Gastrointestinal tract and viral pathogens

Viral gastroenteritis is the most common viral illness that affects the gastro-intestinal(GI)tract,causing inflammation and irritation of the lining of the stomach and intestines.Common signs and symptoms associated with this condition include abdominal pain,diarrhea,and dehydration.The infections commonly involved in viral gastroenteritis are rotavirus,norovirus,and adenovirus,which spread through the fecal-oral and contact routes and cause non-bloody diarrhea.These infections can affect both immunocompetent and immunocompromised individuals.Since the pandemic in 2019,coronavirus gastroenteritis has increased in incidence and prevalence.Morbidity and mortality rates from viral gastroenteritis have declined significantly over the years due to early recognition,treatment with oral rehydration salts,and prompt vaccination.Improved sanitation measures have also played a key role in reducing the transmission of infection.In addition to viral hepatitis causing liver disease,herpes virus,and cytomegalovirus are responsible for ulcerative GI disease.They are associated with bloody diarrhea and commonly occur in im-munocompromised individuals.Hepatitis viruses,Epstein-Barr virus,herpesvirus 8,and human papillomavirus have been involved in benign and malignant diseases.This mini review aims to list different viruses affecting the GI tract.It will cover common symptoms aiding in diagnosis and various important aspects of each viral infection that can aid diagnosis and management.This will help primary care physicians and hospitalists diagnose and treat patients more easily.

Specific CEA-producing colorectal carcinoma cell killing with recombinant adenoviral vector containing cytosine deaminase gene

AIM: To kill CEA positive colorectal carcinoma cells specifically using the E coli cytosine deaminase (CD) suicide gene, a new replication-deficient recombinant adenoviral vector was constructed in which CD gene was controlled under CEA promoter and its in vitro cytotoxic effects were evaluated. METHODS: Shuttle plasmid containing CD gene and regulatory sequence of the CEA gene was constructed and recombined with the right arm of adenovirus genome DNA in 293 cell strain. Dot blotting and PCR were used to identify positive plaques. The purification of adenovirus was performed with ultra-concentration in CsCl step gradients and the titration was measured with plaque formation assay. Cytotoxic effects were assayed with MTT method, The fifty percent inhibition concentration (IC(50)) of 5-FC was calculated using a curve-fitting parameter. The human colorectal carcinoma cell line, which was CEA-producing, and the CEA-nonproducing Hela cell line were applied in cytological tests. An established recombinant adenovirus vector AdCMVCD, in which the CD gene was controlled under CMV promoter, was used as virus control. Quantitative results were expressed as the mean +/- SD of the mean. Statistical analysis was performed using ANOVA test. RESULTS: The desired recombinant adenovirus vector was named AdCEACD. The results of dot blotting and PCR showed that the recombinant adenovirus contained CEA promoter and CD gene. Virus titer was about 5.0 X 10(14)pfu/L(-1) after purification. The CEA-producing Lovo cells were sensitive to 5-FC and had the same cytotoxic effect after infection with AdCEACD and AdCMVCD (The IC(50) values of 5-FC in parent Lovo cells, Lovo cells infected with 100 M.O.I AdCEACD and Lovo cells infected with 10 M.O.I AdCMVCD were 】15000, 216.5+/-38.1 and 128.8+/-25.4 micromol.L(-1), P【0.001, respectively), and the cytotoxicity of 5-FC increased accordingly when the m.o.i of adenoviruses were enhanced (The value of IC(50) of 5-FC was reduced to 27.9+/-4.2 micromol.L(-1) in 1000 M.O.I AdCEACD infected Lovo cells and 24.8+/-7.1 micromol.L(-1) in 100 M.O.I AdCMVCD infected Lovo cells, P【0.05, P【0.01, respectively). The CEA-nonproducing Hela cells had no effect after infection with AdCEACD, but Hela cells had the cytotoxic sensitivity to 5-FC after infection with AdCMVCD (The IC(50) of 5-FC in parent Hele cells and Hela cells infected with AdCMVCD at 10 M.O.I was 】15000 and 214.5+/-31.3 micromol.L(-1), P【0.001). AdCEACD/5-FC system also had bystander effect, and the viability was about 30 percent when the proportion of transfected cells was only 10 percent. CONCLUSION: The recombinant adenovirus vector AdCEACD has the character of cell type-specific gene delivery. The AdCEACD/5-FC system may become a new, potent and specific approach for the gene therapy of CEA-positive neoplasms, especially colon carcinoma.

