Este trabalho foi financiado pelo Fundo de Pesquisa da Islândia e da Universidade da Islândia Fundo de Investigação.

1. Transfecção O clone molecular está contida em dois plasmídeos, p8XSp5-EGFP e p67r, de 12 kb e 4,5 kb, respectivamente. 9,10 <ol><li> Corte quantidades equimolares dos dois plasmídeos, ou seja, 4,4 mg de p8XSp5-EGFP e 1,6 mcg de p67r com XbaI e ligar antes de transfecção. </li><li> Para a ligadura, use uma unidade de Weiss de ligase em uma reação de 50 ul e incubar a 16 ° C durante a noite. </li><li> Quando a ligadura é completada, incubar a mistura de ligadura a 65 ° C por 15 min para inativação da ligase. Este passo pode ser omitido. </li><li> Dois dias antes de semente de transfecção, 10 6 células SCP num frasco de cultura de tecidos T25, e cultivar células por dois dias em 5 ml DMEM + 10% de soro de carneiro e glutamina 2mM sem antibióticos para uma monocamada de 90% confluência. Se as células não tiverem alcançado 90% confluência depois de dois dias, deixar as células a crescer um dia adicional. </li></ol> Nota: O soro de cordeiro pode ser substituído por soro fetal bovino (FBS). Nós usam rotineiramente cordeiro soro, uma vez que algumas cepas de MVV são inibidas por FBS; esta estirpe MVV não é inibida por FBS, no entanto. <ol start="5"><li> Quando as células estão prontos para a transfecção, as alterações médio e DMEM com soro 1% (soro ou cordeiro FBS) sem antibióticos. Usamos Lipofectamin 2000 (Invitrogen) para transfecção. </li><li> Diluir o DNA em 500μl médio Opti-MEM. </li><li> Diluir 20μl Lipofectamin 2000 em 500μl médio Opti-MEM e deixe em temperatura ambiente (RT) por 5 min. </li><li> Após a incubação de 5 minutos, misture o DNA diluído com Lipofectamine diluída 2000 (volume total = mL 1000). Misture delicadamente e incubar por 20-30 min em temperatura ambiente. </li><li> Adicione a mistura de transfecção (1 ml) para o frasco contendo células T25 SCP e médias empresas (5 ml). Mix movimentando-se suavemente. </li><li> Incubar a 37 ° C e 5% CO 2 durante a noite (18-24 h). </li><li> Mudar o dia do meio a seguir para DMEM com soro 1%, 2mM de glutamina, penicilina e estreptomicina 100IU 100IU. </li><li> Monitorar a produção de GFP em células SCP por microscopia fluorescente invertido. Eficiência de transfecção baixo pode ser esperado com essas células primárias, geralmente 5-15%. </li><li> Incubar mais tempo, a 37 ° C, 5% CO 2 por vários dias para permitir a propagação do vírus no frasco. Ele normalmente leva 7-14 dias para a infecção por completo. </li><li> Recolher o vírus por alíquotas do sobrenadante em tubos Eppendorf. Girar em uma microcentrífuga a 3000 rpm por 5 min para remover restos celulares. Transferir o sobrenadante contendo o vírus para novos tubos. Armazenar a -80 ° C. </li></ol> 2. Titulação do vírus <ol><li> Semente de 3x10 4 células SCP em 100 mL meio DMEM suplementado com soro de 10%, a glutamina 