Oncolytic herpes simplex viruses designed for targeted treatment of EGFR-bearing tumors

Oncolytic herpes simplex viruses (oHSVs) have emerged as leading cancer therapeutic agents. Effective oHSV virotherapy may ultimately require both intratumoral and systemic vector administration to target the primary tumor and distant metastases. An attractive approach to enhancing oHSV tumor specificity is engineering the virus envelope glycoproteins for selective recognition of and infection via tumor-specific cell surface proteins. We previously demonstrated that oHSVs could be retargeted to EGFR-expressing cells by the incorporation of a single-chain antibody (scFv) at the N terminus of glycoprotein D (gD). Here, we compared retargeted oHSVs generated by the insertion of scFv, affibody molecule, or VHH antibody ligands at different positions within the N terminus of gD. When compared to the scFv-directed oHSVs, VHH and affibody molecules mediated enhanced EGFR-specific tumor cell entry, spread and cell killing in vitro, and enabled long-term tumor-specific virus replication following intravenous delivery in vivo. Moreover, oHSVs retargeted via a VHH ligand reduced tumor growth upon intravenous injection and achieved complete tumor destruction after intratumoral injection. Systemic oHSV delivery is important for the treatment of metastatic disease, and our enhancements in targeted oHSV design are a critical step in creating an effective tumor-specific oHSVs for safe administration via the bloodstream.

Novel mutations in UL24 and gH rescue efficient infection of an HSV vector retargeted to TrkA

Transductional targeting of herpes simplex virus (HSV)-based gene therapy vectors offers the potential for improved tissue-specific delivery and can be achieved by modification of the viral entry machinery to incorporate ligands that bind the desired cell surface proteins. The interaction of nerve growth factor (NGF) with tropomyosin receptor kinase A (TrkA) is essential for survival of sensory neurons during development and is involved in chronic pain signaling. We targeted HSV infection to TrkA-bearing cells by replacing the signal peptide and HVEM binding domain of glycoprotein D (gD) with pre-pro-NGF. This TrkA-targeted virus (KNGF) infected cells via both nectin-1 and TrkA. However, infection through TrkA was inefficient, prompting a genetic search for KNGF mutants showing enhanced infection following repeat passage on TrkA-expressing cells. These studies revealed unique point mutations in envelope glycoprotein gH and in U_L24, a factor absent from mature particles. Together these mutations rescued efficient infection of TrkA-expressing cells, including neurons, and facilitated the production of a completely retargeted KNGF derivative. These studies provide insight into HSV vector improvements that will allow production of replication-defective TrkA-targeted HSV for delivery to the peripheral nervous system and may be applied to other retargeted vector studies in the central nervous system.

Evolution of the SARS-CoV-2 proteome in three dimensions (3D) during the first 6 months of the COVID-19 pandemic

Understanding the molecular evolution of the SARS-CoV-2 virus as it continues to spread in communities around the globe is important for mitigation and future pandemic preparedness. Three-dimensional structures of SARS-CoV-2 proteins and those of other coronavirusess archived in the Protein Data Bank were used to analyze viral proteome evolution during the first 6 months of the COVID-19 pandemic. Analyses of spatial locations, chemical properties, and structural and energetic impacts of the observed amino acid changes in >48 000 viral isolates revealed how each one of 29 viral proteins have undergone amino acid changes. Catalytic residues in active sites and binding residues in protein-protein interfaces showed modest, but significant, numbers of substitutions, highlighting the mutational robustness of the viral proteome. Energetics calculations showed that the impact of substitutions on the thermodynamic stability of the proteome follows a universal bi-Gaussian distribution. Detailed results are presented for potential drug discovery targets and the four structural proteins that comprise the virion, highlighting substitutions with the potential to impact protein structure, enzyme activity, and protein-protein and protein-nucleic acid interfaces. Characterizing the evolution of the virus in three dimensions provides testable insights into viral protein function and should aid in structure-based drug discovery efforts as well as the prospective identification of amino acid substitutions with potential for drug resistance.

Treatment of glioblastoma with current oHSV variants reveals differences in efficacy and immune cell recruitment

Oncolytic herpes simplex viruses (oHSVs) have demonstrated efficient lytic replication in human glioblastoma tumors using immunodeficient mouse models, but early-phase clinical trials have reported few complete responses. Potential reasons for the lack of efficacy are limited vector potency and the suppressive glioma tumor microenvironment (TME). Here we compare the oncolytic activity of two HSV-1 vectors, a KOS-strain derivative KG4:T124 and an F-strain derivative rQNestin34.5v.1, in the CT2A and GL261N4 murine syngeneic glioma models. rQNestin34.5v1 generally demonstrated a greater in vivo viral burden compared to KG4:T124. However, both vectors were rapidly cleared from CT2A tumors, while virus remained ensconced in GL261N4 tumors. Immunological evaluation revealed that the two vectors induced similar changes in immune cell recruitment to either tumor type at 2 days after infection. However, at 7 days after infection, the CT2A microenvironment displayed the phenotype of an untreated tumor, while GL261N4 tumors exhibited macrophage and CD4+/CD8+ T cell accumulation. Furthermore, the CT2A model was completely resistant to virus therapy, while in the GL261N4 model rQNestin34.5v1 treatment resulted in enhanced macrophage recruitment, impaired tumor progression, and long-term survival of a few animals. We conclude that prolonged intratumoral viral presence correlates with immune cell recruitment, and both are needed to enhance anti-tumor immunity.

