The role of CpG dinucleotides in DNA vaccines

DNA vaccines can induce potent humoral and cellular immune responses without any additional adjuvant. Recent studies indicate that unmethylated CpG dinucleotides within DNA vaccines are immune stimulatory and exert an essential endogenous adjuvant activity. These CpG motifs can be added deliberately to DNA or conventional protein vaccines to enhance the Th1 immune response.

Structure of the anchor-domain of myristoylated and non-myristoylated HIV-1 Nef protein

Negative factor (Nef) is a regulatory myristoylated protein of human immunodeficiency virus (HIV) that has a two-domain structure consisting of an anchor domain and a core domain separated by a specific cleavage site of the HIV proteases. For structural analysis, the HIV-1 Nef anchor domain (residues 2-57) was synthesized with a myristoylated and non-myristoylated N terminus. The structures of the two peptides were studied by1H NMR spectroscopy and a structural model was obtained by restrained molecular dynamic simulations. The non-myristoylated peptide does not have a unique, compactly folded structure but occurs in a relatively extended conformation. The only rather well-defined canonical secondary structure element is a short two-turn alpha-helix (H2) between Arg35 and Gly41. A tendency for another helical secondary structure element (H1) can be observed for the arginine-rich region (Arg17 to Arg22). Myristoylation of the N-terminal glycine residue leads to stabilization of both helices, H1 and H2. The first helix in the arginine-rich region is stabilized by the myristoylation and now contains residues Pro14 to Arg22. The second helix appears to be better defined and to contain more residues (Ala33 to Gly41) than in the absence of myristoylation. In addition, the hydrophobic N-terminal myristic acid residue interacts closely with the side-chain of Trp5 and thereby forms a loop with Gly2, Gly3 and Lys4 in the kink region. This interaction could possibly be disturbed by phosphorylation of a nearby serine residue, and modifiy the characteristic membrane interactions of the HIV-1 Nef anchor domain.

Surface expression of malarial antigens in Salmonella typhimurium: induction of serum antibody response upon oral vaccination of mice

The Escherichia coli OmpA protein can serve as a carrier for the expression of foreign antigens on the surface of gram-negative bacteria. Employing OmpA vectors, immunogenic moieties of the Plasmodium falciparum blood stage antigens SERP and HRPII have been expressed in the attenuated Salmonella typhimurium SR-11 strain. Upon induction, the malaria specific sequences of 189 (HRPII) and 451 (SERP) amino acids, fused into the OmpA protein, have been expressed. By indirect immunofluorescence studies, live bacteria expressing the fusion proteins react anti-SERP and anti-HRPII sera, respectively, indicating that the hybrid OmpA proteins become integrated into the bacterial outer membrane and expose the malarial antigens at the exterior surface. Mice that were immunized orally with S. typhimurium cells expressing HRPII and SERP on their surface show a humoral immune response as determined by the anti-SERP and anti-HRPII IgG and IgM titres. From these experiments it can be concluded that the OmpA surface expression system in combination with established Salmonella vaccine strains can be used to efficiently deliver large antigens to the mucosal immune system.

Specific cleavage sites of Nef proteins from human immunodeficiency virus types 1 and 2 for the viral proteases

Human immunodeficiency virus type 2 (HIV-2) Nef is proteolytically cleaved by the HIV-2-encoded protease. The proteolysis is not influenced by the absence or presence of the N-terminal myristoylation. The main cleavage site is located between residues 39 and 40, suggesting a protease recognition sequence, GGEY-SQFQ. As observed previously for Nef protein from HIV-1, a large, stable core domain with an apparent molecular mass of 30 kDa is produced by the proteolytic activity. Cleavage of Nef from HIV-1 in two domains by its own protease or the protease from HIV-2 is also independent of Nef myristoylation. However, processing of HIV-1 Nef by the HIV-2 protease is less selective than that by the HIV-1 protease: the obtained core fragment is heterogeneous at its N terminus and has an additional cleavage site between amino acids 99 and 100. Preliminary experiments suggest that the full-length Nef of HIV-2 and the core domain are part of the HIV-2 particles, analogous to the situation reported recently for HIV-1.

