Vector Replication Research Articles

Optimal Replication of Random Claims by Ordinary Integrals with Applications In Finance

By the classical Martingale Representation Theorem, replication of random vectors can be achieved via stochastic integrals or solutions of stochastic differential equations. We introduce a new approach to replication of random vectors via adapted differentiable processes generated by a controlled ordinary differential equation. We found that the solution of this replication problem exists and is not unique. This leads to a new optimal control problem: find a replicating process that is minimal in an integral norm. We found an explicit solution of this problem. Possible applications to portfolio selection problems and to bond pricing models are suggested.

Optimal replication of random vectors by ordinary integrals

We consider a problem of replication of random vectors by ordinary integrals in the setting when an underlying random variable is generated by a Wiener process. The goal is to find an optimal adapted process such that its cumulative integral at a fixed terminal time matches this variable. The optimal process has to be minimal in an integral norm.

Investigation of the antimicrobial effect of Neosartorya fischeri antifungal protein (NFAP) after heterologous expression in Aspergillus nidulans

Neosartorya fischeri antifungal protein (NFAP) is a β-defensin-like peptide produced by the N. fischeri NRRL 181 isolate. In this study, we investigated the manifestation of the antimicrobial effect of NFAP via heterologous expression of the nfap gene in an NFAP-sensitive fungus, Aspergillus nidulans. Heterologous expression of the nfap gene was carried out in A. nidulans CS2902 using a pAMA1-based autonomous replicative vector construct. The effect of the produced NFAP on the germination of A. nidulans conidia was investigated by scanning electron microscopy (SEM), and by DAPI and Calcofluor white (CFW) staining. 2',7'-Dichlorodihydrofluorescein diacetate staining and an Annexin V-FITC Apoptosis Detection kit were used to reveal the accumulation of reactive oxygen species (ROS) and the possible apoptotic, necrotic effect. The impact of mono- and divalent cations on the antimicrobial activity of NFAP was also examined. Transformants expressing the nfap gene showed reduced hyphal growth compared with the untransformed strain. This effect was absent in the presence of mono- and divalent cations (50 and 100 mM KCl, Mg(2)SO(4), Na(2)SO(4)). Delayed and abnormal germination was observed in the case of transformants. Conidia developed short branching germination tubes with swollen tips. The great majority of germinating conidia were destroyed after 8 h of cultivation, although a few survived and developed into abnormal hyphae. Damage in the organization of the cell wall, the destruction of chitin filaments and the accumulation of nuclei at the broken hyphal tips were detected by SEM, DAPI and CFW staining. The accumulation of ROS and more frequent apoptotic, necrotic events were also observed in the case of the NFAP-producing A. nidulans strain.

Neo-islet formation in liver of diabetic mice by helper-dependent adenoviral vector-mediated gene transfer.

Type 1 diabetes is caused by T cell-mediated autoimmune destruction of insulin-producing cells in the pancreas. Until now insulin replacement is still the major therapy, because islet transplantation has been limited by donor availability and by the need for long-term immunosuppression. Induced islet neogenesis by gene transfer of Neuogenin3 (Ngn3), the islet lineage-defining specific transcription factor and Betacellulin (Btc), an islet growth factor has the potential to cure type 1 diabetes.Adenoviral vectors (Ads) are highly efficient gene transfer vector; however, early generation Ads have several disadvantages for in vivo use. Helper-dependent Ads (HDAds) are the most advanced Ads that were developed to improve the safety profile of early generation of Ads and to prolong transgene expression1. They lack chronic toxicity because they lack viral coding sequences2-5 and retain only Ad cis elements necessary for vector replication and packaging. This allows cloning of up to 36 kb genes.In this protocol, we describe the method to generate HDAd-Ngn3 and HDAd-Btc and to deliver these vectors into STZ-induced diabetic mice. Our results show that co-injection of HDAd-Ngn3 and HDAd-Btc induces 'neo islets' in the liver and reverses hyperglycemia in diabetic mice.

