PrEP use and unmet PrEP-need among men who have sex with men in London prior to the implementation of a national PrEP programme, a cross-sectional study from June to August 2019

BACKGROUND: Access to prevention options, including HIV pre-exposure prophylaxis (PrEP), remains a public health priority for gay, bisexual, and other men who have sex with men (MSM), especially in London. We describe PrEP use in a London community sample of MSM before the introduction of a national PrEP programme in October 2020. METHODS: From June-August 2019, MSM aged ≥ 18 recruited from London commercial venues were asked to self-complete a sexual health questionnaire and provide an oral fluid sample for anonymous HIV antibody testing. Descriptive analyses of demographic characteristics, service engagement and outcomes, as well as sexual risk and prevention behaviours were examined in the survey population and in those reporting current PrEP use. We performed sequential, multivariate analyses examining current PrEP use in MSM of self-perceived HIV-negative/unknown status with identified PrEP-need defined as the report of condomless anal sex (CAS) in the last three months, or the report of CAS (in the last year) with an HIV-positive/unknown status partner not known to be on HIV treatment, in reflection of UK PrEP guidelines. RESULTS: One thousand five hundred and thirty-fifth questionnaires were completed across 34 venues, where 1408 were analysed. One in five MSM of self-perceived HIV-negative/unknown status reported current PrEP use (19.7%, 242/1230). In men with PrEP-need, 68.2% (431/632) did not report current use. Current PrEP use was associated with age (aOR: 3.52, 95% CI: 1.76-7.02 in men aged 40-44 vs men aged 18-25) and education (aOR: 1.72, 95% CI: 1.01-2.92 in men with ≥ 2 years/still full-time vs no/ < 2 years of education since age 16). CONCLUSION: Among MSM in London, PrEP use is high but there is indication of unmet PrEP-need in men of younger age and lower levels of post-16 education. National programme monitoring and evaluation will require continued community monitoring to guide interventions ensuring equitable PrEP access and uptake in those who could most benefit from PrEP

Characterization of rare spontaneous Human Immunodeficiency Virus viral controllers attending a national United Kingdom clinical service using a combination of serology and molecular diagnostic assays

Background We report outcomes and novel characterization of a unique cohort of 42 individuals with persistently indeterminate human immunodeficiency virus (HIV) status, the majority of whom are HIV viral controllers. Methods Eligible individuals had indeterminate or positive HIV serology, but persistently undetectable HIV ribonucleic acid (RNA) by commercial assays and were not taking antiretroviral therapy (ART). Routine investigations included HIV Western blot, HIV viral load, qualitative HIV-1 deoxyribonucleic acid (DNA), coinfection screen, and T-cell quantification. Research assays included T-cell activation, ART measurement, single-copy assays detecting HIV-1 RNA and DNA, and plasma cytokine quantification. Human immunodeficiency virus seropositivity was defined as ≥3 bands on Western blot; molecular positivity was defined as detection of HIV RNA or DNA. Results Human immunodeficiency virus infection was excluded in 10 of 42 referrals, remained unconfirmed in 2 of 42, and was confirmed in 30 of 42, who were identified as HIV elite controllers (ECs), normal CD4 T-cell counts (median 820/mL, range 805–1336), and normal CD4/CD8 ratio (median 1.8, range 1.2–1.9). Elite controllers had a median duration of elite control of 6 years (interquartile range = 4–14). Antiretroviral therapy was undetected in all 23 subjects tested. Two distinct categories of ECs were identified: molecular positive (n = 20) and molecular negative (n = 10). Conclusions Human immunodeficiency virus status was resolved for 95% of referrals with the majority diagnosed as EC. The clinical significance of the 2 molecular categories among ECs requires further investigation