Nucleic acid immunization protects dogs against challenge with virulent canine parvovirus

Nucleic acid vaccines (NAVs) use expression vectors encoding one or more antigen genes to transfect host cells inducing both humoral and cellular immunity against the expressed antigen. NAV offers major advantages over conventional vaccines for the protection of humans and animals. This study shows that a plasmid DNA (pGT36VP1) encoding the full length VP1 region of canine parvovirus (CPV) induces immunity that protects dogs against challenge with virulent virus. Five dogs without anti-CPV antibodies were injected at 9 months of age with increasing doses of pGT36VP1 or saline. NAV vaccinated dogs showed an increase of serum IgG titer starting 1 week post-injection which peaked at week 2 and remained detectable for at least 14 weeks. A second dose of NAV resulted in an anamnestic response within 1 week. IgG titers peaked at week 3 and 4 after the second injection. All pGT36VP1 vaccinated dogs were protected against infection after virulent CPV challenge regardless of dose and the unvaccinated control dog was fully susceptible. This study demonstrated for the first time that a NAV can protect dogs against an infectious disease.

Comparison of plasmid DNA preparation methods for direct gene transfer and genetic immunization

Plasmid DNA is widely used for direct gene transfer in animals to study gene therapy, gene regulation, drug delivery and genetic immunization. Here we compare cesium chloride and anion-exchange purified plasmid DNA for direct gene transfer in mouse muscle and show no differences in efficiency of transfection with reporter genes or in humoral response to DNA-based immunization.

Heterologous recombination between Autographa californica nuclear polyhedrosis virus DNA and foreign DNA in non-polyhedrin segments of the viral genome

We used the expression vector system of Autographa californica nuclear polyhedrosis virus (AcNPV) and Spodoptera frugiperda insect cells to study mechanisms of recombination in insect cells. We concentrated on the isolation and analysis of heterologous recombinants. The E1 region of human adenovirus type 2 (Ad2) was inserted into regions of the AcNPV genome which lacked apparent homologies to the polyhedrin region. Out of a total of 122 recombinant AcNPV plaques, which hybridized to Ad2 DNA in plaque annealing experiments, 13 recombinants proved heterologous, and 5 of these recombinants could be grown to titers that facilitated virus replication and further investigations of the recombinant DNA. Restriction and Southern blot analyses for all of the recombinants and nucleotide sequence determinations for one of them permitted the mapping of the sites of foreign DNA integration into the AcNPV genome for the heterologous recombinants. These sites were located in the EcoRI-C (map units 42.5-52.4), the EcoRI-L (map units 69.5-72.5), the EcoRI-O (map units 32.6-34.5), and the EcoRI-Q (map units 88.2-89.7) segments of the plaque isolate E AcNPV genome. Two of the heterologous recombinants carried the insert in the EcoRI-L fragment. The nucleotide sequence determinations across the sites of junction between the AcNPV DNA and the foreign (Ad2) DNA in one of the heterologous recombinants, AcNPV-Ad2E1-D, revealed no sequence similarities at or close to the sites of junctions. A short sequence of six nucleotides was deleted from the original EcoRI-O sequence of AcNPV at the site of insertion. The inserted Ad2E1 DNA fragment comprised nucleotides 183-2763; thus nucleotides at the termini had been deleted. In the usual polyhedrin gene-located recombinants, the foreign Ad2 DNA segment was fused to the polyhedrin promoter and recombined presumably via polyhedrin sequence segments in the vector into the polyhedrin gene of AcNPV. In one of the control recombinants, AcNPV-Ad2E1-192, the Ad2E1 DNA segment between nucleotides 1 and 3117 (out of 3322 original nucleotides) was inserted in an inverted orientation between nucleotides -115 and +735 of the polyhedrin gene of AcNPV. This particular polyhedrin sequence was deleted in the process. It was uncertain how this recombinant had been generated. The infectivities of the polyhedrin-located recombinant AcNPV-Ad2E1-192 and of the five heterologous recombinants were compared by single-cycle growth curves to the infectivity of non-recombinant AcNPV.(ABSTRACT TRUNCATED AT 400 WORDS)