Neo-Islet Formation in Liver of Diabetic Mice by Helper-dependent Adenoviral Vector-Mediated Gene Transfer

Type 1 diabetes is caused by T cell-mediated autoimmune destruction of insulin-producing cells in the pancreas. Until now insulin replacement is still the major therapy, because islet transplantation has been limited by donor availability and by the need for long-term immunosuppression. Induced islet neogenesis by gene transfer of Neuogenin3 (Ngn3), the islet lineage-defining specific transcription factor and Betacellulin (Btc), an islet growth factor has the potential to cure type 1 diabetes. Adenoviral vectors (Ads) are highly efficient gene transfer vector; however, early generation Ads have several disadvantages for in vivo use. Helper-dependent Ads (HDAds) are the most advanced Ads that were developed to improve the safety profile of early generation of Ads and to prolong transgene expression1. They lack chronic toxicity because they lack viral coding sequences2-5 and retain only Ad cis elements necessary for vector replication and packaging. This allows cloning of up to 36 kb genes. In this protocol, we describe the method to generate HDAd-Ngn3 and HDAd-Btc and to deliver these vectors into STZ-induced diabetic mice. Our results show that co-injection of HDAd-Ngn3 and HDAd-Btc induces 'neo islets' in the liver and reverses hyperglycemia in diabetic mice.

Begomovirus research in India: A critical appraisal and the way ahead

Begomoviruses are a large group of whitefly-transmitted plant viruses containing single-stranded circular DNA encapsidated in geminate particles. They are responsible for significant yield losses in a wide variety of crops in India. Research on begomoviruses has focussed on the molecular characterization of the viruses, their phylogenetic analyses, infectivities on host plants, DNA replication, transgenic resistance, promoter analysis and development of virus-based gene silencing vectors. There have been a number of reports of satellite molecules associated with begomoviruses. This article aims to summarize the major developments in begomoviral research in India in the last approximately 15 years and identifies future areas that need more attention.

Development of a novel plasmid as a shuttle vector for heterologous gene expression in Mycoplasma yeatsii

A circular plasmid, pMyBK1, was detected in Mycoplasma yeatsii strain GIHT. Analysis of the sequence of the 3432-bp replicon identified two predicted open reading frames (ORFs), one with sequence similarity to multiple plasmid mobilization proteins and one that matches only to hypothetical ORFs encoded by integrated chromosomal elements in the sequenced genomes of two Mycoplasma species. Shuttle vectors were constructed in Escherichia coli which could be introduced into M. yeatsii at high efficiency (104–105 per μg DNA) by electroporation. Independent deletion analysis of the two ORFs disclosed that whereas mob was dispensable, orf2 was necessary for plasmid replication or maintenance. The absence of plasmid-encoded database matches for ORF2 indicates that pMyBK1 represents a novel plasmid family. One shuttle vector was used to demonstrate heterologous expression of the Mycoplasma fermentans malp gene and was stable during multiple passages. The host–plasmid system described has potential application for genetic manipulation in a genus for which few replicative vectors are available.

Interferon-β Sensitivity of Tumor Cells Correlates With Poor Response to VA7 Virotherapy in Mouse Glioma Models

In our recent study, replicative alphaviral vector VA7 was found to be effective against orthotopic human U87-glioma xenografts in an athymic mouse model eradicating the tumors with single intravenous (i.v.) injection. Here, we tested the efficacy of VA7 in immunocompetent orthotopic GL261 and CT-2A glioma models of C57BL/6 mouse in vivo. The cell lines were susceptible to VA7 infection in vitro, but GL261 infection was highly restricted in confluent cell cultures, and mouse interferon-β (IFNβ) pretreatment prevented the replication of VA7 in both cell lines. When mice bearing orthotopic GL261 or CT-2A tumors were administered neurotropic VA7, either i.v. or intracranially (i.c.), the vector was unable to infect the tumor and no survival benefit was achieved. Pretreatments with immunosuppressive cyclophosphamide (CPA) and rapamycin markedly lowered serum-neutralizing antibodies (NAbs) but had no effect on tumor infection or survival. Intracranial GL261 tumors were refractory also in athymic C57BL/6 mice, which have serious defects in their adaptive immunity. Implanted VA7-infected GL261 cells formed tumors with only slightly delayed kinetics and without improving survival thus excluding the participation of physical barriers and indicating robust host IFN action. Mouse and human IFNβ do not seem be species cross-reactive, which might limit the translational relevance of xenograft models in oncolytic virotherapy.