2mM, penicilina e estreptomicina 100IU/ml 100IU/ml, por bem em uma placa de 96 poços. Incubar a 37 ° C, 5% CO 2. </li><li> Se as células são confluentes no dia seguinte, a mudança médio e DMEM com soro 1%, a glutamina 2mM, penicilina e estreptomicina 100IU/ml 100IU/ml, 100 l em cada poço. </li><li> Diluir o vírus da seguinte forma: <ol><li> Adicionar 180 mL DMEM com soro 1%, 2mM de glutamina, penicilina e estreptomicina 100IU/ml 100IU/ml por poço de 4 x 10 poços em um fundo de 96 poços redondos ou V-bottom prato. </li><li> Para diluições em série de dez vezes em quatro vias, adicionar 20 mL de vírus a cada um dos 4wells na primeira coluna da placa, e usando uma pipeta de quatro canais, pipeta cima e para baixo para garantir que as amostras sejam bem misturados. Trocar a ponteira e transferir 20 l para os próximos quatro poços e assim por diante. Deixe o passado sem poços de vírus para controle negativo. </li></ol></li><li> Adicione 100 ml das diluições do vírus às células SCP e médias empresas. </li><li> Incubar a 37 ° C e 5% CO 2. Observe para GFP fluorescência e efeitos citopáticos por duas semanas. Efeitos citopáticos são constituídas por células arredondadas e tornando-se menos transparentes do que as células normais com os processos que se estende para fora, terminando com as multinucleares aparecendo e morte celular. </li><li> Calcule vírus título (TCID50), utilizando o método Reed Muench 11. </li></ol> 3. FACS análise de células infectadas Nota: Para o monitoramento rápido de replicação do vírus, as células infectadas podem ser examinadas por citometria de fluxo. <ol><li> Trypsinize células infectadas (10 ca 5), lavar com PBS 1x e ressuspender em 500μl de PBS. </li><li> Adicionar 500 mL de solução de paraformaldeído 4% (2% de concentração final), incubar a RT por 30 min. </li><li> Células sedimento em uma microcentrífuga a 3000 rpm por 5 min. </li><li> Lavar com PBS 2x5 min e analisar em um analisador FACScan. Contagem de 10.000 eventos. </li></ol> 4. Resultados representativos: Este vírus devem ser totalmente infecciosas e replicar a um título de 10 junho - 10 julho TCID 50 ml /. Células infectadas são fluorescentes e pode ser detected por citometria de fluxo e microscopia de fluorescência. Tipicamente, GFP pode ser detectada em mais de 60% das células em cultura de células infectadas por citometria de fluxo (Fig. 1). Da mesma forma, quando visualizados por microscopia de fluorescência, a maioria das células são fluorescentes (Fig. 2A e B). <img src="/files/ftp_upload/3483/3483fig1.jpg" alt="Figura 1" /> Figura 1. FACScan análise de células infectadas com o SCP KV1772-EGFP vírus após 7 dias de infecção. <img src="/files/ftp_upload/3483/3483fig2.jpg" alt="Figura 2" /> Figura 2. Microscopia de contraste de fase de células infectadas com o SCP KV1772-EGFP após 7 dias de incubação (A). Mesmas células visualizadas por microscopia de fluorescência (B).

