Ventilation during COVID-19 in a school for students with intellectual and developmental disabilities (IDD)

BACKGROUND

This study examined the correlation of classroom ventilation (air exchanges per hour (ACH)) and exposure to CO2 ≥1,000 ppm with the incidence of SARS-CoV-2 over a 20-month period in a specialized school for students with intellectual and developmental disabilities (IDD). These students were at a higher risk of respiratory infection from SARS-CoV-2 due to challenges in tolerating mitigation measures (e.g. masking). One in-school measure proposed to help mitigate the risk of SARS-CoV-2 infection in schools is increased ventilation.

METHODS

We established a community-engaged research partnership between the University of Rochester and the Mary Cariola Center school for students with IDD. Ambient CO2 levels were measured in 100 school rooms, and air changes per hour (ACH) were calculated. The number of SARS-CoV-2 cases for each room was collected over 20 months.

RESULTS

97% of rooms had an estimated ACH ≤4.0, with 7% having CO2 levels ≥2,000 ppm for up to 3 hours per school day. A statistically significant correlation was found between the time that a room had CO2 levels ≥1,000 ppm and SARS-CoV-2 PCR tests normalized to room occupancy, accounting for 43% of the variance. No statistically significant correlation was found for room ACH and per-room SARS-CoV-2 cases. Rooms with ventilation systems using MERV-13 filters had lower SARS-CoV-2-positive PCR counts. These findings led to ongoing efforts to upgrade the ventilation systems in this community-engaged research project.

CONCLUSIONS

There was a statistically significant correlation between the total time of room CO2 concentrations ≥1,000 and SARS-CoV-2 cases in an IDD school. Merv-13 filters appear to decrease the incidence of SARS-CoV-2 infection. This research partnership identified areas for improving in-school ventilation.

New design strategies for ultra-specific CRISPR-Cas13a-based RNA detection with single-nucleotide mismatch sensitivity

An increasingly pressing need for clinical diagnostics has required the development of novel nucleic acid-based detection technologies that are sensitive, fast, and inexpensive, and that can be deployed at point-of-care. Recently, the RNA-guided ribonuclease CRISPR-Cas13 has been successfully harnessed for such purposes. However, developing assays for detection of genetic variability, for example single-nucleotide polymorphisms, is still challenging and previously described design strategies are not always generalizable. Here, we expanded our characterization of LbuCas13a RNA-detection specificity by performing a combination of experimental RNA mismatch tolerance profiling, molecular dynamics simulations, protein, and crRNA engineering. We found certain positions in the crRNA-target-RNA duplex that are particularly sensitive to mismatches and establish the effect of RNA concentration in mismatch tolerance. Additionally, we determined that shortening the crRNA spacer or modifying the direct repeat of the crRNA leads to stricter specificities. Furthermore, we harnessed our understanding of LbuCas13a allosteric activation pathways through molecular dynamics and structure-guided engineering to develop novel Cas13a variants that display increased sensitivities to single-nucleotide mismatches. We deployed these Cas13a variants and crRNA design strategies to achieve superior discrimination of SARS-CoV-2 strains compared to wild-type LbuCas13a. Together, our work provides new design criteria and Cas13a variants to use in future easier-to-implement Cas13-based RNA detection applications.

Migraine inhibitor olcegepant reduces weight loss and IL-6 release in SARS-CoV-2 infected older mice with neurological signs

COVID-19 can result in neurological symptoms such as fever, headache, dizziness, and nausea. However, neurological signs of SARS-CoV-2 infection have been hardly assessed in mouse models. Here, we infected two commonly used wildtype mice lines (C57BL/6 and 129S) with mouse-adapted SARS-CoV-2 and demonstrated neurological signs including motion-related dizziness. We then evaluated whether the Calcitonin Gene-Related Peptide (CGRP) receptor antagonist, olcegepant, used in migraine treatment could mitigate acute neuroinflammatory and neurological responses to SARS-COV-2 infection. We infected wildtype C57BL/6J and 129/SvEv mice, and a 129 αCGRP-null mouse line with a mouse-adapted SARS-CoV-2 virus, and evaluated the effect of CGRP receptor antagonism on the outcome of that infection. First, we determined that CGRP receptor antagonism provided protection from permanent weight loss in older (>12 m) C57BL/6J and 129 SvEv mice. We also observed acute fever and motion-induced dizziness in all older mice, regardless of treatment. However, in both wildtype mouse lines, CGRP antagonism reduced acute interleukin 6 (IL-6) levels by half, with virtually no IL-6 release in mice lacking αCGRP. These findings suggest that migraine inhibitors such as those blocking CGRP signaling protect against acute IL-6 release and subsequent inflammatory events after SARS-CoV-2 infection, which may have repercussions for related pandemic and/or endemic coronaviruses.

Adaptive immune cells are necessary for SARS-CoV-2-induced pathology

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing the ongoing global pandemic associated with morbidity and mortality in humans. Although disease severity correlates with immune dysregulation, the cellular mechanisms of inflammation and pathogenesis of COVID-19 remain relatively poorly understood. Here, we used mouse-adapted SARS-CoV-2 strain MA10 to investigate the role of adaptive immune cells in disease. We found that while infected wild-type mice lost ~10% weight by 3 to 4 days postinfection, rag-/- mice lacking B and T lymphocytes did not lose weight. Infected lungs at peak weight loss revealed lower pathology scores, fewer neutrophils, and lower interleukin-6 and tumor necrosis factor-α in rag-/- mice. Mice lacking αβ T cells also had less severe weight loss, but adoptive transfer of T and B cells into rag-/- mice did not significantly change the response. Collectively, these findings suggest that while adaptive immune cells are important for clearing SARS-CoV-2 infection, this comes at the expense of increased inflammation and pathology.

Ventilation during COVID-19 in a school for students with intellectual and developmental disabilities (IDD)

Background

This study examined the correlation of classroom ventilation (air exchanges per hour (ACH)) and exposure to CO2 ≥1,000 ppm with the incidence of SARS-CoV-2 over a 20-month period in a specialized school for students with intellectual and developmental disabilities (IDD). These students were at a higher risk of respiratory infection from SARS-CoV-2 due to challenges in tolerating mitigation measures (e.g. masking). One in-school measure proposed to help mitigate the risk of SARS-CoV-2 infection in schools is increased ventilation.

Methods

We established a community-engaged research partnership between the University of Rochester and the Mary Cariola Center school for students with IDD. Ambient CO2 levels were measured in 100 school rooms, and air changes per hour (ACH) were calculated. The number of SARS-CoV-2 cases for each room was collected over 20 months.

Results

97% of rooms had an estimated ACH ≤4.0, with 7% having CO2 levels ≥2,000 ppm for up to 3 hours per school day. A statistically significant correlation was found between the time that a room had CO2 levels ≥1,000 ppm and SARS-CoV-2 PCR tests normalized to room occupancy, accounting for 43% of the variance. No statistically significant correlation was found for room ACH and per-room SARS-CoV-2 cases. Rooms with ventilation systems using MERV-13 filters had lower SARS-CoV-2-positive PCR counts. These findings led to ongoing efforts to upgrade the ventilation systems in this community-engaged research project.

Conclusions

There was a statistically significant correlation between the total time of room CO2 concentrations ≥1,000 and SARS-CoV-2 cases in an IDD school. Merv-13 filters appear to decrease the incidence of SARS-CoV-2 infection. This research partnership identified areas for improving in-school ventilation.

Competition Anxiety in Combat Sports and the Importance of Mental Toughness

Combat sports require participants to engage in potentially dangerous forms of contact-based competition. Pressure to succeed, coupled with the risk of severe injury can induce significant levels of anxiety, which if uncontrolled, can negatively impact performance and possibly promote unsporting conduct. The present study examined competitive anxiety levels of combat sports athletes and determined whether self-reported scores were associated with mental toughness and Sportspersonship attitudes. A cross-sectional survey design was used whereby participants (N = 194) completed a battery of questionnaires measuring competitive combat sport experiences, demographic details, Sportspersonship traits (compliance towards rules, respect for opponents, and game perspective), and competition anxiety (somatic, cognitive, and self-confidence; reported retrospectively). Results suggest that mentally tough athletes experience lower levels of cognitive and somatic anxiety, and higher self-confidence, prior to competitions. Findings also found that athletes endorsing more altruistic and respectful attitudes in sport (Sportspersonship) reported higher levels of competition anxiety. The findings demonstrate that mental toughness is allied to positive attributes and could potentially be operationalized to improve both the retention and performance of combat sports athletes. Thus, the authors advocate the use of mental toughness coaching interventions within combat sports.

