POS0194 MORBIDITY AND MORTALITY OF BREAKTHROUGH COVID-19 IN PATIENTS WITH IMMUNE MEDIATED CONDITIONS ON B CELL DEPLETING THERAPIES AND THE EFFECTS OF MONOCLONAL ANTIBODY TREATMENT

Background

Among immunocompromised patients with immune mediated inflammatory diseases (IMIDs), those undergoing therapy with B cell depleting agents are among the most vulnerable to both severe COVID-19 disease and sub-optimal response to COVID-19 vaccines(1). Numerous studies have documented suppressed humoral, but relatively maintained cell mediated, responses to COVID-19 vaccines in these patients. However, the clinical significance of such immunity in terms of protection from infection and its sequelae are poorly understood. We have analyzed a large cohort of vaccinated IMIDs patients undergoing B cell depleting therapy for the presence of breakthrough infection and assessed their outcomes.

Objectives:

To define the frequency and outcomes of COVID-19 breakthrough infection in fully or partially vaccinated IMIDs patients receiving B cell depleting therapies.

To assess the characteristics and risk factors for severe outcomes and death.

Methods

All pharmacy records from within a large health care system were electronically searched for patients undergoing B cell depleting therapies with approved monoclonal antibodies in 2020. Records with ICD codes for IMIDs but not malignancies were included; patients must also have had at least one documented COVID-19 vaccine. From this cohort all patients with breakthrough COVID-19 disease from time of 1st vaccination through December 15, 2021 were identified; each record was hand-reviewed to extract clinical data including vaccine history, demographics, comorbidities, use of monoclonal antibodies, dose and timing of B cell depleting therapy, and outcomes as assessed by an 8 point NIH ordinal scale. Univariate and multivariable logistic/proportional-odds regression models were used to examine the risk factors for severe outcomes.

Results

A total of 1677 IMIDs patients were identified who received any B cell depleting monoclonal antibody and at least one COVID-19 vaccine in 2021. From this cohort 74 patients (4.4%) experienced a breakthrough COVID-19 infection. Among the breakthrough patients 34 (46%) had a rheumatic disease (RA 11, AAV 15, SLE 2), 34 (46%) had CNS inflammatory disease (MS 32, 2 other), and 6 (8%) had immune hematologic/miscellaneous diseases. Four patients had a previous history of COVID-19 infection. Overall 24 (35%) were hospitalized with 11 patients requiring critical level care (15%) and 6 deaths (8 %). All fatal cases had rheumatic diseases. Monoclonal antibodies were given as outpatient therapy to 21 patients and among these only 1 patient was hospitalized without requiring O2 and none died. In univariate analysis only number of comorbidities had a significant positive effect (p=.001) on severe outcomes (i.e. groups 1-4 vs. groups 5-8: Table 1) while monoclonal antibody therapy was associated with more favorable outcomes (p=.005 group 1-2 vs.3-8, Table 1). There were no associations between the dose, duration or timing of the B cell therapy, concomitant therapies including glucocorticoids, vaccine status (incomplete, complete, boosted) or date of vaccination with severe outcomes.

Conclusion

In IMIDs patients treated with B cell depleting therapies breakthrough infections are common with many experiencing severe outcomes. Concomitant comorbidities were associated with risk of severe disease. Monoclonal antibody therapy was used in only 28% but was associated with enhanced clinical outcomes with only 1 in 21 requiring hospitalization and zero mortality. This population of immunocompromised patients remains vulnerable to COVID-19 disease despite vaccination. More aggressive use of outpatient management with monoclonal antibody therapy and other preventive and therapeutic measures are urgently needed.

Reference

[1]Samuel Bitoun et al Rituximab impairs B-cell response but not T-cell response to COVID-19 vaccine in auto-immune diseases First published: 28 December 2021 Arthritis and Rheumatology https://doi.org/10.1002/art.42058

Disclosure of Interests

cassandra calabrese Speakers bureau: Sanofi-regeneron, Consultant of: Sanofi-regeneron, Elizabeth Kirchner Consultant of: Janssen, M Elaine Husni Consultant of: Abbvie, BMS, Novartis, Lilly, Pfizer, UCB, Regeneron, Janssen, Brandon Moss Consultant of: Biogen advisory board, Grant/research support from: Genentech/Roche and Novartis as part of investigator-initiated studies, Anthony Fernandez Consultant of: Consulting: AbbVie, Novartis, Mallinckrodt, UCB, BMS, Boehringer Ingelheim, Alexion, Grant/research support from: Research: AbbVie, Novartis, Pfizer, Corbus, Mallinckrodt, Yuxuan Jin: None declared, Leonard Calabrese Speakers bureau: Sanofi, Janssen, AbbVie, ChemoCentryx, GSK, AstraZeneca, Consultant of: Sanofi, Jansen, AbbVie, ChemoCentryx, GSK, AstraZeneca, BMS, Genentech

"Loneliness can also kill:" a qualitative exploration of outcomes and experiences of the SUPERB peer-befriending scheme for people with aphasia and their significant others

PURPOSE

People with aphasia post-stroke are at risk for depression and social isolation. Peer-befriending from someone with similar experiences may promote wellbeing and provide support. This paper explored the views of people with aphasia and their significant others about peer-befriending.

MATERIALS AND METHODS

We conducted a qualitative study within a feasibility trial (SUPERB) on peer-befriending for people with post-stroke aphasia and low levels of distress. Of the 28 participants randomised to the intervention, semi-structured in-depth interviews were conducted with 10 purposively selected people with aphasia (at both 4- and 10-months post-randomisation) and five of their significant others (at 4-months). Interviews were analysed using Framework Analysis.

