Recombination between African and Asian lineages of Zika virus in vitro and its consequences for viral phenotype

Recombination is a process of extensive genetic exchange that is known to contribute to virus evolution and has been frequently observed in positive-sense RNA viruses. Zika virus (ZIKV) is an emerging arbovirus of the family Flaviviridae with two distinct lineages – African and Asian. While some phylogenetic evidence suggests that recombination in the envelope-encoding region of the ZIKV genome has occurred during evolution, there has been no experimental evidence for ZIKV recombination to date. We conducted co-infections of mammalian and insect cells, using the prototype African ZIKV strain (MR766) and an Asian isolate from the 2015-16 ZIKV outbreak in Brazil (BeH819015), and used a recombinant-specific PCR assay to detect recombinant sequences from total cell RNA extracts. In brief, a 564bp fragment spanning the boundary between the structural and the non-structural genes of the viral genome was amplified using a primer pair consisting of an Asian-specific and an African-specific primer. A total of 24 individual sequences were screened. All were in-frame recombinants and they formed 10 unique junctions. Several of the detected recombinant sequences were chosen for construction of full-length infectious clones to test the viability and phenotype of the recombinant viruses. This study represents the first isolation of recombinant ZIKV sequences from co-infected cultured cells and demonstrates the capacity of ZIKV to recombine in an experimental system. Further investigation is required to better understand the evolutionary potential of this mechanism and its putative role in the emergence of ZIKV.

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Transcriptional control of delta-crystallin gene expression in the chicken embryo lens: demonstration by a new method for measuring mRNA metabolism

Molecular and Cellular Biology ◽

10.1128/mcb.13.6.3282-3290.1993 ◽

1993 ◽

Vol 13 (6) ◽

pp. 3282-3290

Author(s):

X Li ◽

D C Beebe

Keyword(s):

Chicken Embryo ◽

Transcriptional Control ◽

Cultured Cells ◽

Pcr Primers ◽

High Refractive Index ◽

In Vitro Transcription ◽

Equilibrium Density ◽

Specific Pcr ◽

High Concentrations

Crystallins are proteins that accumulate to very high concentrations in the fiber cells of the lens of the eye. Crystallins are responsible for the transparency and high refractive index that are essential for lens function. In the chicken embryo, delta-crystallin accounts for more than 70% of the newly synthesized lens proteins. We used density labeling and gene-specific polymerase chain reaction (PCR) to determine the mechanism regulating the expression of the two very similar delta-crystallin genes. Newly synthesized RNA was separated from preexisting RNA by incubating the lenses with 15N- and 13C-labeled ribonucleosides and then separating newly synthesized, density-labeled RNA from the bulk of light RNA by equilibrium density centrifugation in NaI-KI gradients. The relative abundances of the two crystallin mRNAs in the separated fractions were then determined by PCR. This method permitted the quantitation of newly synthesized processed and unprocessed delta-crystallin mRNAs. Additional studies used intron- and gene-specific PCR primers to determine the relative expression of the two delta-crystallin genes in processed RNA and unprocessed RNA extracted from different regions of the embryonic lens. Results of these tests indicated that the differential expression of the delta-crystallin genes was regulated primarily at the level of transcription. This outcome was not expected on the basis of the results of previous studies, which used in vitro transcription and transfection methods to evaluate the relative strengths of delta-crystallin promoter and enhancer sequences. Our data suggest that the cultured cells used in these earlier studies may not have provided an accurate view of delta-crystallin regulation in the intact lens.

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Visualization of SARS-CoV-2 infection dynamic

10.1101/2021.06.03.446942 ◽

2021 ◽

Author(s):

Chengjin Ye ◽

Kevin Chiem ◽

Jun-Gyu Park ◽

Jesus Silvas ◽

Desarey Morales Vasquez ◽

...

