Early expression of mature αß TCR in CD4-CD8- T cell progenitors enables MHC to drive development of T-ALL bearing NOTCH mutations.

During normal T cell development in mouse and human, a low-frequency population of immature CD4-CD8- double-negative (DN) thymocytes expresses early, mature αß T cell antigen receptor (TCR). We report that these early αß TCR+ DN (EADN) cells are DN3b-DN4 stage and require CD3δ but not major histocompatibility complex (MHC) for their generation/detection. When MHC - is present, however, EADN cells can respond to it, displaying a degree of coreceptor-independent MHC reactivity not typical of mature, conventional αß T cells. We found these data to be connected with observations that EADN cells were susceptible to T cell acute lymphoblastic leukemia (T-ALL) transformation in both humans and mice. Using the OT-1 TCR transgenic system to model EADN-stage αß TCR expression, we found that EADN leukemogenesis required MHC to induce development of T-ALL bearing NOTCH1 mutations. This leukemia-driving MHC requirement could be lost, however, upon passaging the tumors in vivo, even when matching MHC was continuously present in recipient animals and on the tumor cells themselves. These data demonstrate that MHC:TCR signaling can be required to initiate a cancer phenotype from an understudied developmental state that appears to be represented in the mouse and human disease spectrum.

An introduction to the Marburg virus vaccine consortium, MARVAC.

The emergence of Marburg virus (MARV) in Guinea and Ghana triggered the assembly of the MARV vaccine "MARVAC" consortium representing leaders in the field of vaccine research and development aiming to facilitate a rapid response to this infectious disease threat. Here, we discuss current progress, challenges, and future directions for MARV vaccines.

Raine's syndrome: rare disease from neurosurgical perspective.

Raine's syndrome (RS) is a rare genetic disorder. Only 25 cases are in literature. Occurs due to genetic mutation resulting in deranged bone metabolism. Few cases are reported discussing the neurosurgical ramifications of the disease. We report a child diagnosed with RS. He was presented with multisutural synostosis requiring craniofacial intervention with two vault expansions. Additionally, required VP shunt due to hydrocephalus. We consider our case unique among reports of RS, as our patient has survived for 10. He died due to valve obstruction of the VP shunt. We also present a review of relevant medical literature.

Early Open Extensive Suturectomy for the Severe Multisuture Synostosis.

Neonates born with severe multisuture synostosis can present as an emergency. The severe craniocerebral disproportion with or without underlying hydrocephalus and retruded midface can result in raised intracranial pressure and airway compromise within the first few days or weeks of life. This presents a challenging multidisciplinary condition. There is no international consensus on management. There are limited publications available describing the approach to treatment. In our unit, children who present in the neonatal period with severe multisuture synostosis are offered early open extensive suturectomy within the first few months of life. The goals are; reduction in raised intracranial pressure, improvement in head shape and bone formation, and avoidance of a ventriculoperitoneal shunt. This is performed as an adjunct, not a replacement of other traditional skull vault procedures. We describe the technique and postoperative care without the need for a helmet that leads to excellent skull-shape outcomes and avoidance of a ventriculoperitoneal shunt.

The Craniofacial Collaboration UK: Developmental Outcomes in 7- and 10-Year-Old Children With Metopic Synostosis.

The Craniofacial Collaboration (CC-UK) is a shared initiative across the Psychology teams attached to 4 highly specialized craniofacial centers in the United Kingdom. The CC-UK aims to address key limitations in the existing craniofacial literature by analyzing data for homogenous samples of children with craniosynostosis. This article presents the fifth wave of CC-UK data collection, focused on 7- and 10-year olds who have undergone primary corrective surgery for metopic synostosis (MS). Data for children with sagittal synostosis and MS have previously been presented at 3 and 5 years. This paper continues to build on this with consideration to older age groups, presenting the first CC-UK analysis of cognitive assessment data using the Wechsler Abbreviated Scale of Intelligence-Second Edition. Results show that the majority of children with MS fall within the average ranges across behavioral and neurodevelopmental domains. However, several domains indicated a trend of heightened concern when compared with normative data, particularly for parent-reported outcomes, suggesting that there may be some subtle difficulties for children with MS. Consideration of how these findings compare with that of previous CC-UK analyses is explored. Further, implications for clinical practice and future research are considered, with the need for longitudinal analyses, as well as data from multiple perspectives (eg, school, parents, and self) at older age points to establish patterns over time. Through collaboration across the highly specialized craniofacial centers, the CC-UK hopes to work toward this goal moving forward.