New design strategies for ultra-specific CRISPR-Cas13a-based RNA-diagnostic tools with single-nucleotide mismatch sensitivity

The pressing need for clinical diagnostics has required the development of novel nucleic acid-based detection technologies that are sensitive, fast, and inexpensive, and that can be deployed at point-of-care. Recently, the RNA-guided ribonuclease CRISPR-Cas13 has been successfully harnessed for such purposes. However, developing assays for detection of genetic variability, for example single-nucleotide polymorphisms, is still challenging and previously described design strategies are not always generalizable. Here, we expanded our characterization of LbuCas13a RNA-detection specificity by performing a combination of experimental RNA mismatch tolerance profiling, molecular dynamics simulations, protein, and crRNA engineering. We found certain positions in the crRNA-target-RNA duplex that are particularly sensitive to mismatches and establish the effect of RNA concentration in mismatch tolerance. Additionally, we determined that shortening the crRNA spacer or modifying the direct repeat of the crRNA leads to stricter specificities. Furthermore, we harnessed our understanding of LbuCas13a allosteric activation pathways through molecular dynamics and structure-guided engineering to develop novel Cas13a variants that display increased sensitivities to single-nucleotide mismatches. We deployed these Cas13a variants and crRNA design strategies to achieve superior discrimination of SARS-CoV-2 strains compared to wild-type LbuCas13a. Together, our work provides new design criteria and new Cas13a variants for easier-to-implement Cas13-based diagnostics.

KEY POINTS

Certain positions in the Cas13a crRNA-target-RNA duplex are particularly sensitive to mismatches.Understanding Cas13a's allosteric activation pathway allowed us to develop novel high-fidelity Cas13a variants.These Cas13a variants and crRNA design strategies achieve superior discrimination of SARS-CoV-2 strains.

GRAPHICAL ABSTRACT

Utilization and Impact of Symptomatic and Exposure SARS-CoV-2 Testing in K-12 Schools

OBJECTIVES

The Centers for Disease Control and Prevention recommend that schools can offer severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostic (on-demand) testing for students and staff with coronavirus disease 2019 symptoms or exposures. Data related to the uptake, implementation, and effect of school-associated on-demand diagnostic testing have not been described.

METHODS

The Rapid Acceleration of Diagnostics Underserved Populations Return to School program provided resources to researchers to implement on-demand SARS-CoV-2 testing in schools. This study describes the strategies used and uptake among the different testing programs. Risk of positivity was compared for symptomatic and exposure testing during the δ and ο variant periods. We estimated the number of school absence days saved with school-based diagnostic testing.

RESULTS

Of the 16 eligible programs, 7 provided school-based on-demand testing. The number of persons that participated in these testing programs is 8281, with 4134 (49.9%) receiving >1 test during the school year. Risk of positivity was higher for symptomatic testing compared with exposure testing and higher during the ο variant predominant period compared with the δ variant predominant period. Overall, access to testing saved an estimated 13 806 absent school days.

CONCLUSIONS

School-based on-demand SARS-CoV-2 testing was used throughout the school year, and nearly half the participants accessed testing on more than 1 occasion. Future studies should work to understand participant preferences around school-based testing and how these strategies can be used both during and outside of pandemics.

Building School-Academic Partnerships to Implement COVID-19 Testing in Underserved Populations

OBJECTIVE

In April 2021, the US government made substantial investments in students' safe return to school by providing resources for school-based coronavirus disease 2019 (COVID-19) mitigation strategies, including COVID-19 diagnostic testing. However, testing uptake and access among vulnerable children and children with medical complexities remained unclear.

METHODS

The Rapid Acceleration of Diagnostics Underserved Populations program was established by the National Institutes of Health to implement and evaluate COVID-19 testing programs in underserved populations. Researchers partnered with schools to implement COVID-19 testing programs. The authors of this study evaluated COVID-19 testing program implementation and enrollment and sought to determine key implementation strategies. A modified Nominal Group Technique was used to survey program leads to identify and rank testing strategies to provide a consensus of high-priority strategies for infectious disease testing in schools for vulnerable children and children with medical complexities.

RESULTS

Among the 11 programs responding to the survey, 4 (36%) included prekindergarten and early care education, 8 (73%) worked with socioeconomically disadvantaged populations, and 4 focused on children with developmental disabilities. A total of 81 916 COVID-19 tests were performed. "Adapting testing strategies to meet the needs, preferences, and changing guidelines," "holding regular meetings with school leadership and staff," and "assessing and responding to community needs" were identified as key implementation strategies by program leads.

CONCLUSIONS

School-academic partnerships helped provide COVID-19 testing in vulnerable children and children with medical complexities using approaches that met the needs of these populations. Additional work is needed to develop best practices for in-school infectious disease testing in all children.

Generation and Functional Analysis of Defective Viral Genomes during SARS-CoV-2 Infection

Defective viral genomes (DVGs) have been identified in many RNA viruses as a major factor influencing antiviral immune response and viral pathogenesis. However, the generation and function of DVGs in SARS-CoV-2 infection are less known. In this study, we elucidated DVG generation in SARS-CoV-2 and its relationship with host antiviral immune response. We observed DVGs ubiquitously from transcriptome sequencing (RNA-seq) data sets of in vitro infections and autopsy lung tissues of COVID-19 patients. Four genomic hot spots were identified for DVG recombination, and RNA secondary structures were suggested to mediate DVG formation. Functionally, bulk and single-cell RNA-seq analysis indicated the interferon (IFN) stimulation of SARS-CoV-2 DVGs. We further applied our criteria to the next-generation sequencing (NGS) data set from a published cohort study and observed a significantly higher amount and frequency of DVG in symptomatic patients than those in asymptomatic patients. Finally, we observed exceptionally diverse DVG populations in one immunosuppressive patient up to 140 days after the first positive test of COVID-19, suggesting for the first time an association between DVGs and persistent viral infections in SARS-CoV-2. Together, our findings strongly suggest a critical role of DVGs in modulating host IFN responses and symptom development, calling for further inquiry into the mechanisms of DVG generation and into how DVGs modulate host responses and infection outcome during SARS-CoV-2 infection. IMPORTANCE Defective viral genomes (DVGs) are generated ubiquitously in many RNA viruses, including SARS-CoV-2. Their interference activity to full-length viruses and IFN stimulation provide the potential for them to be used in novel antiviral therapies and vaccine development. SARS-CoV-2 DVGs are generated through the recombination of two discontinuous genomic fragments by viral polymerase complex, and this recombination is also one of the major mechanisms for the emergence of new coronaviruses. Focusing on the generation and function of SARS-CoV-2 DVGs, these studies identify new hot spots for nonhomologous recombination and strongly suggest that the secondary structures within viral genomes mediate the recombination. Furthermore, these studies provide the first evidence for IFN stimulation activity of de novo DVGs during natural SARS-CoV-2 infection. These findings set up the foundation for further mechanism studies of SARS-CoV-2 recombination and provide evidence to harness the immunostimulatory potential of DVGs in the development of a vaccine and antivirals for SARS-CoV-2.

Preparation of noninfectious scRNAseq samples from SARS-CoV-2-infected epithelial cells

Coronavirus disease (COVID-19) is an infectious disease caused by the SARS coronavirus 2 (SARS-CoV-2) virus. Direct assessment, detection, and quantitative analysis using high throughput methods like single-cell RNA sequencing (scRNAseq) is imperative to understanding the host response to SARS-CoV-2. One barrier to studying SARS-CoV-2 in the laboratory setting is the requirement to process virus-infected cell cultures, and potentially infectious materials derived therefrom, under Biosafety Level 3 (BSL-3) containment. However, there are only 190 BSL3 laboratory facilities registered with the U.S. Federal Select Agent Program, as of 2020, and only a subset of these are outfitted with the equipment needed to perform high-throughput molecular assays. Here, we describe a method for preparing non-hazardous RNA samples from SARS-CoV-2 infected cells, that enables scRNAseq analyses to be conducted safely in a BSL2 facility-thereby making molecular assays of SARS-CoV-2 cells accessible to a much larger community of researchers. Briefly, we infected African green monkey kidney epithelial cells (Vero-E6) with SARS-CoV-2 for 96 hours, trypsin-dissociated the cells, and inactivated them with methanol-acetone in a single-cell suspension. Fixed cells were tested for the presence of infectious SARS-CoV-2 virions using the Tissue Culture Infectious Dose Assay (TCID50), and also tested for viability using flow cytometry. We then tested the dissociation and methanol-acetone inactivation method on primary human lung epithelial cells that had been differentiated on an air-liquid interface. Finally, we performed scRNAseq quality control analysis on the resulting cell populations to evaluate the effects of our virus inactivation and sample preparation protocol on the quality of the cDNA produced. We found that methanol-acetone inactivated SARS-CoV-2, fixed the lung epithelial cells, and could be used to obtain noninfectious, high-quality cDNA libraries. This methodology makes investigating SARS-CoV-2, and related high-containment RNA viruses at a single-cell level more accessible to an expanded community of researchers.

