Cultured Madin-Darby Canine Kidney Cells Research Articles

A Single-Step Method for Harvesting Influenza Viral Particles from MDCK Cell Culture Supernatant with High Yield and Effective Impurity Removal

Influenza vaccines, which are recommended by the World Health Organization (WHO), are the most effective preventive measure against influenza virus infection. Madin–Darby canine kidney (MDCK) cell culture is an emerging technology used to produce influenza vaccines. One challenge when purifying influenza vaccines using this cell culture system is to efficiently remove impurities, especially host cell double-stranded DNA (dsDNA) and host cell proteins (HCPs), for safety assurance. In this study, we optimized ion-exchange chromatography methods to harvest influenza viruses from an MDCK cell culture broth, the first step in influenza vaccine purification. Bind/elute was chosen as the mode of operation for simplicity. The anion-exchange Q chromatography method was able to efficiently remove dsDNA and HCPs, but the recovery rate for influenza viruses was low. However, the cation-exchange SP process was able to simultaneously achieve high dsDNA and HCP removal and high influenza virus recovery. For the SP process to work, the clarified cell culture broth needed to be diluted to reduce its ionic strength, and the optimal dilution rate was determined to be 1:2 with purified water. The SP process yielded a virus recovery rate exceeding 90%, as measured using a hemagglutination units (HAUs) assay, with removal efficiencies over 97% for HCPs and over 99% for dsDNA. Furthermore, the general applicability of the SP chromatography method was demonstrated with seven strains of influenza viruses recommended for seasonal influenza vaccine production, including H1N1, H3N2, B (Victoria), and B (Yamagata) strains, indicating that the SP process could be utilized as a platform process. The SP process developed in this study showed four advantages: (1) simple operation, (2) a high recovery rate for influenza viruses, (3) a high removal rate for major impurities, and (4) general applicability.

Bioactive Pyrrolo[2,1-f][1,2,4]triazines: Synthesis, Molecular Docking, In Vitro Cytotoxicity Assay and Antiviral Studies

A series of 2,4-disubstituted pyrrolo[2,1-f][1,2,4]triazines containing both aryl and thienyl substituents were synthesized by exploiting the 1,3-cycloaddition reaction of N(1)-ethyl-1,2,4-triazinium tetrafluoroborates with dimethyl acetylenedicarboxylate. The antiviral activity of the synthesized compounds against influenza virus strain A/Puerto Rico/8/34 (H1N1) was studied in experiments on Madin-Darby canine kidney (MDCK) cell culture. Among the pyrrolo[2,1-f][1,2,4]triazine derivatives, compounds with low toxicity and high antiviral activity were identified. Dimethyl 4-(4-methoxyphenyl)-7-methyl-2-p-tolylpyrrolo[2,1-f][1,2,4]triazine-5,6-dicarboxylate was found to demonstrate the best antiviral activity (IC50 4 µg/mL and selectivity index 188). Based on the results of in vitro tests and molecular docking studies performed, a plausible mechanism of action for these compounds was suggested to involve inhibition of neuraminidase.

Antiviral opportunities of Mannich bases derived from triterpenic N-propargylated indoles.

Oleanolic and glycyrrhetic acids alkyne derivatives were synthesized as a result of propargylation of the indole NH-group condensed with the triterpene A-ring, the following aminomethylation led to a series of Mannich bases. The synthesized compounds were tested for their potential inhibition of influenza A/PuertoRico/8/34 (H1N1) virus in Madin-Darby canine kidney (MDCK) cell culture and SARS-CoV-2 pseudovirus in baby hamster kidney-21-human angiotensin-converting enzyme 2 (BHK-21-hACE2) cells. Mannich bases of oleanolic and glycyrrhetic acids N-propargylated indoles 7, 8, and 12 were the most efficacious against influenza virus A with IC50 7-10 μM together with a low toxicity (CC50 > 145 μM) and high selectivity index SI value 20. Indolo-oleanolic acid morpholine amide Mannich base holding N-methylpiperazine moiety 9 showed anti-SARS-CoV-2 pseudovirus activity with EC50 value of 14.8 μM. Molecular docking and dynamics modeling investigated the binding mode of the compounds 7 and 12 into the binding pocket of influenza A virus M2 protein and compound 9 into the RBD domain of SARS-CoV-2 spike glycoprotein.