The Craniofacial Collaboration UK: Developmental Outcomes in 7- and 10-Year-Old Children With Sagittal Synostosis.

The Craniofacial Collaboration UK (CC-UK) protocol is a shared agreement across the 4 UK Highly Specialist Craniofacial Centres (HSCCs) to conduct robust neurodevelopmental and psychosocial clinical screening for children with craniosynostosis. This agreement allows for the analysis of outcomes of a homogenous sample of children with single suture craniosynostosis (SSC), a frequent limitation of the existing research. The current study is the latest analysis of CC-UK data on behavioral, cognitive, and psychosocial outcomes. The focus of this analysis is 7- and 10-year-olds with nonsyndromic sagittal synostosis (SS) who have undergone primary corrective surgery and completed routine clinical screening at 1 of the 4 HSCCs since the introduction of the CC-UK protocol. Due to changes in clinical pathways, only data from 3 HSCCs is included to preserve homogeneity. Results show that the majority of children with SS fall within the average range across behavioral and neurodevelopmental domains. A notable exception was a task involving perceptual reasoning and visuomotor skills (Block Design). Although this difference was small and the mean score remained within the average range, it suggests some increased risk of subtle difficulty with such skills for children with SS. Across other measures, there was no consistent evidence of any significantly increased risk of poorer outcomes, in line with findings of previous CC-UK papers. Understanding the psychological phenotype of SS is a key research priority for parents and clinicians, and the current study is another step toward achieving this goal.

Hyperthermic intrathoracic extracorporeal chemotherapy for secondary malignant pleural disease.

OBJECTIVES: Pleural metastasis has extremely poor prognosis. Resection of pleural implants with infusion of intrathoracic hyperthermic chemotherapy may offer a survival advantage in selected patients. We evaluated the safety and efficacy of hyperthermic intrathoracic extracorporeal chemotherapy (HITEC) in patients who underwent pleurectomy/decortication (P/D) for secondary malignant pleural disease (SPD). METHODS: A total of 101 patients were evaluated over 72 months, with 35 patients electing to proceed with P/D and 60 minutes of HITEC with cisplatin at 42°C. Inclusion criteria were adults 18-79 years with unilateral pleural dissemination. Exclusion criteria were patients without control of primary site, extrathoracic metastatic disease, significant comorbidities, and a history of adverse reaction to cisplatin. RESULTS: Median age was 56 years (36-73); 60% were women. SPD was thymoma in 13, breast cancer in 9, lung cancer in 6, colon cancer in 2, renal cell in 2, and esophageal, anal, and thymic cancers in one each. There was no operative mortality. Postoperative complications occurred in 18 patients (51%). No patient developed renal failure. Median follow-up was 24 months (4-60). The overall survival rate was 61%; 17 patients (49%) developed recurrent disease at a median of 12 months (6-36). There were no recurrences after 36 months Eleven patients (31%) died of metastatic disease at a median of 17 months (7-25). CONCLUSIONS: Surgical cytoreduction of SPD followed by HITEC with cisplatin was well tolerated. No patient developed cisplatin-related toxicities. Long-term follow-up is warranted to determine survival advantage and refinement of inclusion criteria.

Intracranial Empyemas in the COVID-19 Era: A New Phenomenon? A Paediatric Case Series and Review of the Literature.

INTRODUCTION: We present the largest series of paediatric intracranial empyemas occurring after COVID-19 infection to date, and discuss the potential implications of the pandemic on this neurosurgical pathology. METHODS: Patients admitted to our centre between January 2016 and December 2021 with a confirmed radiological diagnosis of intracranial empyema were retrospectively reviewed, excluding non-otorhinological source cases. Patients were grouped according to onset before or after onset of the COVID-19 pandemic and COVID-19 status. A literature review of all post-COVID-19 intracranial empyemas was performed. SPSS v27 was used for statistical analysis. RESULTS: Sixteen patients were diagnosed with intracranial empyema: n = 5 prior to 2020 and n = 11 after, resulting in an average annual incidence of 0.3% prior to onset of the pandemic and 1.2% thereafter. Of those diagnosed since the pandemic, 4 (25%) were confirmed to have COVID-19 on recent PCR test. Time from COVID-19 infection until empyema diagnosis ranged from 15 days to 8 weeks. Mean age for post-COVID-19 cases was 8.5 years (range: 7-10 years) compared to 11 years in non-COVID cases (range: 3-14 years). Streptococcus intermedius was grown in all cases of post-COVID-19 empyema, and 3 of 4 (75%) post-COVID-19 cases developed cerebral sinus thromboses, compared to 3 of 12 (25%) non-COVID-19 cases. All cases were discharged home with no residual deficit. CONCLUSION: Our post-COVID-19 intracranial empyema series demonstrates a greater proportion of cerebral sinus thromboses than non-COVID-19 cases, potentially reflecting the thrombogenic effects of COVID-19. Incidence of intracranial empyema at our centre has increased since the start of the pandemic, causes of which require further investigation and multicentre collaboration.

