This work was funded by both the&#160;Canadian Institutes of Health Research&#160;and&#160;Natural Sciences and the Engineering Research Council of Canada. M. Bisaillon is a Chercheur Boursier Senior from the Fonds de Recherche en Sant&#233; du Qu&#233;bec and also a member of the Centre de Recherche Clinique du Centre Hospitalier Universitaire de Sherbrooke. We thank Dr. Ralf Bartenschlager for the generous gift of the HCV replicon system. We also thank Dr. Charles Rice and Dr. Daniel Lamarre for kindly providing the hepatic cell line. We also want to thank Guillaume Tremblay for technical assistance.

1. תאי הכנה וטיפול <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> בצלחת 24 גם, לשים כיסוי זכוכית בחלק התחתון של הבארות. לשטוף היטב עם כל בופר פוספט (PBS). </li><li style=";text-align:right;direction:rtl"> תאי זרע הא-7 תומכים replicon subgenomic HCV בכל טוב לצפיפות של 5 × 10 4 תאים / טוב. אם אין טיפול לעשות, יכולים להיות שנזרעו התאים בצפיפות גבוהה. מדיום התרבות הוא הנשר בינוני השתנה Dulbecco (DMEM) בתוספת 10% עובריים בסרום שור (FBS), 2 מ&quot;מ L- גלוטמין, פירובט נתרן 1 מ&quot;מ ו -250 מ&quot;ג / מיליליטר G-418 (כדי לשמור על replicon). </li><li style=";text-align:right;direction:rtl"> לדגור על 37 מעלות צלזיוס, 5% CO 2. למחרת, טיפול בתאים עם 3 מיקרומטר של HLF מטוהר מחלב אנושי. </li></ol> 2. Paraformaldehyde / סוכרוז הכנה (12% סוכרוז PAF ו -12%) <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> שים 500 מיליליטר של PBS בכוס ומחמם אותו בין 20 ° C ו 30 מעלות צלזיוס. ממיסים 60 גרם של סוכרוז בPBS. ממיסים 60 גרם של paraformaldehyde (PAF) בפתרון PBS / סוכרוז. לאט לאט להוסיף NaOH 2N (3 עד 7 מיליליטר) עד פתרון ברור מתקבל. </li><li style=";text-align:right;direction:rtl"> התאם ל- pH 7.4 עם HCl. נפח מלא 500 מיליליטר עם PBS. סנן לפי הכבידה על מסנן Whatman. לפני השימוש, לדלל את הפתרון עם PBS לריכוז סופי של PAF 4% וסוכרוז 4% (אחסון 4 מעלות צלזיוס במשך שבוע לכל היותר 1). </li></ol> 3. Immunofluorescence <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> בזמן הרצוי (0 שעה, שעה 2 או 24 שעות של טיפול), לשטוף תאים פעמיים (1 דקות) עם PBS ולתקן עם / 4% סוכרוז / 4% PAF PBS במשך 20 דקות ב RT. התאים הם בדרך כלל במפגש 30-40% ו1.5X10 5 תאים משמשים. </li><li style=";text-align:right;direction:rtl"> Permeabilize תאים עם טריטון 0.15% X-100 ב PBS במשך 5 דקות ב RT ולחסום בסרום 10% נורמלים עז (NGS) בPBS במשך 20 דקות. </li><li style=";text-align:right;direction:rtl"> לדלל את הנוגדן הראשוני של החלבון של עניין ב -10% NGS (לדוגמה: נוגדנים נגד HLF עכבר עיקרי בדילול 1: 1,000). החל הנוגדן הראשוני לתאים. </li><li style=";text-align:right;direction:rtl"> לאחר 4 שעות ב RT או O /N ב 4 ° C, לשטוף את התאים שלוש פעמים במשך 5 דקות עם 10% NGS. כתם התאים עם נוגדנים משני שכותרתו עם fluorochrome המדולל ב 10% NGS (דוגמא: Fluorochrome עם גל עירור של 488 ננומטר קשור לנוגדן אנטי עכבר 1: 1,000) במשך שעה 1 ב RT בחושך. </li><li style=";text-align:right;direction:rtl"> לשטוף את תאי פעם אחת עבור 5 דקות עם PBS ולהכתים את התאים עם 4 &#39;, 6-diamidino-2-phenylindole (DAPI) (1 מיקרוגרם / מיליליטר) במשך 15 דקות ב RT בחושך. </li><li style=";text-align:right;direction:rtl"> לשטוף את התאים פעמיים ל5 דקות עם PBS. הר לכסות משקפיים בהרכבה בינונית SlowFade לפני ההדמיה באמצעות מיקרוסקופ. התאים מוכנים לניתוח על ידי epifluorescence או confocal עכשיו. </li><li style=";text-align:right;direction:rtl"> השתמש בבקרה שונה על מנת להבטיח את הספציפיות של זיהוי. לדוגמא, ניתן להשמיט את כל הנוגדנים כדי לזהות autofluorescence. הנוגדן הראשוני ניתן להשמיט כדי לקבוע את הכתמים שאינם ספציפיים על ידי הנוגדנים משני. לבסוף, אם אפשר, לשלוט תאים או רקמות שלאלבטא גם המולקולה של עניין ניתן להשתמש. </li><li style=";text-align:right;direction:rtl"> דמיינו את הדגימות באמצעות מיקרוסקופ פלואורסצנטי המתאים (epifluorescence או confocal) ומערכות סינון מתאים לתווית הניאון משמשת. יכולות גם להיות מאוחסנות שקופיות בתיבת שקופיות ב&lt; -20 ° C לבדיקה מאוחר יותר. </li></ol> 4. מיקרוסקופ פלואורסצנטי <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> שמור את הדגימות בחושך כדי למנוע photobleaching. הפעל את מקור האור של המיקרוסקופ נבחר (epifluorescence או confocal). </li><li style=";text-align:right;direction:rtl"> הפעל את המיקרוסקופ. הפעל את המצלמה למיקרוסקופ. שים את השקופיות במיקרוסקופ להדמיה. להוסיף שמן טבילה בשקופית להגדיל את הצמצם המספרי של העדשה האובייקטיבית. </li><li style=";text-align:right;direction:rtl"> בחר את המסננים המתאימים. התאם את מיקוד ומטרה מתאימה. התאם את התריסים כדי לזהות את fluorochrome המתאים אבל למנוע photobleaching. שמור את האורות מעל למזער אור רקע כאשר מסתכלים על מדגם. </li><li style=";text-align:right;direction:rtl"> ה שינוימסנני דואר לדמיין fluorochromes השונים (למשל DAPI ולגל עירור של 488 ננומטר). לצלם עם המצלמה. </li></ol>