The therapeutic effects of recombinant adenovirus RA538 on human gastric carcinoma cells in vitro and in vivo

AIM To evaluate the potential of RA-538 genetherapy for gastric carcinoma.METHODS Human gastric carcinoma cell lineSGC7901 treated with Ad-RA538 or Ad-LacZ wereanalysed by X-gal stain,MTT,DNA ladder,Tunel,flow cytometric analysis,PCR,andWestern Blot in vitro.The tumorigenicity andexperimental therapy in nude mice model wereassessed in vivo.RESULTS Ad-LacZ could efficiently transferthe LacZ gene into SGC7901 cells.X-gal-positivecells at MOI 25,50,100,and 200 were 90%,100%,100%,and 100% respectively.Ad-RA538could strongly inhibit cell growth and inducedapoptosis in SGC7901 cells.The proliferation ofthe Ad-RA538-infected SGC7901 cells wasreduced by 76.3%.The mechanism of killing ofgastric carcinoma cells by Ad-RA538 was foundto be apoptosis by DNA ladder,Tunel and flowcytometric analysis.The tumorigenicity in nudemice using Ad-RA538 showed that all three micefailed to form tumor from 7 to 30 days comparedwith Ad-LacZ and parent SGC7901 cells.Experimental therapy on the nude mice modelbearing subcutaneous tumor of SGC790| cells showed that intratumor instillation of Ad-RA538inhibited the growth of the tumors.Ad-RA538-treated tumors were inhibited by 60.66 %,compared with that of the tumor injected withAd-LacZ and mock.CONCLUSION The expression of Ad-RA538 can inhibit growth and induce apoptosis of gastric cancer cell in vitro and in vivo. Ad-RA538 can be used potentially in gene therapy for gastric carcinoma.

The effect of adenovirus expressing wild-type p53 on 5-fluorouracil chemosensitivity is related to p53 status in pancreatic cancer cell lines

AIM:There are conflicting data about p53 function on cellular sensitivity to the cytotoxic action of 5-fluorouracil (5-FU). Therefore the objective of this study was to determine the combined effects of adenovirus-mediated wild-type (wt) p53 gene transfer and 5-FU chemotherapy on pancreatic cancer cells with different p53 gene status. METHODS:Human pancreatic cancer cell lines Capan-1^(p53mut), Capan-2^(p53wt),FAMPAC^(p53mut),PANC1^(p53mut),and rat pancreatic cancer cell lines AS^(p53wt) and DSL6A^(p53null) were used for in vitro studies.Following infection with different ratios of Ad- p53-particles (MOI) in combination with 5-FU,proliferation of tumor cells and apoptosis were quantified by cell proliferation assay (WST-1) and FACS (PI-staining).In addition,DSL6A syngeneic pancreatic tumor cells were inoculated subcutaneously in to Lewis rats for in vivo studies. Tumor size,apoptosis (TUNEL) and survival were determined. RESULTS:Ad-p53 gene transfer combined with 5-FU significantly inhibited tumor cell proliferation and substantially enhanced apoptosis in all four cell lines with an alteration in the p53 gene compared to those two cell lines containing wt-p53.In vivo experiments showed the most effective tumor regression in animals treated with Ad-p53 plus 5-FU.Both in vitro and in vivo analyses revealed that a sublethal dose of Ad-p53 augmented the apoptotic response induced by 5-FU. CONCLUSION:Our results suggest that Ad-p53 may synergistically enhance 5-FU-chemosensitivity most strikingly in pancreatic cancer cells lacking p53 function.These findings illustrate that the anticancer efficacy of this combination treatment is dependent on the p53 gene status of the target tumor cells.

