Production of antiviral "OP7 chimera" defective interfering particles free of infectious virus

Defective interfering particles (DIPs) of influenza A virus (IAV) are suggested for use as broad-spectrum antivirals. We discovered a new type of IAV DIP named "OP7" that carries point mutations in its genome segment (Seg) 7 instead of a deletion as in conventional DIPs (cDIPs). Recently, using genetic engineering tools, we generated "OP7 chimera DIPs" that carry point mutations in Seg 7 plus a deletion in Seg 1. Together with cDIPs, OP7 chimera DIPs were produced in shake flasks in the absence of infectious standard virus (STV), rendering UV inactivation unnecessary. However, only part of the virions harvested were OP7 chimera DIPs (78.7%) and total virus titers were relatively low. Here, we describe the establishment of an OP7 chimera DIP production process applicable for large-scale production. To increase total virus titers, we reduced temperature from 37 to 32 °C during virus replication. Production of almost pure OP7 chimera DIP preparations (99.7%) was achieved with a high titer of 3.24 log10(HAU/100 µL). This corresponded to an 11-fold increase relative to the initial process. Next, this process was transferred to a stirred tank bioreactor resulting in comparable yields. Moreover, DIP harvests purified and concentrated by steric exclusion chromatography displayed an increased interfering efficacy in vitro. Finally, a perfusion process with perfusion rate control was established, resulting in a 79-fold increase in total virus yields compared to the original batch process in shake flasks. Again, a very high purity of OP7 chimera DIPs was obtained. This process could thus be an excellent starting point for good manufacturing practice production of DIPs for use as antivirals. KEY POINTS: • Scalable cell culture-based process for highly effective antiviral OP7 chimera DIPs • Production of almost pure OP7 chimera DIPs in the absence of infectious virus • Perfusion mode production and purification train results in very high titers.

Production of recombinant vesicular stomatitis virus-based vectors by tangential flow depth filtration

Cell culture-based production of vector-based vaccines and virotherapeutics is of increasing interest. The vectors used not only retain their ability to infect cells but also induce robust immune responses. Using two recombinant vesicular stomatitis virus (rVSV)-based constructs, we performed a proof-of-concept study regarding an integrated closed single-use perfusion system that allows continuous virus harvesting and clarification. Using suspension BHK-21 cells and a fusogenic oncolytic hybrid of vesicular stomatitis virus and Newcastle disease virus (rVSV-NDV), a modified alternating tangential flow device (mATF) or tangential flow depth filtration (TFDF) systems were used for cell retention. As the hollow fibers of the former are characterized by a large internal lumen (0.75 mm; pore size 0.65 μm), membrane blocking by the multi-nucleated syncytia formed during infection could be prevented. However, virus particles were completely retained. In contrast, the TFDF filter unit (lumen 3.15 mm, pore size 2-5 μm) allowed not only to achieve high viable cell concentrations (VCC, 16.4-20.6×106 cells/mL) but also continuous vector harvesting and clarification. Compared to an optimized batch process, 11-fold higher infectious virus titers were obtained in the clarified permeate (maximum 7.5×109 TCID50/mL). Using HEK293-SF cells and a rVSV vector expressing a green fluorescent protein, perfusion cultivations resulted in a maximum VCC of 11.3×106 cells/mL and infectious virus titers up to 7.1×1010 TCID50/mL in the permeate. Not only continuous harvesting but also clarification was possible. Although the cell-specific virus yield decreased relative to a batch process established as a control, an increased space-time yield was obtained. KEY POINTS: • Viral vector production using a TFDF perfusion system resulted in a 460% increase in space-time yield • Use of a TFDF system allowed continuous virus harvesting and clarification • TFDF perfusion system has great potential towards the establishment of an intensified vector production.

