Optimization of reovirus production from mouse L-929 cells in suspension culture

Development of a reverse transcription loop mediated isothermal amplification assay for the detection of Mouse reovirus type 3 in laboratory mice

Mouse reovirus type 3 (Reo-3) infection is a viral disease that is harmful for laboratory mice. No rapid and accurate detection methods are currently available for this infection. In this study, we describe a rapid, simple, closed-tube, one step, reverse transcription-loop-mediated isothermal amplification (RT-LAMP) assay for Reo-3 and compare our assay with indirect enzyme-linked immunosorbent assay (ELISA). Three sets of RT-LAMP primers were designed by sequence analysis of a specific conserved sequence of the Reo-3 S1 gene. Using RS2 primer set, the RT-LAMP assay required 60 min at 65 °C to amplify the S1 gene in one step by using Reo-3 RNA template and had no cross-reactivity with the other related pathogens, such as Sendai virus (SV), pneumonia virus of mice (PVM), mouse hepatitis virus (MHV), Ectromelia virus (Ect), minute virus of mice (MVM), P. pneumotropica, B. bronchiseptica, K. pneumonia and P. aeruginosa. in our LAMP reaction system. The limit of detection (LOD) of our RT-LAMP assay is 4 fg/μL. The established RT-LAMP assay enabled visual detection when fluorescence detection reagents were added, and was demonstrated to be effective and efficient. We tested 30 clinical blood samples and five artificial positive samples from SPF mice, the concordance between the two methods for blood samples was 100% compared with indirect ELISA and RT-PCR. Considering its performance, specificity, sensitivity, and repeatability, the developed RT-LAMP could be a valuable tool to supply a more effective Reo-3 detection method in laboratory animal quality monitoring.

Kinetics of Oncolytic Reovirus T3D Replication and Growth Pattern in Mesenchymal Stem Cells

Objective

Currently, application of oncolytic-virus in cancer treatment of clinical trials are growing. Oncolytic-reovirus is an attractive anti-cancer therapeutic agent for clinical testing. Many studies used mesenchymal stem cells (MSCs) as a carrier cell to enhance the delivery and quality of treatment with oncolytic-virotherapy. But, biosynthetic capacity and behavior of cells in response to viral infections are different. The infecting process of reoviruses takes from two-hours to one-week, depends on host cell and the duration of different stages of virus replication cycle. The latter includes the binding of virus particle, entry, uncoating, assembly and release of progeny-viruses. We evaluated the timing and infection cycle of reovirus type-3 strain Dearing (T3D), using one-step replication experiment by molecular and conventional methods in MSCs and L929 cell as control.

Materials and Methods

In this experimental study, L929 and adipose-derived MSCs were infected with different multiplicities of infection (MOI) of reovirus T3D. At different time points, the quantity of progeny viruses has been measured using virus titration assay and quantitative real-time polymerase chain reaction (qRT-PCR) to investigate the ability of these cells to support the reovirus replication. One-step growth cycle were examined by 50% cell culture infectious dose (CCID₅₀) and qRT-PCR.

Results

The growth curve of reovirus in cells shows that MOI: 1 might be optimal for virus production compared to higher and lower MOIs. The maximum quantity of virus production using MOI: 1 was achieved at 48-hours post-infection. The infectious virus titer became stationary at 72-hours post-infection and then gradually decreased. The virus cytopathic effect was obvious in MSCs and this cells were susceptible to reovirus infection and support the virus replication.

Conclusion

Our data highlights the timing schedule for reovirus replication, kinetics models and burst size. Further investigation is recommended to better understanding of the challenges and opportunities, for using MSCs loaded with reovirus in cancer-therapy.

Changes in the mycovirus (LeV) titer and viral effect on the vegetative growth of the edible mushroom Lentinula edodes

This study attempted to cure the edible mushroom Lentinula edodes strain FMRI0339 of the L. edodes mycovirus (LeV) in order to obtain an isogenic virus-free fungal strain as well as a virus-infected strain for comparison. Mycelial fragmentation, followed by being spread on a plate with serial dilutions resulted in a virus-free colony. Viral absence was confirmed with gel electrophoresis after dsRNA-specific virus purification, Northern blot analysis, and PCR using reverse transcriptase (RT-PCR). Once cured, all of fungal cultures remained virus-free over the next two years. Interestingly, the viral titer of LeV varied depending on the culture condition. The titer from the plate culture showed at least a 20-fold higher concentration than that grown in the liquid culture. However, the reduced virus titer in the liquid culture was recovered by transferring the mycelia to a plate containing the same medium. In addition, oxygen-depleted culture conditions resulted in a significant decrease of viral concentration, but not to the extent seen in the submerged liquid culture. Although no discernable phenotypic changes in colony morphology were observed, virus-cured strains showed significantly higher growth rates and mycelial mass than virus-infected strains. These results indicate that LeV infection has a deleterious effect on mycelial growth.

Lactate regulates myogenesis in C2C12 myoblasts in vitro

Satellite cells (SCs) are the resident stem cells of skeletal muscle tissue which play a major role in muscle adaptation, e.g. as a response to physical training. The aim of this study was to examine the effects of an intermittent lactate (La) treatment on the proliferation and differentiation of C2C12 myoblasts, simulating a microcycle of high intensity endurance training. Furthermore, the involvement of reactive oxygen species (ROS) in this context was examined. C2C12 myoblasts were therefore repeatedly incubated for 2 h each day with 10 mM or 20 mM La differentiation medium (DM) and in some cases 20 mM La DM plus different antioxidative substances for up to 5 days. La free (0 mM) DM served as a control. Immunocytochemical staining, Western blot analysis and colorimetric assays were used to assess oxidative stress, proliferation, and differentiation. Results show that La induces oxidative stress, enhances cell-cycle withdrawal, and initiates early differentiation but delays late differentiation in a timely and dose-dependent manner. These effects can be reversed by the addition of antioxidants to the La DM. We therefore conclude that La has a regulatory role in C2C12 myogenesis via a ROS-sensitive mechanism which elicits implications for reassessing some aspects of training and the use of nutritional supplements.

Intracellular ATP and total adenylate concentrations are critical predictors of reovirus productivity from Vero cells

The productivity of reovirus type-3 Dearing was studied in cultures of Vero cells in serum-free media. Viral productivity was dependent upon the metabolic state of the cells rather than the phase of growth at which the cells were infected. Cells at different energy states were established by 24-h incubation in nutrient-depleted media. This resulted in variable intracellular nucleotide concentrations but high cellular viability was maintained. Of the nucleotides analyzed at the time of infection only the intracellular [ATP] and total adenylate nucleotides were positively correlated with viral productivity. The correlated data followed a sigmoidal plot with an equation defined by polynomial regression analysis. Apparent threshold values of 3.2 fmol/cell and 3.3 fmol/cell were established for ATP and total adenylate, respectively, at which the viral production was 50% the maximal value. Cultures with lower ATP and total adenylate levels at the time of infection resulted in as much as a 95% reduction in overall viral titer compared to the control. The adenylate energy charge (AEC) showed a negative correlation with viral production with an AEC value >0.97 resulting in low virus productivity. Intracellular ATP or total adenylate concentration at the point of infection may be used as a predictor of viral yield in bioprocesses designed for virus/vaccine production.