Mean Recency Period for Estimation of HIV-1 Incidence with the BED-Capture EIA and Bio-Rad Avidity in Persons Diagnosed in the United States with Subtype B

HIV incidence estimates are used to monitor HIV-1 infection in the United States. Use of laboratory biomarkers that distinguish recent from longstanding infection to quantify HIV incidence rely on having accurate knowledge of the average time that individuals spend in a transient state of recent infection between seroconversion and reaching a specified biomarker cutoff value. This paper describes five estimation procedures from two general statistical approaches, a survival time approach and an approach that fits binomial models of the probability of being classified as recently infected, as a function of time since seroconversion. We compare these procedures for estimating the mean duration of recent infection (MDRI) for two biomarkers used by the U.S. National HIV Surveillance System for determination of HIV incidence, the Aware BED EIA HIV-1 incidence test (BED) and the avidity-based, modified Bio-Rad HIV-1/HIV-2 plus O ELISA (BRAI) assay. Collectively, 953 specimens from 220 HIV-1 subtype B seroconverters, taken from 5 cohorts, were tested with a biomarker assay. Estimates of MDRI using the non-parametric survival approach were 198.4 days (SD 13.0) for BED and 239.6 days (SD 13.9) for BRAI using cutoff values of 0.8 normalized optical density and 30%, respectively. The probability of remaining in the recent state as a function of time since seroconversion, based upon this revised statistical approach, can be applied in the calculation of annual incidence in the United States.     

Differential expression of interferon responsive genes in rodent models of transmissible spongiform encephalopathy disease

Background

Alzheimer's disease (AD) is characterized by a decline in cognitive function and accumulation of amyloid-β peptide (Aβ) in extracellular plaques. Mutations in amyloid precursor protein (APP) and presenilins alter APP metabolism resulting in accumulation of Aβ42, a peptide essential for the formation of amyloid deposits and proposed to initiate the cascade leading to AD. However, the role of Aβ40, the more prevalent Aβ peptide secreted by cells and a major component of cerebral Aβ deposits, is less clear. In this study, virally-mediated gene transfer was used to selectively increase hippocampal levels of human Aβ42 and Aβ40 in adult Wistar rats, allowing examination of the contribution of each to the cognitive deficits and pathology seen in AD.

Results

Adeno-associated viral (AAV) vectors encoding BRI-Aβ cDNAs were generated resulting in high-level hippocampal expression and secretion of the specific encoded Aβ peptide. As a comparison the effect of AAV-mediated overexpression of APPsw was also examined. Animals were tested for development of learning and memory deficits (open field, Morris water maze, passive avoidance, novel object recognition) three months after infusion of AAV. A range of impairments was found, with the most pronounced deficits observed in animals co-injected with both AAV-BRI-Aβ40 and AAV-BRI-Aβ42. Brain tissue was analyzed by ELISA and immunohistochemistry to quantify levels of detergent soluble and insoluble Aβ peptides. BRI-Aβ42 and the combination of BRI-Aβ40+42 overexpression resulted in elevated levels of detergent-insoluble Aβ. No significant increase in detergent-insoluble Aβ was seen in the rats expressing APPsw or BRI-Aβ40. No pathological features were noted in any rats, except the AAV-BRI-Aβ42 rats which showed focal, amorphous, Thioflavin-negative Aβ42 deposits.

Conclusion

The results show that AAV-mediated gene transfer is a valuable tool to model aspects of AD pathology in vivo, and demonstrate that whilst expression of Aβ42 alone is sufficient to initiate Aβ deposition, both Aβ40 and Aβ42 may contribute to cognitive deficits.     

Large-scale evaluation of candidate genes identifies associations between VEGF polymorphisms and bladder cancer risk

Common genetic variation could alter the risk for developing bladder cancer. We conducted a large-scale evaluation of single nucleotide polymorphisms (SNPs) in candidate genes for cancer to identify common variants that influence bladder cancer risk. An Illumina GoldenGate assay was used to genotype 1,433 SNPs within or near 386 genes in 1,086 cases and 1,033 controls in Spain. The most significant finding was in the 5′ UTR of VEGF (rs25648, p for likelihood ratio test, 2 degrees of freedom = 1 × 10⁻⁵). To further investigate the region, we analyzed 29 additional SNPs in VEGF, selected to saturate the promoter and 5′ UTR and to tag common genetic variation in this gene. Three additional SNPs in the promoter region (rs833052, rs1109324, and rs1547651) were associated with increased risk for bladder cancer: odds ratio (95% confidence interval): 2.52 (1.06–5.97), 2.74 (1.26–5.98), and 3.02 (1.36–6.63), respectively; and a polymorphism in intron 2 (rs3024994) was associated with reduced risk: 0.65 (0.46–0.91). Two of the promoter SNPs and the intron 2 SNP showed linkage disequilibrium with rs25648. Haplotype analyses revealed three blocks of linkage disequilibrium with significant associations for two blocks including the promoter and 5′ UTR (global p = 0.02 and 0.009, respectively). These findings are biologically plausible since VEGF is critical in angiogenesis, which is important for tumor growth, its elevated expression in bladder tumors correlates with tumor progression, and specific 5′ UTR haplotypes have been shown to influence promoter activity. Associations between bladder cancer risk and other genes in this report were not robust based on false discovery rate calculations. In conclusion, this large-scale evaluation of candidate cancer genes has identified common genetic variants in the regulatory regions of VEGF that could be associated with bladder cancer risk.     