In-vivo Evaluation of Nephroprotective Activity of Naringenin against ADPKD and MDCK-derived Cysts

Aim: Determining the in-vivo assessment of Naringenin’s nephroprotective efficacy against Autosomal dominant polycystic kidney disease (ADPKD) and Madin-Darby canine kidney (MDCK) derived cysts. Method: Our research on the molecular mechanism of naringenin, a flavonoid present in plants and berries that has been shown to limit cell growth and protect against cancer in in-vitro and animal models, was conducted using dictyostelium, a simple, controllable biomedical model. Cultured MDCK cells were used to generate differentiated tubule cells, and these findings were extrapolated to a human kidney model employing these cells. Results: While naringenin inhibited growth in dictyostelium, it had no effect on development. In a random-gene-knockout screen, a TRPP2 (polycystin-2) knockout mutant was discovered to be resistant to naringenin’s effects on growth and random-cell movement. Changes in the divalent transient receptor cause polycystic kidney disease type 2 potential cation channel TRPP2. We found that the growth of cysts and MDCK cells might be inhibited by naringenin. Partial resistance to naringenin was achieved in this model by lowering TRPP2 levels via siRNA, as evidenced by the presence of larger cysts following treatment with 3 and 10 M naringenin compared to controls. Naringenin had no effect on chloride secretion. Conclusion: Naringenin’s influence on cell proliferation is mediated by TRPP2 in both dictyostelium and mammalian kidney cells, despite their vast evolutionary distance from one another (polycystin-2). Naringenin will be the subject of more research as a possible new therapeutic treatment for ADPKD

Determining the Potency of Vaccines Containing Clostridium perfringens Epsilon Toxoid via Toxicity Analysis in MDCK Cell Lines

The potency control of the clostridium vaccines containing epsilon toxoid is performed with the Toxin Neutralization Test (TNT). Although TNT is a standard method, it has some disadvantages in terms of animal welfare and method validation studies. For this reason, the development and application of alternative methods are encouraged. However, purification and standardization of antigen, antibody and reference standards in serological-based in vitro methods still remain a significant problem. In this respect, cell culture analyses performed using similar reagents are considered possible alternatives in potency tests of the clostridial vaccines. Based on this approach, epsilon antitoxin levels in the sera of vaccinated rabbits were determined by cytotoxicity assay in mouse TNT and Madin-Darby Canine Kidney (MDCK) cell cultures. The toxicity response in cell culture is similar to the response in mice. A high correlation and a good linear relationship were observed in the results of the two methods. There were no non-specific reactions. These results show that, in potency tests of vaccines containing Clostridium perfringens epsilon toxoid, in vitro MDCK cell line seroneutralization assay can be successfully used instead of in vivo mouse TNT.

Genetic Variants in ARHGEF6 Cause Congenital Anomalies of the Kidneys and Urinary Tract in Humans, Mice, and Frogs.

About 40 disease genes have been described to date for isolated CAKUT, the most common cause of childhood CKD. However, these genes account for only 20% of cases. ARHGEF6, a guanine nucleotide exchange factor that is implicated in biologic processes such as cell migration and focal adhesion, acts downstream of integrin-linked kinase (ILK) and parvin proteins. A genetic variant of ILK that causes murine renal agenesis abrogates the interaction of ILK with a murine focal adhesion protein encoded by Parva , leading to CAKUT in mice with this variant. To identify novel genes that, when mutated, result in CAKUT, we performed exome sequencing in an international cohort of 1265 families with CAKUT. We also assessed the effects in vitro of wild-type and mutant ARHGEF6 proteins, and the effects of Arhgef6 deficiency in mouse and frog models. We detected six different hemizygous variants in the gene ARHGEF6 (which is located on the X chromosome in humans) in eight individuals from six families with CAKUT. In kidney cells, overexpression of wild-type ARHGEF6 -but not proband-derived mutant ARHGEF6 -increased active levels of CDC42/RAC1, induced lamellipodia formation, and stimulated PARVA-dependent cell spreading. ARHGEF6-mutant proteins showed loss of interaction with PARVA. Three-dimensional Madin-Darby canine kidney cell cultures expressing ARHGEF6-mutant proteins exhibited reduced lumen formation and polarity defects. Arhgef6 deficiency in mouse and frog models recapitulated features of human CAKUT. Deleterious variants in ARHGEF6 may cause dysregulation of integrin-parvin-RAC1/CDC42 signaling, thereby leading to X-linked CAKUT.