Undergraduate structural biology education: A shift from users to developers of computation and simulation tools

The use of theory and simulation in undergraduate education in biochemistry, molecular biology, and structural biology is now common, but the skills students need and the curriculum instructors have to train their students are evolving. The global pandemic and the immediate switch to remote instruction forced instructors to reconsider how they can use computation to teach concepts previously approached with other instructional methods. In this review, we survey some of the curricula, materials, and resources for instructors who want to include theory, simulation, and computation in the undergraduate curriculum. There has been a notable progression from teaching students to use discipline-specific computational tools to developing interactive computational tools that promote active learning to having students write code themselves, such that they view computation as another tool for solving problems. We are moving toward a future where computational skills, including programming, data analysis, visualization, and simulation, will no longer be considered an optional bonus for students but a required skill for the 21st century STEM (Science, Technology, Engineering, and Mathematics) workforce; therefore, all physical and life science students should learn to program in the undergraduate curriculum.

Abstract PO089: Comparison of Two oHSV Vectors for the Treatment of Glioblastoma

Glioblastoma multiforme (GBM) is the most common human brain cancer. Despite a well-established standard of care, the 5-year mortality rate of GBM patients is 95%, highlighting the need for innovative therapeutic interventions. A variety of oncolytic viruses, including those derived from herpes simplex virus (oHSV), have been designed for GBM therapy, but early-phase clinical trials have reported few complete responses without evidence of durable anti-tumor immunity. Potential reasons for the lack of efficacy are limited vector potency (i.e., virulence) and the presence of a highly immunosuppressive tumor microenvironment (TME) comprised of few activated lymphocytes, large numbers of immunosuppressive myeloid cells (macrophages, myeloid derived suppressor cells [MDSCs], microglia), and an agglomerate of immunosuppressive cytokines (IL-10, VEGF, MIF, etc.). Herein we explore these obstacles by comparing the anti-tumor activity of two different oHSV designs and by arming oHSV with an immunomodulatory payload designed to encourage the development of anti-tumor immunity. We first compared the activities of an HSV-1 KOS strain derivative designated KG4:T124 or colloquially, 2A5B, and an F strain derivative designated rQNestin34.5v.1 (a similar oHSV, rQNestin34.5v.2, is currently in a phase I clinical trial for GBM). We evaluated viral entry, replication capacity, and cytotoxicity using both murine and human glioma cell lines in vitro. Viral entry was relatively similar between both vectors, but rQNestin34.5v.1 replicated more effectively and generally induced greater viral mediated cytotoxicity. In syngeneic mice, rQNestin34.5v.1 reduced orthotopic GL261N4 tumor burden compared to 2A5B, but neither virus impeded disease progression in the more pernicious CT2A model. Evaluation of either the GL261N4 or CT2A TME revealed that both viruses induced a high influx of tumor associated macrophages, a transient polymorphonuclear (PMN) cell population, but did not alter the frequency of monocytic MDSCs. As a strategy to enhance oHSV efficacy, we sought to differentiate the highly immunosuppressive MDSC population into pro-inflammatory macrophages using oHSV armed with IL-12, a cytokine that has been shown to provide this activity. We show that oHSV:IL-12 induced a significant increase in tumor-associated macrophages and increased the survival of animals bearing either tumor type. Although we observed a low percentage of complete responses with the presence of anti-tumor CTLs demonstrated by tumor rechallenge experiments, IL-12 alone was not sufficient to significantly improve overall long-term animal survival, suggesting that additional arming genes should be considered in combination with IL-12.

Citation Format: Joseph W. Jackson, Bonnie L. Hall, Lisa Bailey, Christophe Quéva, E. Antonio Chiocca, Justus B. Cohen, Joseph C. Glorioso. Comparison of Two oHSV Vectors for the Treatment of Glioblastoma [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO089.

Evolution of the SARS-CoV-2 proteome in three dimensions (3D) during the first six months of the COVID-19 pandemic

Three-dimensional structures of SARS-CoV-2 and other coronaviral proteins archived in the Protein Data Bank were used to analyze viral proteome evolution during the first six months of the COVID-19 pandemic. Analyses of spatial locations, chemical properties, and structural and energetic impacts of the observed amino acid changes in >48,000 viral proteome sequences showed how each one of the 29 viral study proteins have undergone amino acid changes. Structural models computed for every unique sequence variant revealed that most substitutions map to protein surfaces and boundary layers with a minority affecting hydrophobic cores. Conservative changes were observed more frequently in cores versus boundary layers/surfaces. Active sites and protein-protein interfaces showed modest numbers of substitutions. Energetics calculations showed that the impact of substitutions on the thermodynamic stability of the proteome follows a universal bi-Gaussian distribution. Detailed results are presented for six drug discovery targets and four structural proteins comprising the virion, highlighting substitutions with the potential to impact protein structure, enzyme activity, and functional interfaces. Characterizing the evolution of the virus in three dimensions provides testable insights into viral protein function and should aid in structure-based drug discovery efforts as well as the prospective identification of amino acid substitutions with potential for drug resistance.

Point Mutations in Retargeted gD Eliminate the Sensitivity of EGFR/EGFRvIII-Targeted HSV to Key Neutralizing Antibodies

Effective oncolytic virotherapy may require systemic delivery, tumor targeting, and resistance to virus-neutralizing (VN) antibodies. Since herpes simplex virus (HSV) glycoprotein D (gD) is the viral attachment/entry protein and predominant VN target, we examined the impact of gD retargeting alone and in combination with alterations in dominant VN epitopes on virus susceptibility to VN antibodies. We compared the binding of a panel of anti-gD monoclonal antibodies (mAbs) that mimic antibody specificities in human HSV-immune sera to the purified ectodomains of wild-type and retargeted gD, revealing the retention of two prominent epitopes. Substitution of a key residue in each epitope, separately and together, revealed that both substitutions (1) blocked retargeted gD recognition by mAbs to the respective epitopes, and, in combination, caused a global reduction in mAb binding; (2) protected against fusion inhibition by VN mAbs reactive with each epitope in virus-free cell-cell fusion assays; and (3) increased the resistance of retargeted HSV-1 to these VN mAbs. Although the combined modifications of retargeted gD allowed bona fide retargeting, incorporation into virions was partially compromised. Our results indicate that stacking of epitope mutations can additively block retargeted gD recognition by VN antibodies but also that improvements in gD incorporation into virus particles may be required.

