Gli autori apprezzano i contributi di Greg Smith, Lisa Pomeranz, Matt Lyman, Marlies Eldridge, Halina Staniszewska Goraczniak, e membri del laboratorio Enquist nel perfezionare questo protocollo.

1. Primo Giorno: Infezione virale e preparazione del buffer <ol><li> Preparare piatti 50-10 (15 cm di diametro) di cellule di coltura per le infezioni, ad esempio, PK-15 cellule per virus pseudorabbia (PRV) o cellule Vero per l&#39;herpes simplex virus (HSV). </li><li> Quando le cellule sono 95 - confluenti al 100%, li infettano a (MOI) di 5-10. Per fare questo, inoculare ciascuna piastra con magazzino virus in un volume totale di 4 ml per piastra, incubare le piastre per 1 ora a 37 ° C. Placche di roccia dolcemente ogni 15 minuti per assicurarsi che il monostrato cellulare rimane completamente rivestito con l&#39;inoculo del virus. Nel frattempo, scaldare la media per il prossimo passo. </li><li> Dopo un&#39;ora di infezione, aspirare l&#39;inoculo virale dai piatti, aggiungere 15 ml di terreno caldo, e incubare a 37 ° C per 12-20 ore in un incubatore umidificato. </li><li> Preparare buffer LCM (vedi tabella 1) e rock notte a 4 ° C per omogeneizzazione della miscela. Preparare TNE per la risospensione del DNA virale (vedi Tabella 2). </li></ol> 2. Secondo giorno, Fase 1: la lisi cellulare e ultracentrifugazione <ol><li> Verificare visivamente che l&#39;infezione di cellule ha causato uniforme effetto citopatico (CPE). Consentire l&#39;infezione al progresso finché tutte le cellule hanno arrotondato per eccesso, ma non hanno sollevato il piatto. </li><li> Raschiare le cellule infettate nel mezzo, e combinano le cellule e mezzo in 50 ml provette coniche. Il numero di tubi conici necessarie per questo passo dipenderà dal numero di piatti usati per l&#39;infezione nella fase 1.2, ad esempio, un tubo da 50 ml può essere utilizzato per far sedimentare un massimo di 3 piatti a base di 15 ml di mezzo di ogni opzione:. Sciacquare il piastre con 10 ml di PBS e si combinano con le cellule e medie imprese. </li><li> Cellule centrifuga e medie per 10 minuti a 2000 centifugal forza relativa (RCF) a temperatura ambiente, poi aspirare il surnatante e risospendere ogni pellet in 10 ml di PBS. Se il pellet da una infezione virale è stata diffusa in più tubi conici al punto 2.2, questi possono essere ricombinati in un tubo conico in questa fase. Ripetere centrifugazione e aspirazione. Optional: Questo pellet possono essere conservati a -20 ° C e il protocollo ha continuato in un secondo momento. </li></ol> 3. Secondo giorno, Fase 2: ultracentrifugazione Tenere il pellet di cellule e buffer LCM sul ghiaccio, quando possibile durante le fasi seguenti. <ol><li> Aggiungi β-mercaptoetanolo allo 0% glicerolo - buffer LCM. Iniziare il raffreddamento del ultracentrifuga (per il passo 3.9) impostandolo a 4 ° C e accendere il vuoto. </li><li> Risospendere il pellet in 5 ml di glicerolo 0% - buffer LCM fino a quando non è più disomogeneo. Se necessario, il tubo vortex per rompere ogni cellula indisciolto pellet. </li><li> Estrarre con l&#39;aggiunta di 1,5 ml di Freon (1,1,2-tricloro-1 ,2,2-trifluoroetano) e vortex vigorosamente. Immediatamente centrifugare per 10 minuti a 2000 rcf ad una temperatura di 4 ° C. Raccogliere lo strato superiore con un ampio tunnel puntale (evitando l&#39;interfaccia) e il trasferimento in una nuova provetta. Facoltativo: Se il pellet è un solido gelatinoso, si può rapidamente versare lo strato superiore in un nuovo tubo. </li><li> Ripetere l&#39;estrazione Freon e centrifugare di nuovo. </li><li> Raccogliere lo strato superiore (~ 5 ml) e il trasferimento in una nuova provetta ultracentrifuga polyallomer. Aggiungi β-mercaptoetanolo per i restanti due glicerolo - buffer LCM. </li><li> Preparazione di un gradiente nella provetta da centrifuga polyallomer dal sottostante l&#39;estratto Freon (strato superiore) con 3 ml di glicerolo al 5% - LCM (strato intermedio), sottostante e poi di nuovo con 2,5 ml di 45% glicerolo - LCM (strato inferiore). Utilizzare una pipetta sottile per evitare di overflow del contenuto della provetta. </li><li> Se necessario, preparare un tubo equivalente bilancia con le stesse proporzioni di buffer LCM. </li><li> Trasferimento tubi in secchi ultracentrifuga. Equilibrio secchi di 0,1 g di ogni altro, da dolci aggiungendo ulteriore glicerolo 0% - buffer LCM al livello superiore (~ 50-100 microlitri alla volta). </li><li> Utilizzando un ultracentrifuga freddo con un rotore orizzontale o oscillare, ruotare i campioni equilibrato per 1 ora a 77000 rcf (ad esempio 25.000 rpm per un rotore SW41Ti) ad una temperatura di 4 ° C. </li><li> Durante ultracentrifugazione, fare un gancio di vetro per catturare DNA galleggiante nel passaggio precipitazione in etanolo (4.6). Tenere entrambe le estremità di una pipetta Pasteur in vetro e sospendere la sezione centrale a fuoco. Quando una sezione del vetro è quasi fuso, tirare delicatamente per allungare il vetro, piegare delicatamente per creare un gancio ben angolato (&lt;90 gradi), e tirare bruscamente a sbarrare la strada alla fine. Se la punta del gancio vetro è aperto, tenere la punta sulla fiamma in modo che il vetro fonde a sufficienza per chiuderla. </li><li> Dopo l&#39;ultracentrifugazione, si dovrebbe vedere un sottile opaca pellet con una macchia scura al centro. Con attenzione aspirare il liquido dal tubo, tra cui colature lungo i lati, ma evitando il pellet sul fondo della provetta. </li><li> Aggiungere 0,5 ml di TNE a temperatura ambiente. </li><li> Lasciate che i pellet riposare per almeno 10 minuti per permettere l&#39;idratazione del pellet. Optional: Il pellet può anche risospendere in TNE durante la notte, se conservato a 4 ° C. </li></ol> 4. Terzo Giorno: &quot;Ghost&quot; Precipitazione del DNA <ol><li> Spezzare il pellet pipettando con un piccolo foro puntale (ad esempio una punta p200 pipetta). Non preoccupatevi di taglio in questa fase, perché il DNA virale è ancora contenuto in capsidi a questo punto. Aggiungere i seguenti reagenti per il tubo contenente il virale a pellet, a temperatura ambiente, di distruggere capsidi: <ul><li> 4,25 ml TNE </li><li> 