Generation of "OP7 chimera" defective interfering influenza A particle preparations free of infectious virus that show antiviral efficacy in mice

Influenza A virus (IAV) defective interfering particles (DIPs) are considered as new promising antiviral agents. Conventional DIPs (cDIPs) contain a deletion in the genome and can only replicate upon co-infection with infectious standard virus (STV), during which they suppress STV replication. We previously discovered a new type of IAV DIP "OP7" that entails genomic point mutations and displays higher antiviral efficacy than cDIPs. To avoid safety concerns for the medical use of OP7 preparations, we developed a production system that does not depend on infectious IAV. We reconstituted a mixture of DIPs consisting of cDIPs and OP7 chimera DIPs, in which both harbor a deletion in their genome. To complement the defect, the deleted viral protein is expressed by the suspension cell line used for production in shake flasks. Here, DIP preparations harvested are not contaminated with infectious virions, and the fraction of OP7 chimera DIPs depended on the multiplicity of infection. Intranasal administration of OP7 chimera DIP material was well tolerated in mice. A rescue from an otherwise lethal IAV infection and no signs of disease upon OP7 chimera DIP co-infection demonstrated the remarkable antiviral efficacy. The clinical development of this new class of broad-spectrum antiviral may contribute to pandemic preparedness.

Broad-Spectrum Antiviral Activity of Influenza A Defective Interfering Particles against Respiratory Syncytial, Yellow Fever, and Zika Virus Replication In Vitro

New broadly acting and readily available antiviral agents are needed to combat existing and emerging viruses. Defective interfering particles (DIPs) of influenza A virus (IAV) are regarded as promising options for the prevention and treatment of IAV infections. Interestingly, IAV DIPs also inhibit unrelated viral infections by stimulating antiviral innate immunity. Here, we tested the ability of IAV DIPs to suppress respiratory syncytial, yellow fever and Zika virus infections in vitro. In human lung (A549) cells, IAV DIP co-infection inhibited the replication and spread of all three viruses. In contrast, we observed no antiviral activity in Vero cells, which are deficient in the production of interferon (IFN), demonstrating its importance for the antiviral effect. Further, in A549 cells, we observed an enhanced type-I and type-III IFN response upon co-infection that appears to explain the antiviral potential of IAV DIPs. Finally, a lack of antiviral activity in the presence of the Janus kinase 1/2 (JAK1/2) inhibitor ruxolitinib was detected. This revealed a dependency of the antiviral activity on the JAK/signal transducers and activators of transcription (STAT) signaling pathway. Overall, this study supports the notion that IAV DIPs may be used as broad-spectrum antivirals to treat infections with a variety of IFN-sensitive viruses, particularly respiratory viruses.

Semi-continuous Propagation of Influenza A Virus and Its Defective Interfering Particles: Analyzing the Dynamic Competition To Select Candidates for Antiviral Therapy

Defective interfering particles (DIPs) of influenza A virus (IAV) are naturally occurring mutants that have an internal deletion in one of their eight viral RNA (vRNA) segments, rendering them propagation-incompetent. Upon coinfection with infectious standard virus (STV), DIPs interfere with STV replication through competitive inhibition. Thus, DIPs are proposed as potent antivirals for treatment of the influenza disease. To select corresponding candidates, we studied de novo generation of DIPs and propagation competition between different defective interfering (DI) vRNAs in an STV coinfection scenario in cell culture. A small-scale two-stage cultivation system that allows long-term semi-continuous propagation of IAV and its DIPs was used. Strong periodic oscillations in virus titers were observed due to the dynamic interaction of DIPs and STVs. Using next-generation sequencing, we detected a predominant formation and accumulation of DI vRNAs on the polymerase-encoding segments. Short DI vRNAs accumulated to higher fractions than longer ones, indicating a replication advantage, yet an optimum fragment length was observed. Some DI vRNAs showed breaking points in a specific part of their bundling signal (belonging to the packaging signal), suggesting its dispensability for DI vRNA propagation. Over a total cultivation time of 21 days, several individual DI vRNAs accumulated to high fractions, while others decreased. Using reverse genetics for IAV, purely clonal DIPs derived from highly replicating DI vRNAs were generated. We confirm that these DIPs exhibit a superior in vitro interfering efficacy compared to DIPs derived from lowly accumulated DI vRNAs and suggest promising candidates for efficacious antiviral treatment. IMPORTANCE Defective interfering particles (DIPs) emerge naturally during viral infection and typically show an internal deletion in the viral genome. Thus, DIPs are propagation-incompetent. Previous research suggests DIPs as potent antiviral compounds for many different virus families due to their ability to interfere with virus replication by competitive inhibition. For instance, the administration of influenza A virus (IAV) DIPs resulted in a rescue of mice from an otherwise lethal IAV dose. Moreover, no apparent toxic effects were observed when only DIPs were administered to mice and ferrets. IAV DIPs show antiviral activity against many different IAV strains, including pandemic and highly pathogenic avian strains, and even against nonhomologous viruses, such as SARS-CoV-2, by stimulation of innate immunity. Here, we used a cultivation/infection system, which exerted selection pressure toward accumulation of highly competitive IAV DIPs. These DIPs showed a superior interfering efficacy in vitro, and we suggest them for effective antiviral therapy.