Keyword(s):

Viral Infection ◽

Cultured Cells ◽

Imaging System ◽

Reporter Genes ◽

Therapeutic Interventions ◽

Wild Type Virus ◽

Nucleocapsid Gene ◽

Recombinant Viruses

Replication-competent recombinant viruses expressing reporter genes provide valuable tools to investigate viral infection. Low levels of reporter gene expressed from previous reporter-expressing rSARS-CoV-2 have jeopardized their use to monitor the dynamics of SARS-CoV-2 infection in vitro or in vivo. Here, we report an alternative strategy where reporter genes were placed upstream of the viral nucleocapsid gene followed by a 2A cleavage peptide. The higher levels of reporter expression using this strategy resulted in efficient visualization of rSARS-CoV-2 in infected cultured cells and K18 hACE2 transgenic mice. Importantly, real-time viral infection was readily tracked using a non-invasive in vivo imaging system and allowed us to rapidly identify antibodies which are able to neutralize SARS-CoV-2 infection in vivo. Notably, these reporter-expressing rSARS-CoV-2 retained wild-type virus like pathogenicity in vivo, supporting their use to investigate viral infection, dissemination, pathogenesis and therapeutic interventions for the treatment of SARS-CoV-2 in vivo.

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Development of Infectious Clones for Virulent and Avirulent Pichinde Viruses: a Model Virus To Study Arenavirus-Induced Hemorrhagic Fevers

Journal of Virology ◽

10.1128/jvi.00019-09 ◽

2009 ◽

Vol 83 (13) ◽

pp. 6357-6362 ◽

Cited By ~ 45

Author(s):

Shuiyun Lan ◽

Lisa McLay Schelde ◽

Jialong Wang ◽

Naveen Kumar ◽

Hinh Ly ◽

...

Keyword(s):

Guinea Pigs ◽

Small Animal ◽

Hemorrhagic Fever ◽

Virulence Determinants ◽

T7 Promoter ◽

Recombinant Viruses ◽

Hemorrhagic Fevers ◽

Infectious Clones

ABSTRACT Several arenaviruses can cause hemorrhagic fever diseases (VHFs) in humans, the pathogenic mechanism of which is poorly understood due to their virulent nature and the lack of molecular clones. A safe, convenient, and economical small animal model of arenavirus hemorrhagic fever is based on guinea pigs infected by the arenavirus Pichinde (PICV). PICV does not cause disease in humans, but an adapted strain of PICV (P18) causes a disease in guinea pigs that mimics arenavirus hemorrhagic fever in humans in many aspects, while a low-passaged strain (P2) remains avirulent in infected animals. In order to identify the virulence determinants within the PICV genome, we developed the molecular clones for both the avirulent P2 and virulent P18 viruses. Recombinant viruses were generated by transfecting plasmids that contain the antigenomic L and S RNA segments of PICV under the control of the T7 promoter into BSRT7-5 cells, which constitutively express T7 RNA polymerase. By analyzing viral growth kinetics in vitro and virulence in vivo, we show that the recombinant viruses accurately recapitulate the replication and virulence natures of their respective parental viruses. Both parental and recombinant virulent viruses led to high levels of viremia and titers in different organs of the infected animals, whereas the avirulent viruses were effectively controlled and cleared by the hosts. These novel infectious clones for the PICV provide essential tools to identify the virulence factors that are responsible for the severe VHF-like disease in infected animals.

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Isolation and Propagation in Vitro of Peritoneal Mesothelial Cells

Peritoneal Dialysis International ◽

10.1177/089686088900900423 ◽

1989 ◽

Vol 9 (4) ◽

pp. 341-347 ◽

Cited By ~ 41

Author(s):

J. Thomas Hjelle ◽

Barbara T. Golinska ◽

Diane C. Waters ◽

Kevin R. Steidley ◽

David R. McCarroll ◽

...

Keyword(s):

Peritoneal Dialysis ◽

Cell Biology ◽

Life Support ◽

Cultured Cells ◽

Mesothelial Cell ◽

Experimental System ◽

Mesothelial Cells ◽

Growth Media ◽

Peritoneal Mesothelial Cells

Mesothelial cells lining the peritoneal cavity are the primary site of molecular exchange during peritoneal dialysis, a life support system for over 50 000 patients worldwide. In this study, techniques are described for the isolation and propagation in culture of peritoneal mesothelial cells from rats and rabbits. For comparison, mesothelial cells were also obtained from the serosal surface of human colonic tissue. By electron microscopy the cultured cells were found to exhibit microvilli, a well developed endoplasmic reticulum and golgi apparatus, micropinocytotic vesicles, and lipid-filled intracellular vesicles. Immunochemical probes revealed the expression by these cells in vitro of cytokeratin, fibronectin, vimentin, and keratin, but not von Willebrand factor. Mesothelial cells from rat, rabbit, and human exhibited contact inhibition, but differences in growth rates and dependence on supplements to the growth media. This work provides a multispecies comparison of the behavior of mesothelial cells in vitro for the purpose of developing an experimental system for the study of mesothelial cell biology and the role of these cells in peritoneal dialysis.

