Scale-up and manufacturing of clinical-grade self-inactivating γ-retroviral vectors by transient transfection

The need for γ-retroviral (gRV) vectors with a self-inactivating (SIN) design for clinical application has prompted a shift in methodology of vector manufacturing from the traditional use of stable producer lines to transient transfection-based techniques. Herein, we set out to define and optimize a scalable manufacturing process for the production of gRV vectors using transfection in a closed-system bioreactor in compliance with current good manufacturing practices (cGMP). The process was based on transient transfection of 293T cells on Fibra-Cel disks in the Wave Bioreactor. Cells were harvested from tissue culture flasks and transferred to the bioreactor containing Fibra-Cel in the presence of vector plasmid, packaging plasmids and calcium-phosphate in Dulbecco's modified Eagle's medium and 10% fetal bovine serum. Virus supernatant was harvested at 10-14 h intervals. Using optimized procedures, a total of five ecotropic cGMP-grade gRV vectors were produced (9 liters each) with titers up to 3.6 × 10(7) infectious units per milliliter on 3T3 cells. One GMP preparation of vector-like particles was also produced. These results describe an optimized process for the generation of SIN viral vectors by transfection using a disposable platform that allows for the generation of clinical-grade viral vectors without the need for cleaning validation in a cost-effective manner.

Peripheral giant cell granuloma

Peripheral giant cell granuloma is a benign reactive lesion of gingiva. It manifests as a firm, soft, bright nodule or as a sessile or pedunculate mass. This article reports the management of peripheral giant cell granuloma in a 12-year-old boy by surgical excision.

Prosthetic Rehabilitation in Marble Bone Disease

Osteopetrosis is a rare metabolic disease.¹ Dental abnormalities may be attributed to the pathological changes in osteopetrosis. Patients with osteopetrosis are especially susceptible to osteomyelitis of mandible.¹ A 13-year-old girl presented with complaint of jaw swelling on left side. The radiograph of left mandible (lateral oblique view) showed small sequestrum with irregularity and erosions of the man-dibular cortical margins. This case report aims at diagnosis and treatment of osteopetrosis with superadded mandibular osteomyelitis―a are entity.

The woodchuck hepatitis virus post-transcriptional regulatory element reduces readthrough transcription from retroviral vectors

The woodchuck hepatitis virus post-transcriptional regulatory element (WPRE) increases transgene expression from a variety of viral vectors, although the precise mechanism is not known. WPRE is most effective when placed downstream of the transgene, proximal to the polyadenylation signal. We hypothesized that WPRE likely reduces viral mRNA readthrough transcription by improving transcript termination, which in turn would increase viral titers and expression. Using a Cre-lox-mediated plasmid-based assay, we found significant readthrough transcription from gamma-retroviral vector (RV) long terminal repeat (wt RV-LTR) and RV LTR with a self-inactivating deletion (SIN RV-LTR). WPRE, when placed upstream of the RV LTRs, significantly reduced readthrough transcription. Readthrough, present at much lower levels with the SIN HIV-1 LV-LTR, was also reduced with WPRE. When placed in RV vectors, WPRE increased total RV genomic mRNA; and increased viral titers from transiently transfected 293T cells and stable PG13 producer cells by 7- to 15-fold. The mechanism of increased titers and expression was not due to increased nuclear mRNA export, increased rate of viral transcription or a significant increase in viral mRNA half-life. Our results showed that WPRE improved vector genomic transcript termination to increase titers and expression from RVs.

