Biological characteristics and viral susceptibility of a stable dog kidney cell line

Summary A cell line derived in 1956 from normal dog kidney is described. The cells are epithelial, contact-inhibited, and can be maintained in the same culture vessels for periods of more than 2.5 yr. Karyologically, the cells are hypodiploid with a modal number of 72 as opposed to the diploid number of 78. The karyotype indicates male origin of the cells and clonal derivation of extant cultures due to the presence of two marker chormosomes in all metaphases observed. At the 159th passage the dog kidney (DK) cells did not produce tumors in athymic rats. At least 13 viruses of various types produced transmissible cytopathogenic effects in the DK cells, including all of the human influenza viruses investigated. The project was supported in part by an Institutional Research and Development grant from SRI International and Contract Y01 CP8-0500, National Cancer Institute, National Institutes of Health, Bethesda, MD.     

Alvira: comparative genomics of viral strains

MOTIVATION: The Alvira tool is a general purpose multiple sequence alignment viewer with a special emphasis on the comparative analysis of viral genomes. This new tool has been devised specifically to address the problem of the simultaneous analysis of a large number of viral strains. The multiple alignment is embedded in a graph that can be explored at different levels of resolution. AVAILABILITY: The Alvira software is available at: http://bioinfo.genopole-toulouse.prd.fr/Alvira. SUPPLEMENTARY INFORMATION: A tutorial is available at Alvira's homepage.     

Studies on the new cell line TT-I: viral susceptibility and chromosomal changes related to mycoplasma contamination.

For understanding some biological properties of TT-1 cell line established in our laboratory in 1962, its viral susceptibility and the changes in chromosomes related to mycoplasma contamination were studied. TT-1 cells were susceptible to the infection of picorna (Polio type 1, Coxsackie B1 and Echo type 2), measles, Newcastle disease, herpes simplex (type 1), adeno (type 12) and vaccinia viruses. Contamination of TT-1 cells with Mycoplasma hominis was treated successfully with bottromycin A2 (50 microgram/ml). The chromosomes of the cells ranged from 52 to 55 in number and two additional minute chromosomes were found in the cells contaminated with the mycoplasma. However, after treatment with bottromycin, these two minute chromosomes disappeared.     

Gypsy moth cell lines divergent in viral susceptibility

Summary A series of cell lines unique in insect virus susceptibility pattern have been isolated from the ovaries of the gypsy moth (Lymantria dispar: Lepidoptera: Lymantriidae) on a synthetic medium with mammalian and avian serum supplementation. Growth curves showed the poorest growth occurring on peptone-based media with somewhat better growth on amino-acid-based media. The best growth was obtained with combined media. Serological study distinguished the present cell lines from one another and from cell lines derived from other insect species grown routinely in the same laboratory. Baculovirus susceptibility among the new lines varied from no response to a specific complete replication response upon challenge by the homologous (gypsy moth) nuclear polyhedrosis virus. This research was funded in part through a reimbursable agreement with the U.S. Forest Service.     

Development,characterization, and viral susceptibility of a feline (Felis catus) renal cell line (CRFK)

Summary Cell line CRFK, derived from kidney tissue of a normal domestic kitten, was initiated in 1964. With intermittent periods of storage in the frozen state, it has been grown in vitro during more than 200 passages, without apparent loss of susceptibility to selected viruses. Various herpesviruses and feline viruses belonging to differnet virus groups grow readily and with distinct, cytopathic features. The cells now grow as a smooth monolayer of epithelial-like cells; most have 37 chromosomes (2n−1) and are thus aneuploid for cat karyotype. Three distinct marker chromosomes are identified. The cell line, which is free of mycoplasmal contaimination, is useful in feline virus research and diagnostic medicine and has become of particular interest in cancer research. Supported in part by Contract E73-2001-NO1-CP-3-3237 within the Special Virus Cancer Program, National Cancer Institute, National Institutes of Health, Public Health Service and the Morris Animal Foundation and General Research Support funds of the New York State Veterinary College. CRFK cells from stock provided by C. G. Fabricant are available for distribution to investigators from the Cell Culture Laboratory, Naval Biomedical Research Laboratory.     

Olfactory cell derivation and migration

This special issue of the Journal of Molecular Histology is devoted to the unique phenomena of migration and adult neurogenesis observed in the olfactory system. Neural progenitors migrate from the olfactory placode and epithelium (OE) into the central nervous system (CNS) and from the forebrain ventricular region to the olfactory bulb (OB). Not unexpectedly, there are a number of controversies with regard to the mechanisms regulating these phenomena in both developing and adult animals. One especially controversial issue common to both the peripheral (OE) and central (OB) systems is the identity of the slowly dividing multipotent stem cell and the mechanisms regulating the lineage specification of these progenitors which eventually differentiate into neurons and glia. Nine contributions from leading laboratories address these and other issues with respect to progenitors and their integration into OE and OB circuitry in several species.     

Retrovirus producer cell line metabolism: implications on viral productivity

The production of retroviral vectors by human cell lines is still hampered by low titers making it relatively difficult to produce very large quantities of this vector of high interest for clinical gene therapy applications. Thus, to improve vector production, we studied the influence of different sugars alone or combinations of sugars on cell growth, vector titers, and metabolism of the producer cell. The use of fructose at 140 mM or a mixed medium (with glucose at 25 mM and fructose at 140 mM) improved the virus titer three- to fourfold, respectively, and the producer cell productivity by fivefold. The increase in the cell productivity was due to a 1.5-fold increase in the vector stability, the remaining increase being due to higher cell specific productivity. The increase in the productivity was associated with lower glucose oxidation and an increase in the lactate and alanine yield. In the mixed medium, an increase in fatty acids derived from the glucose was observed in parallel with a reduction of glutamate and glutamine synthesis via the tricarboxylic acid (TCA) cycle acetyl-CoA and α-ketoglutarate, respectively. Although the higher productivities were associated with severe changes in the glycolysis, TCA cycle, and glutaminolysis, the cell energetic status monitored by phosphocreatine and adenosine triphosphate levels was not significantly affected. The synthesis of fatty acids and phospholipids were enhanced in the fructose or mixed media and are possibly key parameters in retroviral vector production.     