Multiscale model of defective interfering particle replication for influenza A virus infection in animal cell culture

Cell culture-derived defective interfering particles (DIPs) are considered for antiviral therapy due to their ability to inhibit influenza A virus (IAV) production. DIPs contain a large internal deletion in one of their eight viral RNAs (vRNAs) rendering them replication-incompetent. However, they can propagate alongside their homologous standard virus (STV) during infection in a competition for cellular and viral resources. So far, experimental and modeling studies for IAV have focused on either the intracellular or the cell population level when investigating the interaction of STVs and DIPs. To examine these levels simultaneously, we conducted a series of experiments using highly different multiplicities of infections for STVs and DIPs to characterize virus replication in Madin-Darby Canine Kidney suspension cells. At several time points post infection, we quantified virus titers, viable cell concentration, virus-induced apoptosis using imaging flow cytometry, and intracellular levels of vRNA and viral mRNA using real-time reverse transcription qPCR. Based on the obtained data, we developed a mathematical multiscale model of STV and DIP co-infection that describes dynamics closely for all scenarios with a single set of parameters. We show that applying high DIP concentrations can shut down STV propagation completely and prevent virus-induced apoptosis. Interestingly, the three observed viral mRNAs (full-length segment 1 and 5, defective interfering segment 1) accumulated to vastly different levels suggesting the interplay between an internal regulation mechanism and a growth advantage for shorter viral RNAs. Furthermore, model simulations predict that the concentration of DIPs should be at least 10000 times higher than that of STVs to prevent the spread of IAV. Ultimately, the model presented here supports a comprehensive understanding of the interactions between STVs and DIPs during co-infection providing an ideal platform for the prediction and optimization of vaccine manufacturing as well as DIP production for therapeutic use.

Order-of-magnitude increase in laser-target coupling at near-relativistic intensities using compound parabolic concentrators

Achieving a high conversion efficiency into relativistic electrons is central to short-pulse laser application and fundamentally relies on creating interaction regions with intensities ≫10^{18}W/cm^{2}. Small focal length optics are typically employed to achieve this goal; however, this solution is impractical for large kJ-class systems that are constrained by facility geometry, debris concerns, and component costs. We fielded target-mounted compound parabolic concentrators to overcome these limitations and achieved nearly an order-of-magnitude increase to the conversion efficiency and more than tripled electron temperature compared to flat targets. Particle-in-cell simulations demonstrate that plasma confinement within the cone and formation of turbulent laser fields that develop from cone wall reflections are responsible for the improved laser-to-target coupling. These passive target components can be used to improve the coupling efficiency for all high-intensity short-pulse laser applications, particularly at large facilities with long focal length optics.

Production of relativistic electrons at subrelativistic laser intensities

Relativistic electron temperatures were measured from kilojoule, subrelativistic laser-plasma interactions. Experiments show an order of magnitude higher temperatures than expected from a ponderomotive scaling, where temperatures of up to 2.2 MeV were generated using an intensity of 1×10^{18}W/cm^{2}. Two-dimensional particle-in-cell simulations suggest that electrons gain superponderomotive energies by stochastic acceleration as they sample a large area of rapidly changing laser phase. We demonstrate that such high temperatures are possible from subrelativistic intensities by using lasers with long pulse durations and large spatial scales.

Sexual maturation in East German boys

According to the internationally accepted classification, sexual maturation was investigated in 8685 healthy East German boys by means of the status quo method and the probit regression analysis. The 3rd, 50th and 97th centiles were calculated for the development of both the male external genitalia and pubic and axillary hairs. The findings are in line with those of recent studies from different European countries. Special attention was paid to the stages at the beginning and at the end of sexual maturation, e.g. B 2, B 5; AH2, AH3; PH 2, PH5/6, etc.

