We aimed to understand host factors that affect discriminatory performance of a transcriptomic signature of tuberculosis risk (RISK11).
HIV-negative adults aged 18–60 years were evaluated in a ...prospective study of RISK11 and surveilled for tuberculosis through 15 months. Generalised linear models and receiver-operating characteristic (ROC) regression were used to estimate effect of host factors on RISK11 score (%marginal effect) and on discriminatory performance for tuberculosis disease (area under the curve, AUC), respectively.
Among 2923 participants including 74 prevalent and 56 incident tuberculosis cases, percentage marginal effects on RISK11 score were increased among those with prevalent tuberculosis (+18·90%, 95%CI 12·66−25·13), night sweats (+14·65%, 95%CI 5·39−23·91), incident tuberculosis (+7·29%, 95%CI 1·46−13·11), flu-like symptoms (+5·13%, 95%CI 1·58−8·68), and smoking history (+2·41%, 95%CI 0·89−3·93) than those without; and reduced in males (-6·68%, 95%CI -8·31− -5·04) and with every unit increase in BMI (-0·13%, 95%CI -0·25− -0·01). Adjustment for host factors affecting controls did not change RISK11 discriminatory performance. Cough was associated with 72·55% higher RISK11 score in prevalent tuberculosis cases. Stratification by cough improved diagnostic performance from AUC = 0·74 (95%CI 0·67−0·82) overall, to 0·97 (95%CI 0·90−1·00, p < 0·001) in cough-positive participants. Combining host factors with RISK11 improved prognostic performance, compared to RISK11 alone, (AUC = 0·76, 95%CI 0·69−0·83 versus 0·56, 95%CI 0·46−0·68, p < 0·001) over a 15-month predictive horizon.
Several host factors affected RISK11 score, but only adjustment for cough affected diagnostic performance. Combining host factors with RISK11 should be considered to improve prognostic performance.
Bill and Melinda Gates Foundation, South African Medical Research Council.
We evaluated the diagnostic and prognostic performance of a transcriptomic signature of tuberculosis (TB) risk (RISK11) and QuantiFERON-TB Gold-plus (QFTPlus) as combination biomarkers of TB risk.
...Healthy South Africans who were HIV-negative aged 18–60 years with baseline RISK11 and QFTPlus results were evaluated in a prospective cohort study conducted between Sept 20, 2016 and Dec 20, 2019. Prevalence and incidence-rate ratios were used to evaluate risk of TB. Positive (LR+) and negative (LR–) likelihood ratios were used to compare individual tests versus Both-Positive (RISK11+/QFTPlus+) and Either-Positive (RISK11+ or QFTPlus+) combinations.
Among 2912 participants, prevalent TB in RISK11+/QFTPlus+ participants was 13·3-fold (95% CI 4·2–42·7) higher than RISK11–/QFTPlus–; 2·4–fold (95% CI 1·2–4·8) higher than RISK11+/QFTPlus–; and 4·5-fold (95% CI 2·5–8·0) higher than RISK11–/QFTPlus+ participants. Risk of incident TB in RISK11+/QFTPlus+ participants was 8·3-fold (95% CI 2·5–27·0) higher than RISK11–/QFTPlus–; 2·5-fold (95% CI 1·0–6·6) higher than RISK11+/QFTPlus–; and 2·1-fold (95% CI 1·2–3·4) higher than RISK11–/QFTPlus+ participants, respectively. Compared to QFTPlus, the Both-Positive test combination increased diagnostic LR+ from 1·3 (95% CI 1·2–1·5) to 4·7 (95% CI 3·2–7·0), and prognostic LR+ from 1·4 (95% CI 1·2–1·5) to 2·8 (95% CI 1·5–5·1), but did not improve upon RISK11 alone. Compared with RISK11, the Either-Positive test combination decreased diagnostic LR– from 0·7 (95% CI 0·6–0·9) to 0·3 (95% CI 0·2–0·6), and prognostic LR– from 0·9 (95% CI 0·8–1·0) to 0·3 (0·1–0·7), but did not improve upon QFTPlus alone.