RESULTS

Participants and their significant others were positive about peer-befriending and identified factors which influenced their experience: the befrienders' personal experience of stroke and aphasia, their character traits and the resulting rapport these created, the conversation topics they discussed and settings they met in, and the logistics of befriending, including planning visits and negotiating their end. Interviewees also made evaluative comments about the befriending scheme.

CONCLUSION

Peer-befriending was an acceptable intervention. Benefits for emotional wellbeing and companionship were reported. The shared experience in the befriending relationship was highly valued.Implications for RehabilitationThe lived experience of stroke and aphasia of befrienders was highly valued by people with aphasia receiving peer-befriending.Training, regular supervision, and support for befrienders with practicalities such as organising visits ensured the befriending scheme was perceived as straightforward and acceptable by befriendees.Those receiving peer-befriending would recommend it to others; they found it beneficial, especially in terms of emotional wellbeing and companionship.

"For them and for me": a qualitative exploration of peer befrienders' experiences supporting people with aphasia in the SUPERB feasibility trial

PURPOSE

Peer-befriending, where support is offered by someone with shared lived experience, is an intervention that may facilitate successful adjustment in people experiencing post-stroke aphasia. This paper explores the experiences of the peer-befrienders.

MATERIALS AND METHODS

People with aphasia were recruited as peer-befrienders within the SUPERB trial investigating befriending for people with post-stroke aphasia. The intervention comprised six visits over three months. Peer-befrienders were matched with at least one befriendee and received training and ongoing supervision. They were invited to participate in in-depth interviews which were analysed using framework analysis.

RESULTS

All 10 befrienders participated in interviews, reporting on 19 matches. Seven main themes emerged: content of the sessions; befriender-befriendee relationship; negotiating the visits; handling boundaries and endings; positive impact of the befriending for befrienders and befriendees; and beliefs about the nature and value of peer support. While befrienders described challenges, such as negotiating journeys and witnessing distress, the role was perceived as a "secure challenge" due to the support and training received.

CONCLUSIONS

Befrienders perceived the role as enjoyable and rewarding, and felt they were making a positive difference. They were unanimous in believing that people with aphasia can offer unique and valuable support to others with aphasia.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT02947776, registered 28th October 2016.Implications for rehabilitationPeople with lived experience of stroke and aphasia were able to offer emotional and social peer support to others with aphasia within the SUPERB trial.Although there were challenges, peer befrienders perceived the role as rewarding and satisfying.Peer befrienders valued the training and ongoing supervision and support they received to deliver the intervention.It is recommended that rehabilitation professionals considering offering peer-befriending schemes provide training and ongoing supervision to support peer-befrienders fulfil their role, as well as practical support with, e.g., arranging visits.

The Predictive Ability of Pre-Operative Magnetic Resonance Imaging to Detect Pathological Outcomes in Prostate Cancer

Aims Accurate preoperative knowledge of tumour stage is important in preoperative planning at radical prostatectomy (RP). The aim of this study was to assess the predictive ability of multiparametric MRI for detecting pathological outcomes. Methods A retrospective review was performed of all patients who underwent RP over a 4 year period. Results Preoperative MRI was reported as showing T3 or T4 disease in 26(17.9%) out of 145 patients undergoing RP. Of these, 10(6.9%) had ECE (extra-capsular extension) and 1(0.7%) had SVI (seminal vesicle invasion) on final histology. The sensitivity and specificity of MRI for detecting ECE were 27.3% and 87.6%, respectively. The sensitivity and specificity of MRI for detecting SVI were 11.1% and 97.8%, respectively. The positive predictive values for determining ECE and SVI were 45.5% and 25%, respectively and negative predictive values were 75.9% and 94.4%. Conclusion MRI has good specificity but poor and heterogeneous sensitivity for predicting T3 disease in RP specimen.

HIVIS-DNA or HIVISopt-DNA priming followed by CMDR vaccinia-based boosts induce both humoral and cellular murine immune responses to HIV

Background

In order to develop a more effective prophylactic HIV-1 vaccine it is important optimize the components, improve Envelope glycoprotein immunogenicity as well as to explore prime-boost immunization schedules. It is also valuable to include several HIV-1 subtype antigens representing the world-wide epidemic.

Methods

HIVIS-DNA plasmids which include Env genes of subtypes A, B and C together with Gag subtypes A and B and RTmut/Rev of subtype B were modified as follows: the Envelope sequences were shortened, codon optimized, provided with an FT4 sequence and an immunodominant region mutated. The reverse transcriptase (RT) gene was shortened to contain the most immunogenic N-terminal fragment and fused with an inactivated viral protease vPR gene. HIVISopt-DNA thus contains fewer plasmids but additional PR epitopes compared to the native HIVIS-DNA. DNA components were delivered intradermally to young Balb/c mice once, using a needle-free Biojector® immediately followed by dermal electroporation. Vaccinia-based MVA-CMDR boosts including Env gene E and Gag-RT genes A were delivered intramuscularly by needle, once or twice.

Results

Both HIVIS-DNA and HIVISopt-DNA primed humoral and cell mediated responses well. When boosted with heterologous MVA-CMDR (subtypes A and E) virus inhibitory neutralizing antibodies were obtained to HIV-1 subtypes A, B, C and AE. Both plasmid compositions boosted with MVA-CMDR generated HIV-1 specific cellular responses directed against HIV-1 Env, Gag and Pol, as measured by IFNγ ELISpot. It was shown that DNA priming augmented the vector MVA immunological boosting effects, the HIVISopt-DNA with a trend to improved (Env) neutralization, the HIVIS-DNA with a trend to better (Gag) cell mediated immune reponses.