Pathogenic and pathological characteristic of new type gosling viral enteritis first observed in China

AIM: To study the purifying method and characteristics of new gosling viral enteritis virus (NGVEV),the etiological agent of new gosling viral enteritis (NGVE) which was first recognized in China, as well as the pathomorphological development in goslings infected artificially with NGVEV. METHODS: (1)NGVEV virions were purified by the procedure of treatment with chloroform and ammonium sulfate precipitation, dialysis to remove the sulfate radical and ammonium ion and separation by gel filtration chromatography, and SDS-PAGE. (2)Forty-2-day-old White Sichuan goslings were orally administered with NGVEV and 24 hr later 2 birds were randomly selected and killed at 24hr intervals until death occurred. Specimens(duodenum, ileum, liver, heart, kidney, spleen, lung, proventriculus, pancreas, esophagus, and the intestinal embolus) were taken until all birds in this group died and were sectioned and stained with hemotoxylin and eosin and studied by light microscope. RESULTS: NGVEV shared the typical characteristics of Adenovirus and which structural proteins consisted of 15 polypeptides. Necrosis and sloughing of the epithelial cells covering the villus tips of the duodenum were first observed in goslings 2 days postinfection artificially with NGVEV. With the progress of infection, this lesion rapidly occurred in the epithelium at the base of the villus and with infiltration of the inflammatory cells, the jejunum tended to be involved. With the intensification of mucosa necrosis and inflammatory exudation of the small intestine, fibrinonecrotic enteritis was further developed and embolus composed of either intestinal contents wrapped by pseudo-membrane or of the mixture of fibrous exudate and necrotic intestinal mucosa were observed in the middle-lower part of the small intestine. This structure occluded the intestinal tract and made the intestine dilated in appearance. The intestinal glandular cells underwent degeneration, necrosis and might be found sloughed into the lumen. Hemorrhage and hyperemia could be observed on the lung and kidney. Epithelial cells of the renal tubular underwent degeneration. In some cases, granular degeneration and fatty degeneration could be found in the liver and in some cases at a later stage of this disease the epithelial cells of trachea and proventriculus might be found sloughed. In some cases at an early stage of this disease, cardiac hyperemia and hemorrhage could be observed. Esophagus, pancreas and brain were found normal. Analyses and comparisons between the pathologic lesions of NGVE and Gosling Plague (GP) were available in this paper as well. CONCLUSION: (1)NGVEV is adenovirus. (2)Pathological characteristic could be as the data for NGVE diagnosis.

Adeno-associated virus mediated endostatin gene therapy in combination with topoisomerase inhibitor effectively controls liver tumor in mouse model

AIM:rAAV mediated endostatin gene therapy has been examined as a new method for treating cancer.However, a sustained and high protein delivery is required to achieve the desired therapeutic effects.We evaluated the impact of topoisomerase inhibitors in rAAV delivered endostatin gene therapy in a liver tumor model. METHODS:rAAV containing endostatin expression cassettes were transduced into hepatoma cell lines.To test whether the topoisomerase inhibitor pretreatment increased the expression of endostatin,Western blotting and ELISA were performed.The biologic activity of endostatin was confirmed by endothelial cell proliferation and tube formation assays. The anti-tumor effects of the rAAV-endostatin vector combined with a topoisomerase inhibitor,etoposide,were evaluated in a mouse liver tumor model. RESULTS:Topoisomerase inhibitors,including camptothecin and etoposide,were found to increase the endostatin exPression level in vitro.The over-expressed endostatin, as a result of pretreatment with a topoisomerase inhibitor, was also biologically active.In animal experiments,the combined therapy of topoisomerase inhibitor,etoposide with the rAAV-endostatin vector had the best tumor- suppressive effect and tumor foci were barely observed in livers of the treated mice.Pretreatment with an etoposide increased the level of endostatin in the liver and serum of rAAV-endostatin treated mice.Finally,the mice treated With rAAV-endostatin in combination with etoposide showed the longest survival among the experimental models. CONCLUSION:rAAV delivered endostatin gene therapy in combination with a topoisomerase inhibitor pretreatment is an effective modality for anticancer gene therapy.

