espera que el manejo del pastoreo influya en tener éxito. Con este fin, se evaluó el uso de tres ensayos de pastoreo a largo plazo, el efecto de la carga animal y la relación de ganado-ovejas en la composición y diversidad de los pastizales en Highland Sourveld grassland KwaZulu-en Natal. La diversidad de plantas fue muestreada utilizando la técnica modificada de las parcelas de Whittaker. Análisis de correspondencia canónica fueron utilizados para probar los efectos de los tratamientos sobre la variación de la composición, y los modelos lineares generales fueron usados para probar la respuesta individual de las especies. En una rotación bienal las parcelas quemadas/pastoreadas presentaron el menor número de especies de herbáceas y de todo tipo de plantas, comparadas con las parcelas sin quema y/o pastoreo. Esto se atribuyó al impacto de la actividad de pastoreo durante la época en que se llevó a cabo. Una mayor carga animal dio como resultado una disminución a largo plazo de la riqueza de herbáceas en un experimento pero se incrementó en otro. Al incrementarse la proporción de ovejas sobre el ganado hubo una disminución a largo plazo sobre el número de herbáceas, así como una disminución en el número total. Durante los tres estudios se identificaron especies no gramíneas cuyo comportamiento fue de incremento o disminución en respuesta al aumento en la carga animal. Asimismo, se observó un grupo de plantas que disminuyeron en respuesta al incremento en la proporción de ovinos sobre bovinos. Las restricciones sobre el uso de ensayos a largo plazo para la identificación del efecto del manejo del ganado en la diversidad de las plantas incluyen la carencia de datos iniciales, limitación en las repeticiones, impacto pre-experimentales del sitio de estudio, y la dificultad de evaluar especies pocos comunes.

An Investigation of Genome-Wide Studies Reported Susceptibility Loci for Ulcerative Colitis Shows Limited Replication in North Indians

Genome-Wide Association studies (GWAS) of both Crohn's Disease (CD) and Ulcerative Colitis (UC) have unearthed over 40 risk conferring variants. Recently, a meta-analysis on UC revealed several loci, most of which were either previously associated with UC or CD susceptibility in populations of European origin. In this study, we attempted to replicate these findings in an ethnically distinct north Indian UC cohort. 648 UC cases and 850 controls were genotyped using Infinium Human 660W-quad. Out of 59 meta-analysis index SNPs, six were not in the SNP array used in the study. Of the remaining 53 SNPs, four were found monomorphic. Association (p<0.05) at 25 SNPs was observed, of which 15 were CD specific. Only five SNPs namely rs2395185 (HLA-DRA), rs3024505 (IL10), rs6426833 (RNF186), rs3763313 (BTNL2) and rs2066843 (NOD2) retained significance after Bonferroni correction. These results (i) reveal limited replication of Caucasian based meta-analysis results; (ii) reiterate overlapping molecular mechanism(s) in UC and CD; (iii) indicate differences in genetic architecture between populations; and (iv) suggest that resources such as HapMap need to be extended to cover diverse ethnic populations. They also suggest a systematic GWAS in this terrain may be insightful for identifying population specific IBD risk conferring loci and thus enable cross-ethnicity fine mapping of disease loci.

Transactivation of human parvovirus B19 gene expression in endothelial cells by adenoviral helper functions

Human parvovirus B19 (B19V) DNA is highly prevalent in endothelial cells lining up intramyocardial arterioles and postcapillary venules of patients with chronic myocarditis and cardiomyopathies. We addressed the question of a possible stimulation of B19V gene expression in endothelial cells by infection with adenoviruses. Adenovirus infection led to a strong augmentation of B19V structural and nonstructural proteins in individual endothelial cells infected with B19V or transfected with an infectious B19V genome. Transactivation was mostly mediated at the level of transcription and not due to adenovirus-mediated induction of second-strand synthesis from the single-stranded parvoviral genome. The main adenoviral functions required were E1A and E4orf6, which displayed synergistic effects. Furthermore, a limited B19V genome replication could be demonstrated in endothelial cells and adenovirus infection induced the appearance of putative dimeric replication intermediates. Thus the almost complete block in B19V gene expression seen in endothelial cells can be abrogated by infection with other viruses.

Temperature-sensitive bacterial pathogens generated by the substitution of essential genes from cold-loving bacteria: potential use as live vaccines.

Temperature-sensitive (TS) viruses have been used for decades as vaccines capable of limited replication in their hosts. Although attenuated bacteria, such as the Bacille Calmette-Guérin anti-tuberculosis vaccine, have been used for almost a century, it is only recently that there has been progress in using TS bacterial strains as live vaccines. Decades of work on essential bacterial genes and the recent explosion in the number of available bacterial genomic sequences set the groundwork for the identification of essential genes from diverse bacteria. This knowledge has allowed for the substitution of essential genes from cold-loving bacteria into the chromosomes of pathogenic bacteria. Many of these gene substitutions generated TS pathogenic bacterial strains, and some were demonstrated to provide protective immunity in mice. This work opens the possibility of engineering many pathogenic bacteria to create TS strains that can be used as vaccines.