Conclusions

HIVIS-DNA was modified to obtain HIVISopt-DNA that had fewer plasmids, and additional epitopes. Even with one DNA prime followed by two MVA-CMDR boosts, humoral and cell-mediated immune responses were readily induced by priming with either DNA construct composition. Priming by HIV-DNA augmented neutralizing antibody responses revealed by boosting with the vaccinia-based heterologous sequences. Cellular and antibody responses covered selected strains representing HIV-1 subtypes A, B, C and CRF01_AE. We assume this is related to the inclusion of heterologous full genes in the vaccine schedule.

Prison prescribing practice: practitioners' perspectives on why prison is different

The current prison population in England and Wales has multiple, complex healthcare needs, presenting unique challenges to those caring for prisoners. Prison numbers have increased dramatically in the last 10 years. There are now approximately 84,000 prisoners in England and Wales and 120,000 new episodes of imprisonment each year . The authors all contribute to prison healthcare. Below, we discuss a key issue arising from first-hand experience of prisoners' health and social care needs, the prescription of psycho-active drugs by primary and secondary care practitioners. This is a core medical task, but beset with difficulties. These difficulties are not necessarily encountered in other areas of prison healthcare. However, they do illustrate how providing healthcare to prisoners is complex, often lacking a research base and can have pitfalls that are not obvious to the outsider.

The pre-melt phase of n-alkanes: Crystallographic evidence for a kinked chain structure

Electron diffraction measurements on epitaxially grown crystals of orthorhombic n-hexatriacontane, n-C(36)H(74), give evidence for the chain-defect mechanism for linear chain melting. The derived structural model is also in accord with recent spectroscopic studies of odd-chain n-alkanes, and the diffraction data specifically exclude models based on helices or rigid chain rotors. Stability of a kinked chain structure, moreover, is indicated by an observed hysteresis effect that gives different pretransition temperatures for solution-grown and annealed crystals.

Dinucleotide Sequences at the 5' Ends of Vaccinia Virus mRNA's Synthesized In Vitro

The diversity of dinucleotide sequences at the 5' ends of vaccinia virus mRNA's was determined by a two-dimensional electrophoresis procedure. RNA labeled with S-adenosyl[methyl-(3)H]methionine was synthesized in vitro by enzymes present in vaccinia virus cores. The RNA, ending in m(7)G(5')pppN(m)pN-, was beta-eliminated and treated with alkaline phosphatase. After digestion with RNases T(2), T(1), and A, all eight possible dinucleotides containing G(m) and A(m) were identified. They are, in decreasing order of abundance: G(m)pUp (22%), A(m)pCp (18%), G(m)pAp (16%), G(m)pCp (15%), A(m)pAp (11%), A(m)pUp (10%), A(m)pGp (7%), and G(m)pGp (2%).

Gene expression using the vaccinia virus/ T7 RNA polymerase hybrid system

This unit describes a transient cytoplasmic expression system that relies on the synthesis of the bacteriophage T7 RNA polymerase in the cytoplasm of mammalian cells. A gene of interest is inserted into a plasmid such that it comes under the control of the T7 RNA polymerase promoter (p(T7)). Using liposome-mediated transfection, this recombinant plasmid is introduced into the cytoplasm of cells infected with vTF7-3, a recombinant vaccinia virus encoding bacteriophage T7 RNA polymerase. During incubation, the gene of interest is transcribed with high efficiency by T7 RNA polymerase. For large-scale work, protocols are provided for insertion of the p(T7)-regulated gene into a second recombinant vaccinia virus by homologous recombination and subsequent coinfection with vTF7-3 into cells grown in suspension or for direct transfection into OST7-1 cells (a stable cell line that constitutively expresses the T7 RNA polymerase). Expressed protein is then analyzed by pulse-labeling and purified. One new development to this vaccinia virus/T7 RNA polymerase hybrid expression system described here is the VOTE inducible expression system, which eliminates the need to use two recombinant viruses or a special cell line.

Overview of the vaccinia virus expression system

The vaccinia virus expression system differs from others in that transcription occurs in the cytoplasm of mammalian cells rather than in the nucleus. As a vector, vaccinia virus has a number of useful characteristics, including a capacity that permits cloning large fragments of foreign DNA (20+ kbp) with retention of infectivity, a wide host range, a relatively high level of protein synthesis, and "appropriate" transport, secretion, processing, and posttranslational modifications as dictated by the primary structure of the expressed protein and the cell type used. This overview discusses the life cycle of the vaccinia virus along with effects of vaccinia infection. The vaccinia vector expression system is described along with specific steps for expressing genes using these vectors. Important safety considerations are also presented.

Generation of recombinant vaccinia viruses

This unit first describes how to infect cells with vaccinia virus and then transfect them with a plasmid-transfer vector to generate a recombinant virus. Methods are also presented for purifying vaccinia virus and for isolating viral DNA, which can be used during transfection. Also presented are selection and screening methods used to isolate recombinant viruses and a method for the amplification of recombinant viruses. Finally, a method for live immunostaining that has been used primarily for detection of recombinant modified vaccinia virus Ankara (MVA) is presented.