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	<li>Odell, I. D., Cook, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunofluorescence+techniques.">Immunofluorescence techniques.</a> J Invest Derm. 133 (1), e4 (2013).</li><li>Portugal, J., Waring, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assignment+of+DNA+binding+sites+for+4&#8217;,6-diamidine-2-phenylindole+and+bisbenzimide+(Hoechst+33258).+A+comparative+footprinting+study.">Assignment of DNA binding sites for 4&#8217;,6-diamidine-2-phenylindole and bisbenzimide (Hoechst 33258). A comparative footprinting study.</a> Biochim Biophys Acta. 949 (2), 158-168 (1988).</li><li>Lichtman, J. W., Conchello, J. -. A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+microscopy.">Fluorescence microscopy.</a> Nat Methods. 2 (12), 910-919 (2005).</li><li>St Croix, C. M., Shand, S. H., Watkins, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Confocal+microscopy:+comparisons,+applications,+and+problems.">Confocal microscopy: comparisons, applications, and problems.</a> BioTechniques. 39, S2-S5 (2005).</li><li>Yi, M., Kaneko, S., Yu, D. Y., Murakami, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hepatitis+C+virus+envelope+proteins+bind+lactoferrin.">Hepatitis C virus envelope proteins bind lactoferrin.</a> Journal of virology. 71, 5997-6002 (1997).</li><li>Wakabayashi, H., Oda, H., Yamauchi, K., Abe, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lactoferrin+for+prevention+of+common+viral+infections.">Lactoferrin for prevention of common viral infections.</a> J Inf Chem. 20 (11), 666-671 (2014).</li><li>Picard-Jean, F., Bouchard, S., Lariv&#233;e, G., Bisaillon, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+intracellular+inhibition+of+HCV+replication+represents+a+novel+mechanism+of+action+by+the+innate+immune+Lactoferrin+protein.">The intracellular inhibition of HCV replication represents a novel mechanism of action by the innate immune Lactoferrin protein.</a> Antiviral research. 111, 13-22 (2014).</li><li>Johnson, G. D., Davidson, R. S., McNamee, K. C., Russell, G., Goodwin, D., Holborow, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fading+of+immunofluorescence+during+microscopy:+a+study+of+the+phenomenon+and+its+remedy.">Fading of immunofluorescence during microscopy: a study of the phenomenon and its remedy.</a> J Immunol Methods. 55 (2), 231-242 (1982).</li><li>Green Remington, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=fluorescent+protein:+a+perspective.">fluorescent protein: a perspective.</a> Protein Sci. 20 (9), 1509-1519 (2011).</li></ol>

The authors declare that they have no competing financial interests.