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Hormonal regulation of glutathione S-transferase expression in co-cultured adult rat hepatocytes

Journal of Endocrinology ◽

10.1677/joe.0.1660363 ◽

2000 ◽

Vol 166 (2) ◽

pp. 363-371 ◽

Cited By ~ 25

Author(s):

S Coecke ◽

T Vanhaecke ◽

A Foriers ◽

IR Phillips ◽

A Vercruysse ◽

...

Keyword(s):

Hormonal Regulation ◽

Cultured Cells ◽

Experimental System ◽

Human Growth ◽

Rat Hepatocytes ◽

Isolated Hepatocytes ◽

Adult Rat ◽

Adult Rat Hepatocytes ◽

Translational Level

Glutathione S-transferases (GSTs) are subject to regulation by thyroid and sex hormones and by GH. We have used an in vitro experimental system comprising adult rat hepatocytes co-cultured with rat liver epithelial cells of primitive biliary origin, to distinguish between direct and indirect effects of various hormones on GSTs; to identify the GST subunits affected by individual hormones; and to investigate the level at which the hormones act. Tri-iodothyronine (T3), thyroxine (T4) and 17beta-oestradiol (OE2) reduced GST activities, whereas testosterone, dihydrotestosterone, and human growth hormone (hGH) had little effect on total GST activity. HPLC separation of the various GST subunits revealed that T3 and T4 reduced total GST content, in particular the abundance of subunits M1 and M2. The amount of the Pi-class subunit P1 was reduced by OE2. Treatment of the co-cultured cells with this hormone altered the GST subunit profile to one that is more similar to that observed in freshly isolated hepatocytes. Analysis of mRNAs demonstrated that some of the hormones act at a pre-translational level, whereas others act at a translational or post-translational level to regulate the expression of various GST subunits.

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Transcriptional control of delta-crystallin gene expression in the chicken embryo lens: demonstration by a new method for measuring mRNA metabolism.

Molecular and Cellular Biology ◽

10.1128/mcb.13.6.3282 ◽

1993 ◽

Vol 13 (6) ◽

pp. 3282-3290 ◽

Cited By ~ 4

Author(s):

X Li ◽

D C Beebe

Keyword(s):

Chicken Embryo ◽

Transcriptional Control ◽

Cultured Cells ◽

Pcr Primers ◽

High Refractive Index ◽

In Vitro Transcription ◽

Equilibrium Density ◽

Specific Pcr ◽

High Concentrations

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Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100053711 ◽

1982 ◽

Vol 40 ◽

pp. 210-211

Author(s):

M.J. Murphy ◽

R.R. Price ◽

J.C. Sloman

Keyword(s):

Cultured Cells ◽

Human Tumor ◽

Cell Type ◽

Tumor Mass ◽

Initial Cell ◽

Cloning Assay ◽

Human Tumor Cloning ◽

The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

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Preparation of cultured astrocytes for x-ray microanalysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100156924 ◽

1989 ◽

Vol 47 ◽

pp. 988-989

Author(s):

N.K.R. Smith ◽

K.E. Hunter ◽

P. Mobley ◽

L.P. Felpel

Keyword(s):