Combining two tests such as RISK11 and QFTPlus, with discordant individual performance characteristics does not improve overall discriminatory performance, relative to the individual tests.
Bill and Melinda Gates Foundation, South African Medical Research Council.
Paired- and single-chain T cell receptor (TCR) sequencing are now commonly used techniques for interrogating adaptive immune responses. TCRs targeting the same epitope frequently share motifs ...consisting of critical contact residues. Here we illustrate the key features of tcrdist3, a new Python package for distance-based TCR analysis through a series of three interactive examples. In the first example, we illustrate how tcrdist3 can integrate sequence similarity networks, gene-usage plots, and background-adjusted CDR3 logos to identify TCR sequence features conferring antigen specificity among sets of peptide-MHC-multimer sorted receptors. In the second example, we show how the TCRjoin feature in tcrdist3 can be used to flexibly query receptor sequences of interest against bulk repertoires or libraries of previously annotated TCRs based on matching of similar sequences. In the third example, we show how the TCRdist metric can be leveraged to identify candidate polyclonal receptors under antigenic selection in bulk repertoires based on sequence neighbor enrichment testing, a statistical approach similar to TCRNET and ALICE algorithms, but with added flexibility in how the neighborhood can be defined.
Nucleic acid vaccines, including both RNA and DNA platforms, are key technologies that have considerable promise in combating both infectious disease and cancer. However, little is known about the ...extrinsic factors that regulate nucleic acid vaccine responses and which may determine their effectiveness. The microbiome is recognized as a significant regulator of immune development and response, whose role in regulating some traditional vaccine platforms has recently been discovered. Using germ-free and specific pathogen-free mouse models in combination with different protein, DNA, and mRNA vaccine regimens, we demonstrate that the microbiome is a significant regulator of nucleic acid vaccine immunogenicity. Although the presence of the microbiome enhances CD8+ T cell responses to mRNA lipid nanoparticle immunization, the microbiome suppresses Ig and CD4+ T cell responses to DNA-prime, DNA-protein-boost immunization, indicating contrasting roles for the microbiome in the regulation of these different nucleic acid vaccine platforms. In the case of mRNA lipid nanoparticle vaccination, germ-free mice display reduced dendritic cell/macrophage activation that may underlie the deficient vaccine response. Our study identifies the microbiome as a relevant determinant of nucleic acid vaccine response with implications for continued therapeutic development and deployment of these vaccines.
Members of the
family are the leading causes of mosquito-borne viral disease worldwide. While dengue virus is the most prevalent, the recent Zika virus outbreak in the Americas triggered a WHO public ...health emergency, and yellow fever and West Nile viruses (WNV) continue to cause regional epidemics. Given the sporadic nature of flaviviral epidemics both temporally and geographically, there is an urgent need for vaccines that can rapidly provide effective immunity. Protection from flaviviral infection is correlated with antibodies to the viral envelope (E) protein, which encodes receptor binding and fusion functions. TLR agonist adjuvants represent a promising tool to enhance the protective capacity of flavivirus vaccines through dose and dosage reduction and broadening of antiviral antibody responses. This study investigates the ability to improve the immunogenicity and protective capacity of a promising clinical-stage WNV recombinant E-protein vaccine (WN-80E) using a novel combination adjuvant, which contains a potent TLR-4 agonist and the saponin QS21 in a liposomal formulation (SLA-LSQ). Here, we show that, in combination with WN-80E, optimized SLA-LSQ is capable of inducing long-lasting immune responses in preclinical models that provide sterilizing protection from WNV challenge, reducing viral titers following WNV challenge to undetectable levels in Syrian hamsters. We have investigated potential mechanisms of action by examining the antibody repertoire generated post-immunization. SLA-LSQ induced a more diverse antibody response to WNV recombinant E-protein antigen than less protective adjuvants. Collectively, these studies identify an adjuvant formulation that enhances the protective capacity of recombinant flavivirus vaccines.