Closing the gap: Ion chromatography coupled to high-resolution mass spectrometry to trace highly polar anionic substances in groundwater

Polar, mobile and toxic (PMT), and very polar and very mobile (vPvM) substances pose a threat to the water cycle but are often not covered in conventional environmental monitoring programs. Within this realm of substances, one compound class of concern are pesticides and their transformation products as they are deliberately introduced into the environment. To detect very polar anionic substances, including many pesticide transformation products with log D_OW values ranging between -7.4 and 2.2, an ion chromatography high-resolution mass spectrometry method was developed in this study. Since inorganic anions, such as chloride and sulfate, interfere with the analysis of organic species, their removal via precipitation with Ag/Ba/H cartridges was assessed. To improve LOQs, vacuum-assisted evaporative concentration (VEC) was evaluated. By using VEC and removing inorganic salt ions, the median LOQ improved from 100 ng/L in evian® water without sample treatment to 10 ng/L after enrichment and 30 ng/L in karst groundwater. Using this method, twelve out of 64 substances covered by the final method were found in karst groundwater in concentrations of up to 5600 ng/L, and seven exceeded 100 ng/L. To the authors' knowledge, the dimethenamid TP M31 and chlorothalonil TP SYN548008 were detected for the first time in groundwater samples. The coupling to a high-resolution mass spectrometer also allows for non-target screening and hence, this method presents a powerful tool to tackle PMT/vPvM substances.

Non-homologous recombination between adenovirus and AcNPV DNA fragments in cell-free extracts from insect Spodoptera frugiperda nuclei

In previous work, we have developed a cell-free system from nuclear extracts of hamster cells to study the mechanism of integrative recombination between adenovirus type 12 (Ad12) DNA and hamster cell DNA (Jessberger et al., 1989; Tatzelt et al., 1992). We have also demonstrated that in insect cells the left terminal fragment of Ad2 DNA can insert by non-homologous recombination into the 32.6 to 34.5 map unit (EcoRI-O) fragment and into other segments of Autographa californica nuclear polyhedrosis virus (AcNPV) DNA (Xiong et al., 1991). We have now imitated this recombination event in vitro by incubating the E1 fragment of Ad2 DNA and the EcoRI-O fragment of AcNPV DNA, both in the plasmid-cloned circular forms, with partly purified nuclear extracts from Spodoptera frugiperda insect cells. Proteins from these extracts have been fractionated by gel filtration. After the reextraction of DNA from the incubation mixture, recombinants generated in this cell-free system have been identified directly with the polymerase chain reaction (PCR) by using Taq polymerase and appropriate primers which are unique to either of the two reaction partners. The recombinants identified are all different. The results of control experiments argue against the possibility that unspecific reaction products might have been generated during PCR. Nucleotide sequence determinations in some of the recombinants localize the sites of genetic exchange between the two partners and assess the non-homologous nature of the reaction. The recombinants are characterized by the presence of short patch homologies at or close to the sites of linkage between the reaction partners, as described earlier in the hamster cell system (Tatzelt et al., 1992). The occurrence of recombinants in the cell-free system can also be demonstrated by a biological test in which potential recombinants are isolated by transfection into recA- strains of Escherichia coli.

Characteristics of patients with a lipoprotein(a) assessment – a health insurance claims database analysis

Background

Elevated lipoprotein(a) [Lp(a)] has been established as marker of cardiovascular [CV] risk, however, it is not commonly assessed.

Purpose

The aim of the study was to characterize patients who underwent their first Lp(a) testing regarding sociodemographic characteristics and clinical outcomes.