Generation and functional analysis of defective viral genomes during SARS-CoV-2 infection.. [PMID: 36172120 PMCID: PMC9516852 DOI: 10.1101/2022.09.22.509123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Defective viral genomes (DVGs) have been identified in many RNA viruses as a major factor influencing antiviral immune response and viral pathogenesis. However, the generation and function of DVGs in SARS-CoV-2 infection are less known. In this study, we elucidated DVG generation in SARS-CoV-2 and its relationship with host antiviral immune response. We observed DVGs ubiquitously from RNA-seq datasets of in vitro infections and autopsy lung tissues of COVID-19 patients. Four genomic hotspots were identified for DVG recombination and RNA secondary structures were suggested to mediate DVG formation. Functionally, bulk and single cell RNA-seq analysis indicated the IFN stimulation of SARS-CoV-2 DVGs. We further applied our criteria to the NGS dataset from a published cohort study and observed significantly higher DVG amount and frequency in symptomatic patients than that in asymptomatic patients. Finally, we observed unusually high DVG frequency in one immunosuppressive patient up to 140 days after admitted to hospital due to COVID-19, first-time suggesting an association between DVGs and persistent viral infections in SARS-CoV-2. Together, our findings strongly suggest a critical role of DVGs in modulating host IFN responses and symptom development, calling for further inquiry into the mechanisms of DVG generation and how DVGs modulate host responses and infection outcome during SARS-CoV-2 infection.

Mutation L319Q in the PB1 Polymerase Subunit Improves Attenuation of a Candidate Live-Attenuated Influenza A Virus Vaccine

Influenza A viruses (IAV) remain emerging threats to human public health. Live-attenuated influenza vaccines (LAIV) are one of the most effective prophylactic options to prevent disease caused by influenza infections. However, licensed LAIV remain restricted for use in 2- to 49-year-old healthy and nonpregnant people. Therefore, development of LAIV with increased safety, immunogenicity, and protective efficacy is highly desired. The U.S.-licensed LAIV is based on the master donor virus (MDV) A/Ann Arbor/6/60 H2N2 backbone, which was generated by adaptation of the virus to growth at low temperatures. Introducing the genetic signature of the U.S. MDV into the backbone of other IAV strains resulted in varying levels of attenuation. While the U.S. MDV mutations conferred an attenuated phenotype to other IAV strains, the same amino acid changes did not significantly attenuate the pandemic A/California/04/09 H1N1 (pH1N1) strain. To attenuate pH1N1, we replaced the conserved leucine at position 319 with glutamine (L319Q) in PB1 and analyzed the in vitro and in vivo properties of pH1N1 viruses containing either PB1 L319Q alone or in combination with the U.S. MDV mutations using two animal models of influenza infection and transmission, ferrets and guinea pigs. Our results demonstrated that L319Q substitution in the pH1N1 PB1 alone or in combination with the mutations of the U.S. MDV resulted in reduced pathogenicity (ferrets) and transmission (guinea pigs), and an enhanced temperature sensitive phenotype. These results demonstrate the feasibility of generating an attenuated MDV based on the backbone of a contemporary pH1N1 IAV strain. IMPORTANCE Vaccination represents the most effective strategy to reduce the impact of seasonal IAV infections. Although LAIV are superior in inducing protection and sterilizing immunity, they are not recommended for many individuals who are at high risk for severe disease. Thus, development of safer and more effective LAIV are needed. A concern with the current MDV used to generate the U.S.-licensed LAIV is that it is based on a virus isolated in 1960. Moreover, mutations that confer the temperature-sensitive, cold-adapted, and attenuated phenotype of the U.S. MDV resulted in low level of attenuation in the contemporary pandemic A/California/04/09 H1N1 (pH1N1). Here, we show that introduction of PB1 L319Q substitution, alone or in combination with the U.S. MDV mutations, resulted in pH1N1 attenuation. These findings support the development of a novel LAIV MDV based on a contemporary pH1N1 strain as a medical countermeasure against currently circulating H1N1 IAV.

Supporting COVID-19 School Safety for Children With Disabilities and Medical Complexity

Children with intellectual and developmental disabilities (IDDs) and children with medical complexity (CMC) have been disproportionally impacted by the coronavirus disease 2019 pandemic, including school closures. Children with IDDs and CMC rely on schools for a vast array of educational, therapeutic, medical, and social needs. However, maintaining safe schools for children with IDDs and CMC during the coronavirus disease 2019 pandemic may be difficult because of the unique challenges of implementing prevention strategies, such as masking, social distancing, and hand hygiene in this high-risk environment. Furthermore, children with IDDs and CMC are at a higher risk of infectious complications and mortality, underscoring the need for effective mitigation strategies. The goal of this report is to describe the implementation of several screening testing models for severe acute respiratory syndrome coronavirus 2 in this high-risk population. By describing these models, we hope to identify generalizable and scalable approaches to facilitate safe school operations for children with IDDs and CMC during the current and future pandemics.

Pharmacologic profiling reveals lapatinib as a novel antiviral against SARS-CoV-2 in vitro

The emergence of SARS-CoV-2 virus has resulted in a worldwide pandemic, but effective antiviral therapies are not widely available. To improve treatment options, we conducted a high-throughput screen to uncover compounds that block SARS-CoV-2 infection. A minimally pathogenic human betacoronavirus (OC43) was used to infect physiologically-relevant human pulmonary fibroblasts (MRC5) to facilitate rapid antiviral discovery in a preclinical model. Comprehensive profiling was conducted on more than 600 compounds, with each compound arrayed across 10 dose points. Our screening revealed several FDA-approved agents that can attenuate both OC43 and SARS-CoV-2 viral replication, including lapatinib, doramapimod, and 17-AAG. Importantly, lapatinib inhibited SARS-CoV-2 RNA replication by over 50,000-fold. Further, both lapatinib and doramapimod could be combined with remdesivir to improve antiviral activity in cells. These findings reveal novel therapeutic avenues that could limit SARS-CoV-2 infection.

A Mutated PB1 Residue 319 Synergizes with the PB2 N265S Mutation of the Live Attenuated Influenza Vaccine to Convey Temperature Sensitivity

Current influenza vaccines have modest efficacy. This is especially true for current live attenuated influenza vaccines (LAIV), which have been inferior to the inactivated versions in recent years. Therefore, a new generation of live vaccines may be needed. We previously showed that a mutation at PB1 residue 319 confers enhanced temperature sensitivity and attenuation in an LAIV constructed in the genetic background of the mouse-adapted Influenza A Virus (IAV) strain A/PR/8/34 (PR8). Here, we describe the origin/discovery of this unique mutation and demonstrate that, when combined with the PB2 N265S mutation of LAIV, it conveys an even greater level of temperature sensitivity and attenuation on PR8 than the complete set of attenuating mutations from LAIV. Furthermore, we show that the combined PB1 L319Q and PB2 N265S mutations confer temperature sensitivity on IAV polymerase activity in two different genetic backgrounds, PR8 and A/Cal/04/09. Collectively, these findings show that the PB2 LAIV mutation synergizes with a mutation in PB1 and may have potential utility for improving LAIVs.