Adenovirus-mediated expression of pig α(1,3) galactosyltransferase reconstructs Gal α(1,3) Gal epitope on the surface of human tumor cells

Gal alpha(1, 3) Gal (gal epitope) is a carbohydrate epitope and synthesized in large amount by alpha(1, 3) galactosyltransferase [alpha(1, 3) GT] enzyme on the cells of lower mammalian animals such as pigs and mice. Human has no gal epitope due to the inactivation of alpha(1, 3) GT gene but produces a large amount of antibodies (anti-Gal) which recognize Gal alpha(1, 3) Gal structures specifically. In this study, a replication-deficient recombinant adenoviral vector Ad5sGT containing pig alpha(1, 3) GT cDNA was constructed and characterized. Adenoviral vector-mediated transfer of pig alpha(1, 3) GT gene into human tumor cells such as malignant melanoma A375, stomach cancer SGC-7901, and lung cancer SPC-A-1 was reported for the first time. Results showed that Gal epitope did not increase the sensitivity of human tumor cells to human complement-mediated lysis, although human complement activation and the binding of human IgG and IgM natural antibodies to human tumor cells were enhanced significantly after Ad5sGT transduction. Appearance of gal epitope on the human tumor cells changed the expression of cell surface carbohydrates reacting with Ulex europaeus I (UEA I) lectins, Vicia villosa agglutinin (VVA), Arachis hypogaea agglutinin (PNA), and Glycine max agglutinin (SBA) to different degrees. In addition, no effect of gal epitope on the growth in vitro of human tumor cells was observed in MTT assay.

Immunogenicity of the recombinant adenovirus type 5 vector with type 35 fiber containing HIV-1 gag gene

The immune efficiency of a recombinant adenovirus type 5 with type 35 fiber containing HIV-1 gag gene （rAd5/F35-mod. gag） was investigated in BALB/c mice, in which the rAd5/F35-mod, gag was firstly identified with PCR, then transfected to 293 cells and the in vitro expression level of Gag protein was determined by Western blotting and indirect immuno-fluorescent assay. Mice were immunized with intramuscular injections of rAd5/F35-mod, gag, rAd5-mod, gag or DNA and were boosted after 3 weeks. To test the effect of pre-existing anti-viral immunity on immunization, mice were also injected with Ad5- GFP vector and then immunized 4 and 7 weeks later with Ad5/F35-mod. gag vector. The P24-specific IgG antibody in sera of immunized mice was determined by ELISA and the specific cytotoxic T lymphocyte （CTL） response was assayed by intracellular cytokine staining. It was demonstrated that the rAd5/F35- rood. gag vector could express efficiently the HIV Gag protein in 293 cells in vitro and induce strong HIV- specific immune responses in vivo. The strongest CTL and serum IgG response occurred when mice were immunized twice with injection of rAd5/F35 alone, but the anti-Ad5 antibody after primary infection with adenovirus could inhibit the specific immune responses induced by rAd5/F35 vector. It is concluded that single immunization with recombinant adenovirus rAd5/F35-mod, gag can induce specific CTL and serum IgG antibody responses in mice, but the immunogenicity of rAd5/F35 is comparably weaker than that of rAd5.

Comparative study of catheter-mediated gene transfer into heart

OBJECTIVE: To investigate the feasibility and features of 3 catheter-mediated approaches of gene transfer into heart, including direct myocardial injection (DMI), coronary artery perfusion (CAP), and intrapericardial cavity injection (ICI). METHODS: Fifteen dogs were used, and 0.3 ml (1 x 10(9) pfu) of an adenovirus (Adex1SR LacZ) was injected into the heart by 3 methods. The dogs were killed 5 days following injection, and gene expressions in heart and liver were evaluated by histochemical analysis. RESULTS: The results showed that (1) the CAP method was relatively less damaging and induced sparse LacZ expression in the myocardium, and the gene expression was also found in both vessels within the myocardium and liver; (2) gene transfer by DMI resulted in intense LacZ expression around the injection accompanied by a local inflammatory response; (3) LacZ expression elicited by ICI was detected in either the inner surface of the parietal pericardium or epicardial surface of the heart, and also in the myocardium underlying the visceral pericardium. CONCLUSION: Three catheter-mediated methods of gene transfer into the heart may be used and a reasonable approach should be chosen according to purpose.