Methods

A retrospective analysis was performed on data from 4 million individual patients in a local database that provides complete, longitudinal, anonymized claims data. The data are representative of the German population in terms of age and gender. Lp(a) billing codes documented in the ambulatory setting were used to identify adult patients in 2015 to 2018 (index quarter defined as the first Lp(a) test in the respective year). These patients must not have had any Lp(a) test in the year prior to the index quarter. Patient data needed to be available for at least 1 year before and 1 year after the Lp(a) test or until death, whichever came first. Patients were followed for a maximum of four years.

Results

Within the four-year period, 36.609 patients (0.83% of the analysis set) had an Lp(a) test, of whom the majority (58%) were women. 50% of the women (median age 49 years) and 32% of the men (median age 56 years) were younger than 50 years.

The most prevalent comorbidities (based on International Classification of Diseases, version 10, German modification) at index were: dyslipidemia (E78) 46%, essential hypertension (I10) 46%, dorsalgia (M54) 25%, overweight/obesity (E66) 18%, chronic ischemic heart disease (I25) 16%, type 2 diabetes mellitus (E11) 15%, other coagulation defects (D68) 14%, depressive episodes (F32) 14%; disorders of refraction and accommodation (H52) 13%, somatoform disorders (F45) 13%, other non-toxic goiter (E04) 13%, other hypothyroidism (E03) 13%, and chronic kidney disease (N18) 11%.

The rates of cardiovascular events and procedures are listed in the table below.

Conclusions

Lp(a) tests are rarely performed in Germany. Women are more often tested than men, and in women this is done at a younger age. The data suggest that CV events/ CV hospitalizations frequently trigger the first Lp(a) assessment. The population tested displayed a high prevalence of cardiovascular comorbidities. The data identify an opportunity to better characterize the CV risk by testing Lp(a) once in a lifetime independent of prior CV events as recommended by current European Society of Cardiology/European Atherosclerosis Society guidelines.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): The analysis has been funded by Novartis Pharma GmbH, Nuremberg.

Characteristics of patients with lipoprotein(a) assessment: a health insurance claims database analysis

Background

Elevated lipoprotein(a) (Lp(a)) is an inherited risk factor for cardiovascular disease. Testing for Lp(a) in primary care is recommended by current ESC guidelines to identify persons at risk. We aimed to report contemporary trends in Lp(a) testing in Germany and subsequent changes in treatment strategies and patient's outcome over time.

Methods and results

An observational, retrospective, anonymized claims data analysis was performed on a database with 4 million patients, representative of the German population in the years 2015 to 2018. Patients were eligible when no Lp(a) test was documented in the year prior to the index date/quarter (time point of the first documented Lp(a) test) and if the patient data was available for at least 1 year before and after the Lp(a) test or until death, whichever came first. In a cross-sectional analysis, Lp(a) test rates in the selected database population increased from 0.25% (n=7,432) in 2015 to 0.34% (n=10,257) in 2018. About 57.8% of the tested population was female. Higher test rates were observed in women especially in younger age groups. A subgroup analysis of patients with previous atherosclerotic cardiovascular disease (ASCVD) revealed overall higher Lp(a) test rates (0.43% in 2015, 0.60% in 2018). In a longitudinal analysis, patients tested for Lp(a) and respective controls matched for age, gender and region, were followed for a maximum of four years. Out of 3,139,410 eligible patients, 36,609 (1.17%) were tested for Lp(a) over the study period at a mean age of 51.91 years and were meeting the inclusion criteria. In comparison to matched controls without Lp(a) test, patients tested for Lp(a) had more comorbidities and higher ASCVD risk. The Lp(a)-tested cohort and the control group had similar mortality rates (0.88 vs. 0.94 per 100 person-years (PY), p=0.21). However, total mortality was lower in patients with prior ASCVD and Lp(a) test compared to matched patients with prior ASCVD but no Lp(a) test (Rates: 2.30 vs. 3.64 per 100 PY, p<0.001). Importantly, the patients with Lp(a) test were treated with a higher number of cardiovascular medications, underwent more laboratory examinations, and had more frequent consultations by specialized physicians after the test.