מגיפת HCV נותרה איום גלובלי, עם 80% מהחולים שנדבקו זה עתה התפתחות זיהום כרוני, לשים אותם בסיכון של שחמת, אי ספיקת כבד או קרצינומה hepatocellular. סוכנים אנטי מיקוד שכפול HCV והתבגרות פועל-ישיר מייצגים סוכנים אנטי HCV ראש, כפי שהודגם לאחרונה על ידי אישור הרגולטורים של שני מעכבי ns3 N-ס...

Immunofluorescence is a technique that uses a fluorescence microscope to visualize the distribution and/or localization of a target molecule in a biological sample. Immunofluorescence relies on the specificity of fluorescent-labelled antibodies against their corresponding antigens within a cell1. It is typically used on tissue sections and cultured cell lines in order to analyze the distribution/localization of various biological molecules such as proteins, nucleic acids and glycans. It should be noted that immunofluorescence is often used in combination with other non-antibody methods of fluorescent staining such as the 4',6-diamidino-2-phenylindole (DAPI) stains which are typically used to label DNA2. Moreover, this technique involves fixation of the cells which allows the analysis of cells at a specific time.
Different types of microscopes can be used to analyze immunofluorescence samples. The simplest is the epifluorescence microscope (Figure 1) for which excitation of the fluorochrome and detection of the fluorescence are done through the same light path3. Because most of the excitation light is transmitted through the sample, only reflected excitatory light can reach the objective together with the emitted light. This approach unfortunately leadsto a frequent high signal to noise ratio.In contrast, confocal microscopy (Figure 2) offers a distinct advantage for increasing optical resolution and contrast by means of adding a spatial pinhole placed at the confocal plane of the lens to eliminate out-of-focus light4. This approach allows the reconstruction of three-dimensional structures from the obtained images. However, since an important fraction of the light from the sample is blocked at the pinhole, long exposures are often required.
There are two classes of immunofluorescence techniques, primary (or direct) and secondary (or indirect). Direct immunofluorescence involves a primary antibody linked with a fluorochrome (Figure 3). This method is less frequently used because it provides lower signal, involves higher cost and less flexibility1. Moreover, such antibodies are generally harder to find commercially. On the other hand, the direct attachment of the fluorochrome to the antibody significantly reduces the number of steps in the procedure, saving time and frequently reducing non-specific background signal. This also limits the possibility of antibody cross-reactivty.
Indirect immunofluorescence involves a primary unlabelled antibody which is specific for the epitope of interest1. A secondary antibody which carries the fluorochrome then recognizes the primary antibody and binds to it (Figure 3). Although indirect immunofluorescence is more complex and time consuming than direct immunofluorescence, it is frequently used because of its high sensitivity and it also provides an amplified signal since more than one secondary antibody can attach to each primary antibody. In addition, a vast array of commercial secondary antibodies is available at affordable prices.
Hepatitis C virus (HCV) is a major public-health problem with 130-170 million individuals chronically infected worldwide. In order to halt the epidemic, therapy against HCV will need to be both effective and widely available. Studies focusing on safe and affordable natural product active against HCV have revealed the antiviral activity of the human Lactoferrin (hLF) protein which binds and neutralizes the circulating virion5. In the current study, investigation of hLF activity on the HCV subgenomic replicon system, which is independent from viral entry and shedding, revealed a distinct antireplicative activity of hLF against HCV. This manuscript presents a study in which immunofluorescence assays were performed to monitor the internalization of hLF, an important component of the immune system6, into hepatic cells. Moreover, we monitored the inhibitory potential of hLF on the intracellular replication of the Hepatitis C virus (HCV).

<table><tbody><tr><td>DMEM</td><td>Wisent</td><td>319-005-CL</td><td></td></tr><tr><td>PAF</td><td>BioShop</td><td>PAR070.1</td><td>Flammable solid, skin irritant, lungs and eyes&amp;nbsp;</td></tr><tr><td>PBS</td><td>Wisent</td><td>311-425-CL</td><td>Without Ca&lt;sup&gt;2+ &lt;/sup&gt;&amp;amp; Mg&lt;sup&gt;2+&lt;/sup&gt;</td></tr><tr><td>NGS</td><td>Wisent</td><td>053-150</td><td></td></tr><tr><td>AlexaFluor 488-labeled anti-mouse</td><td>Invitrogen</td><td>A11017</td><td></td></tr><tr><td>AlexaFluor 568-labeled anti-rabbit</td><td>Invitrogeb</td><td>A21069</td><td></td></tr><tr><td>Wheat germ agglutinin Alexa Fluor 488 conjugate (WGA)</td><td>Invitrogen</td><td>W11261</td><td>Potentially mutagenic</td></tr><tr><td>Anti-NS5A rabbit</td><td>Abcam</td><td>ab2594</td><td></td></tr><tr><td>Anti-hLF mouse</td><td>Abcam</td><td>ab10110</td><td></td></tr><tr><td>SlowFade</td><td>Invitrogen</td><td>S36937</td><td></td></tr><tr><td>Hoechst stain</td><td>Life Techn.</td><td>H1399</td><td>Potentially&amp;nbsp;mutagenic&amp;nbsp;
and carcinogenic</td></tr><tr><td>hLF</td><td>Sigma</td><td>L0520</td><td></td></tr><tr><td>Nikon Eclipse visible/epifluorescence Microscope</td><td>Nikon</td><td>TE2000-E</td><td></td></tr><tr><td>epifluorescence/confocal microscope</td><td>Olympus</td><td>FV1000</td><td></td></tr></tbody></table>

immunofluorescence to monitor the cellular uptake of human lactoferrin and its associated antiviral activity against the hepatitis c virus