The Kaposi's sarcoma-associated herpesvirus ORF57 protein: a pleurotropic regulator of gene expression

Herpesviridae comprises over 120 viruses infecting a wide range of vertebrates including humans and livestock. Herpesvirus infections typically produce dermal lesions or immune cell destruction, but can also lead to oncogenesis, especially with KSHV (Kaposi's sarcoma-associated herpesvirus). All herpesviruses are nuclear replicating viruses that subvert cellular processes such as nucleocytoplasmic transport for their advantage. For virus replication to take over the cell and produce lytic infection requires that virus gene expression outpace that of the host cell. KSHV ORF57 (open reading frame 57) appears to play a major role in this by (i) serving as a nuclear export receptor to carry intronless viral mRNAs out of the nucleus and (ii) inhibiting expression of intron-containing host mRNAs. As most of the virally encoded mRNAs are intronless compared with host cell mRNAs, these two mechanisms are critical to overcoming host gene expression.

Efficacy of probiotics in prevention of acute diarrhoea: a meta-analysis of masked, randomised, placebo-controlled trials

To evaluate the evidence for the use of probiotics in the prevention of acute diarrhoea, we did a meta-analysis of the available data from 34 masked, randomised, placebo-controlled trials. Only one trial was community based and carried out in a developing country. Most of the remaining 33 studies were carried out in a developed country in a health-care setting. Evaluating the evidence by types of acute diarrhoea suggests that probiotics significantly reduced antibiotic-associated diarrhoea by 52% (95% CI 35-65%), reduced the risk of travellers' diarrhoea by 8% (-6 to 21%), and that of acute diarrhoea of diverse causes by 34% (8-53%). Probiotics reduced the associated risk of acute diarrhoea among children by 57% (35-71%), and by 26% (7-49%) among adults. The protective effect did not vary significantly among the probiotic strains Saccharomyces boulardii, Lactobacillus rhamnosus GG, Lactobacillus acidophilus, Lactobacillus bulgaricus, and other strains used alone or in combinations of two or more strains. Although there is some suggestion that probiotics may be efficacious in preventing acute diarrhoea, there is a lack of data from community-based trials and from developing countries evaluating the effect on acute diarrhoea unrelated to antibiotic usage. The effect on acute diarrhoea is dependent on the age of the host and genera of strain used.

The herpes simplex virus ICP27 protein: a multifunctional post-transcriptional regulator of gene expression

The herpes simplex virus 1 ICP27 is an essential, highly conserved protein involved in various steps of herpes simplex virus 1 gene regulation as well as in the shut-off of host gene expression during infection. It functions primarily at the post-transcriptional level in inhibiting precursor mRNA splicing and in promoting nuclear export of viral transcripts. These activities are discussed.

Echocardiographic volumetry of the right ventricle

AIMS

The aim of our study was to define the optimal geometric model for two-dimensional volumetry of the right ventricle and its clinical validation.

METHODS AND RESULTS

It has been shown in previous reports that an ellipsoidal shell model best reflects the complex right ventricular geometry. We investigated 82 patients without tricuspid regurgitation and intracardiac shunt. Measurements of right ventricular stroke volume were made in modified apical four chamber and parasternal short axis views both in end-diastole and end-systole. The following controls were used:stroke volume of right ventricle estimated by thermodilution in 22 patients, stroke volume of left ventricle calculated with Teichholz formula in 77 patients, stroke volume of left ventricle estimated by Doppler volumetry in 41 patients. The correlations between right ventricular stroke volume by echocardiography and thermodilution, left ventricular volumetry by Teichholz and Doppler were r=0.87, p<0.001; r=0.91, p<0.001; and r=0.83, p<0.001, respectively.

CONCLUSION

The ellipsoidal shell model of the right ventricle is a good model for right ventricular volumetry.

Zinc supplementation for four months does not affect plasma copper concentration in infants

AIM

The aim of the present study, which was undertaken as a sub-study within a randomized controlled trial of zinc supplementation, was to evaluate the effect of prolonged zinc supplementation on copper status as assessed by hematological markers.

METHODS

Plasma copper and zinc were estimated at baseline and after 120 d of supplementation in a randomly selected infant subset (115) of the children. Of these, 61 children were in a zinc group (Z) getting 10 mg of elemental zinc, and 54 were in a control group (C) getting supplement without zinc.