Adenoviral mediated suicide gene transfer in the treatment of pancreatic cancer

OBJECTIVE: To determine the efficacy of adenovirus mediated suicide gene transduction combined with prodrug 5-fluorocytosine (5FC) as a therapeutic protocol for pancreatic cancer. METHODS: Cytosine Deaminase(CD) gene was cloned into pAdTrack-CMV-CD, pAdTrack-CMV-CD and pAdEasy-1 were recombined in bacteria. The newly recombined adenovirus (Ad)-CD containing green fluorescent protein (GFP) were packaged and propagated in 293 cells and purified by cesium chloride gradient centrifugation. Human pancreatic carcinoma cell line-Patu8988 was infected with this virus, then 5FC was added. XTT assay was used to estimate relative numbers of viable cells. In vivo model of pancreatic cancer was established by injecting 1.0 x 10(7) Patu8988 cells subcutaneously in Balb/c nude mice. When tumors were palpable, Ad-CD was injected into each tumor and 5FC was administered. RESULTS: Positive clones were selected using endonuclease to digest the recombinants and the concentration of viral liquids containing the CD gene was 2 x 10(11) pfu /ml. Significant cytotoxic activity as shown for 5FC in the CD gene transduced 8988 cell line, while little effect was found in the nontransduced pancreatic carcinoma cells. Antitumor effect was observed in Patu8988 xenograft nude mice with in situ CD gene transduction. CONCLUSIONS: CD gene mediated by adenovirus has high infectivity and may be useful for gene therapy in pancreatic carcinoma. These data demonstrate the use of an enzyme prodrug strategy in experimental pancreatic cancer.

Adenovirus induced acute hepatitis in non-human primates after liver-directed gene therapy

OBJECTIVE: To define the mechanism of acute hepatitis in non-human primates after liver directed gene therapy. METHODS: Differences in immune response exhibited by 8 rhesus monkeys receiving adenovirus (Ad) or lipofectamine-mediated gene transfer by various routes, the time course, and the nature of the specific immune responses to both adenoviral vectors and transgene products were studied using HE staining (H&E) and immunohistochemical staining. RESULTS: The monkeys developed mild to moderate acute hepatitis 1 to 3 weeks after intravenous or intrabiliary injection of first generation replication-defective adenoviruses carrying the Escherichia coli lacZ gene. This was accompanied by adenovirus-mediated T-cell proliferation and neutralizing antibodies to the adenovirus. Increased numbers of CD3(+), CD4(+) and CD8(+) T-lymphocytes were detected in the diseased livers, while B-lymphocytes were absent. Hepatocytes demonstrated increased expression of beta 2-microglobulins (beta 2-MG) and HLA-DR antigens in the plasma membranes. The development of acute hepatitis and the accompanying immune abnormalities were delayed in immunosuppressed monkeys until after the discontinuation of immunosuppressive therapy. The monkeys infused with Ad. CMVluc showed more significant and longer durations of hepatitis than the monkeys infused with adenoviruses carrying the lacZ gene. Lipofectamine-mediated gene transfer was inefficient. There was neither lacZ expression nor significant immune response in the liver of monkeys infused with lipofectamine via the portal vein or the common bile duct. CONCLUSION: Immune response to the hepatocytes in liver directed gene therapy is MHC class I restricted and T-cell mediated. Both adenoviral vectors and foreign genes are related to the liver damage. Mild to moderate hepatic inflammation seen with the E-1 deleted vector is reversible. Immunosuppression regimens may prolong transgene expression and delay the development of acute adenoviral hepatitis.

Gene-viral vectors: a promising way to target tumor cells and express anticancer genes simultaneously