Immunofluorescence הוא טכניקת מעבדה הנפוצה ללמוד היבטים רבים של ביולוגיה. הוא משמש בדרך כלל כדי להמחיש את ההפצה ו / או לוקליזציה של מולקולת יעד בתאים וברקמות. Immunofluorescence מסתמך על הספציפיות של נוגדנים שכותרתו ניאון נגד אנטיגנים המתאימים בתוך תא. שניהם יכולים לשמש גישות immunofluorescence ישירות ועקיפות הנשענות על השימוש בנוגדנים קשורים עם fluorochrome. immunofluorescence הישיר בתדירות נמוכה יותר בשימוש משום שהוא מספק אות נמוכה, כרוך בעלות גבוהה יותר ופחות גמישות. לעומת זאת, immunofluorescence העקיף הוא יותר נפוץ בגלל הרגישות הגבוהה שלה ומספק אות מוגברת מאז נוגדן אחד או יותר משני יכול לצרף לכל נוגדן ראשוני. בכתב היד הזה, שניהם במיקרוסקופ epifluorescence ומיקרוסקופיה confocal שמשו כדי לפקח על ההפנמה של לקטופרין האנושי, מרכיב חשוב של מערכת החיסוןמערכת, לתאי כבד. יתר על כן, אנו במעקב הפוטנציאל המעכב של HLF על השכפול תאיים של וירוס הצהבת מסוג C באמצעות immunofluorescence. שני היתרונות וחסרונות הקשורים בגישות אלה נדונים.

היכולת של הקו הסלולרי כבד הא-7 להפנים HLF אקסוגני מנוהל הייתה פיקוח באמצעות immunofluorescence על miscroscope confocal. HLF התווסף לתקשורת והתרבות וההפנמה הורשה למשך 24 שעות, לאחר ש, HLF תאי נשטף עם PBS וקרום שייר מחויב HLF היה מושפל עם טיפול טריפסין 5 דקות (1 מיליליטר). תאים היו reseeded ויורשו לחזור ל...

Watch this Scientific Journal Video about Immunofluorescence to Monitor the Cellular Uptake of Human Lactoferrin and its Associated Antiviral Activity Against the Hepatitis C Virus at JoVE.com

Immunofluorescence to Monitor the Cellular Uptake of Human Lactoferrin and its Associated Antiviral Activity Against the Hepatitis C Virus

The human lactoferrin (hLF) is a component of the immune system. In this study, immunofluorescence assays are used to demonstrate both the hepatocellular uptake of hLF and a qualitative reduction in the hepatitis C virus replication upon treatment with hLF.

Immunofluorescence לפקח על הספיגה הסלולארית של לקטופרין האדם והפעילות הקשורה אנטי נגד וירוס הצהבת מסוג C

Immunofluorescence is a laboratory technique commonly used to study many aspects of biology. It is typically used to visualize the distribution and/or ...

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Immunology and Infection

13.3K Views.  Université de Sherbrooke. The human lactoferrin (hLF) is a component of the immune system. In this study, immunofluorescence assays are used to demonstrate both the hepatocellular uptake of hLF and a qualitative reduction in the hepatitis C virus replication upon treatment with hLF.

Video: Immunofluorescence to Monitor the Cellular Uptake of Human Lactoferrin and its Associated Antiviral Activity Against the Hepatitis C Virus