0,25 ml 10% SDS </li><li> 2 mg proteinasi K </li></ul> Agitare delicatamente per miscelare questi reagenti. Ci dovrebbe essere un leggero aumento della viscosità. </li></ol> Attenzione taglio da qui in poi, ad esempio l&#39;uso di grosso calibro pipette e non vortice del materiale virale <ol start="2"><li> Estratto di proteine ​​virali con l&#39;aggiunta di 5 ml di fenolo-cloroformio e iniziare immediatamente invertendo o vortex per mantenere una emulsione. Mescolare per 10 secondi, quindi l&#39;emulsione centrifuga per 5 minuti a 2000 rcf a temperatura ambiente. Raccogliere il strato superiore con un ampio tunnel punta della pipetta, evitando l&#39;interfaccia, e il trasferimento in una nuova provetta. Optional: Usa ad aggancio di fase gel (PLG), tubi in questa fase per evitare la contaminazione con l&#39;interfaccia. </li><li> Ripetere l&#39;estrazione fenolo-cloroformio e centrifugare di nuovo. </li><li> Dopo la seconda estrazione fenolo-cloroformio, raccogliere lo strato superiore in una provetta di vetro da 30 ml Corex e freddo il tubo a -20 ° C per 10-15 minuti, avendo cura che non congelare. </li><li> Aggiungere 10 ml di etanolo ghiacciato, coprire il tubo (ad esempio allungando un pezzo di Parafilm M sopra le righe), e miscelare immediatamente. Guardare per un DNA &quot;fantasma&quot; a comparire, che consiste in un precipitato ropy sottile. Capovolgere la provetta delicatamente per mescolare ulteriormente e provocare il DNA appiccicoso precipitati di raggruppare insieme. </li><li> Utilizzare un gancio di vetro per catturare il fantasma del DNA (s). Con attenzione macchia il DNA per eliminare il liquido in eccesso, quindi inserire il gancio (punta verso il basso) in una provetta da 1,5 ml e lasciare asciugare. Aggiungi 0,25-0,5 ml di TE per sciogliere il fantasma del DNA. Lasciare risospensione del DNA per procedere per almeno un&#39;ora. DNA conservare a 4 ° C. Facoltativo: per massimizzare la resa del DNA, rompere il gancio di vetro nella provetta da 1,5 ml, in modo che la risospensione fuori i frammenti di vetro possa continuare nel tempo. </li></ol> 5. Rappresentante Risultati Con un sufficientemente elevato MOI, le cellule devono raggiungere la piena CPE entro ~ 18 ore dopo l&#39;infezione (HPI) per i ceppi wild-type PRV, e ~ 24 HPI di wild-type ceppi di HSV-1 (Figura 1). Una volta infettato il pellet cellulare viene raccolta, i passaggi rimanenti protocollo può essere completa in un solo giorno o svolte nell&#39;arco di due giorni (Figura 2). Quando si prepara ganci di vetro per catturare il fantasma del DNA, è importante per rendere l&#39;angolo gancio essere inferiore a 90 gradi, in modo che poi si può andare bene nella base di un tubo da 1,5 ml (Figura 3). Sigillando la punta di questo gancio previene la perdita di DNA all&#39;interno della pipetta. Fantasmi del DNA si formano durante la fase di precipitazione e appariranno come bianco, fili filante (Figura 4). Questi aggregati e bastone tra loro e / o il gancio di vetro utilizzato per catturare il DNA. Così il gancio stesso bicchiere può essere usato per raccogliere più thread di DNA all&#39;interno della soluzione di precipitazione. <table border="1"><tbody><tr><td> Scegli colonna in base al volume desiderato: </td><td> 10 ml </td><td> 15 ml </td><td> 20 ml </td><td> 40 ml </td></tr><tr><td> 1M KCL </td><td> 1,3 ml </td><td> 1,9 ml </td><td> 2,5 ml </td><td> 5 ml </td></tr><tr><td> 1M Tris (pH 7,4) </td><td> 300 ul </td><td> 450 microlitri </td><td> 600 microlitri </td><td> 1,2 ml </td></tr><tr><td> 1M MgCl 2 </td><td> 50 microlitri </td><td> 75 microlitri </td><td> 100 ul </td><td> 200 l </td></tr><tr><td> 0,5 EDTA </td><td> 10 microlitri </td><td> 15 microlitri </td><td> 20 l </td><td> 40 microlitri </td></tr><tr><td> NP40/IGEPAL </td><td> 50 microlitri </td><td> 75 microlitri </td><td> 100 ul </td><td> 200 l </td></tr><tr><td> β-mercaptoetanolo (aggiungere immediatamente prima dell&#39;uso) </td><td> 4,3 microlitri </td><td> 6,5 microlitri </td><td> 8,6 microlitri </td><td> 17,2 microlitri </td></tr><tr><td colspan="5"></td></tr><tr><td colspan="5"> Utilizzare le proporzioni per cento glicerolo desiderato (0, 5 o 45%) </td></tr><tr><td> 0% glicerolo </td><td> Nessuno </td><td> Nessuno </td><td> Nessuno </td><td> Nessuno </td></tr><tr><td> acqua </td><td> 8,3 ml </td><td> 12,5 ml </td><td> 16,7 ml </td><td> 33,4 ml </td></tr><tr><td> 5% di glicerolo </td><td> 0,5 ml </td><td> 0,8 ml </td><td> 1,0 ml </td><td> 2,0 ml </td></tr><tr><td> acqua </td><td> 7,8 ml </td><td> 11,7 ml </td><td> 15,7 ml </td><td> 31,4 ml </td></tr><tr><td> 45% glycerol </td><td> 4,5 ml </td><td> 6,8 ml </td><td> 9,0 ml </td><td> 18,0 ml </td></tr><tr><td> acqua </td><td> 3,8 ml </td><td> 5,7 ml </td><td> 7,7 ml </td><td> 15,4 ml </td></tr></tbody></table> Tabella 1. Ricette per la preparazione di tamponi LCM <table border="1"><tbody><tr><td> Per 50 ml </td></tr><tr><td> 5 ml 1M NaCl </td></tr><tr><td> 2,5 ml 1M Tris, pH 7,5 </td></tr><tr><td> 1 ml di EDTA 0,5 </td></tr><tr><td> 41,5 ml di H 2 O </td></tr></tbody></table> Tabella 2. Preparazione di TNE (0,1 M di NaCl, 50 mM Tris, pH 7,5, 10 mM EDTA) <table border="1"><tbody><tr><td> Per 1 volume L </td></tr><tr><td> 0,2 g KCl </td></tr><tr><td> 0,2 g di KH 2 PO 4 </td></tr><tr><td> 8 g di NaCl </td></tr><tr><td> 1.15g Na 2 HPO 4 </td></tr><tr><td> H 2 O per 1L </td></tr></tbody></table> Tabella 3. Preparazione del PBS (2,7 mM KCl, 1.5 mM KH 2 PO 4; 137 mm NaCl; 8,1 mM Na 2 HPO 4, pH 7,0) <img alt="Figura 1" src="/files/ftp_upload/3151/3151fig1.jpg" /> Figura 1. PK15 cellule (A) prima infezione, (B) a metà strada attraverso l&#39;infezione, e (C) a effetto citopatico (CPE), dopo una molteplicità di infezione. <img alt="Figura 2" src="/files/ftp_upload/3151/3151fig2.jpg" /> Figura 2. Panoramica del protocollo. <img alt="Figura 3" src="/files/ftp_upload/3151/3151fig3.jpg" /> Figura 3. Tre esempi rappresentativi di vetro ami utilizzati per raccogliere i fantasmi del DNA virale. <img alt="Figura 4" src="/files/ftp_upload/3151/3151fig4.jpg" /> Figura 4. Esempio rappresentativo di una ben formata e abbondante DNA &quot;fantasma&quot;.