Conditionally replicative adenovirus-based mda-7/IL-24 expression enhances sensitivity of colon cancer cells to 5-fluorouracil and doxorubicin

Multiple drug resistance (MDR) greatly limits the efficacy of chemotherapy for colon cancer. An adenovirus armed with Melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24; abbreviated to 'IL-24' here) was shown to reverse the MDR of colon cancer cells to oxaliplatin and doxorubicin. However, the relatively low expression level of IL-24 mediated by a replication-deficient adenoviral vector hindered its clinical application. To enhance IL-24-dependentreversion of the MDR phenotype, we utilized a conditionally replicative adenoviral vector, AdBB-IL24, to express IL-24 at a high level for more efficient MDR reversion. An enzyme-linked immunosorbent assay (ELISA) suggested conditionally replicative adenoviral vector-mediated IL-24 expression was elevated in comparison with that of a replication-deficient adenoviral vector, Ad-IL24. AdBB-IL24 was shown to reverse MDR in colon cancer cells more potently than Ad-IL24. The AdBB-IL24-induced MDR reversion was linked to reduced P-glycoprotein (Pgp) and breast cancer resistance protein 1 (BCRP1) expression. Consistently, 5-fluorouracil and doxorubicin induced more apoptosis in AdBB-IL24-infected colon cancer cells compared with that in the Ad-IL24-infected cells. A cell viability assay showed that AdBB-IL24 could enhance the growth-inhibitory effect of 5-fluorouracil and doxorubicin on colon cancer cells more effectively than Ad-IL24 in vitro. In a mouse model, we also found that the combination of 5-fluorouracil and doxorubicin with AdBB-IL24 completely inhibited the growth of colon cancer cells. We here provide evidence supporting conditionally replicative adenoviral vector-based gene therapy as a powerful strategy to enhance mda7/IL-24-dependent MDR reversion of colon cancer cells.

Vector replication and expression of HIV-1 antigens by the HIV/AIDS vaccine candidate MVA-B is not affected by HIV-1 protease inhibitors

MVA-B is an attenuated poxvirus vector expressing human immunodeficiency virus type 1 Env, Gag, Pol, and Nef antigens from clade B, and is considered a promising HIV/AIDS vaccine candidate. Recently, a phase I clinical trial in human healthy volunteers has shown that MVA-B is safe and highly immunogenic, inducing broad, polyfunctional, and long-lasting CD4+ and CD8+ T cell responses to HIV-1 antigens, with preference for effector memory T cells; and it also triggers the induction of specific antibodies to Env in most of the vaccines. While MVA recombinants expressing HIV-1 antigens are being used or plan to use in therapeutic clinical trials, little is known on the effect of HIV-1 highly active antiretroviral therapy in MVA life cycle. To define this role, here we have evaluated in established cell cultures and human dendritic cells to what extent different HIV-1 protease inhibitors affect virus replication and expression of HIV-1 antigens during MVA-B infection. The results obtained revealed that the most commonly used HIV-1 protease inhibitors (atazanavir, ritonavir, and lopinavir) had no effect on MVA-B virus growth kinetics, even at higher concentrations than those normally used on HAART. Furthermore, expression of gp120 and the fused Gag-Pol-Nef polyprotein in permissive and non-permissive cells infected with MVA-B were also not affected. These findings are relevant information for the therapeutic use of MVA-B as an HIV-1/AIDS vaccine.

Development of a Double-Crossover Markerless Gene Deletion System in Bifidobacterium longum: Functional Analysis of the α-Galactosidase Gene for Raffinose Assimilation

Functional analysis of Bifidobacterium genes is essential for understanding host-Bifidobacterium interactions with beneficial effects on human health; however, the lack of an effective targeted gene inactivation system in bifidobacteria has prevented the development of functional genomics in this bacterium. Here, we report the development of a markerless gene deletion system involving a double crossover in Bifidobacterium longum. Incompatible plasmid vectors were used to facilitate a second crossover step. The conditional replication vector pBS423-ΔrepA, which lacks the plasmid replication gene repA, was integrated into the target gene by a first crossover event. Subsequently, the replicative plasmid pTBR101-CM, which harbors repA, was introduced into this integrant to facilitate the second crossover step and subsequent elimination of the excised conditional replication vector from the cells by plasmid incompatibility. The proposed system was confirmed to work as expected in B. longum 105-A using the chromosomal full-length β-galactosidase gene as a target. Markerless gene deletion was tested using the aga gene, which encodes α-galactosidase, whose substrates include raffinose. Almost all the pTBR101-CM-transformed strains became double-crossover recombinants after subculture, and 4 out of the 270 double-crossover recombinants had lost the ability to assimilate raffinose. Genotype analysis of these strains revealed markerless gene deletion of aga. Carbohydrate assimilation analysis and α-galactosidase activity measurement were conducted using both the representative mutant and a plasmid-based aga-complemented strain. These functional analyses revealed that aga is the only gene encoding a functional α-galactosidase enzyme in B. longum 105-A.