Bullying perspectives among rural youth: a mixed methods approach

INTRODUCTION

Few studies have examined violence among rural youth even though it is recognized as a societal concern. A mixed method, descriptive study was conducted to examine violence among rural youth including their perceptions and experiences of it. This article focuses specifically on the perceptions and experiences of bullying among rural youth that were generated from the Qualitative Phase One interviews and Quantitative Phase Two responses.

METHOD

A mixed method study was conducted in two separate phases. The information generated from the Qualitative Phase One (n = 52) was used to develop a survey instrument employed in the subsequent Quantitative Phase Two (n = 180). The youth who were involved in each phase lived in different geographic areas of a Western Canadian province. The qualitative phase generated a number of comments about the experience of being bullied or how it felt to be a bully. In the survey instrument, specific questions related to bullying were embedded within it. Demographic information was collected in both phases of the study. Research assistants were used to collect the data in each phase. The transcripts from the qualitative phase were analyzed for categories and themes. The survey instrument included demographic questions and seventy questions that included a four-point Likert scale. The data were analyzed using SPSS v14 (SPSS Inc; Chicago, IL, USA). For this article, the survey questions that focused on bullying were considered alongside the qualitative comments in order to more fully understand the perceptions and viewpoints of rural youth regarding this particular aspect of violence.

RESULTS

Conducting a mixed method study provides a more in-depth understanding of bullying among youth in the rural context. The pain and humiliation of being bullied provided a personalized understanding of the survey responses that indicated which youth are targets of bullying. For example, comments were made about being picked on because of personal characteristics such as being overweight or dressing in an unacceptable manner. In addition, bullies openly talked about the power they gained from their role. The frequency responses to the questions in the survey confirmed that bullies obtain power from their behavior and that youth who are different are bullied. The participants also noted that something needed to be done to address bullying but remarked that they would not seek professionals' help.

DISCUSSION

The findings negate the myth that rural places are ideal places to raise children. Although the youth did not identify that they would access professionals, it is important for members of rural communities to acknowledge bullying, its impacts and how they can prevent it. Working from the social structure of rural communities is a first step in this process.

CONCLUSION

Rural communities will benefit as a whole if bullying, an important societal concern, is addressed. Building on the social structure of rural communities is important, However, listening to rural youth themselves is the key if true change is to be implemented.

Holocene elephant seal distribution implies warmer-than-present climate in the Ross Sea

We show that southern elephant seal (Mirounga leonina) colonies existed proximate to the Ross Ice Shelf during the Holocene, well south of their core sub-Antarctic breeding and molting grounds. We propose that this was due to warming (including a previously unrecognized period from approximately 1,100 to 2,300 (14)C yr B.P.) that decreased coastal sea ice and allowed penetration of warmer-than-present climate conditions into the Ross Embayment. If, as proposed in the literature, the ice shelf survived this period, it would have been exposed to environments substantially warmer than present.

Can professionals and nonprofessionals work together following a suicide?

Suicide is the taking of one's own life by one's own hand. It is often sudden and creates many emotional reactions for the survivors left behind. Survivor responses can be impacted by a range of circumstances, from how the person died to the reactions of people to the survivor. This contribution examines the uniqueness of survivor grief and how best to help survivors. It is suggested that their grief may be too quickly viewed as pathological, resulting in the premature medicalization of basically normal reactions. It is time for professionals and nonprofessionals to recognize boundaries and work toward mutual goals of health for those persons left behind after a suicide.

Field monitoring and performance evaluation of a field-scale in-well aeration system at a gasoline-contaminated site

Several in-well aeration (IWA) technologies have been used since the early 1990s, but few field studies have been performed to evaluate the extent of water circulation around IWA systems. In this study, 27 discrete monitoring points (MPs) were installed at a gasoline-contaminated site to assess the efficacy of IWA. Pressure transducers and dissolved oxygen (DO) probes were sealed into the MPs, allowing them to be used to characterize subsurface changes in total head and DO with depth, distance and orientation from a central injection well. No change in DO or in hydrocarbon total mass or distribution occurred across the site during two trials (41 and 20 days) of the system. Water level fluctuations during the trials were similar in all MPs, and were due to seasonal water table changes and rainfall events. No circulation cell was established around the IWA well after 41 days of operation, and the impact of the well extended less than 90cm from it. Groundwater only circulated through the sand pack around the well. Little, if any, recharge occurred through the lower screen. Silt accumulated in the well, limiting its operation time, even with a fabric filter sock over the lower screen. Obviously, IWA was ineffective at this site, probably because the horizontal hydraulic conductivity (K(h)) of the soil opposite the lower screen was low (0.09cm per day) and because the distance between the two screens was short relative to the borehole radius. Long remediation times would likely make IWA unattractive at this or other sites where the K(h) of the soil is so low that the air injection rate would have to be low to prevent blowing the well dry.