Conclusion

Lp(a) testing is an indicator of more intensive diagnostic work-up and treatment. Less than 1% of the patients have been newly tested for Lp(a) in 2018. The data identify an opportunity to better characterize ASCVD risk by testing for Lp(a).

Funding Acknowledgement

Type of funding sources: None.

A rapid optimized protocol for downward alkaline Southern blotting of DNA

A simple and efficient 2.5-h Southern blotting procedure is described that uses 0.4 M NaOH to transfer DNA in a downward direction. The resulting blots give signals that are both sharper and 30% stronger than those obtained by conventional upward-transferred blots.

CpG DNA is a potent enhancer of specific immunity in mice immunized with recombinant hepatitis B surface antigen

Unmethylated CpG dinucleotides in bacterial DNA or synthetic oligodeoxynucleotides (ODN) cause B cell proliferation and Ig secretion, monocyte cytokine secretion, and activation of NK cell lytic activity and IFN-gamma secretion in vivo and in vitro. The potent immune activation by CpG ODN suggests possible utility for enhancing immune responses to vaccines. Mice immunized with recombinant hepatitis B virus surface Ag and a CpG ODN as an immune enhancer have titers of Abs against HBsAg (anti-HBs) that are five times higher than those of mice immunized with HBsAg and the standard adjuvant, aluminum hydroxide (alum). Ab titers in mice immunized with HBsAg and both CpG ODN plus alum were 35 times higher than the titers in mice immunized with alum alone, indicating a strong synergistic interaction between the CpG ODN and alum. ODN without CpG motifs had little or no immune-enhancing activity at the doses used herein. Alum induces a Th2 humoral response (mostly IgG1) and no CTL. In contrast, CpG ODN gives a strong Thl response with predominantly IgG2a Abs and CTL, even when mixed with alum. In vitro studies to determine possible mechanisms of CpG immune-enhancing effects show that CpG ODN induce expression of costimulatory molecules on Ag-presenting cells and drive B cell isotype switching in the appropriate cytokine milieu. These studies demonstrate that CpG ODN are promising new immune enhancers for vaccination applications.

Gene therapy for cystic fibrosis in humans by liposome-mediated DNA transfer: the production of resources and the regulatory process

The number of clinical trials using gene transfer technology, either active or under discussion, is increasing rapidly. However, little information is available describing the regulatory procedures or safety specifications that must be considered before initiation of such trials in Europe. We describe the procedure used by our group to produce resources for the first stage of a phase I trial of liposome-mediated gene therapy for cystic fibrosis. The current lack of written and co-ordinated guidance from the numerous interested regulatory agencies within the UK and Europe makes determination of the appropriate safety specifications and procedures for these novel trials difficult, as does the fact that some new agencies (such as the Genetic Therapy Advisory Committee in the UK) and some which are unfamiliar with clinical trials (such as the Department of the Environment) are involved as well as the Medicines Control Agency. In addition, we estimate that the realistic cost of these trials, which in many cases will have to be covered from research budgets provided by government agencies or medical charities, could lead to delays in the clinical application of this important new therapeutic strategy.

Perceived effects and recovery in Oklahoma City firefighters

This survey of 325 Oklahoma City Firefighters examined their perceptions of the effect of the bombing, their recovery and their sources of support. Other variables that were considered in this analysis included age, usefulness of the Critical Incidence Stress Management (CISM) procedures, and attitude, an aggregate variable that accounted for job satisfaction. Of particular importance in this analysis was the finding that support from "faith" was a primary predictor of positive outcome and positive attitude over the one-year period. However, the effect of the variable differed for older and younger firefighters. That is, there was a greater proportion of younger firefighters among those reporting greater support from faith. These data suggest that, at least in this geographic area, chaplains, and other spiritual leaders may play a particularly important role in the aftermath of such a disaster.