High-throughput Detection Method for Influenza Virus

Influenza virus is a respiratory pathogen that causes a high degree of morbidity and mortality every year in multiple parts of the world. Therefore, precise diagnosis of the infecting strain and rapid high-throughput screening of vast numbers of clinical samples is paramount to control the spread of pandemic infections. Current clinical diagnoses of influenza infections are based on serologic testing, polymerase chain reaction, direct specimen immunofluorescence and cell culture 1,2.
Here, we report the development of a novel diagnostic technique used to detect live influenza viruses. We used the mouse-adapted human A/PR/8/34 (PR8, H1N1) virus 3 to test the efficacy of this technique using MDCK cells 4. MDCK cells (104 or 5 x 103 per well) were cultured in 96- or 384-well plates, infected with PR8 and viral proteins were detected using anti-M2 followed by an IR dye-conjugated secondary antibody. M2 5 and hemagglutinin 1 are two major marker proteins used in many different diagnostic assays. Employing IR-dye-conjugated secondary antibodies minimized the autofluorescence associated with other fluorescent dyes. The use of anti-M2 antibody allowed us to use the antigen-specific fluorescence intensity as a direct metric of viral quantity. To enumerate the fluorescence intensity, we used the LI-COR Odyssey-based IR scanner. This system uses two channel laser-based IR detections to identify fluorophores and differentiate them from background noise. The first channel excites at 680 nm and emits at 700 nm to help quantify the background. The second channel detects fluorophores that excite at 780 nm and emit at 800 nm. Scanning of PR8-infected MDCK cells in the IR scanner indicated a viral titer-dependent bright fluorescence. A positive correlation of fluorescence intensity to virus titer starting from 102-105 PFU could be consistently observed. Minimal but detectable positivity consistently seen with 102-103 PFU PR8 viral titers demonstrated the high sensitivity of the near-IR dyes. The signal-to-noise ratio was determined by comparing the mock-infected or isotype antibody-treated MDCK cells.
Using the fluorescence intensities from 96- or 384-well plate formats, we constructed standard titration curves. In these calculations, the first variable is the viral titer while the second variable is the fluorescence intensity. Therefore, we used the exponential distribution to generate a curve-fit to determine the polynomial relationship between the viral titers and fluorescence intensities. Collectively, we conclude that IR dye-based protein detection system can help diagnose infecting viral strains and precisely enumerate the titer of the infecting pathogens.

This method describes the use of Infrared dye based imaging system for detection of H1N1 in bronchioalveolar lavage (BAL) fluid of infected mice at a high sensitivity. This methodology can be performed in a 96- or 384-well plate, requires &lt;10 &mu;l volume of test material and has the potential for concurrent screening of multiple pathogens.

תפוקה גבוהה איתור שיטת וירוס השפעת

Influenza virus is a respiratory pathogen that causes a high degree of morbidity and mortality every year in multiple parts of the world. Therefore, ...

Two Methods of Heterokaryon Formation to Discover HCV Restriction Factors

Hepatitis C virus (HCV) is a hepatotropic virus with a host-range restricted to humans and chimpanzees. Although HCV RNA replication has been observed in human non-hepatic and murine cell lines, the efficiency was very low and required long-term selection procedures using HCV replicon constructs expressing dominant antibiotic-selectable markers1-5. HCV in vitro research is therefore limited to human hepatoma cell lines permissive for virus entry and completion of the viral life cycle. Due to HCVs narrow species tropism, there is no immunocompetent small animal model available that sustains the complete HCV replication cycle 6-8. Inefficient replication of HCV in non-human cells e.g. of mouse origin is likely due to lack of genetic incompatibility of essential host dependency factors and/or expression of restriction factors.
We investigated whether HCV propagation is suppressed by dominant restriction factors in either human cell lines derived from non-hepatic tissues or in mouse liver cell lines. To this end, we developed two independent conditional trans-complementation methods relying on somatic cell fusion. In both cases, completion of the viral replication cycle is only possible in the heterokaryons. Consequently, successful trans-complementation, which is determined by measuring de novo production of infectious viral progeny, indicates absence of dominant restrictions.
Specifically, subgenomic HCV replicons carrying a luciferase transgene were transfected into highly permissive human hepatoma cells (Huh-7.5 cells). Subsequently, these cells were co-cultured and fused to various human and murine cells expressing HCV structural proteins core, envelope 1 and 2 (E1, E2) and accessory proteins p7 and NS2. Provided that cell fusion was initiated by treatment with polyethylene-glycol (PEG), the culture released infectious viral particles which infected na&iuml;ve cells in a receptor-dependent fashion.
To assess the influence of dominant restrictions on the complete viral life cycle including cell entry, RNA translation, replication and virus assembly, we took advantage of a human liver cell line (Huh-7 Lunet N cells 9) which lacks endogenous expression of CD81, an essential entry factor of HCV. In the absence of ectopically expressed CD81, these cells are essentially refractory to HCV infection 10 . Importantly, when co-cultured and fused with cells that express human CD81 but lack at least another crucial cell entry factor (i.e. SR-BI, CLDN1, OCLN), only the resulting heterokaryons display the complete set of HCV entry factors requisite for infection. Therefore, to analyze if dominant restriction factors suppress completion of the HCV replication cycle, we fused Lunet N cells with various cells from human and mouse origin which fulfill the above mentioned criteria. When co-cultured cells were transfected with a highly fusogenic viral envelope protein mutant of the prototype foamy virus (PFV11) and subsequently challenged with infectious HCV particles (HCVcc), de novo production of infectious virus was observed. This indicates that HCV successfully completed its replication cycle in heterokaryons thus ruling out expression of dominant restriction factors in these cell lines. These novel conditional trans-complementation methods will be useful to screen a large panel of cell lines and primary cells for expression of HCV-specific dominant restriction factors.