Field monitoring and performance evaluation of an in situ air sparging system at a gasoline-contaminated site

In situ air sparging (IAS) has been used since the mid-1980s, but few carefully designed field studies have been performed to evaluate its effectiveness. In this study, 27 discrete monitoring points (MPs) were installed at a gasoline-contaminated site to investigate the efficacy of IAS. Each MP was instrumented with a pressure transducer and a Technalithics dissolved oxygen (DO) probe, and located so they could be used to characterize subsurface changes in total head and DO with depth, distance and orientation around a central injection well. Because the blower over-heated and automatically shut down after approximately 30 min and short-circuiting of air into two MPs occurred within 2 min, the study was designed as three sets of three 30-min trials. Longer trials would not have yielded different nor more insightful results. A volume of soil was not oxygenated during any injection. Instead, air traveled directly to at least four of seven different MPs during eight of the nine trials, probably as a result of an air bubble forming beneath a confining layer. The order of air arrival at the MPs varied during the first few trials, but once a preferential pathway was established, it did not collapse between trials and provided the shortest distance to the vadose zone during subsequent trials. Oxygen uptake rates estimated for MPs that received air during any trial exceeded the consumption rates of the Technalithics DO probes, and indicate that the probes could be used for estimating oxygen transfer during system operation or for oxygen uptake measurements during shut-down tests. The data from the monitoring system indicate that IAS is infeasible for remediation of soil and groundwater at this site due to its low horizontal hydraulic conductivity. Similar behavior is anticipated when IAS is applied at other sites with low hydraulic conductivity materials.

Past and Future Grounding-Line Retreat of the West Antarctic Ice Sheet

The history of deglaciation of the West Antarctic Ice Sheet (WAIS) gives clues about its future. Southward grounding-line migration was dated past three locations in the Ross Sea Embayment. Results indicate that most recession occurred during the middle to late Holocene in the absence of substantial sea level or climate forcing. Current grounding-line retreat may reflect ongoing ice recession that has been under way since the early Holocene. If so, the WAIS could continue to retreat even in the absence of further external forcing.

DHR3 is required for the prepupal-pupal transition and differentiation of adult structures during Drosophila metamorphosis

Pulses of the steroid hormone ecdysone activate genetic regulatory hierarchies that coordinate the developmental changes associated with Drosophila metamorphosis. A high-titer ecdysone pulse at the end of larval development triggers puparium formation and induces expression of the DHR3 orphan nuclear receptor. Here we use both a heat-inducible DHR3 rescue construct and clonal analysis to define DHR3 functions during metamorphosis. Clonal analysis reveals requirements for DHR3 in the development of adult bristles, wings, and cuticle, and no apparent function in eye or leg development. DHR3 mutants rescued to the third larval instar also reveal essential functions during the onset of metamorphosis, leading to lethality during prepupal and early pupal stages. The phenotypes associated with these lethal phases are consistent with the effects of DHR3 mutations on ecdysone-regulated gene expression. Although DHR3 has been shown to be sufficient for early gene repression at puparium formation, it is not necessary for this response, indicating that other negative regulators may contribute to this pathway. In contrast, DHR3 is required for maximal expression of the midprepupal regulatory genes, EcR, E74B, and betaFTZ-1. Reductions in EcR and betaFTZ-F1 expression, in turn, lead to submaximal early gene induction in response to the prepupal ecdysone pulse and corresponding defects in adult head eversion and salivary gland cell death. These studies demonstrate that DHR3 is an essential regulator of the betaFTZ-F1 midprepupal competence factor, providing a functional link between the late larval and prepupal responses to ecdysone. Induction of DHR3 in early prepupae ensures that responses to the prepupal ecdysone pulse will be distinct from responses to the late larval pulse and thus that the animal progresses in an appropriate manner through the early stages of metamorphosis.

The RXR homolog ultraspiracle is an essential component of the Drosophila ecdysone receptor

Pulses of the steroid hormone ecdysone function as key temporal signals during insect development, coordinating the major postembryonic developmental transitions, including molting and metamorphosis. In vitro studies have demonstrated that the EcR ecdysone receptor requires an RXR heterodimer partner for its activity, encoded by the ultraspiracle (usp) locus. We show here that usp exerts no apparent function in mid-third instar larvae, when a regulatory hierarchy prepares the animal for the onset of metamorphosis. Rather, usp is required in late third instar larvae for appropriate developmental and transcriptional responses to the ecdysone pulse that triggers puparium formation. The imaginal discs in usp mutants begin to evert but do not elongate or differentiate, the larval midgut and salivary glands fail to undergo programmed cell death and the adult midgut fails to form. Consistent with these developmental phenotypes, usp mutants show pleiotropic defects in ecdysone-regulated gene expression at the larval-prepupal transition. usp mutants also recapitulate aspects of a larval molt at puparium formation, forming a supernumerary cuticle. These observations indicate that usp is required for ecdysone receptor activity in vivo, demonstrate that the EcR/USP heterodimer functions in a stage-specific manner during the onset of metamorphosis and implicate a role for usp in the decision to molt or pupariate in response to ecdysone pulses during larval development.

