Depletion of B cells rejuvenates the peripheral B-cell compartment but is insufficient to restore immune competence in aging.

Aging is associated with increasing prevalence and severity of infections caused by a decline in bone marrow (BM) lymphopoiesis and reduced B-cell repertoire diversity. The current study proposes a strategy to enhance immune responsiveness in aged mice and humans, through rejuvenation of the B lineage upon B-cell depletion. We used hCD20Tg mice to deplete peripheral B cells in old and young mice, analyzing B-cell subsets, repertoire and cellular functions in vitro, and immune responsiveness in vivo. Additionally, elderly patients, previously treated with rituximab healthy elderly and young individuals, were vaccinated against hepatitis B (HBV) after undergoing a detailed analysis for B-cell compartments. B-cell depletion in old mice resulted in rejuvenated B-cell population that was derived from de novo synthesis in the bone marrow. The rejuvenated B cells exhibited a "young"-like repertoire and cellular responsiveness to immune stimuli in vitro. Yet, mice treated with B-cell depletion did not mount enhanced antibody responses to immunization in vivo, nor did they survive longer than control mice in "dirty" environment. Consistent with these results, peripheral B cells from elderly depleted patients showed a "young"-like repertoire, population dynamics, and cellular responsiveness to stimulus. Nevertheless, the response rate to HBV vaccination was similar between elderly depleted and nondepleted subjects, although antibody titers were higher in depleted patients. This study proposes a proof of principle to rejuvenate the peripheral B-cell compartment in aging, through B-cell depletion. Further studies are warranted in order to apply this approach for enhancing humoral immune responsiveness among the elderly population.

Characterization of hepatitis B and delta coinfection in Israel.

BACKGROUND: Characteristics of hepatitis B (HBV) and delta (HDV) coinfection in various geographical regions, including Israel, remain unclear. Here we studied HDV seroprevalence in Israel, assessed HDV/HBV viral loads, circulating genotypes and hepatitis delta antigen (HDAg) conservation. METHODS: Serological anti HDV IgG results from 8969 HBsAg positive individuals tested in 2010-2015 were retrospectively analyzed to determine HDV seroprevalence. In a cohort of HBV/HDV coinfected (n=58) and HBV monoinfected (n=27) patients, quantitative real-time PCR (qRT-PCR) and sequencing were performed to determine viral loads, genotypes and hepatitis delta antigen (HDAg) protein sequence. RESULTS: 6.5% (587/8969) of the HBsAg positive patients were positive for anti HDV antibodies. HDV viral load was >2 log copies/ml higher than HBV viral load in most of the coinfected patients with detectable HDV RNA (86%, 50/58). HDV genotype 1 was identified in all patients, most of whom did not express HBV. While 66.6% (4/6) of the HBV/HDV co-expressing patients carried HBV-D2 only 18.5% (5/27) of the HBV monoinfections had HBV-D2 (p=0.03). Higher genetic variability in the HDAg protein sequence was associated with higher HDV viral load. CONCLUSIONS: The overall significant prevalence of HDV (6.5%) mandates HDV RNA testing for all coinfected patients. Patients positive for HDV RNA (characterized by low HBV DNA blood levels) carried HDV genotype 1. Taken together, the significant HDV seroprevalence and the lack of effective anti-HDV therapy, necessitates strict clinical surveillance especially in patients with higher HDV viral loads and increased viral evolution.

Diagnosis of HIV-1 infection: Performance of Xpert Qual and Geenius supplemental assays in fourth generation ELISA-reactive samples.