<ol>
	<li>Szpara, M. L., Parsons, L., Enquist, L. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sequence+variability+in+clinical+and+laboratory+isolates+of+herpes+simplex+virus+1+reveals+new+mutations.">Sequence variability in clinical and laboratory isolates of herpes simplex virus 1 reveals new mutations.</a> J Virol. 84, 5303-5313 (2010).</li><li>Banfield, B. W., Kaufman, J. D., Randall, J. A., Pickard, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+pseudorabies+virus+strains+expressing+red+fluorescent+proteins:+new+tools+for+multisynaptic+labeling+applications.">Development of pseudorabies virus strains expressing red fluorescent proteins: new tools for multisynaptic labeling applications.</a> J Virol. 77, 10106-10112 (2003).</li><li>Kobiler, O., Lipman, Y., Therkelsen, K., Daubechies, I., Enquist, L. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Herpesviruses+carrying+a+Brainbow+cassette+reveal+replication+and+expression+of+limited+numbers+of+incoming+genomes.">Herpesviruses carrying a Brainbow cassette reveal replication and expression of limited numbers of incoming genomes.</a> Nat Commun. 1, 146-146 (2010).</li><li>Enquist, L. W., Madden, M. J., Schiop-Stanley, P., Vande Woude, G. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cloning+of+herpes+simplex+type+1+DNA+fragments+in+a+bacteriophage+lambda+vector.">Cloning of herpes simplex type 1 DNA fragments in a bacteriophage lambda vector.</a> Science. 203, 541-544 (1979).</li><li>Smith, G. A., Enquist, L. W. <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+transposon+mutagenesis+in+Escherichia+coli+of+a+full-length+infectious+clone+of+pseudorabies+virus,+an+alphaherpesvirus.">Construction and transposon mutagenesis in Escherichia coli of a full-length infectious clone of pseudorabies virus, an alphaherpesvirus.</a> J Virol. 73, 6405-6414 (1999).</li><li>Flint, S. J., Enquist, L. W., Racaniello, V. R., Skalka, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Principles of virology. , (2008).</li><li>Pomeranz, L. E., Reynolds, A. E., Hengartner, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+biology+of+pseudorabies+virus:+impact+on+neurovirology+and+veterinary+medicine.">Molecular biology of pseudorabies virus: impact on neurovirology and veterinary medicine.</a> Microbiol Mol Biol Rev. 69, 462-500 (2005).</li><li>Roizman, B., Pellett, P. E., Knipe, D. M., Howley, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Fields Virology. , 2381-2397 (2001).</li><li>Mendez, I. I., Hermann, L. L., Hazelton, P. R., Coombs, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+comparative+analysis+of+freon+substitutes+in+the+purification+of+reovirus+and+calicivirus.">A comparative analysis of freon substitutes in the purification of reovirus and calicivirus.</a> J Virol Methods. 90, 59-67 (2000).</li><li>Gharabaghi, F., Aymard, M., Trotemann, P., Gerdil, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rapid+and+simplified+micromethod+for+subtyping+varicella-zoster+virus.">A rapid and simplified micromethod for subtyping varicella-zoster virus.</a> J Med Virol. 31, 129-134 (1990).</li><li>Granstedt, A. E., Szpara, M. L., Kuhn, B., Wang, S. S., Enquist, L. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence-based+monitoring+of+in+vivo+neural+activity+using+a+circuit-tracing+pseudorabies+virus.">Fluorescence-based monitoring of in vivo neural activity using a circuit-tracing pseudorabies virus.</a> PLoS One. 4, e6923-e6923 (2009).</li></ol>