<ol>
	<li>Sigurdsson, B., Palsson, P. A., Grimsson, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visna,+a+demyelinating+transmissable+disease+of+sheep.">Visna, a demyelinating transmissable disease of sheep.</a> J. Neuropathol. Exp. Neurol. 14, 389-403 (1957).</li><li>Gorrell, M. D., Brandon, M. R., Sheffer, D., Adams, R. J., Narayan, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ovine+lentivirus+is+macrophagetropic+and+does+not+replicate+productively+in+T+lymphocytes.">Ovine lentivirus is macrophagetropic and does not replicate productively in T lymphocytes.</a> J. Virol. 66, 2679-2688 (1992).</li><li>Andresdottir, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biological+and+genetic+differences+between+lung-+and+brain-derived+isolates+of+maedi-visna+virus.">Biological and genetic differences between lung- and brain-derived isolates of maedi-visna virus.</a> Virus Genes. 16, 281-293 (1998).</li><li>Georgsson, G., Houwers, D. J., Palsson, P. A., Petursson, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression+of+viral+antigens+in+the+central+nervous+system+of+visna-infected+sheep:+an+immunohistochemical+study+on+experimental+visna+induced+by+virus+strains+of+increased+neurovirulence.">Expression of viral antigens in the central nervous system of visna-infected sheep: an immunohistochemical study on experimental visna induced by virus strains of increased neurovirulence.</a> Acta Neuropathol. 77, 299-306 (1989).</li><li>Turelli, P., Guiguen, F., Mornex, J. F., Vigne, R., Querat, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=dUTPase-minus+caprine+arthritis-encephalitis+virus+is+attenuated+for+pathogenesis+and+accumulates+G-to-A+substitutions.">dUTPase-minus caprine arthritis-encephalitis virus is attenuated for pathogenesis and accumulates G-to-A substitutions.</a> J. Virol. 71, 4522-4530 (1997).</li><li>Petursson, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visna+virus+dUTPase+is+dispensable+for+neuropathogenicity.">Visna virus dUTPase is dispensable for neuropathogenicity.</a> J. Virol. 72, 1657-1661 (1998).</li><li>Sigurdsson, B., Thormar, H., Palsson, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cultivation+of+visna+virus+in+tissue+culture.">Cultivation of visna virus in tissue culture.</a> Arch Gesamte Virusforsch. 10, 368-380 (1960).</li><li>Gudmundsdottir, H. S., Olafsdottir, K., Franzdottir, S. R., Andresdottir, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Construction+and+characterization+of+an+infectious+molecular+clone+of+maedi-visna+virus+that+expresses+green+fluorescent+protein.">Construction and characterization of an infectious molecular clone of maedi-visna virus that expresses green fluorescent protein.</a> J. Virol. Methods. 168, 98-102 (2010).</li><li>Andresson, O. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nucleotide+sequence+and+biological+properties+of+a+pathogenic+proviral+molecular+clone+of+neurovirulent+visna+virus.">Nucleotide sequence and biological properties of a pathogenic proviral molecular clone of neurovirulent visna virus.</a> Virology. 193, 89-105 (1993).</li><li>Skraban, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Naturally+occurring+mutations+within+39+amino+acids+in+the+envelope+glycoprotein+of+maedi-visna+virus+alter+the+neutralization+phenotype.">Naturally occurring mutations within 39 amino acids in the envelope glycoprotein of maedi-visna virus alter the neutralization phenotype.</a> J. Virol. 73, 8064-8072 (1999).</li><li>Reed, L. J., Muench, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+method+of+estimating+fifty+percent+endpoints.">A simple method of estimating fifty percent endpoints.</a> American Journal of Hygiene. 27, 493-497 (1938).</li><li>Berkowitz, R. D., Ilves, H., Plavec, I., Veres, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+transfer+systems+derived+from+Visna+virus:+analysis+of+virus+production+and+infectivity.">Gene transfer systems derived from Visna virus: analysis of virus production and infectivity.</a> Virology. 279, 116-129 (2001).</li></ol>