Nonlinear Creep Model of Paper and Corrugated Board Materials

Models of the nonlinear creep behavior of paper, and of the global buckling , local buckling and creep buckling of corrugated board have been developed. The studies of creep and buckling were limited to climate conditions with constant relative humidity. First the short-term elastic buckling of corrugated board panels was studied. Then an appropriate creep equation, based on the Schapery representation, for liner and fluting materials was developed and implemented in a finite element code to study creep buckling and time to failure of a corrugated board panel axially loaded in compression. Experimental tensile creep-recovery tests of 300 g/m2 kraftliner (used for the facing of corrugated boards) and 150 g/m2 semi-chemical testliner (used for the fluting) at 50, 70 and 90%RH were made by a special designed tensile creep tester. Compression creep-recovery tests at 50%RH was made using a compression creep tester developed at STFI. For the short-term loading case, the experimental global buckling and postbuckling deformation performance of a corrugated board panel was found to be in good agreement with the performance predicted by FE-calculation. The calculated local buckling load was however almost 2.5 times higher than the experimentally observed local buckling load in the panel. This discrepancy between the experimental and calculated local buckling load was most probably due to development of global buckling before local buckling of the panel. For the long-term loading case, the Schapery equation was found to give a good representation of the creep behavior of the facing and fluting material and enabled reasonably accurate predictions of the creep behavior of corrugated board. The Schapery representation for paper was implemented in the finite element codes Ansys and Abaqus. In Ansys, the Schapery representation was described by using stress-strain isochrounes and failure of the material was considered by using a Tsai-Wu failure criterion based on a time independent failure strain in the CD and MD at each layer. This model with isochrounes and a material failure criterion was found to be suitable for calculating failure load for a given time to failure. In the calculations made by the finite element code Abaqus no simplification was made of the Schapery representation and no material failure criterion was used. This model is more accurate than the model with isochrounes stress-strain curves in the sense that the influence of stress redistribution on the creep is considered. The model is therefore suitable to study the creep strains of a corrugated board structure as function of time, both the in-plane strains and pre-failure out-of-plane displacements. The creep buckling analysis was verified by tests. It was found that the experimental out-of-plane displacement of the mid-node of a panel under compression load was in good agreement with the calculated out-of-plane displacement

Neutralizing Efficacy of Encapsulin Nanoparticles against SARS-CoV2 Variants of Concern

Rapid emergence of the SARS-CoV-2 variants has dampened the protective efficacy of existing authorized vaccines. Nanoparticle platforms offer a means to improve vaccine immunogenicity by presenting multiple copies of desired antigens in a repetitive manner which closely mimics natural infection. We have applied nanoparticle display combined with the SpyTag–SpyCatcher system to design encapsulin–mRBD, a nanoparticle vaccine displaying 180 copies of the monomeric SARS-CoV-2 spike receptor-binding domain (RBD). Here we show that encapsulin–mRBD is strongly antigenic and thermotolerant for long durations. After two immunizations, squalene-in-water emulsion (SWE)-adjuvanted encapsulin–mRBD in mice induces potent and comparable neutralizing antibody titers of 105 against wild-type (B.1), alpha, beta, and delta variants of concern. Sera also neutralizes the recent Omicron with appreciable neutralization titers, and significant neutralization is observed even after a single immunization

Synergistic decrease of DNA single-strand break repair rates in mouse neural cells lacking both Tdp1 and aprataxin

Ataxia oculomotor apraxia-1 (AOA1) is an autosomal recessive neurodegenerative disease that results from mutations of aprataxin (APTX). APTX associates with the DNA single- and double-strand break repair machinery and is able to remove AMP from 5'-termini at DNA strand breaks in vitro. However, attempts to establish a DNA strand break repair defect in APTX-defective cells have proved conflicting and unclear. We reasoned that this may reflect that DNA strand breaks with 5'-AMP represent only a minor subset of breaks induced in cells, and/or the availability of alternative mechanisms for removing AMP from 5'-termini. Here, we have attempted to increase the dependency of chromosomal single- and double-strand break repair on aprataxin activity by slowing the rate of repair of 3'-termini in aprataxin-defective neural cells, thereby increasing the likelihood that the T-termini at such breaks become adenylated and/or block alternative repair mechanisms. To do this, we generated a mouse model in which APTX is deleted together with tyrosyl DNA phosphodiesterase (TDP1), an enzyme that repairs T-termini at a subset of single-strand breaks (SSBs), including those with 3'-topoisomerase-1 (Top1) peptide. Notably, the global rate of repair of oxidative and alkylation-induced SSBs was significantly slower in Tdp1(-/-)/Aptx(-/-) double knockout quiescent mouse astrocytes compared with Tdp1(-/-) or Aptx(-/-) single knockouts. In contrast, camptothecin-induced Top1-SSBs accumulated to similar levels in Tdp1(-/-) and Tdp1(-/-)/Aptx(-/-) double knockout astrocytes. Finally, we failed to identify a measurable defect in double-strand break repair in Tdp1(-/-),Aptx(-/-) or Tdp1(-/-)/Aptx(-/-) astrocytes. These data provide direct evidence for a requirement for aprataxin during chromosomal single-strand break repair in primary neural cells lacking Tdp1. (C) 2009 Elsevier B.V. All rights reserved