A novel tumor-specific human single-chain Fv selected from an active specific immunotherapy phage display library

A colon tumor-associated antigen, CTAA 28A32-32K (CTA # 2E), related to the annexin family of proteins, was initially identified by its reactivity with a low affinity human IgM monoclonal antibody (mAb), 28A32. Both in vitro lymphoproliferative assays with human peripheral blood lymphocytes and delayed type hypersensitivity responses in patients immunized with autologous colon tumor cells indicated that CTA # 2E elicits potent T cell mediated responses and may be an important antigen in the development of a generic colorectal vaccine (Pomato et al. Vaccine Res 1994;3:145-161). A CTA # 2E-specific, murine hybridoma-derived mAb, 5-11A, which recognizes the amino-terminus of the tumor-associated antigen, exhibited qualitative human colon tumor-specific immunohistochemical reactivity. To rapidly develop a human mAb with similar antigen specificity and tumor reactivity as the murine 5-11A mAb, antibody phage display technology was employed. Two human antibody phage display libraries with 3.1 x 10(7) and 2.3 x 10(8) members were prepared from the variable region genes expressed by circulating B cells of patients undergoing active specific immunotherapy (ASI) with autologous tumor cells, predominantly from the colon, admixed with Bacille Calmette-Guerin (BCG). A CTA # 2E-reactive human single-chain (sc)Fv was selected by panning the larger library on decreasing concentrations of biotinylated tumor-associated antigen in solution. It exhibited similar antigen specificity as the murine hybridoma-derived 5-11A scFv, requiring the presence of the CTA # 2E amino-terminus for reactivity. This human scFv exhibited qualitative human colon tumor-specific immunohistochemical reactivity when displayed as a gene III fusion protein on phage. When reconstructed and expressed as an intact human IgG1, K mAb, its qualitative colon tumor-specificity was unaltered. Two other CTA # 2E-reactive human scFvs were selected from the smaller library by panning initially on decreasing concentrations of CTA # 2E coated to polystyrene and then on biotinylated CTA # 2E in solution. These human scFvs, which exhibited modest reactivity with different epitopes on the CTA # 2E antigen, did not exhibit human colon tumor-specific immunohistochemical reactivity.

The 3'-untranslated region of membrane exon 2 from the gamma 2a immunoglobulin gene contributes to efficient transcription termination

Elements of the mouse Immunoglobulin gamma 2a gene, near the membrane-specific poly(A) addition site, were inserted into a heterologous location in either a synthetic mouse gamma 2b gene or a gpt/SV40 chimeric gene and then assayed for their ability to terminate RNA polymerase II transcription in isolated nuclei of transfected myeloma cells. The intact gamma 2a membrane-specific 3'-untranslated region, with its potential stem loop forming sequences and poly(A) site, is able to efficiently terminate transcription in the absence of the downstream region in which transcription normally terminates (term). Termination efficiency in the presence of the termination fragment decreases either when sequences specifying a potential stem/loop, upstream of the poly(A) region, are interrupted or when the stronger membrane poly(A) site is substituted with a weaker, secretory-specific poly(A) site. We therefore conclude that the gamma 2a membrane-specific untranslated region plays a major role in specifying downstream termination. We further conclude that the immunoglobulin gamma 2a, membrane-specific, 3'-untranslated region can function in the context of the gpt gene, driven by an SV40 promoter, to terminate transcription in a poly(A) site dependent fashion.

Establishment, molecular rescue, and expression of 123AV16-1, a tumor-reactive human monoclonal antibody

The human monoclonal antibody (mAb) 123AV16-1 was generated by Epstein-Barr virus transformation of peripheral blood lymphocytes from a colorectal patient undergoing active specific immunotherapy with an autologous tumor cell-Bacille Calmette-Guérin vaccine. Direct immunohistochemical staining of tumor and normal pairs of tissues indicated that this human IgA1, lambda 2 mAb preferentially reacted with colon tumor epithelium. To generate a recombinant derivative of this Epstein-Barr virus-transformed cell line, we isolated the expressed complete heavy and light chain genes by a novel strategy and cloned them into modified pSV2-neo and pSV2-gpt expression vectors. The recombinant 123AV16-1 human mAb was expressed in both a murine myeloma and a human-murine heteromyeloma and was secreted as both monomers and dimers. The recombinant 123AV16-1 mAb expressed by both cell lines reacted with human colon tumor xenografts in a manner similar to the mAb derived from the Epstein-Barr virus-transformed cell line, indicating that the antibody specificity was not appreciably altered during the molecular rescue, cloning, or expression.

Baboon and cotton-top tamarin B2m cDNA sequences and the evolution of primate beta 2-microglobulin

Nonhuman primates represent phylogenetic intermediates for studying the divergence of human and murine beta 2Ms. We report the nucleotide sequences of B2m cDNA clones from a baboon cell line, 26CB-1 (Papio hamadryas; primates: Cercopithecoidea), and a cotton-top tamarin cell line, 1605L (Saguinus oedipus; primates: Ceboidea). The baboon and tamarin B2m sequences indicate a very slow rate of B2m evolution in primates relative to that in murid rodents. Phenotypic evolution of beta 2M has also been very conservative in primates, with only 9-14 substitutions separating baboon or tamarin beta 2Ms from those of humans or orangutans. Analyses of silent and amino-acid-altering nucleotide substitutions provide evidence that negative selection has acted to limit variability in beta strands of primate beta 2Ms, while positive selection has promoted diversity in non-beta-strand regions of murine beta 2Ms. No evidence for the action of selection upon beta 2M residues that contact the class I heavy chain was found in primates or mice. The finding that different selective forces have operated upon primate and murine beta 2Ms suggests that beta 2M may have evolved to serve distinct functions in primates and mice.

v-erbA and citral reduce the teratogenic effects of all-trans retinoic acid and retinol, respectively, in Xenopus embryogenesis