Characterization of recombinant vaccinia viruses and their products

After a recombinant vaccinia virus is made, its DNA and protein products can be analyzed in several ways. Protocols are provided in this unit for identification of the recombinant virus by PCR (with verification of correct insertion of the DNA by Southern blotting) and by dot-blot hybridization. Also, when antibodies are available, protein expression can be analyzed by immunological methods detailed here such as dot blotting with an antibody, immunoblotting and/or immunoprecipitation. In addition, immunostaining can be used for identification of recombinant plaques as well as for determination of the purity of a recombinant virus stock. All of the protocols in this unit can be used for characterization of modified vaccinia virus Ankara (MVA) recombinant viruses.

Generation of recombinant vaccinia viruses

This unit first describes how to infect cells with vaccinia virus and then transfect them with a plasmid-transfer vector to generate a recombinant virus. Methods are also presented for purifying vaccinia virus and for isolating viral DNA, which can be used during transfection. Also presented are selection and screening methods used to isolate recombinant viruses and a method for the amplification of recombinant viruses. Finally, a method for live immunostaining that has been used primarily for detection of recombinant modified vaccinia virus Ankara (MVA) is presented.

Preparation of cell cultures and vaccinia virus stocks

This unit describes the maintenance of cell lines used with vaccinia virus, both in monolayer cultures and in suspension. The suspended cell culture is then used in the preparation of vaccinia virus stocks. The preparation of chick embryo fibroblasts (CEF) is also presented for use in the production of the highly attenuated and host range-restricted modified vaccinia virus Ankara (MVA) strain of vaccinia virus. Additionally, support protocols are presented for the titration of standard and MVA vaccinia virus stocks.

Characterization of recombinant vaccinia viruses and their products

After a recombinant vaccinia virus is made, its DNA and protein products can be analyzed in several ways. Protocols are provided in this unit for identification of the recombinant virus by PCR (with verification of correct insertion of the DNA by Southern blotting) and by dot-blot hybridization. Also, when antibodies are available, protein expression can be analyzed by immunological methods detailed here such as dot blotting with an antibody, immunoblotting and/or immunoprecipitation. In addition, immunostaining can be used for identification of recombinant plaques as well as for determination of the purity of a recombinant virus stock. All of the protocols in this unit can be used for characterization of modified vaccinia virus Ankara (MVA) recombinant viruses.

Gene expression using the vaccinia virus/T7 RNA polymerase hybrid system

This unit describes a transient cytoplasmic expression system that relies on the synthesis of the bacteriophage T7 RNA polymerase in the cytoplasm of mammalian cells. A gene of interest is inserted into a plasmid such that it comes under the control of the T7 RNA polymerase promoter (p(T7)). Using liposome-mediated transfection, this recombinant plasmid is introduced into the cytoplasm of cells infected with vTF7-3, a recombinant vaccinia virus encoding bacteriophage T7 RNA polymerase. During incubation, the gene of interest is transcribed with high efficiency by T7 RNA polymerase. For large-scale work, protocols are provided for insertion of the p(T7)-regulated gene into a second recombinant vaccinia virus by homologous recombination and subsequent coinfection with vTF7-3 into cells grown in suspension or for direct transfection into OST7-1 cells (a stable cell line that constitutively expresses the T7 RNA polymerase). Expressed protein is then analyzed by pulse-labeling and purified. One new development to this vaccinia virus/T7 RNA polymerase hybrid expression system described here is the VOTE inducible expression system, which eliminates the need to use two recombinant viruses or a special cell line.

Analysis of the monkeypox virus genome

Monkeypox virus (MPV) belongs to the orthopoxvirus genus of the family Poxviridae, is endemic in parts of Africa, and causes a human disease that resembles smallpox. The 196,858-bp MPV genome was analyzed with regard to structural features and open reading frames. Each end of the genome contains an identical but oppositely oriented 6379-bp terminal inverted repetition, which similar to that of other orthopoxviruses, includes a putative telomere resolution sequence and short tandem repeats. Computer-assisted analysis was used to identify 190 open reading frames containing >/=60 amino acid residues. Of these, four were present within the inverted terminal repetition. MPV contained the known essential orthopoxvirus genes but only a subset of the putative immunomodulatory and host range genes. Sequence comparisons confirmed the assignment of MPV as a distinct species of orthopoxvirus that is not a direct ancestor or a direct descendent of variola virus, the causative agent of smallpox.

Oligomeric structure of virion-associated and soluble forms of the simian immunodeficiency virus envelope protein in the prefusion activated conformation

The envelope proteins (env) of simian immunodeficiency virus (SIV) and HIV type 1 assemble to form noncovalently associated oligomers in the endoplasmic reticulum. After cleavage in a Golgi compartment, oligomeric env complexes are transported to the surface of infected cells, where incorporation into budding virions can occur. Difficulties in obtaining adequate quantities of virions retaining env, as well as the unstable nature and hydrophobicity of the oligomer, may account for the absence of previous biophysical studies to determine the oligomeric valency of membrane-associated env. The aim of this study was to evaluate the oligomeric state of SIV env before membrane-fusion activation. Virion-associated env, obtained by crosslinking and detergent extraction, and non-crosslinked secreted env ectodomain (recombinant gp140) were purified by lentil-lectin chromatography and gel filtration as single predominant species. Sedimentation equilibrium-derived mass values for both forms of SIV env were close to those predicted for trimeric assemblies. Determination of the mass of individual molecules by scanning transmission electron microscopy confirmed that SIV virion-associated env and gp140 formed largely homogeneous populations of trimers. Furthermore, a triangular or tri-lobed morphology was clearly visualized in a subset of the trimers.