Não há conflitos de interesse declarados.

A GFP expressar clone molecular de MVV aqui apresentados deve ser útil para analisar as interações da célula hospedeira e patogenicidade do MVV tanto in vitro como in vivo. O vírus obtidos após 7-14 dias de replicação, sem dúvida, adquiriu algumas mutações devido à imprecisão da transcriptase reversa. No entanto, existem limitações para o uso deste clone como um vetor único ciclo. Uma delas é que o uso do clone é restrita a células de ovelhas e cabras de origem. A eficiência de transfecção destas c...

<table border="1"><tbody><tr><td> Nome do reagente </td><td> Companhia </td><td> Número de catálogo </td></tr><tr><td> DMEM </td><td> Gibco </td><td> 10938025 </td></tr><tr><td> Opti-MEM </td><td> Gibco </td><td> 51985018 </td></tr><tr><td> Lipofectamine 2000 </td><td> Invitrogen </td><td> 11668019 </td></tr></tbody></table>

propagating and detecting an infectious molecular clone of maedi-visna virus that expresses green fluorescent protein

Maedi-visna (MVV) é um lentivírus de ovelhas, fazendo com que lentamente progressiva pneumonia intersticial e encefalite 1. As células-alvo primário do MVV in vivo são consideradas das duas linhagem de monócitos. Determinadas estirpes de MVV pode replicar em outros tipos de células, no entanto 3,4. A proteína verde fluorescente é um marcador comumente usado para estudar lentivírus em células vivas. Temos inserido o gene EGFP no gene para dUTPase de MVV. O gene dUTPase está bem conservado em cepas mais lentivírus de ovinos e caprinos e tem se mostrado importante na replicação do CAEV 5. No entanto, dUTPase foi mostrado para ser dispensáveis ​​para a replicação do clone molecular de MVV utilizados neste estudo in vitro e in vivo 6. Replicação MVV é estritamente confinada às células de ovelhas ou cabras origem. Nós usamos uma linhagem de células primárias do plexo coróide de ovelhas (células SCP) para transfecção e propagação do vírus 7. O MVV fluorescentes é totalmente infecciosas e expressão EGFP é estável durante pelo menos seis passagens 8. Há boa correlação entre as medidas de TCID 50 e EGFP. Este vírus deve ser útil para a detecção rápida de células infectadas em estudos de tropismo celular e patogenicidade in vitro e in vivo 8.

Watch this Scientific Journal Video about Propagating and Detecting an Infectious Molecular Clone of Maedi-visna Virus that Expresses Green Fluorescent Protein at JoVE.com

Propagating and Detecting an Infectious Molecular Clone of Maedi-visna Virus that Expresses Green Fluorescent Protein

Nós descrevemos um clone molecular da Maedi-visna vírus que expressa a GFP e é totalmente infecciosas. Replicação deste vírus pode ser detectado por meio de microscopia de fluorescência e citometria de fluxo.

Propagação e detecção de um Clone Infecciosas Molecular da Maedi-visna vírus que expressa a proteína fluorescente verde

Maedi-visna virus (MVV) is a lentivirus of sheep, causing slowly progressive interstitial pneumonia and encephalitis1. The primary target cells of MVV in ...

propagating-detecting-an-infectious-molecular-clone-maedi-visna-virus

Universidad de Cartagena UDEC

Research

JoVE Journal

Immunology and Infection

9.8K visualizações.  University of Iceland. Nós descrevemos um clone molecular da Maedi-visna vírus que expressa a GFP e é totalmente infecciosas. Replicação deste vírus pode ser detectado por meio de microscopia de fluorescência e citometria de fluxo.

Vídeo: Propagating and Detecting an Infectious Molecular Clone of Maedi-visna Virus that Expresses Green Fluorescent Protein

Visualizing Cell-to-cell Transfer of HIV using Fluorescent Clones of HIV and Live Confocal Microscopy

By fusing the green fluorescent protein to their favorite proteins, biologists now have the ability to study living complex cellular processes using fluorescence video microscopy. To track the movements of the human immunodeficiency virus core protein during cell-to-cell transmission of human immunodeficiency virus, we have GFP-tagged the Gag protein in the context of an infectious molecular clone of HIV, called HIV Gag-iGFP. We study this viral clone using video confocal microscopy. In the following visualized experiment, we transfect a human T cell line with HIV Gag-iGFP, and we use fluorescently labeled uninfected CD4+ T cells to serve as target cells for the virus. Using the different fluorescent labels we can readily follow viral production and transport across intercellular structures called virological synapses. Simple gas permeable imaging chambers allow us to observe synapses with live confocal microscopy from minutes to days. These approaches can be used to track viral proteins as they move in from one cell to the next.

This visualized experiment is a guide for utilizing a fluorescent molecular clone of HIV for live confocal imaging experiments.

Visualizando transferência de células-célula de HIV usando Clones fluorescente de HIV e Microscopia Confocal ao vivo

By fusing the green fluorescent protein to their favorite proteins, biologists now have the ability to study living complex cellular processes using ...

