Introduction of RNA virus evolution

Lots of viruses, in particular RNA viruses, have high mutation rates and relatively short generation times. Particle stability during infection in nature or in laboratory triggers the evolutionary event toward different mechanisms such as genome segmentation, point mutation and  recombination. The frequency of mutant genomes increase and modify  the previous distribution, which, consequently, lead to emergence of a new infectious particle. Mutation and selection are the most fundamental processes in evolution. High mutation rate of RNA viruses has an important role in viral fitness. Therefore, it increase our understanding about molecular biology of viral infections and their evolution by selection, mutation could reliably  determine our ability to challenge destructive viruses. This review focuses on existing impressions of genetic organization and mechanisms of RNA viruses evolution

The Convenient and Economical Method to Collect Adipose Mesenchymal Stem Cells

Background: Enzymatic digestion is an essential stage for culturing Mesenchymal Stem Cells (MSCs) and their therapeutic application. Several factors such as being cost-benefit, efficiency, safety, yield and amount of produced cells are determinant for choosing the appropriate enzyme. Collagenase is a conventional enzyme commonly used for enzymatic digestion. However, other enzymes like trypsin and even combination of these enzymes can be used as an alternative strategy in different situations.Materials and Methods: Abdominal subcutaneous adipose tissue was obtained from male BALB/c mice and digested under three different enzymatic processes: collagenase and collagenase/trypsin and trypsin. Cell culture process was performed under standard condition and MSCs at 3rd passage were used for further characterization by flow cytometry. Results: In this study, two different enzymatic methods for digestion of adipose-derived MSCs (ADSCs) of BALB/c mice were investigated. The morphology of cells was pretty different and was more homogenous in collagenase group. Also the yield of cells was varied among groups. Furthermore, the obtained data from flow cytometry revealed that ADSCs were positive for CD90 (70%), CD29 (98%), CD105 (52%) and negative for CD45 (<2%).Conclusion: Application of different enzymes depends on various conditions. Altogether, these data indicate that although use of trypsin in isolation protocol is cost-benefit, it can be used as an alternative method whenever limited number of cells will be needed. However, collagenase as a well-known and conventional method can be used for isolation of larger quantity of cells with several applications.

Recombinant λ-phage nanobioparticles for tumor therapy in mice models

Lambda phages have considerable potential as gene delivery vehicles due to their genetic tractability, low cost, safety and physical characteristics in comparison to other nanocarriers and gene porters. Little is known concerning lambda phage-mediated gene transfer and expression in mammalian hosts. We therefore performed experiments to evaluate lambda-ZAP bacteriophage-mediated gene transfer and expression in vitro. For this purpose, we constructed recombinant λ-phage nanobioparticles containing a mammalian expression cassette encoding enhanced green fluorescent protein (EGFP) and E7 gene of human papillomavirus type 16 (λ-HPV-16 E7) using Lambda ZAP- CMV XR vector. Four cell lines (COS-7, CHO, TC-1 and HEK-239) were transduced with the nanobioparticles. We also characterized the therapeutic anti-tumor effects of the recombinant λ-HPV-16 E7 phage in C57BL/6 tumor mice model as a cancer vaccine. Obtained results showed that delivery and expression of these genes in fibroblastic cells (COS-7 and CHO) are more efficient than epithelial cells (TC-1 and HEK-239) using these nanobioparticles. Despite the same phage M.O.I entry, the internalizing titers of COS-7 and CHO cells were more than TC-1 and HEK-293 cells, respectively. Mice vaccinated with λ-HPV-16 E7 are able to generate potent therapeutic antitumor effects against challenge with E7- expressing tumor cell line, TC-1 compared to group treated with the wild phage. The results demonstrated that the recombinant λ-phages, due to their capabilities in transducing mammalian cells, can also be considered in design and construction of novel and safe phage-based nanomedicines

Autophagy induction regulates influenza virus replication in a time-dependent manner

Autophagy plays a key role in host defence responses against microbial infections by promoting degradation of pathogens and participating in acquired immunity. The interaction between autophagy and viruses is complex, and this pathway is hijacked by several viruses. Influenza virus (IV) interferes with autophagy through its replication and increases the accumulation of autophagosomes by blocking lysosome fusion. Thus, autophagy could be an effective area for antiviral research.Methodology. In this study, we evaluated the effect of autophagy on IV replication. Two cell lines were transfected with Beclin-1 expression plasmid before (prophylactic approach) and after (therapeutic approach) IV inoculation.Results/Key findings. Beclin-1 overexpression in the cells infected by virus induced autophagy to 26 %. The log10haemagglutinin titre and TCID50 (tissue culture infective dose giving 50 % infection) of replicating virus were measured at 24 and 48 h post-infection. In the prophylactic approach, the virus titre was enhanced significantly at 24 h post-infection (P≤0.01), but it was not significantly different from the control at 48 h post-infection. In contrast, the therapeutic approach of autophagy induction inhibited the virus replication at 24 and 48 h post-infection. Additionally, we showed that inhibition of autophagy using 3-methyladenine reduced viral replication. Conclusion. This study revealed that the virus (H1N1) titre was controlled in a time-dependent manner following autophagy induction in host cells. Manipulation of autophagy during the IV life cycle can be targeted both for antiviral aims and for increasing viral yield for virus production