Development of single-cycle replicable human immunodeficiency virus 1 mutants

Non-infectious but antigenic human immunodeficiency virus 1 (HIV-1) particles are essential tool for the research on many topics associated with this virus. Here we report the construction of plasmid containing the HIV-1 genome mutated in the pol gene, which was co-transfected with plasmids expressing the pol gene products reverse transcriptase (RT) and integrase (IN), and the glycoprotein G of vesicular stomatitis virus (VSV-G). The virions produced in HEK 293 T cells were antigenic, but able to replicate only for one cycle, e.g. first generation single-cycle replicable (SCR) virions. The presence of VSV-G in the envelope of these virions had to ensure a wider spectrum of susceptible cell types for the replication of SCR. Replication of the first generation SCR virions in HEK 293T, MT-2, and mouse spleen cells was examined by p24-capture ELISA, syncytium formation assay, and electron microscopy (EM). HEK 293T and MT-2 cell lines showed a similar replication capacity, while primary cultures of mouse spleen cells were much less effective. The infection of MT-2 cells with the first generation of SCR virions yielded the second generation SCR virions, which were non-infectious. Summing up, the HIV-1 SCR virions represent the useful tool for HIV-1 research facilitating a better biological safety. Moreover, considering their antigenic composition and limited replication, SCR virions may be a promising candidate for the vaccine studies.

Interface aware distributed multicast packet replication in ad hoc network using multicast monitoring mobile agent

Deploying multicast communication in mobile ad hoc network (MANET) is a challenging and an intricate issue. This paper proposes a novel idea of hiring an intelligent and smart agent called multicast monitoring mobile agent (M³A) to evaluate the genuineness of downstream multicast router interface in the secure multicast distribution tree backed by Iolus framework. The security vulnerabilities plaguing this unique wedding are emboldened by the incidence of hand-off and Sybil attack. The foot print of these two attacks on multicast routing inflates the copies of multicast packet stored in duplicate packet store (DPS) of the multicast coordinator (MC²)/group head for the discontinued and duplicated group member due to Sybil attack. This agent periodically compares the dynamic delivery threshold limit (D²TL) and packet replication rate (PR²) of the downstream router interface and issues an alarm if a mismatch occurs. The overall objective and contribution of this paper is to ensure consistent and continued sustenance of the multicast packet delivery ratio (MPDR) in the Sybil and hand-off inflicted MANET by deploying a smart agent.

A genome-wide association study to identify genetic determinants of atopy in subjects from the United Kingdom

A genetic component in the development of atopy has been identified. However, numerous heritability models have been proposed with inconsistent replication of susceptibility loci and genes. We sought to use a genome-wide association study approach to examine genetic susceptibility to atopy, which was defined as increased specific IgE levels, positive skin prick test (SPT) responses, or both, within a large discovery cohort and 3 additional white populations. Single nucleotide polymorphisms (SNPs) across the genome were tested for association with increased specific IgE levels (≥ 0.35 kU(A)/L) in the British 1958 Birth Cohort (1083 cases and 2770 control subjects; Illumina 550K Array) to 1 or more allergens, including house dust mite (Der p 1), mixed grass, or cat fur. Independent replication of identified loci (P ≤ .05) was assessed in 3 case-control cohorts from the United Kingdom (n = 3225). Combined analyses of data for top signals across cohorts were conducted for atopic phenotypes: increased specific IgE levels (1378 cases and 3151 control subjects) and positive SPT responses (1058 cases and 2167 control subjects). A single SNP on chromosome 13q14 met genome-wide significance (P = 2.15 × 10(-9)), and a further 6 loci (4.50 × 10(-7) ≤ P ≤ 5.00 × 10(-5)) showed weaker evidence for association with increased specific IgE levels in the British 1958 Birth Cohort. However, no SNPs studied showed consistent association with atopy defined by increased specific IgE levels, positive SPT responses, or both in all study cohorts. Seven putative atopy loci were identified using a genome-wide association study approach but showed limited replication across several white populations. This study suggests that large-scale analyses with results from multiple populations will be needed to reliably identify key genetic factors underlying atopy predisposition.