Nessun conflitto di interessi dichiarati.

Parti di questo protocollo sono stati originariamente sviluppati per l&#39;isolamento del DNA virale nel BSL4 condizioni, ma si adatta altrettanto bene a non BSL condizioni. 4 Si comunemente utilizzano questo protocollo per isolare il DNA dalla alfa-herpesvirus PRV e HSV-1, che hanno genomi di DNA racchiuso in una capside proteica e circondato da un involucro lipidico. 7,8 Tuttavia è probabile direttamente adattabile ad altri virus a DNA di grandi dimensioni, tra cui beta-e gamma-herpes virus e gl...

<table border="1"><tbody><tr><td> Nome del reagente </td><td> Azienda </td><td> Numero di catalogo </td><td> Commenti </td></tr><tr><td> Freon (1,1,2-tricloro-1 ,2,2-trifluoroetano) </td><td> Pescatore </td><td> T178-4 </td><td> Chiedi al tuo istituto per le linee guida sullo smaltimento appropriato dei rifiuti contenenti freon, o vedere Mendez et al. alternative Freon potenziale 9. </td></tr><tr><td> Fase di bloccaggio tubi di gel, Heavy capacità di 15 ml </td><td> 5 PRIME </td><td> 2302850 </td><td> Opzionale </td></tr><tr><td> Polyallomer ultracentrifuga tubi </td><td> Beckman * </td><td> 331372 * </td><td> * Tubi Seleziona appropriato per il proprio ultracentrifuga; questi sono inclusi come esempio solo </td></tr><tr><td> NP-40 / IGEPAL </td><td> Sigma </td><td> I-3021 </td><td></td></tr><tr><td> PK-15 cellule </td><td> ATCC </td><td> CCL-33 </td><td></td></tr><tr><td> Cellule Vero </td><td> ATCC </td><td> CCL-81 </td><td></td></tr><tr><td> PBS </td><td> Hyclone </td><td> SH30028.03 </td><td></td></tr></tbody></table>

preparation of viral dna from nucleocapsids

I virus sono parassiti obbligati cellulare, e quindi lo studio del loro DNA virale richiede materiale isolante lontano da agenti inquinanti e del DNA della cellula ospite. Diverse applicazioni a valle richiedono grandi quantità di puro DNA virale, che viene fornito da questo protocollo. Queste applicazioni includono il sequenziamento del genoma virale, in cui la rimozione del DNA ospite è fondamentale per ottimizzare l&#39;output dei dati per le sequenze virali, e la produzione di nuovi ceppi virali ricombinanti, in cui la co-trasfezione del plasmide purificato e lineare facilita la ricombinazione del DNA virale. 1,2, 3 Questa procedura utilizza una combinazione di estrazioni e la densità a base di centrifugazione per isolare il DNA purificato lineare herpesvirus nucleocapside dalle cellule infette. 4,5 Le fasi iniziali di purificazione scopo di isolare purificata capsidi virale, che contengono e proteggono il DNA virale durante le estrazioni e le fasi di centrifugazione che rimuovono le proteine ​​cellulari e il DNA. Lisi delle nucleocapsidi quindi rilascia DNA virale, e due finali fenolo-cloroformio passi rimuovere le proteine ​​rimanenti. Il DNA finale catturato da una soluzione è altamente concentrato e puro, con un valore medio di 1,90 260/280. A seconda della quantità di cellule infette utilizzati, i rendimenti della gamma DNA virale 150-800 mg o più. La purezza di questo DNA rende stabile durante conservazione a lungo termine a 4C. Questo DNA è quindi ideale per high-throughput sequencing, l&#39;alta fedeltà reazioni di PCR, e trasfezioni. Prima di iniziare la procedura, è importante conoscere il numero medio di cellule per piatto (ad esempio una media di 8 x 10 6 PK-15 cellule in un piatto confluenti 15 cm), e il titolo dello stock virale da utilizzare ( ad esempio, 1 x 10 8 unità formanti placca per ml). Queste sono necessarie per calcolare la molteplicità appropriata di infezione (MOI) per il protocollo. 6 Per esempio, per infettare piatto da 15 cm di PK-15 celle con il brodo sopra virale, ad una MOI di 5, si usa 400 ml di magazzino virale e diluire con 3,6 ml di terreno (volume inoculazione totale di 4 ml per piastra da 15 cm). Molteplici preparazioni di DNA virale può essere preparato allo stesso tempo. Il numero di preparati simultanea è limitata solo dal numero di tubi detenuta dal rotore ultracentrifuga (uno per ogni virus; vedi punto 3.9). Qui si descrive la procedura come se venisse fatto per un virus.