The effects of BmNPV on biochemical changes in primary cultures of Bombyx mori embryonic tissue

The effect of Bombyx mori nuclear polyhedrosis virus (BmNPV) on biochemical changes of TC-100 medium containing 10% fetal bovine serum (FBS) in embryonic primary cultures of silkworm was investigated. The primary cultures that reached 60% confluence were infected by 0.5, 1, and 2-ml viral inoculums (diluted with TC-100 medium representing multiplicity of infection (MOI) of 0.25, 0.5, and 1). Glucose, uric acid, urea, total protein, cholesterol, and alkaline phosphatase were measured in the medium of BmNPV-infected primary cultures. All biochemical compounds showed significant changes. Glucose decreased considerably by about 55 mg/ml, while different concentrations of the virus inoculums did not demonstrate significant differences among them. Total protein had only increased in 2 ml concentration and there were no changes in other concentrations. Uric acid as a by-product accumulated dramatically in all concentrations, while the amount of urea reduced in all treatments and this reduction was more evident in lower concentrations. Cholesterol consumption was high in cultures postinfection, while alkaline phosphatase (ALP) activity decreased in infected cells

Human Papillomavirus Type16- L1 VLP Production in Insect Cells

Objective(s):  Infection by high-risk papillomavirus is regarded as the major risk factor in the development of cervical cancer. Recombinant DNA technology allows expression of the L1 major capsid protein of HPV in different expression systems, which has intrinsic capacity to self-assemble into viral-like particles (VLP). VLPS are non-infectious, highly immunogenic and can elicit neutralizing antibodies. VLP-based HPV vaccines can prevent persistent HPV infections and cervical cancer. In this study recombinant HPV-16 L1 protein was produced in Sf9 insect cells and VLP formation was confirmed. Materials and Methods: Complete HPV-16 L1 gene was inserted into pFast HTa plasmid and transformed into DH10BAC Escherichia coli containing bacmid and helper plasmid. The recombinant Bacmid colonies turned to white and non-recombinant colonies harboring L1 gene remained blue in the presence of X-gal and IPTG in colony selection strategy. To confirm the recombinant bacmid production, PCR was applied using specific L1 primers. To produce recombinant baculovirus, the recombinant bacmid DNA was extracted and transfected into Sf9 cells using Cellfectin. The expression of L1 in Sf9 cells was identified through SDS-PAGE and western blot analysis using specific L1 monoclonal antibody. Self-assembled HPV16L-VLPs in Sf9 cells was confirmed by electron microscopy. Results:The recombinant protein L1 was predominantly ~60 KD in SDS-PAGE with distinct immunoreactivity in western blot analysis and formed VLPS as confirmed by electron microscopy. Conclusion:Application of recombinant baculovirus containing HPV-16 L1 gene will certainly prove to be a constructive tool in production of VLPs for prophylactic vaccine development as well as diagnostic tests

Determining Influenza Virus Shedding at Different Time Points in Madin-Darby Canine Kidney Cell Line

Objective: Monitoring of influenza virus shedding and optimization of multiplicities of infection (MOI) is important in the investigation of a virus one step growth cycle and for obtaining a high yield of virus in vaccine development and conventional basic diagnostic methods. However, eluted infectious viruses may still be present immediately after virus inoculation and when cells are washed following virus cultivation which may lead to a false positive virus infectivity assay.Materials and Methods: In this experimental study, we investigated influenza virus progeny production in Madin-Darby canine kidney (MDCK) cells with five different MOI at determined time points. The results were analyzed by end point titration tests and immunofluorescence assay.Results: Higher titers of eluted virus were observed following a high MOI inoculation of virus in cell culture. Most probably, this was the result of sialic acid residues from viral hemagglutin in proteins that were cleaved by neuraminidase glycoproteins on the surface of the influenza virus, which promoted viral spread from the host cell to the culture supernatant or during endocytosis, where viruses recycle to the cell surface by recycling endosomes which culminated in virus shedding without replication.Conclusion: We demonstrated that the pattern of influenza virus progeny production was dose-dependent and not uniform. This production was influenced by several factors, particularly MOI. Understanding the exact features of viral particle propagation has a major impact in producing high virus yields in the development of vaccines. Use of lower MOI (0.01) could result in accurate, precise quantitative assays in virus diagnosis and titration methods