Informative morphogenetic and phenogenetic variants in children with cleft lip/cleft palate

In 230 patients with nonsyndromic cleft lip/cleft palate (138 boys and 92 girls) and in 226 age related healthy children (137 boys and 89 girls) informative morphogenetic and phenogenetic variants (IMV and PHV, respectively) were investigated. There was no difference between the number of IMVs between both groups (chi 2 = 5.89; d.f. = 3; alpha > 0.70). This finding is in line with the hypothesis that facial cleft disorders occur during blastogenesis, whereas IMVs and PHVs are typical patterns of the embryo- and fetogenesis. The anthropometric findings are contradictory. In a few non-craniofacial phenogenetic variants significant differences were found between the patients and the healthy children. Intrinsic factors or secondary sequelae of the primary defect might additionally act in the morphological fine tuning of children with single cleft lip/cleft palate.

Sexual maturation in East German girls

According to the internationally accepted classification (Tanner, 1962; van Wieringen, 1971), sexual maturation was investigated in 8703 healthy East German girls by means of the status quo method and probit regression analysis. The third, 50th and 97th centiles were calculated for the development of breasts, axillary and pubic hair, and the shape of the hips. The findings were compared with those of recent studies from different European countries. Special attention was paid to the stages at the beginning and at the end of sexual maturation, e.g. B2/B5, AH2/AH3, etc.

Auriculocephalic index: a new anthropometric index for syndrome delineation

We describe a new anthropometric index, the "auriculocephalic index." It results from the ratio between the length of auricle and the corresponding preauricular head height. The index is independent of sex and of age. Normally it ranges between 0.25 (-2s) and 0.33 (+2s). In syndrome delineation it may help to diagnose more precisely large or small auricles as phenogenetic variants.

A somatic cell hybrid panel and DNA probes for physical mapping of human chromosome 7p

To identify by reverse genetics genes on the short arm of human chromosome 7 expected to be involved in the regulation of human craniofacial and limb development, we have set up a human mouse somatic cell hybrid panel that divides 7p into 9 fragments. The breakpoints are defined by deletions or translocations involving one chromosome 7 in the cells of the human cell fusion partners. Particularly densely covered with these cytogenetic anchor points is the proximal area of 7p within and around 7p13. The number of cytogenetic mapping points within proximal 7p could be increased by four, using two diploid human cell lines with small interstitial deletions in this region for dosage studies. We used Southern blots of this panel to assign to 7q or subregions of 7p more than 300 arbitrary DNA probes or genes that provide reference points for physical mapping of 7p. Three reciprocal translocations with one of the breakpoints in 7p13 mark the location of a gene involved in Greig cephalopolysyndactyly syndrome. To define an area in which we could identify candidates for this developmental gene, we established a macrorestriction map using probes flanking the putative gene region. The Greig translocations were found to be located within a 630-kb NotI restriction fragment.

Delayed spontaneous pubertal growth spurt in girls with the Ullrich-Turner syndrome

By means of an appropriate mathematical model (Sager's 2-components-concept) a delayed spontaneous pubertal growth spurt can be demonstrated in girls with 45,X Ullrich-Turner syndrome (UTS) (n1 = 45) as well as in those with 45,X/46,XX mosaicism (n2 = 14) never treated with any growth stimulating drug. On the average, this growth spurt begins later and its extent is smaller (mean growth rate = 3.10 and 2.79 cm, respectively, in the 15th year of chronological age) than in normal girls. The delay in acute growth spurt corresponds very well to the delay of skeletal maturation in the UTS (on the average 2 to 3 years of chronological age).

Long-term follow-up in females with Ullrich-Turner syndrome

In accordance with Nielsen & Stradiot's protocol (1987), we report on the long-term follow-up in 50 adult females with Ullrich-Turner syndrome. Attention is drawn mainly to social problems.