BACKGROUND: Architect (AR) and Vidas (VD) fourth generation HIV screening immunoassays, which identify early stages of HIV infections, could have false positive results especially at low signal/cutoff (S/C) AR values. Geenius HIV1/2 (GS) is a specific confirmation line immunoassay that is not highly sensitive to early HIV infections. An HIV-1 RNA assay may better detect such infections. OBJECTIVES: To evaluate all AR-VD reactive samples with GS results, and to assess Xpert Qual HIV-1 RNA assay (XQ) as an alternative to GS, in the first low S/C AR-VD-reactive samples from a tested individual. STUDY DESIGN: First AR-VD-reactive-GS-tested results from all individuals with resolved HIV status, collected between March 2015 and March 2017 (n = 749), were retrospectively assessed. Samples with AR-VD-reactive-GS-discordant results and those with low S/C AR-VD-reactive results, were tested by XQ. Receiver operating characteristic (ROC) analysis of GS and XQ sensitivity/specificity was performed. RESULTS: Overall, 94.1% (705/749) of AR-VD-reactive results were true HIV-1 positive. All samples with <3 S/C AR values were false positive. XQ resolved all first samples with AR-VD-reactive-GS-discordant results. The diagnostic accuracy of XQ in low (≤33 S/C) AR-VD-reactive samples was better than that of GS (97.6%, 81/83 versus 73.5%, 61/83, p < 0.01). ROC analysis for low S/C AR samples was optimal for pooled XQ and GS results. CONCLUSIONS: Incorporating XQ in the current screening algorithm for the first AR-VD-reactive-GS-discordant samples may significantly reduce overall turn-around time of HIV-1 diagnosis.

Ongoing hepatitis A among men who have sex with men (MSM) linked to outbreaks in Europe in Tel Aviv area, Israel, December 2016 - June 2017.

Between December 2016 and June 2017, 19 Hepatitis A virus (HAV)-positive cases, 17 of which were among men who have sex with men (MSM) were identified in the Tel Aviv area. Seven of the 15 sewage samples collected between January and June 2017 were also HAV-positive. All sequences clustered with two of the three strains identified in the current European HAV outbreak. We demonstrate that despite an efficient vaccination programme, HAV can still be transmitted to an unvaccinated high-risk population.

HCV genotype-1 subtypes and resistance-associated substitutions in drug-naive and in direct-acting antiviral treatment failure patients.

BACKGROUND: Direct-acting antiviral (DAA) treatment regimens and response rates of patients with HCV genotype-1 (GT1) are currently considered subtype-dependent. Identification of clinically relevant resistance-associated substitutions (RASs) in the NS3 and NS5A proteins at baseline and in DAA failures, may also impact clinical decisions. METHODS: In a multicentre cohort study (n=308), NS3 or NS5B sequencing (n=248) was used to discriminate between GT1 subtypes. The correlation between baseline NS3 and NS5A RASs on the 12-week sustained virological response (SVR12) rates of 160 of the patients treated with second-generation DAAs was also assessed. Post-treatment resistance analysis was performed on samples from 58 patients exhibiting DAA virological failure. RESULTS: GT1a, GT1b and GT1d subtypes were identified in 23.0%, 75.4% and 1.2% of tested samples. GT1b was most prevalent (97.7%, 128/131) among patients born in the former Soviet Union. The Q80K NS3 RAS was identified in 17.5% (10/57) of the GT1a carriers, most of whom were Israeli-born. NS3 and NS5A baseline RASs showed a negligible correlation with SVR12 rates. Treatment-emergent RASs were observed among 8.9% (4/45) and 76.9% (10/13) of first- and second-generation DAA failures, respectively, with D168V/E (NS3), Y93H and L31M (NS5A) being the most prevalent mutations. CONCLUSIONS: NS3 sequencing analysis can successfully discriminate between GT1 subtypes and identify NS3 amino acid substitutions. While pre-treatment NS3 and NS5A RASs marginally affect second-generation DAA SVR12 rates, post-treatment resistance analysis should be considered prior to re-therapy.

Evaluation of Xpert HIV-1 Qual assay for resolution of HIV-1 infection in samples with negative or indeterminate Geenius HIV-1/2 results.