The effect of influenza virus on the metabolism of peripheral blood mononuclear cells with a metabolomics approach.

Respiratory viruses have led to many deaths and hospitalizations per year in the world. The influenza virus is one of the most important respiratory viruses. Recently, metabolic studies in viral infections have been widely studied by scientists. Metabolomics states the metabolites present in a living organism under certain conditions. In this study, peripheral blood mononuclear cells were spinoculated using a virus produced by the Madin-Darby canine kidney cell culture system, and cells were harvested following spinoculation by the influenza virus. Isolation of peripheral blood mononuclear cells was performed by Ficoll-Paque density gradient centrifugation. Metabolites were extracted using organic and water approaches. Metabolic profiling was performed by a nontargeted technique using liquid chromatography with tandem mass spectrometry. Multivariate analysis methods were used to determine the main variables. the metabolic pathways involved were determined using databases. Results of the present study showed changes in biosynthesis pathways such as lipids, polyamines, catecholamines, and vitamins. Findings also showed that it is possible to explain the process of inflammation caused by the influenza virus by studying the metabolism of immune cells.

Hydrogen sulfide, a gaseous signaling molecule, elongates primary cilia on kidney tubular epithelial cells by activating extracellular signal-regulated kinase.

Primary cilia on kidney tubular cells play crucial roles in maintaining structure and physiological function. Emerging evidence indicates that the absence of primary cilia, and their length, are associated with kidney diseases. The length of primary cilia in kidney tubular epithelial cells depends, at least in part, on oxidative stress and extracellular signal-regulated kinase 1/2 (ERK) activation. Hydrogen sulfide (H2S) is involved in antioxidant systems and the ERK signaling pathway. Therefore, in this study, we investigated the role of H2S in primary cilia elongation and the downstream pathway. In cultured Madin-Darby Canine Kidney cells, the length of primary cilia gradually increased up to 4 days after the cells were grown to confluent monolayers. In addition, the expression of H2S-producing enzyme increased concomitantly with primary cilia length. Treatment with NaHS, an exogenous H2S donor, accelerated the elongation of primary cilia whereas DL-propargylglycine (a cystathionine γ-lyase inhibitor) and hydroxylamine (a cystathionine-β-synthase inhibitor) delayed their elongation. NaHS treatment increased ERK activation and Sec10 and Arl13b protein expression, both of which are involved in cilia formation and elongation. Treatment with U0126, an ERK inhibitor, delayed elongation of primary cilia and blocked the effect of NaHS-mediated primary cilia elongation and Sec10 and Arl13b upregulation. Finally, we also found that H2S accelerated primary cilia elongation after ischemic kidney injury. These results indicate that H2S lengthens primary cilia through ERK activation and a consequent increase in Sec10 and Arl13b expression, suggesting that H2S and its downstream targets could be novel molecular targets for regulating primary cilia.

Electrical impedance measurement system to assess in-situ experiments on epithelia under ELF magnetic fields exposure

Purpose: The development of an electric impedance meter based on the impedance spectroscopy technique, for in vitro and in situ experimentation, with cellular epithelia submitted to extremely low frequency magnetic fields in a controlled environment. Unlike other reported systems, a strength of the one presented here is that it avoids the influence of external factors on the experiment. Materials and methods: The designed system employs the electrical impedance values obtained by the impedance spectroscopy technique to determine the parameters of the simple equivalent electrical model of a cellular monolayer. The Madin-Darby Canine Kidney (MDCK) cell cultures were used as subjects of study in the experimental protocol. Results: The validation was carried out by comparing the transepithelial electrical impedance data of the cell cultures obtained with the developed system and those of the Cellzscope® commercial system used as the standard. Non-significant differences were obtained. Conclusion: It was confirmed that the developed system provides reliable values of transepithelial electrical impedance to experiment with cell cultures and take advantage of the controlled environment to reduce the effects of experimental management.