Malrotation and Fibroblast Growth Factor Receptor-2-Associated Craniosynostosis: An Underrecognized Association and Management Pathway.

INTRODUCTION: Feeding difficulties are common and multifactorial in children with Fibroblast Growth Factor Receptor-2 (FGFR-2) mutations. Intestinal rotation anomalies have been demonstrated to occur more frequently in animals with FGFR-2 mutations. This study aims to describe intestinal rotation anomalies, surgical management, and feeding assistance in children with FGFR-2 mutations who have undergone upper gastrointestinal (UGI) contrast studies. METHODS: Retrospective data were collected of children born between 1988 and 2020 in a UK quaternary craniofacial unit with FGFR-2-associated craniosynostosis. A consultant survey of approach to malrotation was undertaken. RESULTS: Thirty-four children were included, 17 (50%) female. Six (18%) had UGI symptoms, which included bilious vomiting (n=2), nonbilious vomiting (n=5), retching (n=1), feed intolerance (n=3), and failure to thrive (n=3). Nine had a gastrostomy in situ. Intestinal rotation anomalies occurred in 4 (12%) children, 3 of whom underwent a Ladd procedure and two third required gastrojejunal feeding postoperatively. Consultants agreed that all children with FGFR-2 mutation and UGI symptoms should undergo UGI contrast study, as should children requiring a gastrostomy. DISCUSSION: Intestinal rotation anomalies in children with FGFR-2 mutations occur more frequently than the general population. Prompt consideration of UGI contrast in symptomatic children with FGFR-2 mutation is recommended to enable early surgical management of children with malrotation.

The Craniofacial Collaboration UK: Developmental Outcomes in 5-Year-Old Children With Metopic Synostosis.

The Craniofacial Collaboration (CC-UK) was setup in 2015 as a joint initiative between the Psychology teams attached to the 4 highly specialized craniofacial centers in the United Kingdom. The CC-UK aims to address key limitations in the existing craniofacial literature by applying strict exclusion criteria and collating clinical data on a homogenous sample of children. This article reports the fourth wave of data collection from the CC-UK, with the analysis of developmental and behavioral outcomes for children with metopic synostosis at 5 years old. Previous data for sagittal synostosis at 3 and 5 years, and metopic synostosis at 3 years, have been presented. This paper offers the first analysis of developmental and behavioral parent-report measures at school age for metopic synostosis. All children in the current data set had primary corrective surgery. Findings highlight similar patterns to that of previous research among children with single-suture craniosynostosis, as well as earlier CC-UK analyses, with the majority falling within 1 standard deviation of the normative mean. However, differences across key behavioral and emotional domains, with some areas reporting heightened concerns compared with those detected among sagittal groups, may suggest that subtle differences between individual diagnostic groups are present. This further highlights the importance of utilizing homogenous samples within the field of craniofacial research. To further build upon this work, and to provide a greater understanding of how these difficulties and concerns may develop, or diminish, over time, further consideration to longitudinal outcomes is needed for individual diagnostic groups. Through this collaboration, the authors seek to achieve this goal in their future work.

The Paediatric Vault Score (PVS)-A Novel Scoring Tool for Prioritisation of Surgical Management of Craniosynostosis Patients.