Systemic cancer therapy with a tumor-selective vaccinia virus mutant lacking thymidine kinase and vaccinia growth factor genes

We have demonstrated previously the oncolytic effects of a systemically delivered, replicating vaccinia virus. To enhance the tumor specificity of this vector, we have developed a combined thymidine kinase-deleted (TK-) and vaccinia growth factor-deleted (VGF-) vaccinia virus and investigated its properties in vitro and in vivo. The gene for enhanced green fluorescent protein (EGFP) was inserted into the TK locus of a VGF- vaccinia virus by homologous recombination creating a double-deleted mutant vaccinia virus (vvDD-GFP). Infection of resting and dividing NIH3T3 cells with vvDD-GFP yielded reduced viral recovery compared with wild-type (WT), TK-, or VGF- viruses from resting cultures but equivalent virus recovery from dividing cultures. Eight days after nude mice were injected i.p. with 10(7) plaque-forming units (pfu) of WT, TK-, VGF-, or vvDD-GFP vaccinia virus, tissues and tumor were harvested for viral titer determination. No virus was recovered from the brains of mice injected with vvDD-GFP compared with the other viruses, which ranged from 130 to 28,000 pfu/mg protein; however, equivalent amounts were recovered from tumor. There was no toxicity from vvDD-GFP because nude mice receiving 10(8) pfu of IP vvDD-GFP lived >100 days, whereas mice receiving WT, VGF-, or TK- virus had median survivals of only 6, 17, and 29 days, respectively. Similar results were seen when 10(9) pfu of vvDD-GFP were given. Nude mice bearing s.c. murine colon adenocarcinoma (MC38) had significant tumor regression after treatment with 10(9) pfu of systemic (i.p.) vvDD-GFP compared with control (mean tumor size, 180.71 +/- 35.26 mm(3) versus 2796.79 +/- 573.20 mm(3) 12 days after injection of virus). Our data demonstrate that a TK- and VGF- mutant vaccinia virus is significantly attenuated in resting cells in vitro and demonstrates tumor-specific replication in vivo. It is a promising vector for use in tumor-directed gene therapy, given its enhanced safety profile, tumor selectivity, and the oncolytic effects after systemic delivery.

Vaccinia virus intracellular movement is associated with microtubules and independent of actin tails

Two mechanisms have been proposed for the intracellular movement of enveloped vaccinia virus virions: rapid actin polymerization and microtubule association. The first mechanism is used by the intracellular pathogens Listeria and Shigella, and the second is used by cellular vesicles transiting from the Golgi network to the plasma membrane. To distinguish between these models, two recombinant vaccinia viruses that express the B5R membrane protein fused to enhanced green fluorescent protein (GFP) were constructed. One had Tyr(112) and Tyr(132) of the A36R membrane protein, which are required for phosphorylation and the nucleation of actin tails, conservatively changed to Phe residues; the other had the A36R open reading frame deleted. Although the Tyr mutant was impaired in Tyr phosphorylation and actin tail formation, digital video and time-lapse confocal microscopy demonstrated that virion movement from the juxtanuclear region to the periphery was saltatory with maximal speeds of >2 microm/s and was inhibited by the microtubule-depolymerizing drug nocodazole. Moreover, this actin tail-independent movement was indistinguishable from that of a control virus with an unmutated A36R gene and closely resembled the movement of vesicles on microtubules. However, in the absence of actin tails, the Tyr mutant did not induce the formation of motile, virus-tipped microvilli and had a reduced ability to spread from cell to cell. The deletion mutant was more severely impaired, suggesting that the A36R protein has additional roles. Optical sections of unpermeabilized, B5R antibody-stained cells that expressed GFP-actin and were infected with wild-type vaccinia virus revealed that all actin tails were associated with virions on the cell surface. We concluded that the intracellular movement of intracellular enveloped virions occurs on microtubules and that the motile actin tails enhance extracellular virus spread to neighboring cells.

Human monkeypox and smallpox viruses: genomic comparison

Monkeypox virus (MPV) causes a human disease which resembles smallpox but with a lower person-to-person transmission rate. To determine the genetic relationship between the orthopoxviruses causing these two diseases, we sequenced the 197-kb genome of MPV isolated from a patient during a large human monkeypox outbreak in Zaire in 1996. The nucleotide sequence within the central region of the MPV genome, which encodes essential enzymes and structural proteins, was 96.3% identical with that of variola (smallpox) virus (VAR). In contrast, there were considerable differences between MPV and VAR in the regions encoding virulence and host-range factors near the ends of the genome. Our data indicate that MPV is not the direct ancestor of VAR and is unlikely to naturally acquire all properties of VAR.

Yaba-like disease virus: an alternative replicating poxvirus vector for cancer gene therapy

Vaccinia virus is being investigated as a replicating vector for tumor-directed gene therapy. However, the majority of cancer patients have preformed immunologic reactivity against vaccinia virus, as a result of smallpox vaccination, which may limit its use as a vector. The Yaba-like disease (YLD) virus was investigated here as an alternative, replicating poxvirus for cancer gene therapy. We have demonstrated that the YLD virus does not cross-react with vaccinia virus antibodies, and it replicates efficiently in human tumor cells. YLD virus can be expanded and purified to high titer in CV-1 cells under conditions utilized for vaccinia virus. The YLD virus RNA polymerase was able to express genes regulated by a synthetic promoter designed for use in orthopoxviruses. We sequenced the YLD virus TK gene and created a shuttle plasmid, which allowed the recombination of the green fluorescent protein (GFP) gene into the YLD virus. In a murine model of ovarian cancer, up to 38% of cells in the tumor expressed the GFP transgene 12 days after intraperitoneal virus delivery. YLD virus has favorable characteristics as a vector for cancer gene therapy, and this potential should be explored further.