Activation of calcium/calmodulin-dependent kinase II following bovine rotavirus enterotoxin NSP4 expression

Objective(s): The rotavirus nonstructural protein 4 (NSP4) is responsible for the increase in cytoplasmic calcium concentration through a phospholipase C-dependent and phospholipase C-independent pathways in infected cells. It is shown that increasing of intracellular calcium concentration in rotavirus infected cells is associated with the activation of some members of protein kinases family such as calcium/calmodulin-dependent kinase II, which plays a crucial role in replication and pathogenesis of the virus. The aim of this study was to expression bovine rotavirus NSP4 gene in HEK293 cell and evaluation of its biological effect related to activation of calcium/calmodulin-dependent kinase II in cell culture. Materials and Methods: MA104 cells was used as a sensitive cell for propagation of virus and defined as a positive control. The NSP4 gene was amplified and inserted into an expression vector, and introduced as a recombinant plasmid into HEK293T cells. Western blot analysis was performed as a confirmation test for both expression of NSP4 protein and activation of calcium/calmodulin-dependent kinase II. Results:Expression of NSP4 and activated form of calcium/calmodulin-dependent kinase II were demonstrated by western blotting. Conclusion: It was shown that the expression of biologically active full- length NSP4 protein in HEK293T cells may be associated with some biological properties such as calcium calmodulin kinase II activation, which was indicator of rotaviruses replication and pathogenesi

Efficacy of HPV-16 E7 Based Vaccine in a TC-1 Tumoric Animal Model of Cervical Cancer - page 483

Objective: The human papillomavirus as an etiological agent of cervical cancer doesnot grow adequately in tissue culture systems. The tumor cell line TC-1 continuously expressesthe E6 and E7 oncogenic proteins of HPV, and is considered a suitable tool inlaboratory investigations and vaccine researches against cervical cancer.Materials and Methods: The TC-1 cell line was grown in RPMI 1650 supplemented with10% FBS, glutamine and antibiotics, and was used for tumor development in mice. Six toseven week-old tumor bearing C57BL/6 mice were divided into 3 groups consisting of 7mice per group. The first group received pcDNA-E7, the second group received pcDNA3,and the third group received phosphate buffered saline (PBS). The treated animals weremonitored for their tumor size progression and survival. At last, the tumoric tissues fromautopsied animals were fixed and examined with Mayer's hematoxylin and eosin (H&E).All experiments were done in accordance with guidelines of the Laboratory Animal EthicalCommission of Tarbiat Modares University. Data analysis was performed using the onewayANOVA followed by Tukey's test in both experimental and control groups. A p-value<0.05 was considered significant.Results: There were significant decreases in tumor growth; there were also improvementsin survival among mice in the treated groups (p<0.041). H&E stained sections fromuntreated mice were studied independently in a blinded fashion by two observers andshowed malignant neoplasms composed of severely pleomorphic tumor cells with nuclearenlargement, high nuclear-cytoplasmic (N/C) ratios, and prominent nucleoli in solid andfascicular patterns of growth. High mitotic activity with extensive necrosis was also notedin both test and control groups.Conclusion: The TC-1 lung metastatic model can be used to test the efficacy of variousE7-based therapeutic cancer vaccine strategies for cervical cancer and the prevention ofHPV-related neoplasia

Evaluation of DNA vaccine encoding HPV-16 E7 on Lymphocyte proliferation induction in Human Papilloma Virus-associated tumor animal models

Background & Objective: Human papillomavirus (HPV) oncoproteins, including E6 and E7 are constitutively expressed in cervical cancer cells. These proteins are ideal targets to be used for developing therapeutic vaccines against existing HPV-associated carcinomas. The aim of this study was to measure the proliferation response rate of splenic lymphocytes derived from E7-HPV16 encoding plasmid injection on the tumor mouse model of papillomavirus. Method: C57BL/6 mice were inoculated subcutaneous with 5× 10⁵ TC-1 cells in three times with two weeks intervals and then immunized with HPV-16 E7 DNA vaccine. The proliferation response of splenic cells was measured by MTT assay. IL12 cytokine was measured by ELISA assay and the mass of tumor was calculated with caliper for six weeks. Results: Following the application of DNA vaccines containing E7 therapeutic gene, the proliferative response of splenic cells was provoked significanltly higher than the stimulation in control group (P<0.05). Moreover, the secretion of IL12 was significantly increased in vaccinated mice tumor tissue (P<0.05). The growth of tumor in vaccinated group was markedly decreased in comparison to PBS and pcDNA3 groups (P<0.05). Conclusion: Our findings revealed that the application of DNA vaccine containing E7 gene in a tumor mouse model may induce anti-tumor cellular immune responses