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Preparation of Viral DNA from Nucleocapsids

Noi descriviamo il processo di isolamento del DNA ad alta herpesvirus nucleocapside purezza dalle cellule infette. Il DNA finale catturato dalla soluzione è di alta concentrazione e purezza, rendendolo ideale per high-throughput sequencing, l&#39;alta fedeltà reazioni di PCR, e trasfezioni per produrre nuovi ricombinanti virali.

Estrazione di DNA virale da nucleocapsidi

Viruses are obligate cellular parasites, and thus the study of their DNA requires isolating viral material away from host cell contaminants and DNA. ...

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20.8K Views.  Princeton University. Noi descriviamo il processo di isolamento del DNA ad alta herpesvirus nucleocapside purezza dalle cellule infette. Il DNA finale catturato dalla soluzione è di alta concentrazione e purezza, rendendolo ideale per high-throughput sequencing, l'alta fedeltà reazioni di PCR, e trasfezioni per produrre nuovi ricombinanti virali.

Video: Preparation of Viral DNA from Nucleocapsids

Generation of Recombinant Influenza Virus from Plasmid DNA

Efforts by a number of influenza research groups have been pivotal in the development and improvement of influenza A virus reverse genetics. Originally established in 1999 1,2 plasmid-based reverse genetic techniques to generate recombinant viruses have revolutionized the influenza research field because specific questions have been answered by genetically engineered, infectious, recombinant influenza viruses. Such studies include virus replication, function of viral proteins, the contribution of specific mutations in viral proteins in viral replication and/or pathogenesis and, also, viral vectors using recombinant influenza viruses expressing foreign proteins 3.

Rescue of influenza A viruses from plasmid DNA is a basic and essential experimental technique that allows influenza researchers to generate recombinant viruses to study multiple aspects in the biology of influenza virus, and to be used as potential vectors or vaccines.

Generazione di influenza da virus ricombinante del DNA plasmidi

Efforts by a number of influenza research groups have been pivotal in the development and improvement of influenza A virus reverse genetics. Originally ...

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Immunologia e infezioni

Using a Pan-Viral Microarray Assay (Virochip) to Screen Clinical Samples for Viral Pathogens

The diagnosis of viral causes of many infectious diseases is difficult due to the inherent sequence diversity of viruses as well as the ongoing emergence of novel viral pathogens, such as SARS coronavirus and 2009 pandemic H1N1 influenza virus, that are not detectable by traditional methods. To address these challenges, we have previously developed and validated a pan-viral microarray platform called the Virochip with the capacity to detect all known viruses as well as novel variants on the basis of conserved sequence homology1. Using the Virochip, we have identified the full spectrum of viruses associated with respiratory infections, including cases of unexplained critical illness in hospitalized patients, with a sensitivity equivalent to or superior to conventional clinical testing2-5. The Virochip has also been used to identify novel viruses, including the SARS coronavirus6,7, a novel rhinovirus clade5, XMRV (a retrovirus linked to prostate cancer)8, avian bornavirus (the cause of a wasting disease in parrots)9, and a novel cardiovirus in children with respiratory and diarrheal illness10. The current version of the Virochip has been ported to an Agilent microarray platform and consists of ~36,000 probes derived from over ~1,500 viruses in GenBank as of December of 2009. Here we demonstrate the steps involved in processing a Virochip assay from start to finish (~24 hour turnaround time), including sample nucleic acid extraction, PCR amplification using random primers, fluorescent dye incorporation, and microarray hybridization, scanning, and analysis.

Using a Pan-Viral Microarray Assay Virochip to Screen Clinical Samples for Viral Pathogens

The Virochip is a pan-viral microarray designed to simultaneously detect all known viruses as well as novel viruses on the basis of conserved sequence homology. Here we demonstrate how to run a Virochip assay to analyze clinical samples for the presence of both known and unknown viruses.

Utilizzando un pan-virale Assay Microarray (Virochip) allo schermo campioni clinici di patogeni virali

The diagnosis of viral causes of many infectious diseases is difficult due to the inherent sequence diversity of viruses as well as the ongoing emergence ...