In vitro Effects of a Novel Silver-based Complex on Influenza Virus

Objective: To study the mechanism of antiviral activity of a new silver-based compound of general formula C6H19Ag2N4 LiO6S2 on influenza virus. Materials and Methods: Antiviral properties were investigated on test culture of Madin–Darby canine kidney (MDCK) cells with serial tenfold dilutions of the influenza virus. The completeness of viral inactivation was confirmed by determining the virus titer after a double passage of virus-containing suspension in MDCK cell culture. Reverse transcription polymerase chain reaction analysis of viral RNA, enzyme immunoassay, and transmission electron microscopy for morphological analysis of influenza virus particles were applied for analysis of viral RNA and effect of substance influence. Results: The results indicate a significant change in the antigenic structure of viral proteins of influenza virus by the silver-containing complex. The main inactivation mechanism of influenza virus by the action of the silver-containing complex is associated primarily with the effect on virion protein structure rather than cleavage of the viral RNA. It was revealed that the mechanism for the inactivation of influenza virus is not associated with cleavage of viral RNA corresponding genes M, NS, or nucleoprotein but more probable with changes of the antigen determinants of virion. It was found a significant damaging effect on influenza virus under action of tested substance at concentration higher than 0.4 mM. Conclusion: The novel silver-based complex possesses antiviral properties and could be considered as a prospective antiviral drug.

Sequential and synchronized hypertonicity-induced activation of Rel-family transcription factors is required for osmoprotection in renal cells

NF-κB and TonEBP belong to the Rel-superfamily of transcription factors. Several specific stimuli, including hypertonicity which is a key factor for renal physiology, are able to activate them. It has been reported that, after hypertonic challenge, NF-κB activity can be modulated by TonEBP, considered as the master regulator of transcriptional activity in the presence of changes in environmental tonicity. In the present work we evaluated whether hypertonicity-induced gene transcription mediated by p65/RelA and TonEBP occurs by an independent action of each transcription factor or by acting together. To do this, we evaluated the expression of their specific target genes and cyclooxygenase-2 (COX-2), a common target of both transcription factors, in the renal epithelial cell line Madin-Darby canine kidney (MDCK) subjected to hypertonic environment. The results herein indicate that hypertonicity activates the Rel-family transcription factors p65/RelA and TonEBP in MDCK cells, and that both are required for hypertonic induction of COX-2 and of their specific target genes. In addition, present data show that p65/RelA modulates TonEBP expression and both colocalize in nuclei of hypertonic cultures of MDCK cells. Thus, a sequential and synchronized action p65/RelA → TonEBP would be necessary for the expression of hypertonicity-induced protective genes.

Farklı kültür ortamlarındaki böbrek hücrelerinde osteopontin sentezi ve lokalizasyonu

Osteopontin (OPN) is a glycoprotein which synthesized within the kidney and secreted into the urine by epithelial cells and can inhibit forming the kidney stones especially calcium oxalate stones. The aim of this study is to compare levels of OPN in MDCK (Madin Darby Canine Kidney) cells with different culture conditions and levels of secreted OPN in different culture conditions. Another objective of this study is determination of OPN localization in MDCK cells with different culture conditions. MDCK II (Madin Darby Canine Kidney) cell line were used. OPN expression in MDCK cells was investigated with RT-PCR and agar gel electrophoresis methods. MDCK cells treated with NaHPO4, MgSO4, CaCl2, Na3C6H5O7 and COM, intracellular distribution of osteopontin in that cells were monitored by confocal immunofluorescence microscopy tecnique. Intracellular OPN levels were analysed by Western blot. Secreted OPN in the medium were also analysed by Western blot after immunoprecipitation. Osteopontin levels in different MDCK culture conditions and secreted in extracellular matrix were compared with control groups, there was found any differences between the groups. Intracellular homogen distribution of OPN in cells that made with Na3C6H5O7 and COM solutions were not monitored, osteopontin conglomerates near the cell membrane as a fibrillar aggregate were observed in that cells. Intracellular localization of OPN in different MDCK cell culture conditions was changed. In order to explain functions of OPN, it is necessary that making more researches about structures and modifications of OPN isoforms

Melissa officinalis efficacy against human influenza virus (New H1N1) in comparison with oseltamivir