Craniosynostosis is the premature fusion of the skull sutures, resulting in abnormal skull shape and volume. Timely management is a priority in avoiding raised intracranial pressure which can result in blindness and neurodevelopmental delay. Due to the COVID-19 pandemic, theater access was reduced. A risk stratification scoring system was thus devised to score patients attending surgery and aid in prioritization according to surgical need. The authors present the Paediatric Vault Score (PVS), which can also be customized to each unit's individual protocols. Ten patients on the waiting list were randomly selected and their clinical information was summarized in uniform anonymized reports. Six craniofacial consultants were selected as assessors and given 1 week to independently rank the patients from 1 to 10. Each scorer's ranking was verified against the PVS template and concordance was analyzed using the Kendall tau correlation coefficient (KT). Three cycles of the scoring process were carried out. Improvements were made to the scoring tool following cycle 1. Cycle 1 revealed 2 clinicians to be concordant with the PVS system and 4 to be discordant. Cycle 2 revealed all 6 clinicians to be concordant, with a mean KT score of 0.61. The final cycle revealed all 6 clinicians to be concordant, with a mean KT score of 0.70. Four scorers increased their concordance once the scoring sheet was introduced. Kendall's correlation of concordance calculated the interrater reliability to be 0.81. The PVS is the first known vault scoring system to aid in risk stratification and waiting list prioritization.

Human stem cell-derived thymic epithelial cells enhance human T-cell development in a xenogeneic thymus.

BACKGROUND: Generation of thymic tissue from pluripotent stem cells would provide therapies for acquired and congenital thymic insufficiency states. OBJECTIVES: This study aimed to generate human thymic epithelial progenitors from human embryonic stem cells (hES-TEPs) and to assess their thymopoietic function in vivo. METHODS: This study differentiated hES-TEPs by mimicking developmental queues with FGF8, retinoic acid, SHH, Noggin, and BMP4. Their function was assessed in reaggregate cellular grafts under the kidney capsule and in hybrid thymi by incorporating them into swine thymus (SwTHY) grafts implanted under the kidney capsules of immunodeficient mice that received human hematopoietic stem and progenitor cells (hHSPCs) intravenously. RESULTS: Cultured hES-TEPs expressed FOXN1 and formed colonies expressing EPCAM and both cortical and medullary thymic epithelial cell markers. In thymectomized immunodeficient mice receiving hHSPCs, hES-TEPs mixed with human thymic mesenchymal cells supported human T-cell development. Hypothesizing that support from non-epithelial thymic cells might allow long-term function of hES-TEPs, the investigators injected them into SwTHY tissue, which supports human thymopoiesis in NOD severe combined immunodeficiency IL2Rγnull mice receiving hHSPCs. hES-TEPs integrated into SwTHY grafts, enhanced human thymopoiesis, and increased peripheral CD4+ naive T-cell reconstitution. CONCLUSIONS: This study has developed and demonstrated in vivo thymopoietic function of hES-TEPs generated with a novel differentiation protocol. The SwTHY hybrid thymus model demonstrates beneficial effects on human thymocyte development of hES-TEPs maturing in the context of a supportive thymic structure.

Breaking tolerance with engineered class I antigen-presenting molecules.

Successful efforts to activate T cells capable of recognizing weak cancer-associated self-antigens have employed altered peptide antigens to activate T cell responses capable of cross-reacting on native tumor-associated self. A limitation of this approach is the requirement for detailed knowledge about the altered self-peptide ligands used in these vaccines. In the current study we considered allorecognition as an approach for activating CTL capable of recognizing weak or self-antigens in the context of self-MHC. Nonself antigen-presenting molecules typically contain polymorphisms that influence interactions with the bound peptide and TCR interface. Recognition of these nonself structures results in peptide-dependent alloimmunity. Alloreactive T cells target their inducing alloantigens as well as third-party alloantigens but generally fail to target self-antigens. Certain residues located on the alpha-1/2 domains of class I antigen-presenting molecules primarily interface with TCR. These residues are more conserved within and across species than are residues that determine peptide antigen binding properties. Class I variants designed with amino acid substitutions at key positions within the conserved helical structures are shown to provide strong activating signals to alloreactive CD8 T cells while avoiding changes in naturally bound peptide ligands. Importantly, CTL activated in this manner can break self-tolerance by reacting to self-peptides presented by native MHC. The ability to activate self-tolerant T cells capable of cross-reacting on self-peptide-MHC in vivo represents an approach for inducing autoimmunity, with possible application in cancer vaccines.

The Craniofacial Collaboration UK: Developmental Outcomes in 3-Year-Old Children With Metopic Synostosis.