OBJECTIVE: To develop a new kind of vector system called gene-viral vector, which combines the advantages of gene and virus therapies. METHODS: Using recombinant technology, an anti-tumor gene was inserted into the genome of replicative virus specific for tumor cells. The cell killing effect, reporter gene expression of the green fluorescence protein, anti-tumor gene expression of mouse interleukin-12 (mIL-12) and replication of virus were observed by the methods of cell pathology, fluorescence microscopy, ELISA and electron microscopy, respectively. RESULTS: A new kind of gene-viral vector system of adenovirus, in which the E1b-55 kD gene was deleted but the E1a gene was preserved, was constructed. The vector system, like the replicative virus ONYX-015, replicated and proliferated in tumor cells but not in normal ones. Our vector had an advantage over ONYX-015 in that it carried different kinds of anti-tumor genes to enhance its therapeutic effect. The reporter gene expression of the green fluorescence protein in tumor cells was much better than the adenovirus vector employed in conventional gene the rapy, and the expression in our vector system was as low as or even less than that in the conventional adenovirus gene therapy system. Similar results were observed in experiments with this vector system carrying the anti-tumor gene mIL-12. Replication and proliferation of the virus carrying the mIL-12 gene in tumor cells were confirmed by electron microscopy. CONCLUSIONS: Gene-viral vectors are new vectors with an anti-tumor gene inserted into the genome of replicative virus specific for tumor cells. Because of the specific replication and proliferation of the virus in tumor cells, expression of the anti-tumor gene is increased hundreds to thousands of times. This approach takes full advantages of gene therapy and virus therapy to enhance the effect on the tumor. It overcomes the disadvantages of conventional gene therapy, such as low transfer rate, low gene expression, lack of target tropism, and low anti-tumor activity. We believe that this is a promising means for future tumor treatment.

In situ transduction of cytosine deaminase gene followed by systemic use of 5-fluorocytosine inhibits tumor growth and metastasis in orthotopic prostate cancer mouse models

OBJECTIVE: To investigate the antitumor and anti-metastatic effect of in situ transduction of adenovirus encoding cytosine deaminase (AdCD) followed by the systemic use of 5-fluorocytosine (5-FC) in the orthotopic (o.t.) prostate cancer mouse model. METHODS: The o.t. prostate cancer model of C57BL/6 mouse was developed by o.t. inoculation of RM-1 cells to the subcapsular area of the prostate gland. In situ transduction of the CD gene, followed by systemic use of 5-FC at a daily dosage of 300 mg/kg for 14 days, was performed two days later. RESULTS: Compared with mice treated with Adbeta-gal/5-FC, 5-FC and PBS, mice of the o.t. model receiving in situ treatment of AdCD/5-FC had significant prolongation of survival and suppression of local tumor growth. More importantly, pathological observations showed that metastatic activity occurred in all mice of the PBS, 5-FC and Adbeta-gal groups including metastasis to the iliac lymph node (10/10, 10/10, 10/10) and the lung (8/10, 7/10, 7/10). However, only two out of ten had iliac lymphatic metastasis in the AdCD/5-FC group with no systemic or preaotic lymphatic metastasis, suggesting a strong metastatic inhibitory effect. CONCLUSIONS: In situ transduction of AdCD followed by systemic use of 5-FC leads to the inhibitory effect on tumor growth and metastatic activity in the o.t. mouse model of prostate cancer. Clinically, it may be possible to treat metastatic or recurrent prostate cancer with a novel gene therapy using in situ injection techniques in future.

Efficacy and safety of therapeutic angiogenesis from direct myocardial administration of an adenoviral vector expressing vascular endothelial growth factor 165

OBJECTIVE: To investigate whether direct administration of adenoviral vectors (Ad) containing the complementary deoxyribonucleic acid (cDNA) of vascular endothelial growth factor 165 (Ad-VEGF165) induces porcine coronary collateral vessel formation, improves regional myocardial perfusion and function and is safe. METHODS: Three weeks after miniature swine underwent left thoracotomy and placement of an Ameroid constrictor on the left circumflex coronary artery (LCX), Ad-VEGF165 (n = 6) or the control, Ad expressing beta-galactosidase cDNA (Ad-Gal, n = 6), was directly administered into the ischemic myocardium in the circumflex distribution. All animals were sacrificed 4 wk after the second surgery. Myocardial perfusion and function were assessed by electrocardiogram-gated single photon emission computed tomography (GSPECT) imaging. Ex vivo coronary angiography was performed to examine collateral vessels. Toxicity was assessed by blood analyses on the day just before (day 0) and on day 1, 3, 7, 28 after vector delivery and by vascular, myocardial and liver histology after sacrifice. RESULTS: GSPECT imaging 4 wk after administration of Ad-VEGF165 demonstrated significant reduction in ischemic area (P

基因治疗中的腺病毒载体

通过对腺病毒的纤维蛋白、五邻体蛋白和六邻体蛋白的研究,改善了腺病毒载体对肿瘤细胞的靶向性。利用免疫抑制剂抑制、改造腺病毒壳粒蛋白的抗原表位或尽量减少腺病毒DNA中非必需基因的表达,减少了腺病毒载体的免疫反应。腺病毒载体在基因治疗中具有广泛的应用前景。