Treatment of late blastula/early gastrula stage Xenopus embryos with all-trans retinoic acid results in disruption of the primary body axis through effects on both mesoderm and neuroectoderm. This effect of retinoic acid, coupled with the known presence of retinoic acid in Xenopus embryos has led to the proposal that retinoic acid may be an endogenous morphogen providing positional information in early development. To further elucidate the role of retinoic acid in early Xenopus development, we have attempted to interfere with the retinoic acid signalling pathway both at the level of retinoic acid formation, by treatment with citral (3,7-dimethy-2,6-octadienal), and at the level of nuclear retinoic acid receptor function, by microinjection of v-erbA mRNA. The feasibility of this approach was demonstrated by the ability of citral treatment and v-erbA mRNA injection to reduce the teratogenic effects of exogenous retinol and retinoic acid, respectively, in early Xenopus development. Interestingly, v-erbA mRNA injection and citral treatment of gastrula stage embryos resulted in tadpoles with a similar set of developmental defects. The defects were chiefly found in tissues that received a contribution of cells from the neural crest, suggesting that at least a subset of neural crest cells may be sensitive to the endogenous level of retinoic acid. In accord with this proposal, it was found that the expression patterns of two early markers of cranial neural crest cells, Xtwi and XAP-2, were altered in embryos injected with v-erbA mRNA. These results indicate that structures in addition to the primary axis are regulated by retinoic acid signalling during early Xenopus development.

Variables affecting the T cell receptor V beta repertoire heterogeneity of T cells infiltrating human renal allografts

Donor-specific, alloreactive T cell lines may be grown from cells infiltrating human renal allografts. These T cell lines utilize restricted T cell receptor (TCR) beta-chain variable (V beta) gene repertoires, although long-term culture appears to be necessary for restriction to be observed. This study was undertaken to determine the effects of potential selective pressures on the TCR repertoires of allograft-infiltrating cells. TCR V beta repertoires of 30 allograft-derived T cell populations, cultured for defined, short time periods, were examined using polymerase chain reaction. When first derived, V beta repertoires of graft-infiltrating T cells were as heterogeneous as those of peripheral blood lymphocytes (PBL). There was no relationship between the length of time an allograft was in situ or the extent of HLA mismatch and repertoire heterogeneity. Repertoire restriction was positively correlated with the length of time cells were cultured in vitro. Long-term, alloreactive mixed lymphocyte reactions (MLR), established from normal, unsensitized PBL, also demonstrated V beta repertoire restriction during expansion in vitro. Restricted alloreactive populations emerged much more slowly from the MLR than from the allograft-derived cultures, however, implying that graft infiltrates contain previously activated populations of T cells. This observation, taken together with the fact that long-term, graft-derived cell lines maintain donor specificity, suggests that functional subsets must be allowed to emerge from heterogeneous infiltrates before TCR repertoire may be correlated with alloreactivity and/or graft rejection.

Reconstitution of retinoid X receptor function and combinatorial regulation of other nuclear hormone receptors in the yeast Saccharomyces cerevisiae

The nuclear hormone receptor family of transcription factors regulates gene expression via a complex combinatorial network of interactions. Of particular interest is the ability of retinoid X receptors (RXRs) to form heterodimers with retinoic acid receptors (RARs) and thyroid hormone receptors (TRs), thereby modifying their activities. We report here that RXR, RAR, and TR function can be reconstituted in the yeast Saccharomyces cerevisiae and demonstrate that the combinatorial regulation seen in vertebrate cells can be reproduced in the yeast background. Using this system, we have shown that RARs respond to a wide variety of retinoid ligands but that RXRs are specific for the 9-cis isomer of retinoic acid. RXR enhanced the activity of RARs and TRs on a variety of hormone response elements without demonstrably altering their DNA specificity. Interestingly, the ability of RXR to potentiate gene activation by RARs and by TRs varied for different receptor isoforms.

T cell receptor V beta gene usage in HLA-DR1-reactive human T cell populations. The predominance of V beta 8

The functional specificity and T cell receptor (TCR) V beta gene expression of three class II HLA-DR1-reactive human T cell populations were examined. WP2, a renal allograft-derived, long-term CD4+ T cell line, was specifically cytotoxic for DR1, one of the mismatched antigens present on the allograft. Initial studies of WP2 using six TCR V beta-specific mAb revealed a predominance of T cells expressing a member of the V beta 8 gene family. A smaller, yet significant, number of cells expressed TCR using V beta 5.1. Semiquantitative V beta-specific polymerase chain reaction (PCR) analyses of RNA derived from this T cell line confirmed the presence of V beta 8 and V beta 5.1 messages. The PCR signal for V beta 8 was the strongest, followed by those for V beta 4 and V beta 5. An earlier WP2 culture had a very similar PCR profile, with a dominant signal for V beta 8, although signals for V beta 4 and V beta 5 were considerably lower. Previous PCR analyses of eight other renal allograft-derived, long-term T cell lines, grown under identical in vitro conditions, revealed no other example of predominant usage of V beta 8. We established two replicate long-term, anti-DR1 mixed lymphocyte reactions using PBL from two unrelated normal donors as responder and stimulator. The MLR were given alloantigen every 10 days, and RNA was obtained from the cultured cells immediately prior to each stimulation. PCR analyses of RNA taken at 10-day intervals over a total of 60-70 days indicated that, although the MLR were initially quite heterogeneous with regard to V beta message expression, by the end of the fourth or fifth Ag cycle the predominant PCR signals observed in both MLR were for V beta 8. These results suggest that T cells using V beta 8 gene-encoded segments as part of their TCR may have a selective advantage in responses to DR1.