Isolation of Fidelity Variants of RNA Viruses and Characterization of Virus Mutation Frequency

RNA viruses use RNA dependent RNA polymerases to replicate their genomes. The intrinsically high error rate of these enzymes is a large contributor to the generation of extreme population diversity that facilitates virus adaptation and evolution. Increasing evidence shows that the intrinsic error rates, and the resulting mutation frequencies, of RNA viruses can be modulated by subtle amino acid changes to the viral polymerase. Although biochemical assays exist for some viral RNA polymerases that permit quantitative measure of incorporation fidelity, here we describe a simple method of measuring mutation frequencies of RNA viruses that has proven to be as accurate as biochemical approaches in identifying fidelity altering mutations. The approach uses conventional virological and sequencing techniques that can be performed in most biology laboratories. Based on our experience with a number of different viruses, we have identified the key steps that must be optimized to increase the likelihood of isolating fidelity variants and generating data of statistical significance. The isolation and characterization of fidelity altering mutations can provide new insights into polymerase structure and function1-3. Furthermore, these fidelity variants can be useful tools in characterizing mechanisms of virus adaptation and evolution4-7.

The present article describes the steps required to isolate and characterize RNA polymerase fidelity variants of RNA viruses and how to use mutation frequency data to confirm fidelity changes in tissue culture.

Isolamento di varianti di virus RNA Fidelity e caratterizzazione di frequenza Virus Mutation

RNA viruses use RNA dependent RNA polymerases to replicate their genomes. The intrinsically high error rate of these enzymes is a large contributor to the ...

Separation of Single-stranded DNA, Double-stranded DNA and RNA from an Environmental Viral Community Using Hydroxyapatite Chromatography

Viruses, particularly bacteriophages (phages), are the most numerous biological entities on Earth1,2. Viruses modulate host cell abundance and diversity, contribute to the cycling of nutrients, alter host cell phenotype, and influence the evolution of both host cell and viral communities through the lateral transfer of genes 3. Numerous studies have highlighted the staggering genetic diversity of viruses and their functional potential in a variety of natural environments. 
Metagenomic techniques have been used to study the taxonomic diversity and functional potential of complex viral assemblages whose members contain single-stranded DNA (ssDNA), double-stranded DNA (dsDNA) and RNA genotypes 4-9. Current library construction protocols used to study environmental DNA-containing or RNA-containing viruses require an initial nuclease treatment in order to remove nontargeted templates 10. However, a comprehensive understanding of the collective gene complement of the virus community and virus diversity requires knowledge of all members regardless of genome composition. Fractionation of purified nucleic acid subtypes provides an effective mechanism by which to study viral assemblages without sacrificing a subset of the community&#x2019;s genetic signature. 
Hydroxyapatite, a crystalline form of calcium phosphate, has been employed in the separation of nucleic acids, as well as proteins and microbes, since the 1960s11. By exploiting the charge interaction between the positively-charged Ca2+ ions of the hydroxyapatite and the negatively charged phosphate backbone of the nucleic acid subtypes, it is possible to preferentially elute each nucleic acid subtype independent of the others. We recently employed this strategy to independently fractionate the genomes of ssDNA, dsDNA and RNA-containing viruses in preparation of DNA sequencing 12. Here, we present a method for the fractionation and recovery of ssDNA, dsDNA and RNA viral nucleic acids from mixed viral assemblages using hydroxyapatite chromotography.

We describe an efficient method to separate single-stranded DNA, double-stranded DNA and RNA molecules from environmental viral communities. Nucleic acids are fractionated using hydroxyapatite chromatography with increasing concentrations of phosphate-containing buffers. This method permits the isolation of all viral nucleic acid types from environmental samples.

Separazione di DNA a singolo filamento, doppia elica del DNA e RNA da una Comunità Ambientale virale usando la cromatografia idrossiapatite

Viruses, particularly bacteriophages (phages), are the most numerous biological entities on Earth1,2.  Viruses modulate host cell abundance and diversity, ...

A Simple Chelex Protocol for DNA Extraction from Anopheles spp.

Endemic countries are increasingly adopting molecular tools for efficient typing, identification and surveillance against malaria parasites and vector mosquitoes, as an integral part of their control programs1,2,3,4,5. For sustainable establishment of these accurate approaches in operations research to strengthen malaria control and elimination efforts, simple and affordable methods, with parsimonious reagent and equipment requirements are essential6,7,8. Here we present a simple Chelex-based technique for extracting malaria parasite and vector DNA from field collected mosquito specimens.
We morphologically identified 72 Anopheles gambiae sl. from 156 mosquitoes captured by pyrethrum spray catches in sleeping rooms of households within a 2,000 km2 vicinity of the Malaria Institute at Macha. After dissection to separate the head and thorax from the abdomen for all 72 Anopheles gambiae sl. mosquitoes, the two sections were individually placed in 1.5 ml microcentrifuge tubes and submerged in 20 &mu;l of deionized water. Using a sterile pipette tip, each mosquito section was separately homogenized to a uniform suspension in the deionized water. Of the ensuing homogenate from each mosquito section, 10 &mu;l was retained while the other 10 &mu;l was transferred to a separate autoclaved 1.5 ml tube. The separate aliquots were subjected to DNA extraction by either the simplified Chelex or the standard salting out extraction protocol9,10. The salting out protocol is so-called and widely used because it employs high salt concentrations in lieu of hazardous organic solvents (such as phenol and chloroform) for the protein precipitation step during DNA extraction9.
Extracts were used as templates for PCR amplification using primers targeting arthropod mitochondrial nicotinamide adenine dinucleotide dehydrogenase (NADH) subunit 4 gene (ND4) to check DNA quality11, a PCR for identification of Anopheles gambiae sibling species10 and a nested PCR for typing of Plasmodium falciparum infection12. Comparison using DNA quality (ND4) PCR showed 93% sensitivity and 82% specificity for the Chelex approach relative to the established salting out protocol. Corresponding values of sensitivity and specificity were 100% and 78%, respectively, using sibling species identification PCR and 92% and 80%, respectively for P. falciparum detection PCR. There were no significant differences in proportion of samples giving amplicon signal with the Chelex or the regular salting out protocol across all three PCR applications. The Chelex approach required three simple reagents and 37 min to complete, while the salting out protocol entailed 10 different reagents and 2 hr and 47 min' processing time, including an overnight step. Our results show that the Chelex method is comparable to the existing salting out extraction and can be substituted as a simple and sustainable approach in resource-limited settings where a constant reagent supply chain is often difficult to maintain.