Expression of adenovirus-mediated neurotrophin-3 gene in Schwann cells of sciatic nerve in rats

Objective: To investigate the expression of neurotrophin-3 (NT-3) gene in Schwann cells of rat sciatic nerve introduced by an adenovirus vector in vivo. Methods: A recombinant adenovirus vector for NT-3 (Ad-NT-3) was propagated in 293 packaging cells and titered with tissue culture infectious dose 50 (TCID 50). Ad-NT-3 was injected directly into the rat sciatic nerve after transection and immediate repair. Immunohistochemical staining was employed to determine the expression of NT-3 in Schwann cells in rat sciatic nerve and the expressive intensity of the tissue slices of the sciatic nerve was measured with LEICA M550 image analysis system. Results: On the 2nd day after injection of Ad-NT-3, positive stain in the Schwann cells was apparent in the vicinity of anastomosis. NT-3 expression increased significantly on the 7th day (P< 0.01) and then decreased 14-28 days after injection (P< 0.01). There was no significant difference of NT-3 expression between the 14th and 28th day groups (P> 0.05). Compared with the 2nd day group, the 14th and 28th day groups still maintained a relatively high level of NT-3 (P< 0.01). Intact and repaired nerves, which were injected with adenovirus encoding LacZ genes ( Ad-LacZ) or physiological saline served as controls, showed no NT-3-positive Schwann cells. Conclusions: An adenovirus vector can be used to induce efficiently the expression of NT-3 gene in Schwann cells of rat peripheral nerves following nerve injury and repair, which suggests that neurotrophic factors can be introduced into Schwann cells with an adenovirus vector to promote peripheral nerve regeneration.

Adenovirus-mediated and tumor-specific transgene expression of the sodium-iodide symporter from the human telomerase reverse transcriptase promoter enhances killing of lung cancer cell line in vitro

Background The sodium-iodide symporter （NIS） protein can mediate the active radioiodine uptake.The human telomerase reverse transcriptase （hTERT） promoter is known to be selectively reactivated in majority of tumors and hence could be used for tumor targeting.We constructed a recombinant adenovirus containing the human sodium iodide symporter （hNIS） gene directed by the hTERT promoter, characterized the ability of infected cells in uptaking iodide, and explored the therapeutic efficacy of 131I in a lung cancer cell line in vitro.Methods The hTERT promoter was amplified by PCR from DNA isolated from log-phase HepG2 cells, subcloned into lineralized FL＊-hNIS/pcDNA3, and then the hTERT-hNIS sequence was subcloned into the shuttle plasmid pAdTrack.The recombinant adenovirus Ad-hTERT-hNIS was constructed by AdEasy system.A positive control adenovirusAd-CMV-hNIS and a negative control adenovirus Ad-CMV were created similarly.A549 cells were transduced with recombinant adenoviruses.125I uptake studies and sodium perchlorate suppression studies were used to confirm hNIS expression and function.Toxic effects of 131I on tumor cells were studied by in vitro clonogenic assay.Results We first successfully constructed an adenovirus mediated transgene expression system of the hNIS under the control of hTERT promoter.When infected with recombinant adenovirus constructs expressing hNIS directed by hTERTand CMV-promoters （Ad-hTERT-hNIS and Ad-CMV-hNIS, respectively）, the lung cancer cell line A549 had increased ability to uptake radioiodide up to 23- and 30- fold compared to the control parental cells, respectively.The radioiodide uptake ability of both the Ad-CMV-hNIS and Ad-hTERT-hNIS transduced cell lines were repressed 11-fold by sodium perchlorate （NaCIO4）.The subsequent in vitro clonogenic assay of the infected A549 cell line was further repressed to 23% （Ad-CMV-hNIS） and 30% （Ad-hTERT-hNIS） of the control group after receiving radioiodide for 7 hours （P 〈0.001）.Conclusion Our preliminary study indicates that an adenovirus mediated transgene expression system of the hNIS under the control of hTERT promoter has the potential to become an effective wide-spectrum yet highly specific anti-cancer strategy.