A single amino acid mutation in CDR3 of the 3-14-9 L chain abolished expression of the IDA 10-defined idiotope and antigen binding

The ABPC 48 myeloma protein and the 3-14-9 mAb derive their V region genes from the same VH and V kappa gene families. They also share a cross-reactive idiotope defined by the anti-Id mAb IDA 10. Whereas ABPC 48 is specific for bacterial levan, 3-14-9 showed a significant Ag-binding activity to aminophenyl-beta-N-acetylglucosaminide (AZO). In order to define the molecular basis of idiotope expression and Ag-binding activity, we have cloned the genes encoding the 3-14-9 H and L chain V region genes, generated antibodies that carry mutations within the L chain genes, by site-directed mutagenesis, and investigated the effects of those mutations with respect to IDA 10 idiotope expression and binding to AZO. Our findings show that, whereas expression of the IDA 10-defined idiotope requires association of both the H and L chains, a single change (glycine to phenylalanine) at position 91 in the third complementarity-determining region of the L chain abolished both idiotope expression and Ag-binding activity. In addition, a L chain change of alanine to threonine at position 25 allowed idiotope expression to some extent but significantly reduced binding activity to AZO. These data suggest that a single amino acid change can play a crucial role in the functional activity and structural integrity of antibodies.

A single amino acid mutation in CDR3 of the 3-14-9 L chain abolished expression of the IDA 10-defined idiotope and antigen binding

The ABPC 48 myeloma protein and the 3-14-9 mAb derive their V region genes from the same VH and V kappa gene families. They also share a cross-reactive idiotope defined by the anti-Id mAb IDA 10. Whereas ABPC 48 is specific for bacterial levan, 3-14-9 showed a significant Ag-binding activity to aminophenyl-beta-N-acetylglucosaminide (AZO). In order to define the molecular basis of idiotope expression and Ag-binding activity, we have cloned the genes encoding the 3-14-9 H and L chain V region genes, generated antibodies that carry mutations within the L chain genes, by site-directed mutagenesis, and investigated the effects of those mutations with respect to IDA 10 idiotope expression and binding to AZO. Our findings show that, whereas expression of the IDA 10-defined idiotope requires association of both the H and L chains, a single change (glycine to phenylalanine) at position 91 in the third complementarity-determining region of the L chain abolished both idiotope expression and Ag-binding activity. In addition, a L chain change of alanine to threonine at position 25 allowed idiotope expression to some extent but significantly reduced binding activity to AZO. These data suggest that a single amino acid change can play a crucial role in the functional activity and structural integrity of antibodies.

PCR-based analysis of the T-cell receptor V beta multigene family: experimental parameters affecting its validity

The validity of semiquantitative, PCR-based analysis of gene expression within a multigene family, the human T-cell receptor (TCR) beta chain variable region family, was investigated. Primer comparability was addressed by grouping hybridization temperatures and limiting the size range of amplified fragments. Primers selected satisfied criteria for comprehensiveness, match to targets and discrimination of nontargets. Specificity was enhanced by maximizing mismatches with nontargets and using an elevated hybridization temperature. Reaction conditions are described that ensure specificity while maintaining sensitivity. Several results confirmed primer specificity. Limits on precision were documented: probable error was 3%-7% of mean value for target prevalences (% of all TCR mRNA represented by a particular V beta) in the 5%-40% range. Accuracy was limited by the nonlinear relationship between target prevalence and signal obtained. Because of this relationship, the effect of the observed limits of precision varied. Valid distinctions were possible between sufficiently separated prevalences, i.e., 0%-1%, 3%-5%, 10%, 30%, greater than 50%. Additional concerns addressed include: standardization of signals, coamplifiation and effects of primer artifacts, and the nature of the mRNA pool. Only when theoretical and practical limits in precision and accuracy are acknowledged can semiquantitative, PCR-based analysis be used with confidence to assess gene usage within a large, multigene family.

T cell receptor V beta gene usage in allograft-derived cell lines analyzed by a polymerase chain reaction technique

T cell receptor V beta gene usage in renal allograft-derived T cell lines was investigated using a semiquantitative, polymerase chain reaction (PCR)-based technique. A panel of V beta-specific primers was carefully designed to have uniform hybridization characteristics, enhancing comparability, and high specificity based on 3' mismatches between primers and nontarget V regions. PCR data were in concordance with previous phenotypic, functional, and Southern blot analyses, but the PCR technique proved to be more sensitive and comprehensive. For example, the EH3 cell line was confirmed to be polyclonal, with a number of different V beta genes mediating anti-DR8-linked reactivity. Sequence analysis showed the most prevalent signals obtained by PCR, those for V beta 7 and V beta 20, probably corresponded to the only two rearrangements detected by Southern. The J2 cell line was shown to be polyclonal in early culture, when it was mostly CD8+ and B35-reactive. Late cultures and a subclone were CD4+, possessed DR3-linked reactivity, and evidenced only one PCR signal: V beta 6. Similarly, the MH3 cell line was shown to be polyclonal early in culture, when it was reactive toward A11 and A29. In late cultures, when Southern analysis indicated clonality, only anti-A11 reactivity was maintained, and the predominant PCR signal was for V beta 17. Other alloreactivities were also attributed to specific V beta. The Kng cell line, alloreactive to A28, yielded two strong PCR signals; V beta 2 and V beta 9. The Mijo line, DR1-reactive, gave a predominant signal for V beta 12. Thus in spite of variable in vitro selection occurring in some lines and great initial heterogeneity documented by PCR, this technique was still capable of identifying V beta genes that persist in vitro, become predominant, and are associated with specific, allograft-directed alloreactivities.