Viral vectored granulocyte-macrophage colony stimulating factor inhibits vaccine protection in an SIV challenge model: Protection correlates with neutralizing antibody

In a previous vaccine study, we reported significant and apparently sterilizing immunity to high-dose, mucosal, simian immunodeficiency virus (SIV) quasi-species challenge [27]. The vaccine consisted of vectors based on vesicular stomatitis virus (VSV) expressing simian immunodeficiency virus (SIV) gag and env genes, a boost with propagating replicon particles expressing the same SIV genes, and a second boost with VSV-based vectors. Concurrent with that published study we had a parallel group of macaques given the same doses of vaccine vectors, but in addition, we included a third VSV vector expressing rhesus macaque GM-CSF in the priming immunization only. We report here that addition of the vector expressing GM-CSF did not enhance CD8 T cell or antibody responses to SIV antigens, and almost completely abolished the vaccine protection against high-dose mucosal challenge with SIV. Expression of GM-CSF may have limited vector replication excessively in the macaque model. Our results suggest caution in the use of GM-CSF as a vaccine adjuvant, especially when expressed by a viral vector. Combining vaccine group animals from this study and the previous study we found that there was a marginal but significant positive correlation between the neutralizing antibody to a neutralization resistant SIV Env and protection from infection.

Construction and Packaging of Herpes simplex Virus/Adeno-Associated Virus (HSV/AAV) Hybrid Amplicon Vectors

Herpes simplex virus type 1 (HSV-1)-based amplicon vectors conserve most properties of the parental virus: broad host range, the ability to transduce dividing and nondiving cells, and a large transgene capacity. This permits incorporation of genomic sequences as well as cDNA, large transcriptional regulatory sequences for cell-specific expression, multiple transgene cassettes, or genetic elements from other viruses. Hybrid vectors use elements from HSV-1 that allow replication and packaging of large-vector DNA into highly infectious particles, and elements from other viruses that confer genetic stability to vector DNA in the transduced cell. For example, adeno-associated virus (AAV) has the unique ability to integrate its genome into a specific site on human chromosome 19. The viral rep gene and the inverted terminal repeats (ITRs) that flank the AAV genome are sufficient for this process. However, AAV-based vectors have a very small transgene capacity and do not conventionally contain the rep gene to support site-specific genomic integration. HSV/AAV hybrid vectors contain both HSV-1 replication and packaging functions and the AAV rep gene and a transgene cassette flanked by the AAV ITRs. This combines the large transgene capacity of HSV-1 with the capability of site-specific genomic transgene integration and long-term transgene expression of AAV. This protocol describes the preparation of HSV/AAV hybrid vectors using a replication-competent/conditional, packaging-defective HSV-1 genome cloned as a bacterial artificial chromosome (BAC) to provide helper functions for vector replication and packaging. The advantages and limitations of such vectors compared to standard HSV-1 amplicon vectors are also discussed.

Inhibition of Indoleamine-2,3-dioxygenase (IDO) in Glioblastoma Cells by Oncolytic Herpes Simplex Virus

Successful oncolytic virus treatment of malignant glioblastoma multiforme depends on widespread tumor-specific lytic virus replication and escape from mitigating innate immune responses to infection. Here we characterize a new HSV vector, JD0G, that is deleted for ICP0 and the joint sequences separating the unique long and short elements of the viral genome. We observed that JD0G replication was enhanced in certain glioblastoma cell lines compared to HEL cells, suggesting that a vector backbone deleted for ICP0 may be useful for treatment of glioblastoma. The innate immune response to virus infection can potentially impede oncolytic vector replication in human tumors. Indoleamine-2,3-dioxygenase (IDO) is expressed in response to interferon γ (IFNγ) and has been linked to both antiviral functions and to the immune escape of tumor cells. We observed that IFNγ treatment of human glioblastoma cells induced the expression of IDO and that this expression was quelled by infection with both wild-type and JD0G viruses. The role of IDO in inhibiting virus replication and the connection of this protein to the escape of tumor cells from immune surveillance suggest that IDO downregulation by HSV infection may enhance the oncolytic activity of vectors such as JD0G.