Persistent viral infection affects tumorigenicity of a neuroblastoma cell line

A mouse neuroblastoma cell line (clone NS20Y) is highly tumorigenic in syngeneic A/J mice. When this clone was persistently infected with measles virus (NS20Y/MS) it failed to grow or form tumors in conventional A/J or nude mice, even when large numbers of cells were inoculated. As doubling time, serum dependence, and anchorage-independent growth on agar did not differ significantly between NS20Y and NS20Y/MS, lack of tumorigenicity of the persistently infected cells is unlikely to be due to an intrinsic property of the cells. NS20Y/MS cells were found to be effectively rejected in athymic nude as well as conventional syngeneic mice. However, injection of mice with either anti-interferon or anti-asialo GM1 serum, both of which have been shown to deplete natural killer (NK) cells in vivo, enabled NS20Y/MS cells to form large tumors. Unexpectedly, treatment of mice with silica also allowed the NS20Y/MS cells to form tumors. Under these conditions, it was shown that silica caused a significant decrease in NK activity as late as 7 days after a single injection. Although NS20Y/MS were not susceptible to NK cell lysis in vitro, the in vivo data suggest that NK cells are in fact the prime mechanism in the rejection of this persistently virus-infected neuroblastoma cell line by athymic and conventional syngeneic mice. The results indicate that NK activity may be greater or more sensitively detected in vivo than in vitro.     

Role of the embryology laboratory in the human embryonic stem cell line derivation process

With the introduction of regenerative medicine and cell therapy programmes by means of human embryonic stem cells (hESC), several research centres have begun projects of derivation of hESC lines. In some stem cell banks, such as the Andalusian Stem Cell Bank, the law also permits the creation of these cell lines. Therefore, the recovery of cryopreserved embryos, their culture and the subsequent derivation to hESC lines requires a suitable embryology laboratory and specialized and highly qualified staff. Moreover, new techniques, from therapeutic nuclear transfer, need this type of laboratory and staff, too. Several International Associations have drawn up some guidelines for laboratories where embryos are manipulated and they reflect the physical space, the staff and the equipment needed in these kinds of laboratories. Nevertheless, we can see that these guidelines do not distinguish between IVF laboratories and other laboratories that obtain hESC lines, so it would be convenient to make a distinction. Following these guidelines, we have tried to draw up concurrent aspects applicable to areas of embryology within stem cell banks. So, the design and the specific implementation programmes for these areas and other research centres with this area but which do not use IVF techniques is vital to develop embryonic cell lines in optimum conditions for future therapeutic applications, although maybe it is rather premature to standardize this type of research.     

Stable expression of bioactive recombinant pleurocidin in a fish cell line

Pleurocidin (Ple), a linear cationic peptide of 25 amino acids, is a member of a larger family of antimicrobial peptides present in flatfish. Previous studies have shown that Ple displays a strong antimicrobial activity against a broad spectrum of bacteria and appears to play a role in innate host defence. In this work, the genomic sequence encoding the Ple prepropeptide has been isolated from Limanda limanda and cloned in a vector under the control of a non-viral promoter (the carp β-actin promoter). By using this construction, expression of bioactive Ple was demonstrated in transformed fish cell lines continuously growing for more than 2 years. Furthermore, the study of Ple processing, maturation and secretion (by using fusion with green fluorescence protein) and the high bactericidal activity of the secreted recombinant Ple (detectable in cell supernatants without any concentration) are all reported here, as no other recombinant Ple or fish antimicrobial peptide have been expressed before to that extent. Such an overexpression of recombinant Ple or any other related antimicrobial peptide might improve the chances to develop new antibiotic agents, as well as to provide essential information about the mechanism of action, range of activity and the role in the innate immune response of antibiotic peptides.     

Stable and high-level production of recombinant Factor IX in human hepatic cell line

Hemophilia B is a genetic disease of the coagulation system that affects one in 30,000 males worldwide. Recombinant human Factor IX (rhFIX) has been used for hemophilia B treatment, but the amount of active protein generated by these systems is inefficient, resulting in a high-cost production of rhFIX. In this study, we developed an alternative for rhFIX production. We used a retrovirus system to obtain two recombinant cell lines. We first tested rhFIX production in the human embryonic kidney 293 cells (293). Next, we tested a hepatic cell line (HepG2) because FIX is primarily expressed in the liver. Our results reveal that intracellular rhFIX expression was more efficient in HepG2/rhFIX (46%) than in 293/rhFIX (21%). The activated partial thromboplastin time test showed that HepG2/rhFIX expressed biologically active rhFIX 1.5 times higher than 293/rhFIX (P = 0.016). Recovery of rhFIX from the HepG2 by reversed-phase chromatography was straightforward. We found that rhFIX has a pharmacokinetic profile similar to that of FIX purified from human plasma when tested in hemophilic B model. HepG2/rhFIX cell line produced the highest levels of rhFIX, representing an efficient in vitro expression system. This work opens up the possibility of significantly reducing the costs of rhFIX production, with implications for expanding hemophilia B treatment in developing countries.