The molecular mechanism of induction of unfolded protein response by Chlamydia

The unfolded protein response (UPR) contributes to chlamydial pathogenesis, as a source of lipids and ATP during replication, and for establishing the initial anti-apoptotic state of host cell that ensures successful inclusion development. The molecular mechanism(s) of UPR induction by Chlamydia is unknown. Chlamydia use type III secretion system (T3SS) effector proteins (e.g, the Translocated Actin-Recruiting Phosphoprotein (Tarp) to stimulate host cell's cytoskeletal reorganization that facilitates invasion and inclusion development. We investigated the hypothesis that T3SS effector-mediated assembly of myosin-II complex produces activated non-muscle myosin heavy chain II (NMMHC-II), which then binds the UPR master regulator (BiP) and/or transducers to induce UPR. Our results revealed the interaction of the chlamydial effector proteins (CT228 and Tarp) with components of the myosin II complex and UPR regulator and transducer during infection. These interactions caused the activation and binding of NMMHC-II to BiP and IRE1α leading to UPR induction. In addition, specific inhibitors of myosin light chain kinase, Tarp oligomerization and myosin ATPase significantly reduced UPR activation and Chlamydia replication. Thus, Chlamydia induce UPR through T3SS effector-mediated activation of NMMHC-II components of the myosin complex to facilitate infectivity. The finding provides greater insights into chlamydial pathogenesis with the potential to identify therapeutic targets and formulations.     

Regional Activation of Myosin II in Cancer Cells Drives Tumor Progression via a Secretory Cross-Talk with the Immune Microenvironment

1. Download high-res image (352KB)
2. Download full-size image

     

Mysterious `crystals': found attached to the epidermal peritoneum of marine tubificid (Annelida,Clitellata) species

Marine tubificids are abundant and diverse in the carbonate sediments of Bermuda, as well as in many other tropical and subtropical locations. Recently, during microscopic observations of living specimens, crystal-like structures were observed attached to the coelomic peritoneum and in the coelomic cavity of some Bermuda species, including phallodrilines of the genera Aktedrilus and Pectinodrilus,and a rhyacodriline of the genus Heterodrilus. Similar structures were not seen in tubificid species of Thallasodrilides and other limnodriloidines, a second species of Heterodrilus, a tubificine of the genusTubificoides, a phallodriline of the genus Bathydrilus,nor in a number of marine enchytraeid genera and species found in Bermuda. The crystal-like structures have two needle arms, each about 5–10 m long and about 0.5 m in diameter, meeting at an obtuse angle. At the junction of the arms, there is a small membrane-bound `knob', about 1 m in diameter, which may be continuous with the coelomic peritoneum. The numbers of `crystals' per individual worm are estimated at 100–400 per body segment, or well over 2 × 10³ in an adult worm. `Crystals' are found: throughout the length of the worms, in all individuals of species in which `crystals' occur, and over the range of environmental conditions where these species are found in Bermuda. Simple digestions with hypochlorite, weak and dilute acids, and staining with nuclear and cytoplasmic stains indicate that the composition of the knob is organic and the arms inorganic. The fluorescent tracer Calcein (Sigma) was not incorporated into any structures during a 24-h bath incubation of living worms, and the `crystals' do not show birefringence when viewed between crossed polarizing filters. These last two results do not support an hypothesis that these are calcium carbonate `crystals'. Geographically, the crystal-like structures are widespread, and have also been observed in a species of immature (unidentified) marine tubificid from Rottnest Island, Western Australia.     

An important role of phospholipase Cgamma1 in pre-B-cell development and allelic exclusion

Phospholipase Cgamma1 (PLCgamma1) has been reported to be expressed predominantly in T cells and to play an important role in T-cell receptor signaling. Here we show that PLCgamma1 is expressed throughout B-cell development, with high expression in B-cell progenitors, and is involved in pre-B-cell receptor (pre-BCR) signaling. Reduced expression of PLCgamma1, in the absence of PLCgamma2 (PLCgamma1+/-PLCgamma2-/-), impedes early B-cell development at the pro-B- to pre-B-cell transition and impairs immunoglobulin heavy chain allelic exclusion, hallmarks of defective pre-BCR signaling. In contrast, early B-cell development is largely normal, whereas late B-cell maturation is impaired in the absence of PLCgamma2 alone (PLCgamma2-/-) and overexpression of PLCgamma1 in PLCgamma2-/- mice fails to restore BCR-mediated B-cell proliferation and maturation. These studies reveal an essential role of PLCgamma1, distinct from that of PLCgamma2, in B-cell development.