HIV frequently escapes CD8 T cell responses, leading to the accumulation of viral adaptations. We recently demonstrated that during chronic HIV infection, adapted epitopes can promote maturation of ...dendritic cells (DCs) through direct CD8 T cell interactions and lead to enhanced HIV
-infection of CD4 T cells. Here, we sought to determine the role of such adaptations following HIV MRKAd5 vaccination. We observed that vaccine-induced adapted epitope-specific CD8 T cells promoted higher levels of DC maturation than nonadapted ones and that these matured DCs significantly enhanced HIV
-infection. These matured DCs were associated with higher levels of interleukin 5 (IL-5) and IL-13 and a lower level of CXCL5, which have been shown to impact DC maturation, as well as a lower level of CXCL16. Finally, we observed that vaccine recipients with high HLA-I-associated adaptation became HIV infected more quickly. Our results offer another possible mechanism for enhanced infection among MRKAd5 vaccinees.
Despite the well-established contribution of CD8 T cells in HIV control, prior CD8 T cell-based HIV vaccines have failed to demonstrate any efficacy in preventing viral infection. One such vaccine, known as the MRKAd5 vaccine, showed a potential increased risk of viral infection among vaccine recipients. However, the underlying mechanism(s) remains unclear. In this study, we observed that vaccine recipients with high adaptation to their HLA-I alleles were associated with an increased HIV infection risk in comparison to the others. Similar to what we observed in HIV infection in the prior study, adapted epitope-specific CD8 T cells obtained from vaccine recipients exhibit a greater capacity in facilitating viral infection by promoting dendritic cell maturation. Our findings provide a possible explanation for the enhanced viral acquisition risk among MRKAd5 vaccine recipients and highlight the importance of optimizing vaccine design with consideration of HLA-I-associated HIV adaptation.
The engineered outer domain germline targeting version 8 (eOD-GT8) 60-mer nanoparticle was designed to prime VRC01-class HIV-specific B cells that would need to be matured, through additional ...heterologous immunizations, into B cells that are able to produce broadly neutralizing antibodies. CD4 T cell help will be critical for the development of such high-affinity neutralizing antibody responses. Thus, we assessed the induction and epitope specificities of the vaccine-specific T cells from the IAVI G001 phase 1 clinical trial that tested immunization with eOD-GT8 60-mer adjuvanted with AS01
. Robust polyfunctional CD4 T cells specific for eOD-GT8 and the lumazine synthase (LumSyn) component of eOD-GT8 60-mer were induced after two vaccinations with either the 20- or 100-microgram dose. Antigen-specific CD4 T helper responses to eOD-GT8 and LumSyn were observed in 84 and 93% of vaccine recipients, respectively. CD4 helper T cell epitope "hotspots" preferentially targeted across participants were identified within both the eOD-GT8 and LumSyn proteins. CD4 T cell responses specific to one of these three LumSyn epitope hotspots were observed in 85% of vaccine recipients. Last, we found that induction of vaccine-specific peripheral CD4 T cells correlated with expansion of eOD-GT8-specific memory B cells. Our findings demonstrate strong human CD4 T cell responses to an HIV vaccine candidate priming immunogen and identify immunodominant CD4 T cell epitopes that might improve human immune responses either to heterologous boost immunogens after this prime vaccination or to other human vaccine immunogens.