G-quadruplex ligands targeting telomeres do not inhibit HIV promoter activity and cooperate with latency reversing agents in killing latently infected cells

Altered telomere maintenance mechanism (TMM) is linked to increased DNA damage at telomeres and telomere uncapping. We previously showed that HIV-1 latent cells have altered TMM and are susceptible to ligands that target G-quadruplexes (G4) at telomeres. Susceptibility of latent cells to telomere targeting could potentially be used to support approaches to eradicate HIV reservoirs. However, G4 ligands also target G-quadruplexes in promoters blocking gene transcription. Since HIV promoter sequence can form G-quadruplexes, we investigated whether G4 ligands interfere with HIV-1 promoter activity and virus reactivation from latency, and whether telomere targeting could be combined with latency reversing agents (LRAs) to promote elimination of HIV reservoirs. Our results indicate that Sp1 binding region in HIV-1 promoter can adopt G4 structures in duplex DNA, and that in vitro binding of Sp1 to G-quadruplex is blocked by G4 ligand, suggesting that agents targeting telomeres interfere with virus reactivation. However, our studies show that G4 agents do not affect HIV-1 promoter activity in cell culture, and do not interfere with latency reversal. Importantly, primary memory CD4 + T cells infected with latent HIV-1 are more susceptible to combined treatment with LRAs and G4 ligands, indicating that drugs targeting TMM may enhance killing of HIV reservoirs. Using a cell-based DNA repair assay, we also found that HIV-1 infected cells have reduced efficiency of DNA mismatch repair (MMR), and base excision repair (BER), suggesting that altered TMM in latently infected cells could be associated with accumulation of DNA damage at telomeres and changes in telomeric caps.

Studying platelet-HIV interactions and potential to promote viral spread

HIV-infected individuals experience persistent inflammation, which is associated with increased platelet activation. There is growing evidence that platelets contribute to immune responses, through the release of inflammatory granules and complex formation with other cells including monocytes and CD4+ T-cells, both of which are susceptible to infection. Previous studies have found evidence that HIV is engulfed by platelets. However, such studies were primarily conducted in vitro. It is important to study consequences of HIV-platelet interactions, and to ascertain whether or not they occur in patients.

We confirmed previous in vitro findings through co-culturing platelets from healthy donors, with HIV virions, and using electron microscopy identified virus-like particles inside platelets. Utilizing RNAscope in tandem with RT-PCR we created a timeline of virus-platelet associations and found viral genomic RNA remained associated with platelets for a prolonged period of time. Importantly, platelet-associated virus remained infectious, as platelets were able to spread infection to activated CD4+ T-cells in coculture experiments. Furthermore, we established a system to screen for HIV-positive platelets. We isolated platelets from cART-naïve viremic patients and performed super resolution microscopy and imagestream flow cytometry. This analysis revealed evidence of HIV-positive platelets in these infected individuals. In contrast, the amount of HIV-positive platelets was drastically, although not entirely, reduced following 3 months of cART treatment. Our findings suggest that platelet-virus interactions may be important in contributing to viral spread, and the development and maintenance of viral reservoirs.

A Live Attenuated Influenza Vaccine Elicits Enhanced Heterologous Protection When the Internal Genes of the Vaccine Are Matched to Those of the Challenge Virus

Influenza A virus (IAV) causes significant morbidity and mortality, despite the availability of viral vaccines. The efficacy of live attenuated influenza vaccines (LAIVs) has been especially poor in recent years. One potential reason is that the master donor virus (MDV), on which all LAIVs are based, contains either the internal genes of the 1960 A/Ann Arbor/6/60 or the 1957 A/Leningrad/17/57 H2N2 viruses (i.e., they diverge considerably from currently circulating strains). We previously showed that introduction of the temperature-sensitive (ts) residue signature of the AA/60 MDV into a 2009 pandemic A/California/04/09 H1N1 virus (Cal/09) results in only 10-fold in vivo attenuation in mice. We have previously shown that the ts residue signature of the Russian A/Leningrad/17/57 H2N2 LAIV (Len LAIV) more robustly attenuates the prototypical A/Puerto Rico/8/1934 (PR8) H1N1 virus. In this work, we therefore introduced the ts signature from Len LAIV into Cal/09. This new Cal/09 LAIV is ts in vitro, highly attenuated (att) in mice, and protects from a lethal homologous challenge. In addition, when our Cal/09 LAIV with PR8 hemagglutinin and neuraminidase was used to vaccinate mice, it provided enhanced protection against a wild-type Cal/09 challenge relative to a PR8 LAIV with the same attenuating mutations. These findings suggest it may be possible to improve the efficacy of LAIVs by better matching the sequence of the MDV to currently circulating strains.IMPORTANCE Seasonal influenza infection remains a major cause of disease and death, underscoring the need for improved vaccines. Among current influenza vaccines, the live attenuated influenza vaccine (LAIV) is unique in its ability to elicit T-cell immunity to the conserved internal proteins of the virus. Despite this, LAIV has shown limited efficacy in recent years. One possible reason is that the conserved, internal genes of all current LAIVs derive from virus strains that were isolated between 1957 and 1960 and that, as a result, do not resemble currently circulating influenza viruses. We have therefore developed and tested a new LAIV, based on a currently circulating pandemic strain of influenza. Our results show that this new LAIV elicits improved protective immunity compared to a more conventional LAIV.

993. Combining Key Residues of the Russian and US Live-Attenuated Influenza Viruses for a More Attenuated Virus

Background

The Live Attenuated Influenza Virus (LAIV) used in the United States is based on the cold-passaged A/AnnArbor/6/60 strain (AA). An alternative LAIV (Len), developed from the cold-passaged A/Leningrad/134/17/57 strain, has also been used in some countries outside the United States. Recent concerns with the efficacy and safety of the current US LAIV warrant the development of an improved LAIV.

Methods

We used in vitro minireplicon and multicycle viral growth assays to analyze the combined effects of polymerase mutations from LAIV (AA) and LAIV (Len) on the phenotype of PR8. Mini-replicon assays were performed in HEK-293T cells with firefly luciferase under the control of the influenza virus NP promoter; we controlled for cell density with a constitutively active Renilla luciferase. Multicycle growth curve experiments were performed at 33°C, 37°C, and 39°C in MDCK cells with an m.o.i. of 0.001. Mean values for triplicate infections at 12, 24, 48, and 72 hours were plotted as TCID50/mL.

Results

Control experiments showed replication of PR8 (AA) and PR8 (Len) in MDCK cells was significantly decreased as compared with WT PR8 at 37°C and 39°C at 24–48 hour time points, but not at 33C (the temperature of nasal passages). We found that polymerase activity was up to 3 logs more temperature-sensitive (ts) at 37°C and 39°C with the combined Len and AA mutations using the mini-replicon assay. In the growth curve experiments, the combined Len and AA mutations conferred up to a 4-log decrease in replication levels at 37°C as compared with PR8 (Len) and an even greater decrease compared with PR8 (AA).

Conclusion

Our findings suggest combining the AA and Len LAIV polymerase mutations decreases LAIV replication at body temperature (37°C), as compared with either LAIV alone. This could be useful in developing an improved LAIV that is safer in vulnerable hosts (e.g., children under the age of 2 who may be vulnerable to wheezing), while also permitting dose escalation that might result in greater efficacy.

Minireplicon assay.

Polymerase activity of combination mutants.

Multicycle replication kinetics of combination mutants (red) against PR8 Len (black) at 33C (solid), 37C (dashed) and 39C (dotted).

Disclosures

All authors: No reported disclosures.

Display of the HIV envelope protein at the yeast cell surface for immunogen development

As a step toward the development of variant forms of Env with enhanced immunogenic properties, we have expressed the glycoprotein in the yeast surface display system in a form that can be subjected to random mutagenesis followed by screening for forms with enhanced binding to germline antibodies. To optimize the expression and immunogenicity of the yeast-displayed Env protein, we tested different approaches for cell wall anchoring, expression of gp120 and gp140 Env from different viral strains, the effects of introducing mutations designed to stabilize Env, and the effects of procedures for altering N-linked glycosylation of Env. We find that diverse forms of HIV envelope glycoprotein can be efficiently expressed at the yeast cell surface and that gp140 forms of Env are effectively cleaved by Kex2p, the yeast furin protease homolog. Multiple yeast-displayed gp120 and gp140 proteins are capable of binding to antibodies directed against the V3-variable loop, CD4 binding site, and gp41 membrane-proximal regions, including some antibodies whose binding is known to depend on Env conformation and N-linked glycan. Based on antibody recognition and sensitivity to glycosidases, yeast glycosylation patterns partially mimic high mannose-type N-glycosylation in mammalian cells. However, yeast-displayed Env is not recognized by some anti-Env antibodies sensitive to quaternary structure, suggesting either that the displayed protein exists in a monomeric state or that for these antibodies, yeast glycosylation in certain regions hinders recognition or access. Consistent with studies in other systems, reconstructed predicted unmutated precursors to anti-Env antibodies exhibit little affinity for the yeast-displayed envelope protein.