Unique temperature-sensitive defect in vaccinia virus morphogenesis maps to a single nucleotide substitution in the A30L gene

Marker rescue experiments demonstrated that the genetic lesion of a previously isolated vaccinia virus temperature-sensitive mutant which forms multilayered envelope structures with lucent interiors and foci of viroplasm with dense centers mapped to the A30L open reading frame. A single base change, resulting in a nonconservative Ser-to-Phe substitution at residue 17, was associated with degradation of the A30L protein at elevated temperatures.

Correspondence of the functional epitopes of poxvirus and human interleukin-18-binding proteins

Molluscum contagiosum virus, a human poxvirus that causes persistent small benign skin tumors, encodes a variety of putative immune defense proteins. Three such proteins, MC51L, MC53L, and MC54L, have 20 to 35% amino acid sequence identities with human interleukin-18 (hIL-18)-binding protein (hIL-18BP), a naturally occurring antagonist of the proinflammatory cytokine IL-18. We previously demonstrated that seven amino acids within the immunoglobulin-like domain of hIL-18BP were important for high-affinity binding to hIL-18. Model building indicated that MC54L, which has been shown to bind hIL-18, contains five of the seven amino acids at corresponding positions in its immunoglobulin-like domain, the exceptions being the conservative substitution of isoleucine for a leucine and the nonconservative substitution of valine for a phenylalanine. We found that individual alanine substitutions for these six identical or highly conserved amino acids of MC54L caused changes in affinity and binding free energy for hIL-18 that were quantitatively similar to those produced by mutagenesis of hIL-18BP. Furthermore, when the nonconserved valine of MC54L was mutated to phenylalanine, making it more like hIL-18BP, its affinity for hIL-18 increased more than 10-fold. In addition, the carboxyl-terminal half of MC54L, which has no similarity with hIL-18BP, was dispensable for hIL-18 binding. Thus, despite their relatively low overall sequence identity, MC54L and hIL-18BP have similar hIL-18 binding sites and functional epitopes. On the other hand, MC51L and MC53L have nonconservative substitutions of three to six of the seven critical amino acids of hIL-18BP and neither protein bound hIL-18, suggesting that they may interact with unidentified ligands.

Vaccinia virus F13L protein with a conserved phospholipase catalytic motif induces colocalization of the B5R envelope glycoprotein in post-Golgi vesicles

The wrapping of intracellular mature vaccinia virions by modified trans-Golgi or endosomal cisternae to form intracellular enveloped virions is dependent on at least two viral proteins encoded by the B5R and F13L open reading frames. B5R is a type I integral membrane glycoprotein, whereas F13L is an unglycosylated, palmitylated protein with a motif that is conserved in a superfamily of phospholipid-metabolizing enzymes. Microscopic visualization of the F13L protein was achieved by fusing it to the enhanced green fluorescent protein (GFP). F13L-GFP was functional when expressed by a recombinant vaccinia virus in which it replaced the wild-type F13L gene or by transfection of uninfected cells with a plasmid vector followed by infection with an F13L deletion mutant. In uninfected or infected cells, F13L-GFP was associated with Golgi cisternae and post-Golgi vesicles containing the LAMP 2 late endosomal-lysosomal marker. Association of F13L-GFP with vesicles was dependent on an intact phospholipase catalytic motif and sites of palmitylation. The B5R protein was also associated with LAMP2-containing vesicles when F13L-GFP was coexpressed, but was largely restricted to Golgi cisternae in the absence of F13L-GFP or when the F13L moiety was mutated. We suggest that the F13L protein, like its human phospholipase D homolog, regulates vesicle formation and that this process is involved in intracellular enveloped virion membrane formation.

Vaccinia virus A30L protein is required for association of viral membranes with dense viroplasm to form immature virions

The previously uncharacterized A30L gene of vaccinia virus has orthologs in all vertebrate poxviruses but no recognizable nonpoxvirus homologs or functional motifs. We determined that the A30L gene was regulated by a late promoter and encoded a protein of approximately 9 kDa. Immunoelectron microscopy of infected cells indicated that the A30L protein was associated with viroplasm enclosed by crescent and immature virion membranes. The A30L protein was also present in mature virions and was partially released by treatment with a nonionic detergent and reducing agent, consistent with a location in the matrix between the core and envelope. To determine the role of the A30L protein, we constructed a stringent conditional lethal mutant with an inducible A30L gene. In the absence of inducer, synthesis of viral early and late proteins occurred but the proteolytic processing of certain core proteins was inhibited, suggesting an assembly block. Inhibition of virus maturation was confirmed by electron microscopy. Under nonpermissive conditions, we observed aberrant large, dense, granular masses of viroplasm with clearly defined margins; viral crescent membranes that appeared normal except for their location at a distance from viroplasm; empty immature virions; and an absence of mature virions. The data indicated that the A30L protein is needed for vaccinia virus morphogenesis, specifically the association of the dense viroplasm with viral membranes.