ObjectiveTo evaluate the antiviral activity of Melissa officinalis (MO) extract against the influenza virus H1N1 in vitro. MethodsThe cytotoxicity of MO extract was identified on Madin-Darby canine kidney (MDCK) cell culture by MTT assay. The virus was inoculated to the cells (multiplicity of infection = 0.1) in two protocols. In protocol 1, the MO extracts at concentrations of 0.005, 0.050, 0.010, 0.100 and 0.500 mg/mL were incubated with the virus for one hour pre-inoculation. In protocol 2, the mentioned concentrations of MO extracts were added to the cells one-hour post infection. Furthermore, the antiviral effect of oseltamivir with different concentrations was tested as the positive controls. The 50% tissue culture infective dose, neutralizing index and hemagglutination titer were determined. ResultsThe medicine oseltamivir and MO extracts were not toxic for MDCK at concentrations less than 1 mg/mL. All utilized concentrations of MO extracts were vigorously efficient to decrease the viral yield in both experiments. The 50% tissue culture infective dose of the groups containing up to 0.100 mg/mL of MO extracts in the first experiment in compare with 0.050 mg/mL in the second experiment reduced to 0. Although hemagglutination tests showed little titers, the viral quantity significantly decreased in both experiments. By the way, the medicine oseltamivir could completely suppress viral replication in MDCK. ConclusionsThe present study suggests that MO extracts have a potent anti-influenza effect in cell culture.

Severe and Fatal Influenza Cases in Russia in 2014-2015

This paper aims to characterize herd immunity of the population inhabiting Asian part of Russia before influenza epidemic and to describe influenza viruses isolated from severe cases including cases with fatal outcomes in the 2014-2015 epidemic season. HI test enabled us to study 3888 serum samples from healthy individuals including 1939 samples collected from poultry farm workers. We showed that none of the 3888 samples produced positive results with the antigens A/H5N1, А(H5N8) and A/H7N9. 41% of the samples are positive to A/California/07/09(H1N1pdm09), 36% of the samples are positive to A/Texas/50/2012 (H3N2), 40% of the samples are positive to B/Brisbane/60/2008 (Victoria lineage) and 47% of the samples are positive to B/Massachusetts/2/2012 (Yamagata lineage). In the 2014-2015 epidemic season 25 clinical and 19 autopsy samples were collected from individuals with severe flu-like infection. Fifteen influenza A(H3N2), two influenza A(H1N1pdm09) and one influenza B (Yamagata) virus strains were isolated in Madin-Darby Canine Kidney cell culture. All viruses exhibited normal inhibition by oseltamivir and zanamivir. A/KMAO/1/2015 and A/Kurgan/149/2015 were antigenically characterized as A/California/07/2009-like. Their hemagglutinin (HA) gene sequences fell into the predominant genetic group 6B and were similar to other recent H1N1pdm09 viruses circulating in Asian region. Eight H3N2 isolated viruses (A/Omsk/160/2015, A/Krasnoyarsk/324/2015, A/NizhnyNovgorod/788/2015, A/Omsk/141/2015, A/Buryatia/19/2015, A/Komi/99/2015, A/Novosibirsk/122/2015 and A/Chelyabinsk/160/2015) were characterized as A/Hong Kong/4801/2014-like and seven viruses (A/Irkutsk/88/2015, A/Krasnoyarsk/365/2015, A/Blagoveshchensk/19/2015, A/Kemerovo/2/2015, A/Chelyabinsk/160/2015, A/Chelyabinsk/192/2015 and A/Novosibirsk/64/2015) as A/Switzerland/9715293/2013-like. Their HA gene sequences belong to 3C.2a and 3C.3a genetic groups, respectively. B/Yekaterinburg/155/2015 virus was antigenically similar to B/Phuket/3073/2013 with HA sequence belonging to Y3 genetic group. Obtained findings are important for adjustment of public health measures and vaccine strategy in Russia.

Atenolol Renal Secretion Is Mediated by Human Organic Cation Transporter 2 and Multidrug and Toxin Extrusion Proteins.