We describe two methods for conditional trans-complementation of hepatitis C virus (HCV) assembly and the completion of the full viral life cycle, which rely on heterokaryon formation. These techniques are suitable to screen for cell lines that express dominant restriction factors, which preclude production of infectious HCV progeny.

שתי שיטות של גיבוש Heterokaryon לגלות גורמים הגבלת HCV

Hepatitis C virus (HCV) is a hepatotropic virus with a host-range restricted to humans and chimpanzees. Although HCV RNA replication has been observed in ...

A Protocol for Analyzing Hepatitis C Virus Replication

Hepatitis C Virus (HCV) affects 3% of the world&#8217;s population and causes serious liver ailments including&#160;chronic hepatitis, cirrhosis, and hepatocellular carcinoma. HCV is an enveloped RNA virus belonging to the family Flaviviridae. Current treatment is not fully effective and causes adverse side effects. There is no HCV vaccine available. Thus, continued effort is required for developing a vaccine and better therapy. An HCV cell culture system is critical for studying various stages of HCV growth including viral entry, genome replication, packaging, and egress. In the current procedure presented, we used a wild-type intragenotype 2a chimeric virus, FNX-HCV, and a recombinant FNX-Rluc virus carrying a Renilla luciferase reporter gene to study the virus replication. A human hepatoma cell line (Huh-7 based) was used for transfection of in vitro transcribed HCV genomic RNAs. Cell-free culture supernatants, protein lysates and total RNA were harvested at various time points post-transfection to assess HCV growth. HCV genome replication status was evaluated by quantitative RT-PCR and visualizing the presence of HCV double-stranded RNA. The HCV protein expression was verified by Western blot and immunofluorescence assays using antibodies specific for HCV NS3 and NS5A proteins. HCV RNA transfected cells released infectious particles into culture supernatant and the viral titer was measured. Luciferase assays were utilized to assess the replication level and infectivity of reporter HCV. In conclusion, we present various virological assays for characterizing different stages of the HCV replication cycle.

Hepatitis C Virus (HCV) is a major human pathogen that causes liver disorders, including cirrhosis and cancer. An HCV infectious cell culture system is essential for understanding the molecular mechanism of HCV replication and developing new therapeutic approaches. Here we describe a protocol to investigate various stages of the HCV replication cycle.

פרוטוקול לניתוח שכפול נגיף הצהבת מסוג C

Hepatitis C Virus (HCV) affects 3% of the world&#8217;s population and causes serious liver ailments including&#160;chronic hepatitis, cirrhosis, and ...

A Method to Assess Fc-mediated Effector Functions Induced by Influenza Hemagglutinin Specific Antibodies

Antibodies play a crucial role in coupling the innate and adaptive immune responses against viral pathogens through their antigen binding domains and Fc-regions. Here, we describe how to measure the activation of Fc effector functions by monoclonal antibodies targeting the influenza virus hemagglutinin with the use of a genetically engineered Jurkat cell line expressing an activating type 1 Fc-Fc&#947;R. Using this method, the contribution of specific Fc-Fc&#947;R interactions conferred by immunoglobulins can be determined using an in vitro assay.

We describe a method to measure the activation of Fc-mediated effector functions by antibodies that target the influenza virus hemagglutinin. This assay can also be adapted to assess the ability of monoclonal antibodies or polyclonal sera targeting other viral surface glycoproteins to induce Fc-mediated immunity.

שיטה להערכת פונקציות אפקטור בתיווך Fc המושרה על ידי שפעת Hemagglutinin נוגדנים ספציפיים

Antibodies play a crucial role in coupling the innate and adaptive immune responses against viral pathogens through their antigen binding domains and ...

Development and Validation of an Ultrasensitive Single Molecule Array Digital Enzyme-linked Immunosorbent Assay for Human Interferon-&#945;

The main aim of this protocol is to describe the development and validation of an interferon (IFN)-&#945; single molecule array digital Enzyme-Linked ImmunoSorbent Assay (ELISA) assay. This system enables the quantification of human IFN-&#945; protein with unprecedented sensitivity, and with no cross-reactivity for other species of IFN.
The first key step of the protocol is the choice of the antibody pair, followed by the conjugation of the capture antibody to paramagnetic beads, and biotinylation of the detection antibody. Following this step, different parameters such as assay configuration, detector antibody concentration, and buffer composition can be modified until optimum sensitivity is achieved. Finally, specificity and reproducibility of the method are assessed to ensure confidence in the results. Here, we developed an IFN-&#945; single molecule array assay with a limit of detection of 0.69 fg/mL using high-affinity autoantibodies isolated from patients with biallelic mutations in the autoimmune regulator (AIRE) protein causing autoimmune polyendocrinopathy syndrome type 1/autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APS1/APECED). Importantly, these antibodies enabled detection of all 13 IFN-&#945; subtypes.
This new methodology allows the detection and quantification of IFN-&#945; protein in human biological samples at attomolar concentrations for the first time. Such a tool will be highly useful in monitoring the levels of this cytokine in human health and disease states, most particularly infection, autoimmunity, and autoinflammation.