Imunologia e Infecção

Specific Marking of HIV-1 Positive Cells using a Rev-dependent Lentiviral Vector Expressing the Green Fluorescent Protein

Most of HIV-responsive expression vectors are based on the HIV promoter, the long terminal repeat (LTR). While responsive to an early HIV protein, Tat, the LTR is also responsive to cellular activation states and to the local chromatin activity where the integration has occurred. This can result in high HIV-independent activity, and has restricted the usefulness of LTR-based reporter to mark HIV positive cells 1,2,3. Here, we constructed an expression lentiviral vector that possesses, in addition to the Tat-responsive LTR, numerous HIV DNA sequences that include the Rev-response element and HIV splicing sites 4,5,6. The vector was incorporated into a lentiviral reporter virus, permitting highly specific detection of replicating HIV in living cell populations. The activity of the vector was measured by expression of the green fluorescence protein (GFP). The application of this vector as reported here offers a novel alternative approach to existing methods, such as in situ PCR or HIV antigen staining, to identify HIV-positive cells. The vector can also express therapeutic genes for basic or clinical experimentation to target HIV-positive cells.

We have developed a lentiviral vector that possesses, in addition to the Tat-responsive LTR, the Rev-response element (RRE) that can regulate reporter gene expression in an HIV-1 Tat- and Rev-dependent fashion. The vector permits the specific detection of replicating HIV in living cells via the expression of GFP.

Marcação específica de HIV-1 células positivas utilizando um Vector Rev-dependente Lentivirus Expressando a Proteína Verde Fluorescente

Most of HIV-responsive expression vectors are based on the HIV promoter, the long terminal repeat (LTR). While responsive to an early HIV protein, Tat, ...

Viral Tracing of Genetically Defined Neural Circuitry

Classical methods for studying neuronal circuits are fairly low throughput. Transsynaptic viruses, particularly the pseudorabies (PRV) and rabies virus (RABV), and more recently vesicular stomatitis virus (VSV), for studying circuitry, is becoming increasingly popular. These higher throughput methods use viruses that transmit between neurons in either the anterograde or retrograde direction.
Recently, a modified RABV for monosynaptic retrograde tracing was developed. (Figure 1A). In this method, the glycoprotein (G) gene is deleted from the viral genome, and resupplied only in targeted neurons. Infection specificity is achieved by substituting a chimeric G, composed of the extracellular domain of the ASLV-A glycoprotein and the cytoplasmic domain of the RABV-G (A/RG), for the normal RABV-G1. This chimeric G specifically infects cells expressing the TVA receptor1. The gene encoding TVA can been delivered by various methods2-8. Following RABV-G infection of a TVA-expressing neuron, the RABV can transmit to other, synaptically connected neurons in a retrograde direction by nature of its own G which was co-delivered with the TVA receptor. This technique labels a relatively large number of inputs (5-10%)2 onto a defined cell type, providing a sampling of all of the inputs onto a defined starter cell type.
We recently modified this technique to use VSV as a transsynaptic tracer9. VSV has several advantages, including the rapidity of gene expression. Here we detail a new viral tracing system using VSV useful for probing microcircuitry with increased resolution. While the original published strategies by Wickersham et al.4 and Beier et al.9 permit labeling of any neurons that project onto initially-infected TVA-expressing-cells, here VSV was engineered to transmit only to TVA-expressing cells (Figure 1B). The virus is first pseudotyped with RABV-G to permit infection of neurons downstream of TVA-expressing neurons. After infecting this first population of cells, the virus released can only infect TVA-expressing cells. Because the transsynaptic viral spread is limited to TVA-expressing cells, presence of absence of connectivity from defined cell types can be explored with high resolution. An experimental flow chart of these experiments is shown in Figure 2. Here we show a model circuit, that of direction-selectivity in the mouse retina. We examine the connectivity of starburst amacrine cells (SACs) to retinal ganglion cells (RGCs).

A method of tracing synaptically connected neurons is described. We use TVA specificity of an upstream cell to probe whether a cell population of interest receives synaptic input from genetically defined cell types.

Rastreamento de viral geneticamente definido Neural dos circuitos

Classical methods for studying neuronal circuits are fairly low throughput. Transsynaptic viruses, particularly the pseudorabies (PRV) and rabies virus ...