RESULTS

Baseline plasma zinc was comparable in the two groups; post-supplementation zinc was significantly higher (Z 93.0 +/- 3.6 vs C 60.6 +/- 8.0) in the zinc supplementation group. There was no significant difference in the mean/median copper levels between the zinc and control groups. The percentage of children with plasma copper <100 microg/dl was also not significantly different between groups (baseline Z 14.8%, C 11.1%; post-supplementation Z 18.0%, C 11.1%). There were no differences between the zinc and control groups after 120 d of supplementation in hemoglobin (Hgb), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), or number of lymphocytes or granulocytes.

CONCLUSION

Zinc supplementation of 10 mg/d for 4 mo in this study did not affect copper status, as assessed by plasma copper concentration and hematological parameters, diagnostics of copper deficiency.

Comparative analysis of the outer membrane protein profiles of isolates of the Pasteurella multocida (B:2) associated with haemorrhagic septicaemia

Outer membrane proteins (OMP) of P. multocida (serotype B:2) field isolates (n = 6) and a vaccine strain (P-52) were extracted by a sarkosyl method and characterized using SDS-PAGE and immunoblotting. About 20 polypeptide bands were observed in the profile of the vaccine strain with MW ranging from 16 to 90 kDa and, based on band thickness and intensity of staining, three polypeptides of MW 31, 33 and 37 kDa were considered to be the major OMPs. The profiles of the field isolates showed minor differences when compared with that of the vaccine strain. The OMP of 33 kDa was only expressed by the vaccine strain. Four field isolates expressed an OMP of 39 kDa, which did not appear in the profiles of the remaining two field isolates and the P-52 strain. Similarly, an OMP of 25 kDa was exclusively seen in the profile of a single isolate. By immunoblotting studies, using anti-P. multocida (P-52) whole-cell hyperimmune serum raised in rabbits as well as buffalo immune sera, it became evident that the polypeptide of 37 kDa was the most antigenic OMP in the profiles of all the isolates, including the P-52 strain. Other polypeptides were either weakly antigenic or visible in the profile of only a few of the isolates. The study thus identified the major OMP of P. multocida (B:2) and suggested that this highly antigenic 37 kDa OMP has potential for further protective and immunodiagnostic studies.

Heterophile antibodies indicate progression of autoimmunity in human type 1 diabetes mellitus before clinical onset

We previously reported serum cytokines in a group of long term non-progressors to Type 1 diabetes; this reactivity detected in ELISA is now identified as heterophile antibody in some sera. Here, we characterize heterophile antibody activity. A 14 kDa-polypeptide from heterophile antibody containing serum bound to an anti-IL-4 column, but IL-4 was not detected by Western blot or by MS/MS sequencing. However, in 2/13 heterophile antibody positive sera, T-cell growth was potentiated and was blocked by an anti-human immunoglobulin. To examine the relationship between low affinity heterophile antibody presence and disease progression, 1100 archived serum samples were analyzed with two pairs of antibodies from 443 diabetes-free first degree relatives of Type 1 diabetes mellitus patients for heterophile antibody; 95 individuals developed diabetes on follow-up. Twenty-two individuals, whose serum was heterophile antibody positive with the second pair of antibodies (but negative with the first pair of antibodies), had a significantly higher incidence of developing diabetes after five years. Thirty-seven individuals with heterophile antibody reactivity with the first pair of antibodies, regardless of reactivity with the second pair of antibodies, had a significantly lower incidence of developing diabetes. While we cannot exclude the presence of genuine cytokine in all sera, these data indicate the presence of distinct groups of heterophile antibodies in patients at high risk to develop diabetes. Thus, anti-Ig heterophilic antibodies with different immunochemical reactivities are linked to the progression of or protection from Type 1 diabetes autoimmunity.