Here we present a protocol to describe the development and validation of a single molecule array digital ELISA assay, which enables the ultra-sensitive detection of all IFN-&#945; subtypes in human samples.

פיתוח ובדיקת של מולקולה בודדת העדינה מערך דיגיטלי מקושרים-אנזים Immunosorbent Assay עבור אינטרפרון אנושי-α

The main aim of this protocol is to describe the development and validation of an interferon (IFN)-&#945; single molecule array digital Enzyme-Linked ...

A High-throughput Cre-Lox Activated Viral Membrane Fusion Assay to Identify Inhibitors of HIV-1 Viral Membrane Fusion

This assay is designed to specifically report on HIV-1 fusion via the expression of green fluorescent protein (GFP) detectable by flow cytometry or fluorescence microscopy. An HIV-1 reporter virus (HIV-1 Gag-iCre) is generated by inserting Cre recombinase into the HIV-1 genome between the matrix and the capsid proteins of the Gag polyprotein. This results in a packaging of Cre recombinase into virus particles, which is then released into a target cell line stably expressing a Cre recombinase-activated red fluorescent protein (RFP) to GFP switch cassette. In the basal state, this cassette expresses RFP only. Following the delivery of Cre recombinase into the target cell, the RFP, flanked by loxP sites, excises, resulting in GFP expression. This assay can be used to test any inhibitors of viral entry (specifically at the fusion step) in cell-free and cell-to-cell infection systems and has been used to identify a class of purinergic receptor antagonists as novel inhibitors of HIV-1 viral membrane fusion.

We describe a cell-based assay to report on HIV-1 fusion via the expression of green fluorescent protein detectable by flow cytometry or fluorescence microscopy. It can be used to test inhibitors of viral entry (specifically at the fusion step) in cell-free and cell-to-cell infection systems.

Cre-עצלן תפוקה גבוהה מופעל ממברנה ויראלי Assay פיוז'ן לזהות מעכבי של היתוך ממברנה נגיפי HIV-1

This assay is designed to specifically report on HIV-1 fusion via the expression of green fluorescent protein (GFP) detectable by flow cytometry or ...

Detection of Viral RNA by Fluorescence in situ Hybridization (FISH)

Viruses that infect cells elicit specific changes to normal cell functions which serve to divert energy and resources for viral replication. Many aspects of host cell function are commandeered by viruses, usually by the expression of viral gene products that recruit host cell proteins and machineries. Moreover, viruses engineer specific membrane organelles or tag on to mobile vesicles and motor proteins to target regions of the cell (during de novo infection, viruses co-opt molecular motor proteins to target the nucleus; later, during virus assembly, they will hijack cellular machineries that will help in the assembly of viruses). Less is understood on how viruses, in particular those with RNA genomes, coordinate the intracellular trafficking of both protein and RNA components and how they achieve assembly of infectious particles at specific loci in the cell. The study of RNA localization began in earlier work. Developing lower eukaryotic embryos and neuronal cells provided important biological information, and also underscored the importance of RNA localization in the programming of gene expression cascades. The study in other organisms and cell systems has yielded similar important information. Viruses are obligate parasites and must utilise their host cells to replicate. Thus, it is critical to understand how RNA viruses direct their RNA genomes from the nucleus, through the nuclear pore, through the cytoplasm and on to one of its final destinations, into progeny virus particles 1.
FISH serves as a useful tool to identify changes in steady-state localization of viral RNA. When combined with immunofluorescence (IF) analysis 22, FISH/IF co-analyses will provide information on the co-localization of proteins with the viral RNA3. This analysis therefore provides a good starting point to test for RNA-protein interactions by other biochemical or biophysical tests 4,5, since co-localization by itself is not enough evidence to be certain of an interaction. In studying viral RNA localization using a method like this, abundant information has been gained on both viral and cellular RNA trafficking events 6. For instance, HIV-1 produces RNA in the nucleus of infected cells but the RNA is only translated in the cytoplasm. When one key viral protein is missing (Rev) 7, FISH of the viral RNA has revealed that the block to viral replication is due to the retention of the HIV-1 genomic RNA in the nucleus 8. 
Here, we present the method for visual analysis of viral genomic RNA in situ. The method makes use of a labelled RNA probe. This probe is designed to be complementary to the viral genomic RNA. During the in vitro synthesis of the antisense RNA probe, the ribonucleotide that is modified with digoxigenin (DIG) is included in an in vitro transcription reaction. Once the probe has hybridized to the target mRNA in cells, subsequent antibody labelling steps (Figure 1) will reveal the localization of the mRNA as well as proteins of interest when performing FISH/IF.