Atenolol is a β-blocker widely used in the treatment of hypertension. Atenolol is cleared predominantly by the kidney by both glomerular filtration and active secretion, but the molecular mechanisms involved in its renal secretion are unclear. Using a panel of human embryonic kidney cell lines stably expressing human organic cation transporter (hOCT) 1-3, human organic anion transporter (hOAT) 1, hOAT3, human multidrug and toxin extrusion protein (hMATE) 1, and hMATE2-K, we found that atenolol interacted with both organic cation and anion transporters. However, it is transported by hOCT1, hOCT2, hMATE1, and hMATE2-K, but not by hOCT3, hOAT1, and hOAT3. A detailed kinetic analysis coupled with absolute quantification of membrane transporter proteins by liquid chromatography-tandem mass spectrometry revealed that atenolol is an excellent substrate for the renal transporters hOCT2, hMATE1, and hMATE2-K. The Km values for hOCT2, hMATE1, and hMATE2-K are 280 ± 4, 32 ± 5, and 76 ± 14 μM, respectively, and the calculated turnover numbers are 2.76, 0.41, and 2.20 s(-1), respectively. To demonstrate unidirectional transepithelial transport of atenolol, we developed and functionally validated a hOCT2/hMATE1 double-transfected Madin-Darby canine kidney cell culture model. Transwell studies showed that atenolol transport in the basal (B)-to-apical (A) direction is 27-fold higher than in the A-to-B direction, whereas its B-to-A/A-to-B transport ratio was only 2 in the vector-transfected control cells. The overall permeability of atenolol in the B-to-A direction in hOCT2/hMATE1 cells was 44-fold higher than in control cells. Together, our data support that atenolol tubular secretion is mediated through the hOCT2/hMATEs secretion pathway and suggest a significant role of organic cation transporters in the disposition of an important antihypertensive drug.

The exocyst gene Sec10 regulates renal epithelial monolayer homeostasis and apoptotic sensitivity.

The highly conserved exocyst protein complex regulates polarized exocytosis of subsets of secretory vesicles. A previous study reported that shRNA knockdown of an exocyst central subunit, Sec10 (Sec10-KD) in Madin-Darby canine kidney (MDCK) cells disrupted primary cilia assembly and 3D cyst formation. We used three-dimensional collagen cultures of MDCK cells to further investigate the mechanisms by which Sec10 and the exocyst regulate epithelial polarity, morphogenesis, and homeostasis. Sec10-KD cysts initially demonstrated undisturbed lumen formation although later displayed significantly fewer and shorter primary cilia than controls. Later in cystogenesis, control cells maintained normal homeostasis, while Sec10-KD cysts displayed numerous apoptotic cells extruded basally into the collagen matrix. Sec10-KD MDCK cells were also more sensitive to apoptotic triggers than controls. These phenotypes were reversed by restoring Sec10 expression with shRNA-resistant human Sec10. Apico-basal polarity appeared normal in Sec10-KD cysts, whereas mitotic spindle angles differed significantly from controls, suggesting a planar cell polarity defect. In addition, analysis of renal tubules in a newly generated kidney-specific Sec10-knockout mouse model revealed significant defects in primary cilia assembly and in the targeted renal tubules; abnormal epithelial cell extrusion was also observed, supporting our in vitro results. We hypothesize that, in Sec10-KD cells, the disrupted exocyst activity results in increased apoptotic sensitivity through defective primary cilia signaling and that, in combination with an increased basal cell extrusion rate, it affects epithelial barrier integrity and homeostasis.

HGF-induced serine 897 phosphorylation of EphA2 regulates epithelial morphogenesis of MDCK cells in 3D culture

Expression of EphA2 is upregulated in various cancers that are derived from epithelial cells and correlates with the ability of a cancer cell to undergo migration and invasion. Here we have investigated the role of EphA2 in the epithelial morphogenesis of Madin-Darby canine kidney (MDCK) cells in three-dimensional culture. We show that EphA2 is phosphorylated on serine residue 897 through hepatocyte growth factor (HGF) stimulation using a phosphatidylinositol 3-kinase (PI3K)-Akt-dependent mechanism and that this phosphorylation is required for the formation of extensions, the first step of tubulogenesis, in MDCK cysts. By contrast, stimulation using the ligand ephrinA1 dephosphorylates EphA2 on serine residue 897 and suppresses the HGF-induced morphological change. Furthermore, activation of the small GTPase RhoG is involved in the HGF-induced formation of extensions downstream of EphA2. These observations suggest that a ligand-independent activity of EphA2 contributes to epithelial morphogenesis.

Production of canine adenovirus type 2 in serum-free suspension cultures of MDCK cells.