ABSTRACT: The Craniofacial Collaboration UK (CC-UK) has been established across the 4 highly specialized craniofacial centers in the UK since 2015. This joint collective aims to address the current limitations within developmental craniofacial research, using robust clinical data from a homogenous sample of children. This paper presents the third wave of findings from the CC-UK, with consideration to developmental and behavioral parent-report measures. Whilst previous data for sagittal synostosis have been presented, this article summarizes the analysis of these outcomes for children with metopic synostosis (MS) at 3 years who have undergone primary corrective surgery. Results highlight similar patterns to that of earlier CC-UK work, with the majority of children falling within 1 standard deviation of the population normative means across all measures. However, statistically significant difficulties were found between group means for children with MS on various developmental and behavioral domains. Prosocial skills and peer difficulties were reported as the greatest areas of behavioral concern for parents, with prosocial skills found to be below the level expected for their chronological age. In order to further understand the developmental trajectory of children with MS, longitudinal examination of individual diagnostic and specific age groups with single-suture craniosynostosis is crucial. The continuation of the CC-UK provides an opportunity to attain this goal.

Rectal Acquisition of Simian Immunodeficiency Virus (SIV) SIVmac239 Infection despite Vaccine-Induced Immune Responses against the Entire SIV Proteome.

Given the complex biology of human immunodeficiency virus (HIV) and its remarkable capacity to evade host immune responses, HIV vaccine efficacy may benefit from the induction of both humoral and cellular immune responses of maximal breadth, potency, and longevity. Guided by this rationale, we set out to develop an immunization protocol aimed at maximizing the induction of anti-Envelope (anti-Env) antibodies and CD8+ T cells targeting non-Env epitopes in rhesus macaques (RMs). Our approach was to deliver the entire simian immunodeficiency virus (SIV) proteome by serial vaccinations. To that end, 12 RMs were vaccinated over 81 weeks with DNA, modified vaccinia Ankara (MVA), vesicular stomatitis virus (VSV), adenovirus type 5 (Ad5), rhesus monkey rhadinovirus (RRV), and DNA again. Both the RRV and the final DNA boosters delivered a near-full-length SIVmac239 genome capable of assembling noninfectious SIV particles and inducing T-cell responses against all nine SIV proteins. Compared to previous SIV vaccine trials, the present DNA-MVA-VSV-Ad5-RRV-DNA regimen resulted in comparable levels of Env-binding antibodies and SIV-specific CD8+ T-cells. Interestingly, one vaccinee developed low titers of neutralizing antibodies (NAbs) against SIVmac239, a tier 3 virus. Following repeated intrarectal marginal-dose challenges with SIVmac239, vaccinees were not protected from SIV acquisition but manifested partial control of viremia. Strikingly, the animal with the low-titer vaccine-induced anti-SIVmac239 NAb response acquired infection after the first SIVmac239 exposure. Collectively, these results highlight the difficulties in eliciting protective immunity against immunodeficiency virus infection.IMPORTANCE Our results are relevant to HIV vaccine development efforts because they suggest that increasing the number of booster immunizations or delivering additional viral antigens may not necessarily improve vaccine efficacy against immunodeficiency virus infection.

Isolated Frontosphenoidal Craniosynostosis: The Alder Hey Experience and a Novel Algorithm to Aid Diagnosis.

ABSTRACT: Unilateral synostotic frontal plagiocephaly is most commonly due to a premature fusion of the frontoparietal suture. However, the coronal ring comprises of major and minor sutures and these sutures in isolation or in combination can result in similar clinical presentations which can make diagnosis challenging and result in a delay in referral to a craniofacial surgeon for timely management. Isolated frontosphenoidal craniosynostosis is a rare clinical entity with only 49 cases reported in the English literature to date. The authors present our series of 4 patients to add to this cohort of patients and describe key characteristics to distinguish frontoparietal from isolated frontosphenoidal synostosis and introduce a means of differentiating these 2 diagnoses from posterior deformational plagiocephaly and unilateral lambdoid synostosis. All previous case reports have been diagnosed after radiological imaging but the authors have devised a novel algorithm to aid the clinician in diagnosis of craniosynostosis before any radiological imaging.

Part 1: Surgical Correction in 231 Trigonocephaly Patients - The Alder Hey Experience.