BACKGROUND: Diagnosis of HIV infection is a multistage algorithm. Following screening with 4(th) generation combination immunoassay, confirmation of HIV infection is performed with an antibody assay that differentiates HIV-1 from HIV-2 infection. In the newly updated algorithm, samples that are nonreactive or indeterminate in the differentiation assay are to be tested with an HIV-1 nucleic acid amplification (NAAT) test for resolution. Xpert HIV-1 Qual is a new NAAT assay approved for the identification of HIV infection in whole and dried blood. OBJECTIVES: To assess the performance of Xpert HIV-1 Qual supplementary assay in resolving the clinical status of serum samples reactive by 4(th) generation immunoassays and indeterminate or negative by Geenius HIV-1/2 confirmatory assay. STUDY DESIGN: In a retrospective study, samples from 97 individuals for whom the true HIV-1 status was already known (by follow-up samples) and which were negative or indeterminate by HIV-1/2 Geenius assay were tested with Xpert Qual HIV-1 assay. RESULTS: Xpert Qual assay correctly classified all 97 samples from HIV-1 positive (n=49) and negative (n=48) individuals. The sensitivity and specificity of Xpert Qual when using the true HIV status as a reference were 100% (92.7-100% at 95% confidence interval [CI] and 92.6-100% at 95% CI, respectively). CONCLUSIONS: Applying Xpert Qual HIV-1 assay in the new HIV multi-stage diagnostic algorithm correctly classified 100% of HIV-1 infections including 49 from HIV-1 carriers who have not yet seroconverted. With this assay the total time required for acute HIV diagnosis could be significantly reduced.

Aging affects B-cell antigen receptor repertoire diversity in primary and secondary lymphoid tissues.

The elderly immune system is characterized by reduced responses to infections and vaccines, and an increase in the incidence of autoimmune diseases and cancer. Age-related deficits in the immune system may be caused by peripheral homeostatic pressures that limit bone marrow B-cell production or migration to the peripheral lymphoid tissues. Studies of peripheral blood B-cell receptor spectratypes have shown that those of the elderly are characterized by reduced diversity, which is correlated with poor health status. In the present study, we performed for the first time high-throughput sequencing of immunoglobulin genes from archived biopsy samples of primary and secondary lymphoid tissues in old (74 ± 7 years old, range 61-89) versus young (24 ± 5 years old, range 18-45) individuals, analyzed repertoire diversities and compared these to results in peripheral blood. We found reduced repertoire diversity in peripheral blood and lymph node repertoires from old people, while in the old spleen samples the diversity was larger than in the young. There were no differences in somatic hypermutation characteristics between age groups. These results support the hypothesis that age-related immune frailty stems from altered B-cell homeostasis leading to narrower memory B-cell repertoires, rather than changes in somatic hypermutation mechanisms.

[B lymphocyte clonal evolution of human reactive lymph nodes revealed by lineage tree analysis].

INTRODUCTION: Hypermutation and selection processes, characterizing T-dependent B cell responses taking place in germinal centers of lymph nodes, lead to B cell receptor affinity maturation. Those immune responses lead to the development of memory B cells and plasma cells that secrete high amounts of antibody molecules. The dynamics of B cell clonal evolution during affinity maturation has significant importance in infectious and autoimmune diseases, malignancies and aging. Immunoglobulin (Ig) gene mutational Lineage tree construction by comparing variable regions of Ig-gene sequences to the Ig germline gene is an interesting approach for studying B cell cLonal evolution. Lineage tree shapes and Ig gene mutations can be evaluated not only qualitatively and intuitively, but also quantitatively, and thus reveal important information related to hypermutation and selection. AIM: In this paper we describe the experimental protocols that we used for PCR amplification of Igvariable region genes from human formalin fixed paraffin embedded reactive lymph node tissues and the subsequent bioinformatical analyses of sequencing data using Ig mutational lineage trees. RESULTS: B cell populations of three out of four reactive Lymph node tissues were composed of several clones. Most of the Ig gene mutational lineage trees were small and narrow. Significant differences were not detected by quantification of Lineage trees. SUMMARY: B lymphocyte clones that were detected in human reactive lymph node tissues represent major responding clones in normal polyclonal immune response. This result is in line with the polyclonal profile of B Lymphocyte populations that reside in reactive lymph node tissues.