Evaluation of HSV-1 and adenovirus vector-mediated infection, replication and cytotoxicity in lymphoma cell lines

Lymphoma is not a common focus for viral therapy as many researchers do not consider lymphoma as a suitable target for viral vectors. In the present study, the infection, replication and cytotoxicity of herpes simplex virus (HSV) and adenovirus vectors were screened and evaluated in different lymphoma cell lines. Three recombinant viruses, BAC-HSV-1-eGFP, Adv-eGFP and an NV1020-like oncolytic HSV-1 virus strain named BAC-HSV-1-eGFP-delIRs, inserted with green fluorescent protein (GFP) as a reporter, were applied to evaluate the efficiency of viral infection and replication and cytotoxicity to lymphoma cells. Four types of lymphoma cell lines (SNK-6, Jurkat, Raji and Hut 78) were examined. We found that the HSV-1 vector, BAC-HSV-1-eGFP, was able to infect and replicate in the three lymphoma cell lines (Jurkat, Raji and Hut 78) and inhibit the growth of these cells more efficiently than adenovirus vector Adv-eGFP. The sensitivity of the four types of lymphoma cell lines to the viral vectors was different. The human cutaneous TL cell line Hut 78 was more sensitive to the viral vectors than the other cell lines. However, the human NK/T lymphoma cell line SNK-6 was not infected by any of the viral vectors and did not allow replication of the viruses. In conclusion, lymphoma may be a potential target for HSV-1 vector-mediated viral therapy.

137. The Sequential Proteolysis and Liberation of the Intracellular Domain of CD44 Modulates Adenoviral Vector Transgene Expression and Replication of Adenovirus

137. The Sequential Proteolysis and Liberation of the Intracellular Domain of CD44 Modulates Adenoviral Vector Transgene Expression and Replication of Adenovirus

Abstract 5397: Human mesenchymal stem cell-based cell carrier for tumor-homing delivery of replicating retrovirus vectors in glioblastoma models

Abstract In previous studies, we have demonstrated that replicating murine leukemia virus (RMLV)-based vectors can achieve highly efficient in vivo delivery of prodrug activating genes in glioblastoma models, with infection restricted to actively dividing tumor cells without spread to extratumoral sites, resulting in significantly prolonged survival upon prodrug administration; this approach is now being tested in a multi-center clinical trial. RMLV vectors can eventually spread to almost all actively dividing GBM cells over time. We are seeking to further improve the efficiency of this novel therapeutic strategy by engineering human mesenchymal stem cells (MSC) to function as RMLV vector producer cells (MSC-VPC). Primary MSC have been shown to actively migrate through tumor masses beyond the immediate injection site and track to diffusely infiltrating tumor foci. In the present study, we developed optimized methods for engineering MSC-VPC, and we then further examined tumor transduction efficiency of MSC-mediated RMLV delivery, and how this delivery method might affect vector replication kinetics in vivo. First, we evaluated the vector productivity of MSC-VPC in U87 human glioblastoma cells in vitro. Primary human MSCs were infected with RMLV vector AC3-GFP, expressing the GFP marker gene. These MSC were then re-plated at very low density onto a monolayer of naïve U87 glioma cells, and fluorescence was monitored over time. Under the fluorescent microscope, progressive spread of the RMLV vector released from the MSCs could be confirmed, as indicated by increasing GFP(+) U87 cells over time. Next, we tested MSC-VPC in intracranial U87 tumor models in vivo. Five days after intracranial tumor cell implantation, 1E3 transduction units (TU) of AC3-GFP vector or 5E3 MSC-VPC (∼20% pretransduced with AC3-GFP) were stereotactically injected at the tumor site. Tumors were harvested and digested on day 9 for FACS analysis to detect GFP expression. While the highest percentage of GFP(+) cells was 28.6% in the vector supernatant-treated group, up to 45% transduction efficiency was achieved in the MSC-VPC group. These results suggest the use of MSCs as tumor-homing carriers may be provide more efficient delivery of RMLV vectors in human glioma models. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5397. doi:10.1158/1538-7445.AM2011-5397

Abstract 5386: Therapeutic efficacy of RMLV vectors in human and murine glioma models