Natural Seminal Amyloids as Targets for Development of Synthetic Inhibitors of HIV Transmission

Amyloids refer to a class of protein or peptide aggregates that are heterogeneous in size, morphology, and composition, and are implicated to play a central role in many neurodegenerative and systemic diseases. The strong correlation between biological activity and extent of aggregation of amyloidogenic proteins and peptides has led to an explosion of research efforts to target these materials with synthetic molecules or engineered antibodies to try to attenuate their function in disease pathology. Although many of these efforts to attenuate amyloid function have shown great promise in laboratory settings, the vast majority of work has been focused on targeting amyloids associated with neurologic diseases, which has been met with significant additional challenges that preclude clinical evaluation. Only recently have researchers started applying their efforts toward neutralizing the activity of amyloids associated with non-neurologic diseases. For instance, small peptides present in high abundance in human semen have been found to aggregate into amyloid-like fibrils, with in vitro experiments indicating that these amyloid fibrils could potentially increase the rate of infection of pathogens such as HIV by over 400 000-fold during sexual contact. Mechanistic investigations of naturally occurring seminal amyloid species such as Semen-derived Enhancer of Virus Infection (SEVI) and related natural peptide aggregates suggest that these materials interact strongly with virus particles and cell surfaces, facilitating viral attachment and internalization into cells and, thus, possibly promoting sexual transmission of disease. Such amyloid mediators in HIV transmission represent an attractive target for development of chemical approaches to attenuate their biological activity. For instance, the activity of seminal amyloids in genital fluids potentially allows for topical delivery of amyloid-targeting molecules, which could minimize common problems with systemic toxicity or permeability across biological barriers. In addition, molecules that target these amyloid mediators in viral attachment could potentially work synergistically with current antiviral agents to reduce the rate of HIV transmission. This Account will briefly summarize some of the key evidence in support of the capability of SEVI to enhance viral infection, and will highlight examples, many from our group, of recent efforts aimed at inhibiting its activity using synthetic small molecules, oligomeric peptides, and polymeric materials. We present various chemical strategies that have shown promise for neutralizing the role of SEVI in HIV transmission including the development of aggregation inhibitors of SEVI fibril formation, small molecule amyloid binders that modulate the charge or structure of SEVI, and synthetic molecules that form bioresistive coatings on SEVI and inhibit its interaction with the virus or cell surface. We discuss some unique challenges that hamper translation of these molecular strategies toward clinical evaluation, and propose several opportunities for researchers to address these challenges.

HIV-1 Frameshift RNA-Targeted Triazoles Inhibit Propagation of Replication-Competent and Multi-Drug-Resistant HIV in Human Cells

The HIV-1 frameshift-stimulating (FSS) RNA, a regulatory RNA of critical importance in the virus’ life cycle, has been posited as a novel target for anti-HIV drug development. We report the synthesis and evaluation of triazole-containing compounds able to bind the FSS with high affinity and selectivity. Readily accessible synthetically, these compounds are less toxic than previously reported olefin congeners. We show for the first time that FSS-targeting compounds have antiviral activity against replication-competent HIV in human cells, including a highly cytopathic, multidrug-resistant strain. These results support the viability of the HIV-1 FSS RNA as a therapeutic target and more generally highlight opportunities for synthetic molecule-mediated interference with protein recoding in a wide range of organisms.

Hydrophobic Nanoparticles Reduce the β-Sheet Content of SEVI Amyloid Fibrils and Inhibit SEVI-Enhanced HIV Infectivity

Semen-derived enhancer of virus infection (SEVI) fibrils are naturally abundant amyloid aggregates found in semen that facilitate viral attachment and internalization of human immunodeficiency virus (HIV) in cells, thereby increasing the probability of infection. Mature SEVI fibrils are composed of aggregated peptides exhibiting high β-sheet secondary structural characteristics. Herein, we show that polymers containing hydrophobic side chains can interact with SEVI and reduce its β-sheet content by ∼45% compared with the β-sheet content of SEVI in the presence of polymers with hydrophilic side chains, as estimated by polarization modulation-infrared reflectance absorption spectroscopy measurements. A nanoparticle (NP) formulation of this hydrophobic polymer reduced SEVI-mediated HIV infection in TMZ-bl cells by 60% compared with the control treatment. Although these NPs lacked specific amyloid-targeting groups, thus requiring high concentrations to observe biological activity, the use of hydrophobic interactions to alter the secondary structure of amyloids represents a useful approach to neutralizing the SEVI function. These results could, therefore, have general implications in the design of novel materials that can modify the activity of amyloids associated with a variety of other neurological and systemic diseases.

Nanoparticles decorated with viral antigens are more immunogenic at low surface density

There is an urgent need to develop protective vaccines for high priority viral pathogens. One approach known to enhance immune responses to viral proteins is to display them on a nanoparticle (NP) scaffold. However, little is known about the effect of protein density on the B cell response to antigens displayed on NPs. To address this question HIV-1 Envelope (Env) and influenza hemagglutinin (HA) were displayed on a polystyrene-based NP scaffold at various densities - corresponding to mean antigen distances that span the range encountered on naturally occurring virions. Our studies revealed that NPs displaying lower densities of Env or HA more efficiently stimulated antigen-specific B cells in vitro, as measured by calcium flux, than did NPs displaying higher antigen densities. Similarly, NPs displaying a low density of Env or HA also elicited higher titers of antigen-specific serum IgG in immunized BALB/c mice (including elevated titers of hemagglutination-inhibiting antibodies), as well as an increased frequency of antigen-specific antibody secreting cells in the lymph node, spleen and bone marrow. Importantly, our studies showed that the enhanced B cell response elicited by the lower density NPs is likely secondary to more efficient development of follicular helper CD4 T cells and germinal center B cells. These findings demonstrate that the density of antigen on a NP scaffold is a critical determinant of the humoral immune response elicited, and that high density display does not always result in an optimal response.

Display of HIV-1 Envelope Protein on Lambda Phage Scaffold as a Vaccine Platform

The generation of a strong antibody response to target antigens is a major goal for vaccine development. Here we describe the display of the human immunodeficiency virus (HIV) envelope spike protein (Env) on a virus-like scaffold provided by the lambda phage capsid. Phage vectors, in general, have advantages over mammalian virus vectors due to their genetic tractability, inexpensive production, suitability for scale-up, as well as their physical stability, making them an attractive vaccine platform.

Quantification of Cerebral Vascular Architecture using Two-photon Microscopy in a Mouse Model of HIV-induced Neuroinflammation

Human Immunodeficiency Virus 1 (HIV-1) infection frequently results in HIV-1 Associated Neurocognitive Disorders (HAND), and is characterized by a chronic neuroinflammatory state within the central nervous system (CNS), thought to be driven principally by virally-mediated activation of microglia and brain resident macrophages. HIV-1 infection is also accompanied by changes in cerebrovascular blood flow (CBF), raising the possibility that HIV-associated chronic neuroinflammation may lead to changes in CBF and/or in cerebral vascular architecture. To address this question, we have used a mouse model for HIV-induced neuroinflammation, and we have tested whether long-term exposure to this inflammatory environment may damage brain vasculature and result in rarefaction of capillary networks. In this paper we describe a method to quantify changes in cortical capillary density in a mouse model of neuroinflammatory disease (HIV-1 Tat transgenic mice). This generalizable approach employs in vivo two-photon imaging of cortical capillaries through a thin-skull cortical window, as well as ex vivo two-photon imaging of cortical capillaries in mouse brain sections. These procedures produce images and z-stack files of capillary networks, respectively, which can be then subjected to quantitative analysis in order to assess changes in cerebral vascular architecture.

Chronic central nervous system expression of HIV-1 Tat leads to accelerated rarefaction of neocortical capillaries and loss of red blood cell velocity heterogeneity

OBJECTIVES

HIV-1 infection of the CNS is associated with impairment of CBF and neurocognitive function, and accelerated signs of aging. As normal aging is associated with rarefaction of the cerebral vasculature, we set out to examine chronic viral effects on the cerebral vasculature.