Repression of vaccinia virus Holliday junction resolvase inhibits processing of viral DNA into unit-length genomes

The vaccinia virus A22R gene encodes a protein that is homologous to the bacterial enzyme RuvC and specifically cleaves and resolves four-way DNA Holliday junctions into linear duplex products. To investigate the role of the vaccinia virus Holliday junction resolvase during an infection, we constructed two recombinant viruses: vA22-HA, which has a short C-terminal epitope tag appended to the A22R open reading frame, and vA22i, in which the original A22R gene is deleted and replaced by an inducible copy. Polyacrylamide gel electrophoresis and Western blot analysis of extracts and purified virions from cells infected with vA22-HA revealed that the resolvase was expressed after the onset of DNA replication and incorporated into virion cores. vA22i exhibited a conditional replication defect. In the absence of an inducer, (i) viral protein synthesis was unaffected, (ii) late-stage viral DNA replication was reduced, (iii) most of the newly synthesized viral DNA remained in a branched or concatemeric form that caused it to be trapped at the application site during pulsed-field gel electrophoresis, (iv) cleavage of concatemer junctions was inhibited, and (v) virion morphogenesis was arrested at an immature stage. These data indicated multiple roles for the vaccinia virus Holliday junction resolvase in the replication and processing of viral DNA into unit-length genomes.

Safety of modified vaccinia virus Ankara (MVA) in immune-suppressed macaques

Modified vaccinia virus Ankara (MVA)-based recombinant viruses have been shown to be potent vaccine candidates for several infectious and neoplastic diseases. Since a major application of these live, replication-deficient vectors would be their use in immunocompromised or potentially immunocompromised individuals, a preclinical safety study was carried out. Macaques were inoculated with high doses of MVA (10(9)) via various routes, after immune-suppression by total-body irradiation, anti-thymocyte globulin treatment, or measles virus (MV) infection. No clinical, haematological or pathological abnormalities related to MVA inoculation were observed during a 13-day follow-up period. The presence of MVA genomes was demonstrated by nested PCR during the course of the experiment in all macaques, but from none of these animals replication competent MVA could be reisolated. These data suggest that MVA can safely be used as a basis for recombinant human vaccines, and that it is also safe for use in immunocompromised individuals.

Reduction of simian-human immunodeficiency virus 89.6P viremia in rhesus monkeys by recombinant modified vaccinia virus Ankara vaccination

Since cytotoxic T lymphocytes (CTLs) are critical for controlling human immunodeficiency virus type 1 (HIV-1) replication in infected individuals, candidate HIV-1 vaccines should elicit virus-specific CTL responses. In this report, we study the immune responses elicited in rhesus monkeys by a recombinant poxvirus vaccine and the degree of protection afforded against a pathogenic simian-human immunodeficiency virus SHIV-89.6P challenge. Immunization with recombinant modified vaccinia virus Ankara (MVA) vectors expressing SIVmac239 gag-pol and HIV-1 89.6 env elicited potent Gag-specific CTL responses but no detectable SHIV-specific neutralizing antibody (NAb) responses. Following intravenous SHIV-89.6P challenge, sham-vaccinated monkeys developed low-frequency CTL responses, low-titer NAb responses, rapid loss of CD4+ T lymphocytes, high-setpoint viral RNA levels, and significant clinical disease progression and death in half of the animals by day 168 postchallenge. In contrast, the recombinant MVA-vaccinated monkeys demonstrated high-frequency secondary CTL responses, high-titer secondary SHIV-89.6-specific NAb responses, rapid emergence of SHIV-89.6P-specific NAb responses, partial preservation of CD4+ T lymphocytes, reduced setpoint viral RNA levels, and no evidence of clinical disease or mortality by day 168 postchallenge. There was a statistically significant correlation between levels of vaccine-elicited CTL responses prior to challenge and the control of viremia following challenge. These results demonstrate that immune responses elicited by live recombinant vectors, although unable to provide sterilizing immunity, can control viremia and prevent disease progression following a highly pathogenic AIDS virus challenge.

Determination of the functional epitopes of human interleukin-18-binding protein by site-directed mutagenesis

The human interleukin (IL)-18-binding protein (hIL-18BP) is a naturally occurring antagonist of IL-18, a proinflammatory cytokine that is related to IL-1beta and has an important role in defense against microbial invaders. As its name implies, the hIL-18BP binds to IL-18 with high affinity and prevents the interaction of IL-18 with its receptor. We genetically modified the C terminus of hIL-18BP by appending a 15-amino acid biotinylation recognition site and a six-histidine tag and then performed site-directed mutagenesis to determine the functional epitopes that mediate efficient binding to IL-18. The mutated IL-18BPs were secreted from mammalian cells, captured by metal affinity chromatography, biotinylated in situ, eluted, and immobilized on streptavidin-coated chips. Using surface plasmon resonance, we identified seven amino acids of hIL-18BP which, when changed individually to alanine, caused an 8-750-fold decrease in binding affinity, largely because of increased off-rates. These seven amino acids localized to the predicted beta-strand c and d of hIL-18BP immunoglobulin-like domain, and most had hydrophobic side chains. Just two amino acids, tyrosine 97 and phenylalanine 104, contributed approximately 50% of the binding free energy. Information obtained from these studies could contribute to the design of molecular antagonists of IL-18 for treatment of inflammatory diseases.

Regulation of viral intermediate gene expression by the vaccinia virus B1 protein kinase

The B1 gene of vaccinia virus encodes a serine/threonine protein kinase that is expressed early after infection. Under nonpermissive conditions, temperature-sensitive mutants (ts2 and ts25) that map to B1 fail to efficiently replicate viral DNA. Our goal was to extend studies on the function of B1 by determining if the kinase is required for intermediate or late gene expression, two events that ordinarily depend on viral DNA replication. First, we established that early viral gene expression occurred at the nonpermissive temperature. By using a transfection procedure that circumvents the viral DNA replication requirement, we found that reporter genes regulated by an intermediate promoter were transcribed only under conditions permissive for expression of active B1. To assay late gene expression, the T7 RNA polymerase gene was inserted into the genome of ts25 to form ts25/T7. A DNA replication-independent late gene transcription system was established by cotransfecting plasmids containing T7 promoter-driven late gene transcription factors and a late promoter reporter gene into ts25/T7-infected cells. Late genes, unlike intermediate genes, were expressed at the nonpermissive temperature. Last, we showed that overexpression of B1 stimulated intermediate but inhibited late gene expression in cells infected with wild-type virus.