Abstract Unique among replicating viruses being developed as oncolytic agents, replicating murine leukemia virus (RMLV) retroviruses propagate without immediate lysis of host cells and maintain viral persistence through stable integration. Due to its intrinsic inability to infect quiescent post-mitotic cells and susceptibility to innate antiviral defenses that exist in normal cells but are inactivated in many cancers, RMLV vector replication has been shown to be highly tumor-selective. We have previously demonstrated that RMLV vectors are capable of highly efficient replication in tumor cells, and we have found significantly enhanced survival benefit in a variety of cancer models in vivo when RMLV vectors are employed for delivery of prodrug activator genes such as yeast cytosine deaminase (yCD), which mediates the conversion of inactive prodrug 5-fluorocytosine (5FC) to the anti-cancer drug, 5-fluorouracil (5FU). In the present study, we tested a newly developed RMLV vector with modified virus backbone sequences and a codon-optimized yCD gene (Toca511). First, we examined in vitro cytotoxicity using human (U87) and murine (TU-2449) glioma cell lines by MTS assay. The cell viability of Toca511-transduced cells was reduced by >80% after 5 or 8 days of exposure to the prodrug, respectively. Second, we examined the therapeutic efficiency of this newly developed vector in subcutaneous U87 human glioblastoma models and TU2449 syngeneic mouse models. Toca511-mediated prodrug activator therapy strongly inhibited tumor growth in both subcutaneous models. Third, therapeutic efficacy was evaluated, and the minimum effective doses of 5FC prodrug and Toca511 vector determined in an intracranial U87 xenograft model. Systemic administration of 5FC resulted in significant inhibition of bioluminescent signals in mice whose tumors had been infected with Toca511 but not in control mice, associated with significant survival benefit even after injecting only 1×1e3 total vector units (p=0.0015). These data suggest that we have been successful in developing an improved retrovirus vector that shows strong therapeutic efficacy when used for prodrug activator gene therapy in both subcutaneous and intracranial xenograft models of human and/or murine glioma. This vector has now entered Phase I/II clinical trials for glioblastoma. Now, with the use of RMLV vectors such as Toca511, the original promise of retrovirus-mediated gene therapy strategies for cancer may finally be fulfilled. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5386. doi:10.1158/1538-7445.AM2011-5386

4′- C -Methyl-2′-Deoxyadenosine and 4′- C -Ethyl-2′-Deoxyadenosine Inhibit HIV-1 Replication

It is important to develop new anti-HIV drugs that are effective against the existing drug-resistant mutants. Because the excision mechanism is an important pathway for resistance to nucleoside analogs, we are preparing analogs that retain a 3'-OH and can be extended after they are incorporated by the viral reverse transcriptase. We show that 4'-C-alkyl-deoxyadenosine (4'-C-alkyl-dA) compounds can be phosphorylated in cultured cells and can inhibit the replication of HIV-1 vectors: 4'-C-methyl- and 4'-C-ethyl-dA show both efficacy and selectivity against HIV-1. The compounds are also effective against viruses that replicate using reverse transcriptases (RTs) that carry nucleoside reverse transcriptase inhibitor resistance mutations, with the exception of the M184V mutant. Analysis of viral DNA synthesis in infected cells showed that viral DNA synthesis is blocked by the incorporation of either 4'-C-methyl- or 4'-C-ethyl-2'-deoxyadenosine. In vitro experiments with purified HIV-1 RT showed that 4'-C-methyl-2'-dATP can compete with dATP and that incorporation of the analog causes pausing in DNA synthesis. The 4'-C-ethyl compound also competes with dATP and shows a differential ability to block DNA synthesis on RNA and DNA templates. Experiments that measure the ability of the compounds to block DNA synthesis in infected cells suggest that this differential block to DNA synthesis also occurs in infected cells.

Treatment of experimental autoimmune encephalomyelitis in SJL/J mice with a replicative HSV-1 vector expressing interleukin-5

Experimental autoimmune encephalomyelitis (EAE) is an autoimmune inflammation of the central nervous system and is used as the experimental model of multiple sclerosis (MS). The exact mechanism behind the disease is still unknown, but interleukin (IL)-17 expressing T cells are thought to mediate the disease. Toll-like receptors (TLRs) are known to have a role in the innate immune response against pathogens, and several TLRs have also a role in the disease course of EAE. Here, we show that treatment with a herpes simplex virus type 1 vector expressing the Th2 cytokine IL-5 ameliorates EAE and decreases the numbers of infiltrating lymphocytes in the brain. The effect involves downregulation of TLR 2, 3 and 9 mRNA expression and upregulation of type I interferons (IFNs) in brains during onset of disease. The elevated expression of type I IFNs was also observed during recovery.