Functional interaction between the two zinc finger domains of the v-erb A oncoprotein

The v-erb A oncogene of avian erythroblastosis virus is a mutated and virally transduced copy of a host cell gene encoding a thyroid hormone receptor. The protein expressed by the v-erb A oncogene binds to DNA and acts as a dominant negative inhibitor of both the thyroid hormone receptor and the closely related retinoic acid receptor. The v-erb A protein has sustained two amino acid alterations within its DNA-binding domain relative to that of c-erb A, one of which, at serine 61, is known to be important for v-erb A function in the neoplastic cell. We report here that the second alteration, at threonine 78, also plays an important, although more indirect, role: alteration of the sequence at threonine 78 such that it resembles that of c-erb A can act as an intragenic suppressor and can partially restore function to a v-erb A protein rendered defective due to a mutation at position 61. Threonine 78 lies within the D-box of the v-erb A protein, a region thought to mediate receptor-receptor dimerizations, and is not in physical proximity to the serine at position 61. It therefore appears that an indirect interaction occurs between these two sites and that this interaction is crucial for v-erb A function.

Plasma cell-regulated polyadenylation at the Ig gamma 2b secretion-specific poly(A) site

We found that the sequences downstream of the Ig gamma 2b secretory-specific (sec) poly(A) site play an important role in the preferential production of sec Ig mRNA during plasma B cell development. The Ig gamma 2b mRNA production in a deletion mutant (delta-Kpn) lacking the Ig sec poly(A) site and downstream consensus element (dsc) has been previously shown to default to the use of the downstream membrane-specific (mb) poly(A) site. In this study restoration of the Ig sec poly(A) site and dsc to the delta-Kpn gene causes a significant increase in the use of the sec poly(A) site vs mb poly(A) site in stable transfectants of plasma but not memory B cell tumors, indicating plasma cell-specific recognition of the Ig sec dsc. Restoration of the poly(A) cleavage site alone to delta-Kpn did not restore regulation. Substitution of an SV40 downstream poly(A) element for the Ig dsc in the delta-Kpn gene also does not restore regulation. The data further indicate that although the Ig dsc is clearly very important in the plasma cell-regulated expression, the difference in the processing ratios of the restored vs the intact Ig gamma 2b gene in plasma cells suggests that there are other yet to be defined sequences that may also play a role in the intact gene. Insertion of a 130-nucleotide segment of the gene containing the Ig sec poly(A) site and dsc into a heterologous, guanosyl phosphotransferase gene resulted in plasma cell-regulated polyadenylation of the sec poly(A) site. Neither the mb nor the SV40 early poly(A) sites and their respective dscs, in similar gpt chimeras, were regulated. Therefore the region downstream of the Ig sec poly(A) site plays an essential role in regulating polyadenylation at the sec poly(A) site in plasma cells but not memory cells. A model involving a plasma cell-specific recognition factor for the Ig sec dsc is presented.

Plasma cell-regulated polyadenylation at the Ig gamma 2b secretion-specific poly(A) site

We found that the sequences downstream of the Ig gamma 2b secretory-specific (sec) poly(A) site play an important role in the preferential production of sec Ig mRNA during plasma B cell development. The Ig gamma 2b mRNA production in a deletion mutant (delta-Kpn) lacking the Ig sec poly(A) site and downstream consensus element (dsc) has been previously shown to default to the use of the downstream membrane-specific (mb) poly(A) site. In this study restoration of the Ig sec poly(A) site and dsc to the delta-Kpn gene causes a significant increase in the use of the sec poly(A) site vs mb poly(A) site in stable transfectants of plasma but not memory B cell tumors, indicating plasma cell-specific recognition of the Ig sec dsc. Restoration of the poly(A) cleavage site alone to delta-Kpn did not restore regulation. Substitution of an SV40 downstream poly(A) element for the Ig dsc in the delta-Kpn gene also does not restore regulation. The data further indicate that although the Ig dsc is clearly very important in the plasma cell-regulated expression, the difference in the processing ratios of the restored vs the intact Ig gamma 2b gene in plasma cells suggests that there are other yet to be defined sequences that may also play a role in the intact gene. Insertion of a 130-nucleotide segment of the gene containing the Ig sec poly(A) site and dsc into a heterologous, guanosyl phosphotransferase gene resulted in plasma cell-regulated polyadenylation of the sec poly(A) site. Neither the mb nor the SV40 early poly(A) sites and their respective dscs, in similar gpt chimeras, were regulated. Therefore the region downstream of the Ig sec poly(A) site plays an essential role in regulating polyadenylation at the sec poly(A) site in plasma cells but not memory cells. A model involving a plasma cell-specific recognition factor for the Ig sec dsc is presented.

T-cell receptor gene usage and expression in renal allograft-derived T-cell lines

Southern blot analyses indicate that the T-cell receptors of alloreactive T-cell lines derived from needle biopsies of human kidney allografts are selected based on beta-chain usage. In order to examine this selection at the level of T-cell-receptor expression, we have generated monoclonal antibodies directed toward the T-cell-receptors of three allograft-derived T-cell lines, MH3, WP3, and EH3. Monoclonal antibodies have been isolated which appear to react specifically with each of these three T-cell lines. One anti-MH3 antibody precipitates a molecule from the surface of MH3 cells that comigrates with the alpha/beta TcR on a polyacrylamide gel. Ten WP3-reactive monoclonal antibodies were identified which cause a modulation of CD3 from the surface of WP3 T cells, although none as yet precipitates a molecule from lysates of surface 125I-labeled WP3 cells. Since Northern blot analysis of EH3 RNA has revealed that a member of the V beta 6 gene family is expressed by this T-cell line, we are attempting to identify a monoclonal antibody reactive with this V beta 6 gene product.

The hospitalized elderly and intergenerational conflict

In a study investigating intergenerational conflict between adult children and their hospitalized, chronically ill elderly parents, data on present and future conflict, areas of conflict, and presence of negative feelings were collected from both generations. Adult children and their parents report the presence of both types of conflict as well as negative feelings. However, some marked differences of perception between the generations for the variables under study were found. The older generation cite much less conflict. These findings as well as implications for practice are discussed.