[Clinical evaluation of testicular size in boys and adolescents]

On 596 healthy boys and adolescents from 4 to 17 years of age measurements of the length and the width of the left testis as well as of the thickness of scrotal skin were carried out by means of a caliper, and the testis volume was secondarily calculated. Age specific mean values (means) and their +/- 2 s-limits are listed. Nonlinear s-shaped regression lines of the three main parameters clearly underline that the greatest increase is to be found in the length of testis. Consequently, as an indicator for gonadal developmental disturbances instead of testis volume measuring of testis length is recommended for routine in the physical examination of inpatients and outpatients as well as for the screening of schoolboys and male teenagers.

[A staged plan for laboratory diagnosis of hereditary metabolic diseases]

When clinical evidence provides grounds for suspecting inborn errors of metabolism it is urgent to perform the necessary, relevant, specific laboratory investigations in good time and with a view to quality. Normally, the realization depends on individual initiatives and the use of laboratories mainly designed for pediatrics and human genetics. Consequently the results are equally a matter of chance. Nothing in this situation can be changed in principle by using the catalogue of services of the Society for Human Genetics of the GDR. Central administrative provisions are necessary to improve the present unsatisfactory situation. Proposals for regulations, division of responsibility and a graduated programme of parameters are discussed here with a view to establishing uniform procedures.

[Familial Noonan syndrome]

A family with Noonan syndrome is described. The expressivity of the clinical feature is identical in all the cases observed. The importance of interdisciplinary and prospective medical care is emphasized.

[Ullrich-Turner syndrome and anorexia nervosa--an association?]

It is reported about the clinical progress of a 15 years old girl suffering from anorexia nervosa with Ulrich-Turner's syndrome. Etiological aspects are discussed. It is derived from calculations that there is a suspicious fact of an association of both disorders.

[Cytogenetic detection of Prader-Willi syndrome in infancy]

In the case of characteristic chromosomal deletion of chromosome 15(q11----q13) the diagnosis of the Prader-Willi syndrome can be already confirmed in early infancy as shown in our case report. In this connection cytogenetic high-resolution techniques are indispensable. Cytogenetic and clinical problems are discussed.

Greig syndrome in a large kindred due to reciprocal chromosome translocation t(6;7)(q27;p13)

We report on cases of Greig syndrome segregating in a large kindred over four generations due to reciprocal translocation t(6;7)(q27;p13) and on a patient from this pedigree with a severe malformation syndrome due to duplication 7(p13----pter). The clinical findings are discussed as possible consequence of a gene mutation due to the break at 7p13.

Increased methotrexate-induced chromosome breakage in patients with free trisomy 21 and their parents

Increased susceptibility of chromosomes from peripheral blood lymphocytes to the antimetabolite methotrexate (2 X 10(-6) M) has been found in patients with free trisomy 21 and their parents (N = 14). The level of induced chromatid and chromosome breaks is lowest in normal controls intermediate in patients' mothers and fathers, and highest in trisomy 21 patients. The findings are viewed as a special type of cytogenetic polymorphism or as a defective chromosomal infrastructure, also in the parents of trisomic children.

Isochromosome (18q) in siblings

A report is presented on a familial occurrence of isochromosome (18q) in a newborn infant and in a fetus in the 24th week of gestation after amniocentesis.

Body height in Turner's syndrome

Disease-specific growth curves for Turner's syndrome were calculated by means of 2nd order homogeneous differential equations with constant coefficients, taking different cytogenetical subtypes into account. Comparison of these growth curves between X-monosomic (n = 64) and 46,XX/45,X-mixoploid (n = 20) patients reveals no differences, in contrast to the commonly accepted opinion.

[Behavior of the hypothalamo-hypophyseal axis in a patient with asymmetric mixed gonadal dysgenesis (chromosome pattern 45,XO/46,XY) before and after gonad excision after with arginine, GRH and TRH stimulation]

In a 12 years old patient with asymmetric mixed gonadal dysgenesis (karyotype 45, XO/46,XY) a stimulation test with arginine, gonadotropin-releasing hormone (GRH) and thyreotropin-releasing hormone (TRH) was performed before and after exstirpation of the gonads as well as after application of sex steroids. FSH, LH, PRL, HGH, TSH, testosterone and oestradiol were determined by radioimmunoassay. The results show an intact hypothalamo-pituitary axis which reacts with a normal negative feedback with respect to the secretion of gonadotropins after application of sex steroids.