Preparation of cell cultures and vaccinia virus stocks

This unit describes the maintenance of cell lines used with vaccinia virus, both in monolayer cultures and in suspension. The suspended cell culture is then used in the preparation of vaccinia virus stocks. The preparation of chick embryo fibroblasts (CEF) is also presented for use in the production of the highly attenuated and host range-restricted modified vaccinia virus Ankara (MVA) strain of vaccinia virus. Additionally, support protocols are presented for the titration of standard and MVA vaccinia virus stocks.

Visualization of intracellular movement of vaccinia virus virions containing a green fluorescent protein-B5R membrane protein chimera

We produced an infectious vaccinia virus that expressed the B5R envelope glycoprotein fused to the enhanced green fluorescent protein (GFP), allowing us to visualize intracellular virus movement in real time. Previous transfection studies indicated that fusion of GFP to the C-terminal cytoplasmic domain of B5R did not interfere with Golgi localization of the viral protein. To determine whether B5R-GFP was fully functional, we started with a B5R deletion mutant that made small plaques and inserted the B5R-GFP gene into the original B5R locus. The recombinant virus made normal-sized plaques and acquired the ability to form actin tails, indicating reversal of the mutant phenotype. Moreover, immunogold electron microscopy revealed that both intracellular enveloped virions (IEV) and extracellular enveloped virions contained B5R-GFP. By confocal microscopy of live infected cells, we visualized individual fluorescent particles, corresponding to IEV in size and shape, moving from a juxtanuclear location to the periphery of the cell, where they usually collected prior to association with actin tails. The fluorescent particles could be seen emanating from cells at the tips of microvilli. Using a digital camera attached to an inverted fluorescence microscope, we acquired images at 1 frame/s. At this resolution, IEV movement appeared saltatory; in some frames there was no net movement, whereas in others movement exceeded 2 microm/s. Further studies indicated that IEV movement was reversibly arrested by the microtubule-depolymerizing drug nocodazole. This result, together with the direction, speed, and saltatory motion of IEV, was consistent with a role for microtubules in intracellular transport of IEV.

Control of a mucosal challenge and prevention of AIDS by a multiprotein DNA/MVA vaccine

Heterologous prime/boost regimens have the potential for raising high levels of immune responses. Here we report that DNA priming followed by a recombinant modified vaccinia Ankara (rMVA) booster controlled a highly pathogenic immunodeficiency virus challenge in a rhesus macaque model. Both the DNA and rMVA components of the vaccine expressed multiple immunodeficiency virus proteins. Two DNA inoculations at 0 and 8 weeks and a single rMVA booster at 24 weeks effectively controlled an intrarectal challenge administered 7 months after the booster. These findings provide hope that a relatively simple multiprotein DNA/MVA vaccine can help to control the acquired immune deficiency syndrome epidemic.

Molluscum contagiosum virus inhibitors of apoptosis: The MC159 v-FLIP protein blocks Fas-induced activation of procaspases and degradation of the related MC160 protein

Molluscum contagiosum virus contains two open reading frames, MC159 and MC160, that encode proteins with death effector domains resembling those of cellular regulators of apoptosis. Previous transfection analyses indicated that the MC159 protein binds to cellular FADD and inhibits Fas-induced cytolysis. For further studies, we inserted the MC159 or MC160 gene into the genome of vaccinia virus that had its own major anti-apoptosis gene deleted. The MC159-expressing virus blocked Fas-induced activation of caspase-3 and -8, degradation of PARP, and cleavage of DNA, whereas the parental vaccinia virus did not. The MC159 protein bound to procaspase-8, in addition to FADD, and was included in a complex with Fas upon receptor activation. Although the MC160 protein associated with FADD and procaspase-8 in co-immunoprecipitation studies, no protection against morphological or biochemical changes associated with Fas-induced apoptosis were discerned and the MC160 protein itself was degraded. Co-expression of MC159, as well as other caspase inhibitors, protected the MC160 protein from degradation, suggesting a functional relationship between the two viral proteins.

Elicitation of high-frequency cytotoxic T-lymphocyte responses against both dominant and subdominant simian-human immunodeficiency virus epitopes by DNA vaccination of rhesus monkeys

Increasing evidence suggests that the generation of cytotoxic T-lymphocyte (CTL) responses specific for a diversity of viral epitopes will be needed for an effective human immunodeficiency virus type 1 (HIV-1) vaccine. Here, we determine the frequencies of CTL responses specific for the simian immunodeficiency virus Gag p11C and HIV-1 Env p41A epitopes in simian-human immunodeficiency virus (SHIV)-infected and vaccinated rhesus monkeys. The p11C-specific CTL response was high frequency and dominant and the p41A-specific CTL response was low frequency and subdominant in both SHIV-infected monkeys and in monkeys vaccinated with recombinant modified vaccinia virus Ankara vectors expressing these viral antigens. Interestingly, we found that plasmid DNA vaccination led to high-frequency CTL responses specific for both of these epitopes. These data demonstrate that plasmid DNA may be useful in eliciting a broad CTL response against multiple epitopes.