Neurociência

Methodology for the Efficient Generation of Fluorescently Tagged Vaccinia Virus Proteins

Tagging of viral proteins with fluorescent proteins has proven an indispensable approach to furthering our understanding of virus-host interactions. Vaccinia virus (VACV), the live vaccine used in the eradication of smallpox, is particularly amenable to fluorescent live-cell microscopy owing to its large virion size and the ease with which it can be engineered at the genome level. We report here an optimized protocol for generating recombinant viruses. The minimal requirements for targeted homologous recombination during vaccinia replication were determined, which allows the simplification of construct generation. This enabled the alliance of transient dominant selection (TDS) with a fluorescent reporter and metabolic selection to provide a rapid and modular approach to fluorescently label viral proteins. By streamlining the generation of fluorescent recombinant viruses, we are able to facilitate downstream applications such as advanced imaging analysis of many aspects of the virus-host interplay that occurs during virus replication.

A rapid and modular protocol for the generation of recombinant vaccinia viruses expressing fluorescently&#160;tagged proteins simultaneously using the method of transient dominant selection is described here.

Metodologia para a Geração Eficiente de Proteínas do Vírus da Vaccinia marcadas fluorescentes

Tagging of viral proteins with fluorescent  proteins has proven an indispensable approach to furthering our understanding  of virus-host interactions. ...

Vaccinia Reporter Viruses for Quantifying Viral Function at All Stages of Gene Expression

Poxviruses are a family of double stranded DNA viruses that include active human pathogens such as monkeypox, molluscum contagiousum, and Contagalo virus. The family also includes the smallpox virus, Variola. Due to the complexity of poxvirus replication, many questions still remain regarding their gene expression strategy. In this article we describe the conceptualization and usage of recombinant vaccinia viruses that enable real-time measurement of single and multiple stages of viral gene expression in a high-throughput format. This is enabled through the use of spectrally distinct fluorescent proteins as reporters for each of three stages of viral replication. These viruses provide a high signal-to-noise ratio while retaining stage specific expression patterns, enabling plate-based assays and microscopic observations of virus propagation and replication. These tools have uses for antiviral discovery, studies of the virus-host interaction, and evolutionary biology.

We describe the usage of a fluorescent reporter vaccinia virus that enables real-time measurement of viral infectivity and gene expression through the stage-specific expression of spectrally distinct reporter fluorophores. We detail a plate-based method for accurately identifying the stage at which virus replication is affected in response to small molecule inhibition.

Repórter Vaccinia vírus para quantificar Função Viral em todas as fases da Expressão Gênica

Poxviruses are a family of double stranded DNA viruses that include active human pathogens such as monkeypox, molluscum contagiousum, and Contagalo virus. ...

Intracerebroventricular and Intravascular Injection of Viral Particles and Fluorescent Microbeads into the Neonatal Brain

In the study on the pathogenesis of viral encephalitis, the infection method is critical. The first of the two main infectious routes to the brain is the hematogenous route, which involves infection of the endothelial cells and pericytes of the brain. The second is the intracerebroventricular (ICV) route. Once within the central nervous system (CNS), viruses may spread to the subarachnoid space, meninges, and choroid plexus via the cerebrospinal fluid. In experimental models, the earliest stages of CNS viral distribution are not well characterized, and it is unclear whether only certain cells are initially infected. Here, we have analyzed the distribution of cytomegalovirus (CMV) particles during the acute phase of infection, termed primary viremia, following ICV or intravascular (IV) injection into the neonatal mouse brain. In the ICV injection model, 5 &#181;l of murine CMV (MCMV) or fluorescent microbeads were injected into the lateral ventricle at the midpoint between the ear and eye using a 10-&#181;l syringe with a 27 G needle. In the IV injection model, a 1-ml syringe with a 35 G needle was used. A transilluminator was used to visualize the superficial temporal (facial) vein of the neonatal mouse. We infused 50 &#181;l of MCMV or fluorescent microbeads into the superficial temporal vein. Brains were harvested at different time points post-injection. MCMV genomes were detected using the in situ hybridization method. Fluorescent microbeads or green fluorescent protein expressing recombinant MCMV particles were observed by fluorescent microscopy. These techniques can be applied to many other pathogens to investigate the pathogenesis of encephalitis.