ABSTRACT: Isolated metopic synostosis presents with a range of severity, from a palpable ridge as the sole presenting feature to a constellation of features resulting in trigonocephaly. At our unit, patients on the moderate to severe end of the phenotypic spectrum of trigonocephaly are offered fronto-orbital advancement and remodeling. The authors present our series of trigonocephaly patients who have undergone surgical correction. From January 2000 to January 2020, the authors operated on 231 patients with trigonocephaly. The average age at surgery was 18 months, with an average follow-up of 77.4 months. Seventy-nine percent of patients had no comorbidity. Ten percent of patients sustained a dural tear with no long-term consequences. The total early complication rate was 12.1%. The most common early complications were wound infection and wound dehiscence at 7.4% and 3.9% respectively. The total reoperation rate was 6.5%. The introduction of infection prevention and control measures over the 2 decades at our unit reduced the reoperation rate to 1.1%. The most common late complication was temporal recession in 20.8% of patients, none of whom required aesthetic correction. The recurrence rate of a metopic ridge was 2.3% with no patients requiring further surgery. None of our patients required calvarial remodeling for raised intracranial pressure after the primary fronto-orbital advancement and remodeling. There were no life-threatening complications or mortalities in our cohort. The authors present recommendations which include an infection control care bundle, cessation of surgical drains, and practice adjustments to reduce risks of infection and risk of requiring further calvarial remodelling for raised intracranial pressure.

The Frequency of Vaccine-Induced T-Cell Responses Does Not Predict the Rate of Acquisition after Repeated Intrarectal SIVmac239 Challenges in Mamu-B*08+ Rhesus Macaques.

Approximately 50% of rhesus macaques (RMs) expressing the major histocompatibility complex class I (MHC-I) allele Mamu-B*08 spontaneously control chronic-phase viremia after infection with the pathogenic simian immunodeficiency virus mac239 (SIVmac239) clone. CD8+ T-cell responses in these animals are focused on immunodominant Mamu-B*08-restricted SIV epitopes in Vif and Nef, and prophylactic vaccination with these epitopes increases the incidence of elite control in SIVmac239-infected Mamu-B*08-positive (Mamu-B*08+ ) RMs. Here we evaluated if robust vaccine-elicited CD8+ T-cell responses against Vif and Nef can prevent systemic infection in Mamu-B*08+ RMs following mucosal SIV challenges. Ten Mamu-B*08+ RMs were vaccinated with a heterologous prime/boost/boost regimen encoding Vif and Nef, while six sham-vaccinated MHC-I-matched RMs served as the controls for this experiment. Vaccine-induced CD8+ T cells against Mamu-B*08-restricted SIV epitopes reached high frequencies in blood but were present at lower levels in lymph node and gut biopsy specimens. Following repeated intrarectal challenges with SIVmac239, all control RMs became infected by the sixth SIV exposure. By comparison, four vaccinees were still uninfected after six challenges, and three of them remained aviremic after 3 or 4 additional challenges. The rate of SIV acquisition in the vaccinees was numerically lower (albeit not statistically significantly) than that in the controls. However, peak viremia was significantly reduced in infected vaccinees compared to control animals. We found no T-cell markers that distinguished vaccinees that acquired SIV infection from those that did not. Additional studies will be needed to validate these findings and determine if cellular immunity can be harnessed to prevent the establishment of productive immunodeficiency virus infection.IMPORTANCE It is generally accepted that the antiviral effects of vaccine-induced classical CD8+ T-cell responses against human immunodeficiency virus (HIV) are limited to partial reductions in viremia after the establishment of productive infection. Here we show that rhesus macaques (RMs) vaccinated with Vif and Nef acquired simian immunodeficiency virus (SIV) infection at a lower (albeit not statistically significant) rate than control RMs following repeated intrarectal challenges with a pathogenic SIV clone. All animals in the present experiment expressed the elite control-associated major histocompatibility complex class I (MHC-I) molecule Mamu-B*08 that binds immunodominant epitopes in Vif and Nef. Though preliminary, these results provide tantalizing evidence that the protective efficacy of vaccine-elicited CD8+ T cells may be greater than previously thought. Future studies should examine if vaccine-induced cellular immunity can prevent systemic viral replication in RMs that do not express MHC-I alleles associated with elite control of SIV infection.

Bacterially expressed HIV-1 gp120 outer-domain fragment immunogens with improved stability and affinity for CD4-binding site neutralizing antibodies.