Short technical reports. Effects of lipopolysaccharide on transfection efficiency in eukaryotic cells

The suitability of different purification methods for preparation of plasmid DNA for transfection into eukaryotic cells was systematically investigated. The reporter plasmid, pRSVcat, was prepared using several methods, and residual impurities in the preparations were quantitated. Transfection with these preparations was performed with several cell lines (HeLa, Huh7, COS7 and LMH) and two transfection methods: liposome-mediated and calcium phosphate transfection. Transfection efficiencies were determined by measuring chloramphenicol acetyltransferase expression. Higher transfection efficiencies were obtained with plasmid preparations of higher purity (those prepared by anion-exchange chromatography or two rounds of CsCl-gradient centrifugation) than with preparations of lower purity (those prepared using a silica-based DNA adsorption method or a single round of CsCl centrifugation). The results also demonstrated specifically that increasing concentrations of lipopolysaccharides in plasmid preparations directly correlate with decreasing transfection efficiencies.

Tracing pesticide dynamics: High resolution offers new insights to karst groundwater quality

Generally, karst aquifers and springs are highly susceptible to contamination due to the high permeability and, therefore, groundwater flow velocities. The often thin soil cover, accompanied by dolines, can lead to fast infiltration of precipitation water loaded with mobilized contaminants such as pesticides and their transformation products. To date, continuous, temporally highly resolved in-situ monitoring to decipher concentration dynamics for a broad range of pesticides is missing. Therefore, a transportable HPLC-HRMS/MS system (MS2field) was positioned at two karst study sites in the Swiss Jura. Water samples were collected and analyzed for pesticides and their transformation products in-situ every 20 min for 6 weeks in 2021 and 8 weeks in 2022. During the spraying season in 2021, six rain events at site 1 and three at site 2 in 2022 were captured. Concurrently, the water quality parameters electrical conductivity, pH, nitrate, turbidity, and water level, were monitored continuously at high temporal resolution. Further, bacterial cell counts were monitored via online flow cytometry. In 2021, several pesticides and pesticide transformation products were detected in peak concentrations after rain events, of which metamitron showed the highest concentration of up to 1000 ng/L. In one rain event, the Swiss federal and EU drinking water limit of 100 ng/L was exceeded for up to 38 h. Compared with highly frequent MS2field samples collected every 20 min, 42-hours composite samples severely underestimated peak concentrations for all compounds, especially for labile ones. Therefore, it was demonstrated that exceedences of the regulatory limit would have been missed if just composite sampling would have been conducted. Peak concentrations of pesticides coincided with peaks in nitrate concentration and bacterial cell counts following rain events. The correlation analysis showed strong correlations between the three analyzed contaminants (pesticides, nitrate and bacteria), and the proxy parameters electrical conductivity, and pH. The investigation of a second spring revealed similar dynamics indicating that these can be expected in other karst aquifers as well.

Liposome mediated in vivo gene transfer into different tissues of the gastrointestinal tract

The possibility to transfer and express genetic material in mammalian cells represents a new approach to the treatment of genetic and acquired disorders. So far, most studies use in vitro techniques to introduce foreign DNA into cultured cells, followed by reintroduction of these genetically altered cells into living organisms. In the present study we demonstrate that the LacZ marker gene can be selectively delivered, by in vivo techniques, to various locations of the gastrointestinal tract. Genetic material was targeted to the stomach, the colon, the liver and the pancreas using cationic liposomes. For transfer into the stomach and colon an intraluminal application, in the liver a portal access and in the pancreas an intraductal infusion was chosen. 48 hours after administration, the LacZ gene product beta-galactosidase could be localized in these tissues by cytochemistry. These experiments suggest a new approach to study gastrointestinal physiology and may offer novel aspects for the treatment of gastrointestinal diseases.