Cultured Cells ◽

Elemental Content ◽

Elemental Distribution ◽

Sprague Dawley ◽

X Ray ◽

Cultured Astrocytes ◽

Freeze Dried ◽

Ultimate Objective

Electron probe energy dispersive x-ray microanalysis (XRMA) offers a powerful tool for the determination of intracellular elemental content of biological tissue. However, preparation of the tissue specimen , particularly excitable central nervous system (CNS) tissue , for XRMA is rather difficult, as dissection of a sample from the intact organism frequently results in artefacts in elemental distribution. To circumvent the problems inherent in the in vivo preparation, we turned to an in vitro preparation of astrocytes grown in tissue culture. However, preparations of in vitro samples offer a new and unique set of problems. Generally, cultured cells, growing in monolayer, must be harvested by either mechanical or enzymatic procedures, resulting in variable degrees of damage to the cells and compromised intracel1ular elemental distribution. The ultimate objective is to process and analyze unperturbed cells. With the objective of sparing others from some of the same efforts, we are reporting the considerable difficulties we have encountered in attempting to prepare astrocytes for XRMA.Tissue cultures of astrocytes from newborn C57 mice or Sprague Dawley rats were prepared and cultured by standard techniques, usually in T25 flasks, except as noted differently on Cytodex beads or on gelatin. After different preparative procedures, all samples were frozen on brass pins in liquid propane, stored in liquid nitrogen, cryosectioned (0.1 μm), freeze dried, and microanalyzed as previously reported.

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EVALUATION OF TISSUE STEROID BINDING IN VITRO

Acta Endocrinologica ◽

10.1530/acta.0.068s223 ◽

1971 ◽

Vol 68 (1_Suppl) ◽

pp. S223-S246 ◽

Cited By ~ 2

Author(s):

C. R. Wira ◽

H. Rochefort ◽

E. E. Baulieu

Keyword(s):

Protein Binding ◽

Binding Sites ◽

Experimental System ◽

Specific Protein ◽

Coupling Mechanism ◽

Target Tissue ◽

Protein Binding Sites ◽

Definition Of ◽

Hormone Specificity

ABSTRACT The definition of a RECEPTOR* in terms of a receptive site, an executive site and a coupling mechanism, is followed by a general consideration of four binding criteria, which include hormone specificity, tissue specificity, high affinity and saturation, essential for distinguishing between specific and nonspecific binding. Experimental approaches are proposed for choosing an experimental system (either organized or soluble) and detecting the presence of protein binding sites. Techniques are then presented for evaluating the specific protein binding sites (receptors) in terms of the four criteria. This is followed by a brief consideration of how receptors may be located in cells and characterized when extracted. Finally various examples of oestrogen, androgen, progestagen, glucocorticoid and mineralocorticoid binding to their respective target tissues are presented, to illustrate how researchers have identified specific corticoid and mineralocorticoid binding in their respective target tissue receptors.

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IN VITRO METHODS FOR THE STUDY OF THE ADENOHYPOPHYSIAL FUNCTIONS TO SECRETE GONADOTROPHIN

Acta Endocrinologica ◽

10.1530/acta.0.068s027 ◽

1971 ◽

Vol 68 (1_Suppl) ◽

pp. S27-S40 ◽

Cited By ~ 1

Author(s):

T. Kobayashi ◽

T. Kigawa ◽

M. Mizuno ◽

T. Watanabe

Keyword(s):

Cell Culture ◽

Organ Culture ◽

Cultured Cells ◽

Cell Sheet ◽

Short Term ◽

Hypothalamic Extract ◽

Numerous Cell ◽

Single Cell Culture ◽

Almost All

ABSTRACT There are several in vitro methods to analyse the function of the adenohypophysis or the mechanisms of its regulation. The present paper deals with single cell culture, organ culture and short term incubation techniques by which the morphology and gonadotrophin-secreting function of the adenohypophysis were studied. In trypsin-dispersed cell culture, the adenohypophysial cells showed extensive propagation to form numerous cell colonies and finally develop into a confluent monolayer cell sheet covering completely the surface of culture vessels. Almost all of the cultured cells, however, became chromophobic, at least at the end of the first week of cultivation, when gonadotrophin was detectable neither in the culture medium nor in the cells themselves. After the addition of the hypothalamic extract, gonadotrophin became detectable again, and basophilic or PAS-positive granules also reappeared within the cells, suggesting that the gonadotrophs were stimulated by the extract to produce gonadotrophin. In organ culture and short term incubation, the incorporation of [3H] leucine into the adenohypophysial cells in relation to the addition of hypothalamic extract was examined. It was obvious that the ability to incorporate [3H] leucine into the gonadotrophs in vitro was highly dependent upon the presence of the hypothalamic extract.

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