Protein minimization is an attractive approach for designing vaccines against rapidly evolving pathogens such as human immunodeficiency virus, type 1 (HIV-1), because it can help in focusing the immune response toward conserved conformational epitopes present on complex targets. The outer domain (OD) of HIV-1 gp120 contains epitopes for a large number of neutralizing antibodies and therefore is a primary target for structure-based vaccine design. We have previously designed a bacterially expressed outer-domain immunogen (ODEC) that bound CD4-binding site (CD4bs) ligands with 3-12 µm affinity and elicited a modest neutralizing antibody response in rabbits. In this study, we have optimized ODEC using consensus sequence design, cyclic permutation, and structure-guided mutations to generate a number of variants with improved yields, biophysical properties, stabilities, and affinities (KD of 10-50 nm) for various CD4bs targeting broadly neutralizing antibodies, including the germline-reverted version of the broadly neutralizing antibody VRC01. In contrast to ODEC, the optimized immunogens elicited high anti-gp120 titers in rabbits as early as 6 weeks post-immunization, before any gp120 boost was given. Following two gp120 boosts, sera collected at week 22 showed cross-clade neutralization of tier 1 HIV-1 viruses. Using a number of different prime/boost combinations, we have identified a cyclically permuted OD fragment as the best priming immunogen, and a trimeric, cyclically permuted gp120 as the most suitable boosting molecule among the tested immunogens. This study also provides insights into some of the biophysical correlates of improved immunogenicity.

Mamu-B*17+ Rhesus Macaques Vaccinated with env, vif, and nef Manifest Early Control of SIVmac239 Replication.

Certain major histocompatibility complex class I (MHC-I) alleles are associated with spontaneous control of viral replication in human immunodeficiency virus (HIV)-infected people and simian immunodeficiency virus (SIV)-infected rhesus macaques (RMs). These cases of "elite" control of HIV/SIV replication are often immune-mediated, thereby providing a framework for studying anti-lentiviral immunity. In this study, we examined how vaccination impacts SIV replication in RMs expressing the MHC-I allele Mamu-B*17 Approximately 21% of Mamu-B*17+ and 50% of Mamu-B*08+ RMs control chronic-phase viremia after SIVmac239 infection. Because CD8+ T cells targeting Mamu-B*08-restricted SIV epitopes have been implicated in virologic suppression in Mamu-B*08+ RMs, we investigated whether this might also be true for Mamu-B*17+ RMs. Two groups of Mamu-B*17+ RMs were vaccinated with genes encoding Mamu-B*17-restricted epitopes in Vif and Nef. These genes were delivered by themselves (group 1) or together with env (group 2). Group 3 included MHC-I-matched RMs and served as the control group. Surprisingly, the group 1 vaccine regimen had little effect on viral replication compared to group 3, suggesting that unlike Mamu-B*08+ RMs, preexisting SIV-specific CD8+ T cells alone do not facilitate long-term virologic suppression in Mamu-B*17+ RMs. Remarkably, however, 5/8 group 2 vaccinees controlled viremia to <15 viral RNA copies/ml soon after infection. No serological neutralizing activity against SIVmac239 was detected in group 2, although vaccine-elicited gp140-binding antibodies correlated inversely with nadir viral loads. Collectively, these data shed new light on the unique mechanism of elite control in Mamu-B*17+ RMs and implicate vaccine-induced, nonneutralizing anti-Env antibodies in the containment of immunodeficiency virus infection.IMPORTANCE A better understanding of the immune correlates of protection against HIV might facilitate the development of a prophylactic vaccine. Therefore, we investigated simian immunodeficiency virus (SIV) infection outcomes in rhesus macaques expressing the major histocompatibility complex class I allele Mamu-B*17 Approximately 21% of Mamu-B*17+ macaques spontaneously controlled chronic phase viremia after SIV infection, an effect that may involve CD8+ T cells targeting Mamu-B*17-restricted SIV epitopes. We vaccinated Mamu-B*17+ macaques with genes encoding immunodominant epitopes in Vif and Nef alone (group 1) or together with env (group 2). Although neither vaccine regimen prevented SIV infection, 5/8 group 2 vaccinees controlled viremia to below detection limits shortly after infection. This outcome, which was not observed in group 1, was associated with vaccine-induced, nonneutralizing Env-binding antibodies. Together, these findings suggest a limited contribution of Vif- and Nef-specific CD8+ T cells for virologic control in Mamu-B*17+ macaques and implicate anti-Env antibodies in containment of SIV infection.