Type 2 Vaccine‐Derived Poliovirus from Patients with Acute Flaccid Paralysis in China: Current Immunization Strategy Effectively Prevented Its Sustained Transmission

In China, 5 patients with acute flaccid paralysis (AFP) associated with type 2 vaccine-derived poliovirus (VDPV) were identified by an AFP surveillance system from 1996 through 2009. A maximum-likelihood tree shows that all 5 Chinese VDPVs were independent. These 5 VDPVs were 100-216 d old according to the number of synonymous substitutions per synonymous site and 176-292 d old according to the number of substitutions per site. This result indicates limited virus replication since the administration of the initiating oral polio vaccine (OPV) dose, which is consistent with the rapid evolution rate of poliovirus genomes. The above-mentioned VDPVs have important implications in the global polio eradication initiative. Localized, limited, and transient circulation may be typical of OPVs; hence, independent VDPVs could be found because of the large population and excellent surveillance system, which permitted early detection and response, but sustained transmission was limited because of high population immunity.

Gravel seeding – A suitable technique for restoring the seabed following marine aggregate dredging?

Restoration of offshore marine habitats is a relatively new concept, with attempts in the European Union being largely instigated by requirements of various strategic directives. In this experiment, we investigate the practicality and effectiveness of gravel seeding, using a commercial aggregate dredging vessel, in order to recreate a gravel habitat. The experimental design consisted of a Treatment and Control site, both within an area of historic dredging characterised by an overburden of sand, and a gravel dominated Reference site. All sites were surveyed, using a combination of acoustic, camera and grab techniques, 2 months before, and then at 0, 12 and 22 months after the deposition of 4444 m 3 of gravel dominated sediments within the Treatment site. Although financial and practical constraints limited replication of the Treatment to one area, and so precluded strong statistical conclusions, our results suggested that the technique was both practically feasible, and successful in terms of returning the physical and biological attributes at the Treatment site to a state more representative of gravelly substrata in the wider, un-impacted environment.

Modifications in the Polymerase Genes of a Swine-Like Triple-Reassortant Influenza Virus To Generate Live Attenuated Vaccines against 2009 Pandemic H1N1 Viruses

On 11 June 2009, the World Health Organization (WHO) declared that the outbreaks caused by novel swine-origin influenza A (H1N1) virus had reached pandemic proportions. The pandemic H1N1 (H1N1pdm) virus is the predominant influenza virus strain in the human population. It has also crossed the species barriers and infected turkeys and swine in several countries. Thus, the development of a vaccine that is effective in multiple animal species is urgently needed. We have previously demonstrated that the introduction of temperature-sensitive mutations into the PB2 and PB1 genes of an avian H9N2 virus, combined with the insertion of a hemagglutinin (HA) tag in PB1, resulted in an attenuated (att) vaccine backbone for both chickens and mice. Because the new pandemic strain is a triple-reassortant (TR) virus, we chose to introduce the double attenuating modifications into a swine-like TR virus isolate, A/turkey/OH/313053/04 (H3N2) (ty/04), with the goal of producing live attenuated influenza vaccines (LAIV). This genetically modified backbone had impaired polymerase activity and restricted virus growth at elevated temperatures. In vivo characterization of two H1N1 vaccine candidates generated using the ty/04 att backbone demonstrated that this vaccine is highly attenuated in mice, as indicated by the absence of signs of disease, limited replication, and minimum histopathological alterations in the respiratory tract. A single immunization with the ty/04 att-based vaccines conferred complete protection against a lethal H1N1pdm virus infection in mice. More importantly, vaccination of pigs with a ty/04 att-H1N1 vaccine candidate resulted in sterilizing immunity upon an aggressive intratracheal challenge with the 2009 H1N1 pandemic virus. Our studies highlight the safety of the ty/04 att vaccine platform and its potential as a master donor strain for the generation of live attenuated vaccines for humans and livestock.

Wolbachia-Mediated Resistance to Dengue Virus Infection and Death at the Cellular Level

BackgroundDengue is currently the most important arthropod-borne viral disease of humans. Recent work has shown dengue virus displays limited replication in its primary vector, the mosquito Aedes aegypti, when the insect harbors the endosymbiotic bacterium Wolbachia pipientis. Wolbachia-mediated inhibition of virus replication may lead to novel methods of arboviral control, yet the functional and cellular mechanisms that underpin it are unknown.Methodology/Principal FindingsUsing paired Wolbachia-infected and uninfected Aedes-derived cell lines and dengue virus, we confirm the phenomenon of viral inhibition at the cellular level. Although Wolbachia imposes a fitness cost to cells via reduced proliferation, it also provides a significant degree of protection from virus-induced mortality. The extent of viral inhibition is related to the density of Wolbachia per cell, with highly infected cell lines showing almost complete protection from dengue infection and dramatically reduced virus titers compared to lines not infected with the bacteria.Conclusions/SignificanceWe have shown that cells infected with Wolbachia display inhibition of dengue virus replication, that the extent of inhibition is related to bacterial density and that Wolbachia infection, although costly, will provide a fitness benefit in some circumstances. Our results parallel findings in mosquitoes and flies, indicating that cell line models will provide useful and experimentally tractable models to study the mechanisms underlying Wolbachia-mediated protection from viruses.