The genetic diversity of circulating HIV-1 strains poses a major barrier to the design, development and evaluation of HIV-1 vaccines. The assessment of both vaccine- and natural infection-elicited T ...cell responses is commonly done with multivalent peptides that are designed to maximally capture the diversity of potential T cell epitopes (PTEs) observed in natural circulating sequences. However, depending on the sequence diversity of viral subtypes and number of the HIV immunogens under investigation, PTE estimates, including HLA-guided computational methods, can easily generate enormous peptide libraries. Evaluation of T cell epitope specificity using such extensive peptide libraries is usually limited by sample availability, even for high-throughput and robust epitope mapping techniques like ELISpot assays. Here we describe a novel, two-step protocol for in-vitro polyclonal expansion of CD8 T cells from a single vial of frozen PBMC, which facilitated the screening 441 HIV-1 Gag peptides for immune responses among 32 HIV-1 positive subjects and 40 HIV-1 negative subjects for peptide qualification. Using a pooled-peptide mapping strategy, epitopes were mapped in two sequential ELISpot assays; the first ELISpot screened 33 large peptide pools using CD8 T cells expanded for 7 days, while the second step tested pool-matrix peptides to identify individual peptides using CD8 T cells expanded for 10 days. This comprehensive epitope screening established the breadth and magnitude of HIV-1 Gag-specific CD8 T cells and further revealed the extent of immune responses to variable/polymorphic epitopes.
•A novel, two-step protocol for in-vitro polyclonal expansion of CD8 T cells from a single vial of frozen PBMC.•In-vitro polyclonal expansion of CD8 T-cells facilitated the screening of hundreds of HIV-1 epitopes per individual.•The efficiency of ELISpot assays was improved through peptide pool matrices that allowed single peptide deconvolution.
Performance of blood transcriptomic tuberculosis (TB) signatures in longitudinal studies and effects of TB-preventive therapy and coinfection with HIV or respiratory organisms on transcriptomic ...signatures has not been systematically studied.
We evaluated longitudinal kinetics of an 11-gene blood transcriptomic TB signature, RISK11, and effects of TB-preventive therapy (TPT) and respiratory organisms on RISK11 signature score, in HIV-uninfected and HIV-infected individuals.
RISK11 was measured in a longitudinal study of RISK11-guided TPT in HIV-uninfected adults, a cross-sectional respiratory organisms cohort, or a longitudinal study in people living with HIV (PLHIV). HIV-uninfected RISK11
participants were randomized to TPT or no TPT; RISK11
participants received no TPT. PLHIV received standard-of-care antiretroviral therapy and TPT. In the cross-sectional respiratory organisms cohort, viruses and bacteria in nasopharyngeal and oropharyngeal swabs were quantified by real-time quantitative PCR.
RISK11
status was transient in most of the 128 HIV-negative participants with longitudinal samples; more than 70% of RISK11
participants reverted to RISK11
by 3 months, irrespective of TPT. By comparison, reversion from a RISK11
state was less common in 645 PLHIV (42.1%). Non-HIV viral and nontuberculous bacterial organisms were detected in 7.2% and 38.9% of the 1,000 respiratory organisms cohort participants, respectively, and among those investigated for TB, 3.8% had prevalent disease. Median RISK11 scores (%) were higher in participants with viral organisms alone (46.7%), viral and bacterial organisms (42.8%), or prevalent TB (85.7%) than those with bacterial organisms other than TB (13.4%) or no organisms (14.2%). RISK11 could not discriminate between prevalent TB and viral organisms.
Positive RISK11 signature status is often transient, possibly due to intercurrent viral infection, highlighting potentially important challenges for implementation of these biomarkers as new tools for TB control.
Abstract
HLA-I–associated human immunodeficiency virus (HIV) adaptation is known to negatively affect disease progression and CD8 T-cell responses. We aimed to assess how HLA-I–associated adaptation ...affects HIV vaccine–induced CD8 T-cell responses in 2 past vaccine efficacy trials. We found that vaccine-encoded adapted epitopes were less immunogenic than vaccine-encoded nonadapted epitopes, and adapted epitope-specific responses were less polyfunctional than nonadapted epitope-specific responses. Along those lines, vaccine recipients with higher HLA-I adaptation to the Gag vaccine insert mounted less polyfunctional CD8 T-cell responses at the protein level. Breadth of response, which correlated with viral control in recipients who became infected, is also dampened by HLA-I adaptation. These findings suggest that HLA-I–associated adaptation is an important consideration for strategies aiming to induce robust CD8 T-cell responses.
PDF