METHODS

DOX-inducible HIV-1 Tat-tg and WT control mice were used. Animals were treated with DOX for three weeks or five to seven months. Cerebral vessel density and capillary segment length were determined from quantitative image analyses of sectioned cortical tissue. In addition, movement of red blood cells in individual capillaries was imaged in vivo using multiphoton microscopy, to determine RBCV and flux.

RESULTS

Mean RBCV was not different between Tat-tg mice and age-matched WT controls. However, cortical capillaries from Tat-tg mice showed a significant loss of RBCV heterogeneity and increased RBCF that was attributed to a marked decrease in total cortical capillary length (35-40%) compared to WT mice.

CONCLUSIONS

Cerebrovascular rarefaction is accelerated in HIV-1 Tat-transgenic mice, and this is associated with alterations in red cell blood velocity. These changes may have relevance to the pathogenesis of HIV-associated neurocognitive disorders in an aging HIV-positive population.

Inhibition of the enhancement of infection of human immunodeficiency virus by semen-derived enhancer of virus infection using amyloid-targeting polymeric nanoparticles

The semen-derived enhancer of virus infection (SEVI) is a natural amyloid material that has been shown to substantially increase viral attachment and infectivity of HIV in cells. We previously reported that synthetic monomeric and oligomeric amyloid-targeting molecules could form protein-resistive coatings on SEVI and inhibit SEVI- and semen-mediated enhancement of HIV infectivity. While oligomeric amyloid-binding compounds showed substantial improvement in apparent binding to SEVI compared to monomeric compounds, we observed only a modest correlation between apparent binding to SEVI and activity for reducing SEVI-mediated HIV infection. Here, we synthesized amyloid-binding polyacrylate-based polymers and polymeric nanoparticles of comparable size to HIV virus particles (∼150 nm) to assess the effect of sterics on the inhibition of SEVI-mediated enhancement of HIV infectivity. We show that these polymeric materials exhibit excellent capability to reduce SEVI-mediated enhancement of HIV infection, with the nanoparticles exhibiting the greatest activity (IC50 value of ∼4 μg/mL, or 59 nM based on polymer) of any SEVI-neutralizing agent reported to date. The results support that the improved activity of these nanomaterials is likely due to their increased size (diameters = 80-200 nm) compared to amyloid-targeting small molecules and that steric interactions may play as important a role as binding affinity in inhibiting viral infection mediated by SEVI amyloids. In contrast to the previously reported SEVI-neutralizing, amyloid-targeting molecules (which required concentrations at least 100-fold above the Kd to observe activity), the approximate 1:1 ratio of apparent Kd to IC50 for activity of these polymeric materials suggests the majority of polymer molecules that are bound to SEVI contribute to the inhibition of HIV infectivity enhanced by SEVI. Such size-related effects on physical inhibition of protein-protein interactions may open further opportunities for the use of targeted nanomaterials in disease intervention.

Pharmacologic inhibition of MLK3 kinase activity blocks the in vitro migratory capacity of breast cancer cells but has no effect on breast cancer brain metastasis in a mouse xenograft model

Brain metastasis of breast cancer is an important clinical problem, with few therapeutic options and a poor prognosis. Recent data have implicated mixed lineage kinase 3 (MLK3) in controlling the in vitro migratory capacity of breast cancer cells, as well as the metastasis of MDA-MB-231 breast cancer cells from the mammary fat pad to distant lymph nodes in a mouse xenograft model. We therefore set out to test whether MLK3 plays a role in brain metastasis of breast cancer cells. To address this question, we used a novel, brain penetrant, MLK3 inhibitor, URMC099. URMC099 efficiently inhibited the migration of breast cancer cells in an in vitro cell monolayer wounding assay, and an in vitro transwell migration assay, but had no effect on in vitro cell growth. We also tested the effect of URMC099 on tumor formation in a mouse xenograft model of breast cancer brain metastasis. This analysis showed that URMC099 had no effect on the either the frequency or size of breast cancer brain metastases. We conclude that pharmacologic inhibition of MLK3 by URMC099 can reduce the in vitro migratory capacity of breast cancer cells, but that it has no effect on either the frequency or size of breast cancer brain metastases, in a mouse xenograft model.

Abstract 315: The Role of Mixed Lineage Kinase 3 in Inflammatory Cell-Fibroblast Communication

Mixed lineage kinase 3 (MLK3) is a ubiquitously expressed pro-inflammatory, pro-apoptotic mitogen activated protein kinase kinase kinase (MAP3K). MLK3 is a key regulator of the p38 and c-jun terminal kinase (JNK) pathways and has been studied in cancer and neurodegenerative disease. Although the p38 and JNK pathways have been studied in the cardiac function and disease, little is known regarding the role of MLK3 in the heart. Studies in our laboratory have indicated that MLK3 RNA is highly expressed in macrophages, cardiomyocytes and cardiac fibroblasts, suggesting an important role in cardiac function. Recently published work has indicated that MLK3 plays an important role in inflammatory cell motility, leading us to hypothesize that MLK3 is involved in inflammatory cell-fibroblast communication during cardiac disease. Knockout (KO) or inhibition of MLK3 using the novel small molecule inhibitor URMC-099 does not significantly affect heart rate, mean arterial pressure, systolic pressure, minimum or maximum dp/dt compared to wild type (WT) controls as measured by invasive hemodynamics at 3 months of age. Echocardiographic analysis indicates that MLK3 KO or inhibition does not affect cardiac architecture or cardiac function, indicated by fractional shortening or ejection fraction. However, upon transaortic constriction (TAC), MLK3 KO and URMC-099 treatment results in decreases in Mac-3 positive staining at 3 and 7 days post-TAC as well as decreases in CD-45 staining 7 days post-TAC compared to WT TAC operated, vehicle treated controls, suggesting that MLK3 KO and drug treatment may attenuate the early inflammatory response after TAC. Studies examining the relationship between the MLK3 mediated inflammatory response and subsequent fibrosis and cardiac dysfunction post-TAC are currently ongoing.

Theoretical model of critical issues in informed consent in HIV vaccine trials

The informed consent process (ICP) for HIV vaccine trials poses unique challenges and would benefit from improvements to its historically based structure and format. Here, we propose a theoretical framework that provides a basis for systematically evaluating and addressing these challenges. The proposed framework follows a linear pathway, starting with the precondition of voluntariness, three main variables of valid decision-making (competency, provision of information and understanding) and then the consequential outcome of either refusal or consent to participate. The existing literature reveals that culturally appropriate provision of information and resultant understanding by the vaccine trial participant are among the most significant factors influencing the authenticity of valid decision-making, though they may be overridden by other considerations, such as individual altruism, mistrust, and HIV-related stigma. Community collaborations to foster bidirectional transmission of information and more culturally tailored consenting materials, therefore, represent a key opportunity to enhance the ICP. By providing a visual synopsis of the issues most critical to IC effectiveness in a categorical and relational manner, the framework provided here presents HIV vaccine researchers a tool by which the ICP can be more systematically evaluated and consequently improved.

Classification of HHV-6A and HHV-6B as distinct viruses

Shortly after the discovery of human herpesvirus 6 (HHV-6), two distinct variants, HHV-6A and HHV-6B, were identified. In 2012, the International Committee on Taxonomy of Viruses (ICTV) classified HHV-6A and HHV-6B as separate viruses. This review outlines several of the documented epidemiological, biological, and immunological distinctions between HHV-6A and HHV-6B, which support the ICTV classification. The utilization of virus-specific clinical and laboratory assays for distinguishing HHV-6A and HHV-6B is now required for further classification. For clarity in biological and clinical distinctions between HHV-6A and HHV-6B, scientists and physicians are herein urged, where possible, to differentiate carefully between HHV-6A and HHV-6B in all future publications.

MLK3 regulates fMLP-stimulated neutrophil motility

INTRODUCTION

Mixed lineage kinase 3 (MLK3) is part of the intracellular regulatory system that connects extracellular cytokine or mitogen signals received through G-protein coupled receptors to changes in gene expression. MLK3 activation stimulates motility of epithelial cells and epithelial-derived tumor cells, but its role in mediating the migration of other cell types remains unknown. Since neutrophils play a crucial role in innate immunity and contribute to the pathogenesis of several diseases, we therefore examined whether MLK3 might regulate the motility of mouse neutrophils responding to a chemotactic stimulus, the model bacterial chemoattractant fMLP.