The potential of adherent Madin Darby Canine Kidney (MDCK) cells for the production of influenza viruses and canine adenovirus type 2 (CAV-2) for vaccines or gene therapy approaches has been shown. Recently, a new MDCK cell line (MDCK.SUS2) that was able to grow in suspension in a fully defined system was established. In this work, we investigated whether the new MDCK.SUS2 suspension cell line is suitable for the amplification of CAV-2 under serum-free culture conditions. Cell growth performance and CAV-2 production were evaluated in three serum-free media: AEM, SMIF8, and EXCELL MDCK. CAV-2 production in shake flasks was maximal when AEM medium was used, resulting in an amplification ratio of infectious particles (IP) of 142 IP out/IP in and volumetric and cell-specific productivities of 2.1 × 10(8) IP/mL and 482 IP/cell, respectively. CAV-2 production was further improved when cells were cultivated in a 0.5-L stirred tank bioreactor. To monitor infection and virus production, cells were analyzed by flow cytometry. A correlation between the side scatter measurement and CAV-2 productivity was found, which represents a key feature to determine the best harvesting time during process development of gene therapy vectors that do not express reporter genes. This work demonstrates that MDCK.SUS2 is a suitable cell substrate for CAV-2 production, constituting a step forward in developing a production process transferable to industrial scales. This could allow for the production of high CAV-2 titers either for vaccination or for gene therapy purposes.

Comparison of immunogenicity of cell-and egg-passaged viruses for manufacturing MDCK cell culture-based influenza vaccines

While cell culture-based technology has been recently used for manufacturing influenza vaccines, currently available seed viruses are mostly egg-derived reassortants that are egg-adapted to achieve high virus growth in eggs. For use as viruses for cell culture-based influenza vaccine manufacturing, egg-adapted viral seeds may undergo several passages in manufacturing cell lines. However, the suitability of such cell-passaged viruses for vaccine production remains largely unelucidated. In this study, influenza viruses produced in suspension Madin-Darby canine kidney (MDCK) cell cultures were compared to those produced in embryonated hen's eggs for manufacturing MDCK cell culture-based influenza vaccines through comparability studies of virus productivity and vaccine immunogenicity. The results indicate no change in the amino acid sequence of the main antigens, including hemagglutinin (HA) and neuraminidase (NA), of cell-passaged viruses after three passages in suspension MDCK cells. In lab-scale (3-L) single-use bioreactors, suspension MDCK culture supernatants inoculated with cell-passaged viruses were found to show higher virus productivity, suspension MDCK culture supernatants inoculated with egg-passaged viruses, in respect to the HA titers and HA contents determined by single radial immunodiffusion. Finally, comparable hemagglutination inhibition and influenza-specific IgG titers were determined in the mice immunized with cell culture-based vaccines produced with cell- or egg-passaged viruses. These results indicate that MDCK cell-passaged viruses from egg-adapted viruses, as well as egg-derived seed virus, are suitable for MDCK cell culture-based influenza vaccine production.

Sec10 and the Exocyst are Necessary for Renal Epithelial Monolayer Homeostasis and Ciliogenesis In Vitro and In Vivo

The eight‐protein exocyst complex regulates targeted delivery of exocytic vesicles. A previous report demonstrated that shRNA‐knockdown of Sec10 (Sec10‐KD), a central subunit of the exocyst, in Madin‐Darby canine kidney (MDCK) cells disrupted primary cilia assembly and 3D cyst formation. To further study the mechanisms by which Sec10 and the exocyst regulate epithelial polarity, morphogenesis, and homeostasis, we used three dimensional collagen cultures of MDCK cells. Sec10‐KD cysts initially showed undisturbed lumen formation, even though subsequently displayed significantly fewer and shorter primary cilia than controls. Later in cystogenesis, while Sec10‐KD cysts showed numerous apoptotic cells extruded basally into the collagen matrix, control cells maintained normal homeostasis. Sec10‐KD MDCK cells were also more sensitive to apoptotic triggers than controls. Apico‐basal polarity appeared normal in Sec10‐KD cysts, while a planar cell polarity defect was suggested by the differences in mitotic spindle angles between knockdowns and controls. Furthermore, analysis of renal tubules in our recently generated kidney‐specific Sec10 knockout mouse model revealed significant defects in primary cilia assembly and in the targeted renal tubules, abnormal epithelial cell extrusion was also observed, supporting our in vitro findings. We hypothesize that in Sec10‐KD cells, the disrupted exocyst activity leads to an increased apoptotic sensitivity through disrupted primary cilia signaling, and in combination with an increased basal cell extrusion rate, it affects epithelial barrier integrity and homeostasis.Supported by: the NIH, March of Dimes, UH RCMI‐BRIDGES and HRFDCC at University of Alabama.