Here, we describe a simple method of intracerebroventricular and intravascular injection of viral particles or fluorescent microbeads into the neonatal mouse brain. The localization pattern of the virus and nanoparticles could be detected by microscopic evaluation or by in situ hybridization.

Intracerebroventricular e intravascular A injeção de Viral partículas e fluorescentes microesferas no cérebro Neonatal

In the study on the pathogenesis of viral encephalitis, the infection method is critical. The first of the two main infectious routes to the brain is the ...

Monitoring of Ubiquitin-proteasome Activity in Living Cells Using a Degron (dgn)-destabilized Green Fluorescent Protein (GFP)-based Reporter Protein

Proteasome is the main intracellular organelle involved in the proteolytic degradation of abnormal, misfolded, damaged or oxidized proteins 1, 2. Maintenance of proteasome activity was implicated in many key cellular processes, like cell's stress response 3, cell cycle regulation and cellular differentiation 4 or in immune system response 5. The dysfunction of the ubiquitin-proteasome system has been related to the development of tumors and neurodegenerative diseases 4, 6. Additionally, a decrease in proteasome activity was found as a feature of cellular senescence and organismal aging 7, 8, 9, 10. Here, we present a method to measure ubiquitin-proteasome activity in living cells using a GFP-dgn fusion protein. To be able to monitor ubiquitin-proteasome activity in living primary cells, complementary DNA constructs coding for a green fluorescent protein (GFP)&#x2013;dgn fusion protein (GFP&#x2013;dgn, unstable) and a variant carrying a frameshift mutation (GFP&#x2013;dgnFS, stable 11) are inserted in lentiviral expression vectors. We prefer this technique over traditional transfection techniques because it guarantees a very high transfection efficiency independent of the cell type or the age of the donor. The difference between fluorescence displayed by the GFP&#x2013;dgnFS (stable) protein and the destabilized protein (GFP-dgn) in the absence or presence of proteasome inhibitor can be used to estimate ubiquitin-proteasome activity in each particular cell strain. These differences can be monitored by epifluorescence microscopy or can be measured by flow cytometry.

Monitoring of Ubiquitin-proteasome Activity in Living Cells Using a Degron dgn-destabilized Green Fluorescent Protein GFP-based Reporter Protein

A method to monitor ubiquitin-proteasome activity in living cells is described. A degron-destabilized GFP- (GFP-dgn) and a stable GFP-dgnFS fusion protein are generated and transduced into the cell using a lentiviral expression vector. This technique allows to generate a stable GFP-dgn/GFP-dgnFS expressing cell line in which ubiquitin-proteasome activity can be easily assessed using epifluorescence or flow cytometry.

Monitoramento da ubiquitina-proteassoma Atividade em células vivas Usando um Degron (dgn) desestabilizado Green Fluorescent Protein Protein Repórter (GFP) com base em

Proteasome is the main intracellular organelle involved in the proteolytic degradation of abnormal, misfolded, damaged or oxidized proteins 1, 2. ...

Biologia

Live Imaging and Quantification of Viral Infection in K18 hACE2 Transgenic Mice Using Reporter-Expressing Recombinant SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic has been caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To date, SARS-CoV-2 has been responsible for over 242 million infections and more than 4.9 million deaths worldwide. Similar to other viruses, studying SARS-CoV-2 requires the use of experimental methods to detect the presence of virus in infected cells and/or in animal models. To overcome this limitation, we generated replication-competent recombinant (r)SARS-CoV-2 that expresses bioluminescent (nanoluciferase, Nluc) or fluorescent (Venus) proteins. These reporter-expressing rSARS-CoV-2 allow tracking viral infections in vitro and in vivo based on the expression of Nluc and Venus reporter genes. Here the study describes the use of rSARS-CoV-2/Nluc and rSARS-CoV-2/Venus to detect and track SARS-CoV-2 infection in the previously described K18 human angiotensin-converting enzyme 2 (hACE2) transgenic mouse model of infection using in vivo imaging systems (IVIS). This rSARS-CoV-2/Nluc and rSARS-CoV-2/Venus show rSARS-CoV-2/WT-like pathogenicity and viral replication in vivo. Importantly, Nluc and Venus expression allow us to directly track viral infections in vivo and ex vivo, in infected mice. These rSARS-CoV-2/Nluc and rSARS-CoV-2/Venus represent an excellent option to study the biology of SARS-CoV-2 in vivo, to understand viral infection and associated COVID-19 disease, and to identify effective prophylactic and/or therapeutic treatments to combat SARS-CoV-2 infection.