METHODS

The expression of Mlk3 in mouse neutrophils was determined by immunocytochemistry and by RT-PCR. In vitro chemotaxis in a gradient of fMLP, fMLP-stimulated random motility, fMLP-stimulated F-actin formation were measured by direct microscopic observation using neutrophils pre-treated with a novel small molecule inhibitor of MLK3 (URMC099) or neutrophils obtained from Mlk3-/- mice. In vivo effects of MLK3 inhibition were measured by counting the fMLP-induced accumulation of neutrophils in the peritoneum following pre-treatment with URMC099 in wild-type C57Bl/6 or mutant Mlk3-/- mice.

RESULTS

The expression of Mlk3 mRNA and protein was observed in neutrophils purified from wild-type C57Bl/6 mice but not in neutrophils from mutant Mlk3-/- mice. Chemotaxis by wild-type neutrophils induced by a gradient of fMLP was reduced by pre-treatment with URMC099. Neutrophils from C57Bl/6 mice pretreated with URMC099 and neutrophils from Mlk3-/- mice moved far less upon fMLP-stimulation and did not form F-actin as readily as untreated neutrophils from C57Bl/6 controls. In vivo recruitment of neutrophils into the peritoneum by fMLP was significantly reduced in wild-type mice treated with URMC099, as well as in untreated Mlk3-/- mice-thereby confirming the role of MLK3 in neutrophil migration.

CONCLUSIONS

Mlk3 mRNA is expressed in murine neutrophils. Genetic or pharmacologic inhibition of MLK3 blocks fMLP-mediated motility of neutrophils both in vitro and in vivo, suggesting that MLK3 may be a therapeutic target in human diseases characterized by exuberant neutrophil migration.

9G4+ antibodies isolated from HIV-infected patients neutralize HIV-1 and have distinct autoreactivity profiles

Potent HIV-1 specific broadly neutralizing antibodies (BNA) are uncommon in HIV infected individuals, and have proven hard to elicit by vaccination. Several, isolated monoclonal BNA are polyreactive and also recognize self-antigens, suggesting a breach of immune tolerance in persons living with HIV (PLWH). Persons with systemic lupus erythematosus (SLE) often have elevated levels of autoreactive antibodies encoded by the VH4-34 heavy chain immunoglobulin gene whose protein product can be detected by the 9G4 rat monoclonal antibody. We have recently found that levels of these “9G4+” antibodies are also elevated in PLWH. However, the putative autoreactive nature of these antibodies and the relationship of such reactivities with HIV neutralization have not been investigated. We therefore examined the autoreactivity and HIV neutralization potential of 9G4+ antibodies from PLWH. Results show that 9G4+ antibodies from PLWH bound to recombinant HIV-1 envelope (Env) and neutralized viral infectivity in vitro, whereas 9G4+ antibodies from persons with SLE did not bind to Env and failed to neutralize viral infectivity. In addition, while 9G4+ antibodies from PLWH retained the canonical anti-i reactivity that mediates B cell binding, they did not display other autoreactivities common to SLE 9G4+ antibodies, such as binding to cardiolipin and DNA and had much lower reactivity with apoptotic cells. Taken together, these data indicate that the autoreactivity of 9G4+ antibodies from PLWH is distinct from that of SLE patients, and therefore, their expansion is not due to a general breakdown of B cell tolerance but is instead determined in a more disease-specific manner by self-antigens that become immunogenic in the context of, and possibly due to HIV infection. Further studies of 9G4+ B cells may shed light on the regulation of B cell tolerance and interface between the generation of specific autoreactivities and the induction of antiviral immunity in persons living with HIV.

Use of bacteriophage particles displaying influenza virus hemagglutinin for the detection of hemagglutination-inhibition antibodies

Bacteriophage lambda capsids provide a flexible molecular scaffold that can be engineered to display a wide range of exogenous proteins, including full-length viral glycoproteins produced in eukaryotic cells. One application for such particles lies in the detection of virus-specific antibodies, since they may obviate the need to work with infectious stocks of highly pathogenic or emerging viruses that can pose significant biosafety and biocontainment challenges. Bacteriophage lambda capsids were produced that displayed an insect-cell derived, recombinant H5 influenza virus hemagglutinin (HA) on their surface. The particles agglutinated red blood cells efficiently, in a manner that could be blocked using H5 HA-specific monoclonal antibodies. The particles were then used to develop a modified hemagglutinination-inhibition (HAI) assay, which successfully identified human sera with H5 HA-specific HAI activity. These results demonstrate the utility of HA-displaying bacteriophage capsids for the detection of influenza virus-specific HAI antibodies.

Discovery, synthesis, and characterization of an orally bioavailable, brain penetrant inhibitor of mixed lineage kinase 3

Inhibition of mixed lineage kinase 3 (MLK3) is a potential strategy for treatment of Parkinson's disease and HIV-1 associated neurocognitive disorders (HAND), requiring an inhibitor that can achieve significant brain concentration levels. We report here URMC-099 (1) an orally bioavailable (F = 41%), potent (IC50 = 14 nM) MLK3 inhibitor with excellent brain exposure in mouse PK models and minimal interference with key human CYP450 enzymes or hERG channels. The compound inhibits LPS-induced TNFα release in microglial cells, HIV-1 Tat-induced release of cytokines in human monocytes and up-regulation of phospho-JNK in Tat-injected brains of mice. Compound 1 likely functions in HAND preclinical models by inhibiting multiple kinase pathways, including MLK3 and LRRK2 (IC50 = 11 nM). We compare the kinase specificity and BBB penetration of 1 with CEP-1347 (2). Compound 1 is well tolerated, with excellent in vivo activity in HAND models, and is under investigation for further development.

Poor Aerobic Fitness May Contribute to Cognitive Decline in HIV-infected Older Adults

The HIV-infected older adult (HOA) community is particularly vulnerable to cognitive impairment. Previous studies in the general older adult population have reported that lower scores on tests of cognitive function often correlate negatively with aerobic fitness [5-7]. HIV-infected individuals have significantly reduced aerobic fitness and physical function compared to HIV-uninfected individuals. Determining important correlates of cognitive ability may be beneficial in not only detecting precursors to future cognitive impairments, but also target areas for interventions. The purpose of this study was to investigate the relationship between cognitive ability and aerobic fitness in HIV-infected older adults. We conducted a cross-sectional study of HOA on antiretroviral therapy (ART) >50 years of age. Domain specific cognitive function was assessed by means of a neuropsychological battery. Aerobic fitness (VO2peak) was assessed using a graded, progressive treadmill test. Thirty-seven HOA on ART (mean±SD: age 59±6 years, BMI 28±5, CD4 663±337 cells/ml, duration since HIV diagnosis 17±7 years; 81% males) completed the cognitive tests. Several domains of cognition were significantly associated with VO2peak by Spearman correlation analysis (p<0.05). By step-wise adjusted regression VO2peak was most frequently and significantly related to many cognitive domains such as verbal and visual memory, visual perception, and language (p<0.05). We found that participants with higher Vo2peak were less likely to have more severe forms of HIV-associated neurocognitive disorders (HAND) such as mild neurocognitive disorder (OR=0.65; p=0.01) and HIV-associated dementia (OR=0.64; p=0.0006). In HOA and in conclusion, aerobic fitness is related to cognitive performance on various tasks. The likelihood of cognitive impairment increased with lower fitness levels. Therefore, increased fitness may serve an important factor in maintenance of cognition and neural integrity for aging HIV-infected individuals. Future prospective and large scale studies are needed to evaluate the effect of fitness and vascular stiffness and function on cognition and brain structure among HOA.

Abstract 301: Targeting Mixed Lineage Kinases in pathological cardiac fibroblast activation and intercellular communication

Cardiovascular disease (CVD) and the final clinical iteration, heart failure (HF), affect more than 82 million Americans yearly, affects >5.7 million). Although the cardiac myocyte has long been the focus of cardiac cellular research, our lab and others have demonstrated that pathological activation of cardiac fibroblasts (CF) after onset of disease or cardiac injury is also a key player in HF pathogenesis. Pathologic activation of CFs causes a release of various paracrine and autocrine factors that target cardiomyocytes (CM), local inflammatory cells and the CFs themselves. Elucidating the mechanisms involved in pathological ‘support cell (CF)’- ‘functional cell (CM)’ communication may hold therapeutic promise.