A Simple Chelex Protocol for DNA Extraction from Anopheles spp.

A rapid and affordable way to extract quality malaria parasite and vector DNA from mosquito specimens is described. Capitalizing on chelating properties of Chelex resin, the simple method enables genotyping of malaria parasites in mosquito mid-gut and salivary gland phases, as well as molecular identification of the Anopheles sibling species by PCR.

Un protocollo Chelex semplice per l&#39;estrazione del DNA da<em&gt; Anopheles</em&gt; Spp.

Endemic countries are increasingly adopting molecular tools for  efficient typing, identification and surveillance against malaria parasites and  vector ...

Establishing a Liquid-covered Culture of Polarized Human Airway Epithelial Calu-3 Cells to Study Host Cell Response to Respiratory Pathogens In vitro

The apical and basolateral surfaces of airway epithelial cells demonstrate directional responses to pathogen exposure in vivo. Thus, ideal in vitro models for examining cellular responses to respiratory pathogens polarize, forming apical and basolateral surfaces. One such model is differentiated normal human bronchial epithelial cells (NHBE). However, this system requires lung tissue samples, expertise isolating and culturing epithelial cells from tissue, and time to generate an air-liquid interface culture.
Calu-3 cells, derived from a human bronchial adenocarcinoma, are an alternative model for examining the response of proximal airway epithelial cells to respiratory insult1, pharmacological compounds2-6, and bacterial7-9 and viral pathogens, including influenza virus, rhinovirus and severe acute respiratory syndrome - associated coronavirus10-14. Recently, we demonstrated that Calu-3 cells are susceptible to respiratory syncytial virus (RSV) infection in a manner consistent with NHBE15,16 . Here, we detail the establishment of a polarized, liquid-covered culture (LCC) of Calu-3 cells, focusing on the technical details of growing and culturing Calu-3 cells, maintaining cells that have been cultured into LCC, and we present the method for performing respiratory virus infection of polarized Calu-3 cells.
To consistently obtain polarized Calu-3 LCC, Calu-3 cells must be carefully subcultured before culturing in Transwell inserts. Calu-3 monolayer cultures should remain below 90% confluence, should be subcultured fewer than 10 times from frozen stock, and should regularly be supplied with fresh medium. Once cultured in Transwells, Calu-3 LCC must be handled with care. Irregular media changes and mechanical or physical disruption of the cell layers or plates negatively impact polarization for several hours or days. Polarization is monitored by evaluating trans-epithelial electrical resistance (TEER) and is verified by evaluating the passive equilibration of sodium fluorescein between the apical and basolateral compartments17,18 . Once TEER plateaus at or above 1,000 &Omega;&times;cm2, Calu-3 LCC are ready to use to examine cellular responses to respiratory pathogens.

Establishing a Liquid-covered Culture of Polarized Human Airway Epithelial Calu-3 Cells to Study Host Cell Response to Respiratory Pathogens In vitro

The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.

Creazione di un liquido coperto Cultura polarizzata Airway epiteliali umane Calu-3 celle per studio cellulare risposta dell&#39;ospite agli agenti patogeni delle vie respiratorie<em&gt; In vitro</em

The  apical and basolateral surfaces of airway epithelial cells demonstrate  directional responses to pathogen exposure in  vivo. Thus, ideal in vitro ...

Averaging of Viral Envelope Glycoprotein Spikes from Electron Cryotomography Reconstructions using Jsubtomo

Enveloped viruses utilize membrane glycoproteins on their surface to mediate entry into host cells. Three-dimensional structural analysis of these glycoprotein &#8216;spikes&#8217; is often technically challenging but important for understanding viral pathogenesis and in drug design. Here, a protocol is presented for viral spike structure determination through computational averaging of electron cryo-tomography data. Electron cryo-tomography is a technique in electron microscopy used to derive three-dimensional tomographic volume reconstructions, or tomograms, of pleomorphic biological specimens such as membrane viruses in a near-native, frozen-hydrated state. These tomograms reveal structures of interest in three dimensions, albeit at low resolution. Computational averaging of sub-volumes, or sub-tomograms, is necessary to obtain higher resolution detail of repeating structural motifs, such as viral glycoprotein spikes. A detailed computational approach for aligning and averaging sub-tomograms using the Jsubtomo software package is outlined. This approach enables visualization of the structure of viral glycoprotein spikes to a resolution in the range of 20-40 &#197; and study of the study of higher order spike-to-spike interactions on the virion membrane. Typical results are presented for Bunyamwera virus, an enveloped virus from the family Bunyaviridae. This family is a structurally diverse group of pathogens posing a threat to human and animal health.