Acute myocardial infarction late after Mustard procedure for dextrotransposition of the great arteries

Systemic right ventricular dysfunction has been closely linked to late mortality and sudden cardiac death in patients with Mustard procedure for dextrotransposition of the great arteries. Two young patients with dextrotransposition of the great arteries late after Mustard procedure who presented with acute transmural myocardial infarction and sudden cardiac death (one patient) without prior exertional angina or causative coronary abnormalities are reported. It is surmised that acute coronary emboli originating from a severely dilated, hypocontractile systemic ventricle were the cause of transmural myocardial infarction. This phenomenon may be an important and as yet unrecognized factor in late morbidity and mortality in such patients.

High-level erythroid-specific gene expression in primary human and murine hematopoietic cells with self-inactivating lentiviral vectors

Use of oncoretroviral vectors in gene therapy for hemoglobinopathies has been impeded by low titer vectors, genetic instability, and poor expression. Fifteen self- inactivating (SIN) lentiviral vectors using 4 erythroid promoters in combination with 4 erythroid enhancers with or without the woodchuck hepatitis virus postregulatory element (WPRE) were generated using the enhanced green fluorescent protein as a reporter gene. Vectors with high erythroid-specific expression in cell lines were tested in primary human CD34(+) cells and in vivo in the murine bone marrow (BM) transplantation model. Vectors containing the ankyrin-1 promoter showed high-level expression and stable proviral transmission. Two vectors containing the ankyrin-1 promoter and 2 erythroid enhancers (HS-40 plus GATA-1 or HS-40 plus 5-aminolevulinate synthase intron 8 [I8] enhancers) and WPRE expressed at levels higher than the HS2/beta-promoter vector in bulk unilineage erythroid cultures and individual erythroid blast-forming units derived from human BM CD34(+) cells. Sca1(+)/lineage(-) Ly5.1 mouse hematopoietic cells, transduced with these 2 ankyrin-1 promoter vectors, were injected into lethally irradiated Ly5.2 recipients. Eleven weeks after transplantation, high-level expression was seen from both vectors in blood (63%-89% of red blood cells) and erythroid cells in BM (70%-86% engraftment), compared with negligible expression in myeloid and lymphoid lineages in blood, BM, spleen, and thymus (0%-4%). The I8/HS-40-containing vector encoding a hybrid human beta/gamma-globin gene led to 43% to 113% human gamma-globin expression/copy of the mouse alpha-globin gene. Thus, modular use of erythroid-specific enhancers/promoters and WPRE in SIN-lentiviral vectors led to identification of high-titer, stably transmitted vectors with high-level erythroid-specific expression for gene therapy of red cell diseases.

Gene therapy of a mouse model of protoporphyria with a self-inactivating erythroid-specific lentiviral vector without preselection

Successful treatment of blood disorders by gene therapy has several complications, one of which is the frequent lack of selective advantage of genetically corrected cells. Erythropoietic protoporphyria (EPP), caused by a ferrochelatase deficiency, is a good model of hematological genetic disorders with a lack of spontaneous in vivo selection. This disease is characterized by accumulation of protoporphyrin in red blood cells, bone marrow, and other organs, resulting in severe skin photosensitivity. Here we develop a self-inactivating lentiviral vector containing human ferrochelatase cDNA driven by the human ankyrin-1/beta-globin HS-40 chimeric erythroid promoter/enhancer. We collected bone marrow cells from EPP male donor mice for lentiviral transduction and injected them into lethally irradiated female EPP recipient mice. We observed a high transduction efficiency of hematopoietic stem cells resulting in effective gene therapy of primary and secondary recipient EPP mice without any selectable system. Skin photosensitivity was corrected for all secondary engrafted mice and was associated with specific ferrochelatase expression in the erythroid lineage. An erythroid-specific expression was sufficient to reverse most of the clinical and biological manifestations of the disease. This improvement in the efficiency of gene transfer with lentiviruses may contribute to the development of successful clinical protocols for erythropoietic diseases.