Mixed lineage kinase 3 (MLK3) is a stress activated mitogen-activated protein kinase kinase kinase (MAPKKK) involved in pro-apoptotic pathways. Inhibition of MLK3 in HAND results in the attenuation of microglial cell activation, preservation of neuronal function and synaptic structures. The parity between microglia-neuron communication and CF-CM communication and the effects of pathological activation on the respective support cells for each tissue type suggested a role for MLK3 in aberrant CF-CM cross-talk associated with the development and progression of HF. Preliminary data in mice subjected to a pharmacological model of HF (chronic isoproterenol) that were treated with a small molecule inhibitor (URMC-099) of MLK3 demonstrated a reduction in the development of myocardial fibrosis compared to vehicle treated animals. Additionally, small molecule MLK3 inhibition attenuated the development of myocardial hypertrophy as measured by heart weight: body weight and heart weight: tibia length ratios. Studies in cultured neonatal rat ventricular fibroblasts (NRVF) demonstrated that small molecule MLK3 inhibition attenuated CF activation and transition to a myofibroblast phenotype, including reductions of pathologic CF markers such as α-SMA, IL-6, IL-1β, and others. Our data demonstrate that MLK3 plays an important role in pathologic CF-CM communication and myocardial hypertrophy, and suggest that small molecule inhibition of MLK3 holds therapeutic promise for HF.

Directional Histogram Ratio at Random Probes: A Local Thresholding Criterion for Capillary Images

With the development of micron-scale imaging techniques, capillaries can be conveniently visualized using methods such as two-photon and whole mount microscopy. However, the presence of background staining, leaky vessels and the diffusion of small fluorescent molecules can lead to significant complexity in image analysis and loss of information necessary to accurately quantify vascular metrics. One solution to this problem is the development of accurate thresholding algorithms that reliably distinguish blood vessels from surrounding tissue. Although various thresholding algorithms have been proposed, our results suggest that without appropriate pre- or post-processing, the existing approaches may fail to obtain satisfactory results for capillary images that include areas of contamination. In this study, we propose a novel local thresholding algorithm, called directional histogram ratio at random probes (DHR-RP). This method explicitly considers the geometric features of tube-like objects in conducting image binarization, and has a reliable performance in distinguishing small vessels from either clean or contaminated background. Experimental and simulation studies suggest that our DHR-RP algorithm is superior over existing thresholding methods.

The new small-molecule mixed-lineage kinase 3 inhibitor URMC-099 is neuroprotective and anti-inflammatory in models of human immunodeficiency virus-associated neurocognitive disorders

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) is a significant source of disability in the HIV-infected population. Even with stringent adherence to anti-retroviral therapy, >50% of patients living with HIV-1 will develop HAND (Heaton et al., 2010). Because suppression of viral replication alone is not enough to stop HAND progression, there is a need for an adjunctive neuroprotective therapy in this population. To this end, we have developed a small-molecule brain-penetrant inhibitor with activity against mixed-lineage kinase 3 (MLK3), named URMC-099. MLK3 activation is associated with many of the pathologic hallmarks of HAND (Bodner et al., 2002, 2004; Sui et al., 2006) and therefore represents a prime target for adjunctive therapy based on small-molecule kinase inhibition. Here we demonstrate the anti-inflammatory and neuroprotective effects of URMC-099 in multiple murine and rodent models of HAND. In vitro, URMC-099 treatment reduced inflammatory cytokine production by HIV-1 Tat-exposed microglia and prevented destruction and phagocytosis of cultured neuronal axons by these cells. In vivo, URMC-099 treatment reduced inflammatory cytokine production, protected neuronal architecture, and altered the morphologic and ultrastructural response of microglia to HIV-1 Tat exposure. In conclusion, these data provide compelling in vitro and in vivo evidence to investigate the utility of URMC-099 in other models of HAND with the goal of advancement to an adjunctive therapeutic agent.

Pharmacokinetic interactions of CEP-1347 and atazanavir in HIV-infected patients

CEP-1347 is a potent inhibitor of mixed lineage kinase (MLK), which was investigated for ameliorating HIV-associated neurocognitive disorders. CEP-1347 and atazanavir pharmacokinetics were determined when CEP-1347 50 mg twice daily was administered to HIV-infected patients (n = 20) receiving combination antiretroviral therapy including atazanavir and ritonavir (ATV/RTV, 300/100 mg) once daily continuously. Co-administration of CEP-1347 and ATV/RTV resulted with significant changes in pharmacokinetics of ATV but not RTV. Specifically, an increase in ATV accumulation ratio of 15 % (p = 0.007) and a prolongation of T(½) from 12.7 to 15.9 h (p = 0.002) were observed. The results suggested that co-administration of CEP-1347 with ATV/RTV in HIV-infected patients might result in limited impact on ATV but not on RTV pharmacokinetics.

Anti-idiotypic monobodies derived from a fibronectin scaffold

Mimetics of conformational protein epitopes have broad applications but have been difficult to identify using conventional peptide phage display. The 10th type III domain of human fibronectin (FNfn10) has two extended, randomizable surface-exposed loops and might be more amenable to the identification of such mimetics. We therefore selected a library of FNfn10 clones, randomized in both loops (15 residues in all), for binding to monoclonal antibodies (mAbs) that recognize the HIV-1 envelope glycoprotein. Anti-idiotypic monobodies (αIMs) mimicking both "linear" epitopes (2F5 and 4E10 mAbs) and conformational epitopes (b12 and VRC01 mAbs) were generated. αIMs selected against 2F5 and 4E10 frequently displayed sequence homology to the corresponding linear native epitopes. In the case of b12 and VRC01, we expected that the two constrained loop domains of FNfn10 would both contribute to complex conformational interactions with target antibodies. However, mutagenesis studies revealed differences from this simple model. An αIM selected against b12 was found to bind its cognate antibody via only a few residues within the BC loop of FNfn10, with minimal contribution from the FG loop. Unexpectedly, this was sufficient to generate a protein that engaged its cognate antibody in a manner very similar to that of HIV-1 Env, and with a strong KD (43 nM). In contrast, an αIM selected against VRC01 engaged its cognate antibody in a manner that was dependent on both BC and FG loop sequences. Overall, these data suggest that the FNfn10 scaffold can be used to identify complex structures that mimic conformational protein epitopes.

Transient hypercapnia reveals an underlying cerebrovascular pathology in a murine model for HIV-1 associated neuroinflammation: role of NO-cGMP signaling and normalization by inhibition of cyclic nucleotide phosphodiesterase-5

BACKGROUND

Cerebral blood flow (CBF) is known to be dysregulated in persons with human immunodeficiency virus 1 (HIV-1), for uncertain reasons. This is an important issue because impaired vasoreactivity has been associated with increased risk of ischemic stroke, elevated overall cardiovascular risk and cognitive impairment.

METHODS

To test whether dysregulation of CBF might be due to virally-induced neuroinflammation, we used a well-defined animal model (GFAP-driven, doxycycline-inducible HIV-1 Tat transgenic (Tat-tg) mice). We then exposed the mice to a brief hypercapnic stimulus, and assessed cerebrovascular reactivity by measuring 1) changes in cerebral blood flow, using laser Doppler flowmetry and 2) changes in vascular dilation, using in vivo two-photon imaging.

RESULTS

Exposure to brief hypercapnia revealed an underlying cerebrovascular pathology in Tat-tg mice. In control animals, brief hypercapnia induced a brisk increase in cortical flow (20.8% above baseline) and vascular dilation, as measured by laser Doppler flowmetry and in vivo two-photon microscopy. These responses were significantly attenuated in Tat-tg mice (11.6% above baseline), but cortical microvascular morphology and capillary density were unaltered, suggesting that the functional pathology was not secondary to vascular remodeling. To examine the mechanistic basis for the diminished cerebrovascular response to brief hypercapnia, Tat-tg mice were treated with 1) gisadenafil, a phosphodiesterase 5 (PDE5) inhibitor and 2) tetrahydrobiopterin (BH4). Gisadenafil largely restored the normal increase in cortical flow following hypercapnia in Tat-tg mice (17.5% above baseline), whereas BH4 had little effect. Gisadenafil also restored the dilation of small (<25 μm) arterioles following hypercapnia (19.1% versus 20.6% diameter increase in control and Tat-tg plus gisadenafil, respectively), although it failed to restore full dilation of larger (>25 μm) vessels.

CONCLUSIONS

Taken together, these data show that HIV-associated neuroinflammation can cause cerebrovascular pathology through effects on cyclic guanosine monophosphate (cGMP) metabolism and possibly on PDE5 metabolism.