This protocol describes the dynamics of viral infections using luciferase- and fluorescence-expressing recombinant (r)SARS-CoV-2 and an in vivo imaging systems (IVIS) in K18 hACE2 transgenic mice to overcome the need of secondary approaches required to study SARS-CoV-2 infections in vivo.

Imagem ao vivo e quantificação da infecção viral em K18 hACE2 Camundongos transgênicos usando o recombinante SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic has been caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To date, SARS-CoV-2 has ...

Green Fluorescent Protein-based Expression Screening of Membrane Proteins in Escherichia coli

The production of recombinant membrane proteins for structural and functional studies remains technically challenging due to low levels of expression and the inherent instability of many membrane proteins once solubilized in detergents. A protocol is described that combines ligation independent cloning of membrane proteins as GFP fusions with expression in Escherichia coli detected by GFP fluorescence. This enables the construction and expression screening of multiple membrane protein/variants to identify candidates suitable for further investment of time and effort. The GFP reporter is used in a primary screen of expression by visualizing GFP fluorescence following SDS polyacrylamide gel electrophoresis (SDS-PAGE). Membrane proteins that show both a high expression level with minimum degradation as indicated by the absence of free GFP, are selected for a secondary screen. These constructs are scaled and a total membrane fraction prepared and solubilized in four different detergents. Following ultracentrifugation to remove detergent-insoluble material, lysates are analyzed by fluorescence detection size exclusion chromatography (FSEC). Monitoring the size exclusion profile by GFP fluorescence provides information about the mono-dispersity and integrity of the membrane proteins in different detergents. Protein: detergent combinations that elute with a symmetrical peak with little or no free GFP and minimum aggregation are candidates for subsequent purification. Using the above methodology, the heterologous expression in E. coli of SED (shape, elongation, division, and sporulation) proteins from 47 different species of bacteria was analyzed. These proteins typically have ten transmembrane domains and are essential for cell division. The results show that the production of the SEDs orthologues in E. coli was highly variable with respect to the expression levels and integrity of the GFP fusion proteins. The experiment identified a subset for further investigation.

Green Fluorescent Protein-based Expression Screening of Membrane Proteins in Escherichia coli

A streamlined approach to screening for the expression of recombinant membrane proteins in Escherichia coli based on fusion to green fluorescent protein is presented.

Verde Fluorescente à base de proteínas Expressão Rastreio de Proteínas de Membrana em<em&gt; Escherichia coli</em

The production of recombinant membrane proteins for structural and functional studies remains technically challenging due to low levels of expression and ...

Molecular Cloning

Molecular cloning is a set of methods, which are used to insert recombinant DNA into a vector - a carrier of DNA molecules that will replicate recombinant DNA fragments in host organisms. The DNA fragment, which may be a gene, can be isolated from a prokaryotic or eukaryotic specimen. Following isolation of the fragment of interest, or insert, both the vector and insert must be cut with restriction enzymes and purified. The purified pieces are joined together though a technique called ligation. The enzyme that catalyzes the ligation reaction is known as ligase.
This video explains the major methods that are combined, in tandem, to comprise the overall molecular cloning procedure. Critical aspects of molecular cloning are discussed, such as the need for molecular cloning strategy and how to keep track of transformed bacterial colonies. Verification steps, such as checking purified plasmid for the presence of insert with restrictions digests and sequencing are also mentioned.

Molecular Cloning: Principle, Procedure, and Applications

Clonagem Molecular

Molecular cloning is a set of methods, which are used to insert recombinant DNA into a vector - a carrier of DNA molecules that will replicate recombinant ...