An approach is presented for determining structures of viral membrane glycoprotein complexes using a combination of electron cryo-tomography and sub-tomogram averaging with the computational package Jsubtomo.

Della media di Viral Busta Glicoproteina Spikes da Electron Cryotomography Ricostruzioni con Jsubtomo

Enveloped viruses utilize membrane glycoproteins on their surface to mediate entry into host cells. Three-dimensional structural analysis of these ...

Isolation of Viral Replication Compartment-enriched Sub-nuclear Fractions from Adenovirus-infected Normal Human Cells

During infection of human cells by adenovirus (Ad), the host cell nucleus is dramatically reorganized, leading to formation of nuclear microenvironments through the recruitment of viral and cellular proteins to sites occupied by the viral genome. These sites, called replication compartments (RC), can be considered viral-induced nuclear domains where the viral genome is localized and viral and cellular proteins that participate in replication, transcription and post-transcriptional processing are recruited. Moreover, cellular proteins involved in the antiviral response, such as tumor suppressor proteins, DNA damage response (DDR) components and innate immune response factors are also co-opted to RC. Although RC seem to play a crucial role to promote an efficient and productive replication cycle, a detailed analysis of their composition and associated activities has not been made. To facilitate the study of adenoviral RC and potentially those from other DNA viruses that replicate in the cell nucleus, we adapted a simple procedure based on velocity gradients to isolate Ad RC and established a cell-free system amenable to conduct morphological, functional and compositional studies of these virus-induced subnuclear structures, as well as to study their impact on host-cell interactions.

We provide a novel strategy to isolate viral replication compartments (RC) from adenovirus (Ad)-infected human cells. This approach represents a cell-free system that can help to elucidate the molecular mechanisms regulating viral genome replication and expression as well as regulation of viral-host interactions established at the RC.

Isolamento di frazioni sub-nucleare virale replica Vano-arricchite da Adenovirus-infetti cellule normali umane

During infection of human cells by adenovirus (Ad), the host cell nucleus is dramatically reorganized, leading to formation of nuclear microenvironments ...

The Development of Lyophilized Loop-mediated Isothermal Amplification Reagents for the Detection of Coxiella burnetii

Coxiella burnetii, the agent causing Q fever, is an obligate intracellular bacterium. PCR based diagnostic assays have been developed for detecting C. burnetii DNA in cell cultures and clinical samples. PCR requires specialized equipment and extensive end user training, and therefore, it is not suitable for routine work especially in a resource-constrained area. We have developed a loop-mediated isothermal amplification (LAMP) assay to detect the presence of C. burnetii in patient samples. This method is performed at a single temperature around 60 &#176;C in a water bath or heating block. The sensitivity of this LAMP assay is very similar to PCR with a detection limit of about 25 copies per reaction. This report describes the preparation of the reaction using lyophilized reagents and visualization of results using hydroxynaphthol blue (HNB) or a UV lamp with fluorescent intercalating dye in the reaction. The LAMP reagents were lyophilized and stored at room temperature (RT) for one month without loss of detection sensitivity. This LAMP assay is particularly robust because the reaction mixture preparation does not involve complex steps. This method is ideal for use in resource-limited settings where Q fever is endemic.

The Development of Lyophilized Loop-mediated Isothermal Amplification Reagents for the Detection of Coxiella burnetii

We described here a simple loop-mediated isothermal amplification (LAMP) method using lyophilized reagents for the detection of C. burnetii in patient samples.

Lo sviluppo del liofilizzato Loop-mediate isotermici amplificazione reagenti per la rilevazione di<em&gt; Burnetii Coxiella</em

Coxiella burnetii, the agent causing Q fever, is an obligate intracellular bacterium. PCR based diagnostic assays have been developed for detecting C. ...

Measuring Influenza Neuraminidase Inhibition Antibody Titers by Enzyme-linked Lectin Assay

Antibodies to neuraminidase (NA), the second most abundant surface protein on influenza virus, contribute toward protection against influenza. Traditional methods to measure NA inhibiting (NI) antibody titers are not practical for routine serology. This protocol describes the enzyme-linked lectin assay (ELLA), a practical alternative method to measure NI titers that is performed in 96 well plates coated with a large glycoprotein substrate, fetuin. NA cleaves terminal sialic acids from fetuin, exposing the penultimate sugar, galactose. Peanut agglutinin (PNA) is a lectin with specificity for galactose and therefore the extent of desialylation can be quantified using a PNA-horseradish peroxidase conjugate, followed by addition of a chromogenic peroxidase substrate. The optical density that is measured is proportional to NA activity. To measure NI antibody titers, serial dilutions of sera are incubated at 37 &#176;C O/N on fetuin-coated plates with a fixed amount of NA. The reciprocal of the highest serum dilution that results in &#8805;50% inhibition of NA activity is designated as the NI antibody titer. The ELLA provides a practical format for routine evaluation of human antibody responses following influenza infection or vaccination.

We describe the enzyme-linked lectin assay (ELLA) for measuring influenza neuraminidase (NA)-inhibition antibody titers in sera. The assay uses peanut agglutinin to quantify galactose residues that become accessible when NA removes sialic acid from fetuin-coated, 96-well plates.

Misurare Influenza neuraminidasi Inibizione anticorpo I titoli da Enzyme-linked lectina Assay

Antibodies to neuraminidase (NA), the second most abundant surface protein on influenza virus, contribute toward protection against influenza. Traditional ...