Detection of Viral RNA by Fluorescence in situ Hybridization FISH

A fluorescence in situ hybridization (FISH) method was developed to visually detect viral genomic RNA using fluorescence microscopy. A probe is made with specificity to the viral RNA that can then be identified using a combination of hybridization and immunofluorescence techniques. This technique offers the advantage of identifying the localization of the viral RNA or DNA at steady-state, providing information on the control of intracellular virus trafficking events.

זיהוי של רנ&quot;א נגיפי על ידי הקרינה<em&gt; באתרו</em&gt; הכלאה (דגים)

Viruses  that infect cells elicit specific changes to normal cell functions which serve  to divert energy and resources for viral replication. Many ...

Biology

Single-Cell Multiplexed Fluorescence Imaging to Visualize Viral Nucleic Acids and Proteins and Monitor HIV, HTLV, HBV, HCV, Zika Virus, and Influenza Infection

Capturing the dynamic replication and assembly processes of viruses has been hindered by the lack of robust in situ hybridization (ISH) technologies that enable sensitive and simultaneous labeling of viral nucleic acid and protein. Conventional DNA fluorescence in situ hybridization (FISH) methods are often not compatible with immunostaining. We have therefore developed an imaging approach, MICDDRP (multiplex immunofluorescent cell-based detection of DNA, RNA and protein), which enables simultaneous single-cell visualization of DNA, RNA, and protein. Compared to conventional DNA FISH, MICDDRP utilizes branched DNA (bDNA) ISH technology, which dramatically improves oligonucleotide probe sensitivity and detection. Small modifications of MICDDRP enable imaging of viral proteins concomitantly with nucleic acids (RNA or DNA) of different strandedness. We have applied these protocols to study the life cycles of multiple viral pathogens, including human immunodeficiency virus (HIV)-1, human T-lymphotropic virus (HTLV)-1, hepatitis B virus (HBV), hepatitis C virus (HCV), Zika virus (ZKV), and influenza A virus (IAV). We demonstrated that we can efficiently label viral nucleic acids and proteins across a diverse range of viruses. These studies can provide us with improved mechanistic understanding of multiple viral systems, and in addition, serve as a template for application of multiplexed fluorescence imaging of DNA, RNA, and protein across a broad spectrum of cellular systems.

Presented here is a protocol for a fluorescence imaging approach, multiplex immunofluorescent cell-based detection of DNA, RNA, and protein (MICDDRP), a method capable of simultaneous fluorescence single-cell visualization of viral protein and nucleic acids of different type and strandedness. This approach can be applied to a diverse range of systems.

הדמיה פלואורסצנטית מרובת תאים בודדים כדי לדמיין חומצות גרעין וחלבונים ויראליים ולפקח על HIV, HTLV, HBV, HCV, נגיף זיקה וזיהום שפעת

Capturing the dynamic replication and assembly processes of viruses has been hindered by the lack of robust in situ hybridization (ISH) technologies that ...

An Immunofluorescence Method to Measure the Neutralization of Human Cytomegalovirus

This video demonstrates an immunofluorescence assay designed to measure the neutralization of Human Cytomegalovirus (HCMV). Virus-specific antibodies are mixed with the virus and incubated with human fibroblast cells. The antibodies neutralize the virus, rendering it unable to infect the host cells, while non-neutralized viruses infect the cells. After incubation, the extent of neutralization is determined by quantifying the virus-infected cells using immunofluorescence.

שיטה immunofluorescence למדוד את נטרול של cytomegalovirus אנושי

1. Preparation of target cells for infection

	Seed target cells the day prior to performing the experiment in a 96-well plate (the &#39;target&#39; ...

JoVE Encyclopedia of Experiments

Immunology

Immunodiagnostics

Imaging and Visualization Techniques

A Viral Attachment Assay for Screening of Antiviral Compounds

Source: Tai, C. et al., <a href="https://app.jove.com/v/53124">Early Viral Entry Assays for the Identification and Evaluation of Antiviral Compounds.</a> J. Vis. Exp.&#160;(2015)
This video demonstrates a viral attachment assay for screening antiviral compounds. Using genetically modified hepatitis C virus and luciferase, it assesses inhibitory effects on viral attachment, as indicated by lower light intensity in co-treated wells compared to wells treated with the virus alone.

בדיקת התקשרות ויראלית לבדיקת תרכובות אנטי-ויראליות

NOTE: Ensure that all procedures involving cell culture and virus infection are conducted in certified biosafety hoods that are appropriate for the ...