This work has been supported by Elizabeth E. Kennedy Research Award.

.1 הכנת הזנים מפיק <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> Streak זן דלקת ריאות להיבדק לייצור bacteriocin על 5% צלחת אגר סויה tryptic דם כבשים ממניות מקפיא -80 מעלות צלזיוס. הערה: השימוש בצלחות דם לצמיחה ראשונית של הזן להיבדק לעיכוב מגדיל מאוד את שחזור של assay. בנוסף, זנים שאינן דלקת ריאות אחרות המייצרים bacteriocins ניתן להשתמש למרות שתנאי גידול, ייתכן שיצטרכו להיות שונה לאורגניזם ספציפי. יש לנו להשתמש mitis Streptococcus וקטיס Lactococcus בassay הכיסוי בהצלחה. </li><li style=";text-align:right;direction:rtl"> דגירה את הצלחת למשך הלילה (O / N) על 37 מעלות צלזיוס עם 5% CO 2. </li><li style=";text-align:right;direction:rtl"> לאחר הדגירה של זן המפיק, להכין הצלחת אגר סויה tryptic (TSA) על ידי pipetting 3,000 4,000 יחידות של קטלאז על צלחות המכילות 25 מ&quot;ל של TSA ולהפיץ את פתרון קטלאז באמצעות חרוזים זכוכית סטרילית. בואו יבש הצלחת במשך כ10 דקות תחתארון בטיחות ביולוגי. </li><li style=";text-align:right;direction:rtl"> לאסוף כמות נראית לעין של חיידקים על קצה פיפטה. לדקור את קצה פיפטה לתוך צלחת TSA המיובש. הערה: יותר מ מתח מפיק אחד יכולה להיות נדקרת לתוך צלחת TSA יחידה. חשוב חלל את הדקירות, כך שהילות וכתוצאה מכך אינן חופפות. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> במידת האפשר, כולל ידוע bacteriocin מפיק כביקורת חיובית ולהתאמץ כדי לשמש בשכבה כביקורת שלילית. הערה: בקרות חיוביות ושליליות הן כבר פורסמו בעבר, והם זמינים לפי בקשה 10. </li></ol></li><li style=";text-align:right;direction:rtl"> דגירה צלחת TSA מכיל דקירות מרובות על 37 מעלות צלזיוס עם 5% CO 2 למשך 6 שעות. </li></ol> 2 מניות גליצרול ביצוע של הזנים הכיסוי <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> הכן מניות גליצרול (תרבויות גדלו שלב אמצע מעריכי ואז מאוחסנות ב-80 מעלות צלזיוס לאחר התוספת של גליצרול) לפני היום של assay הכיסוי. לחסן 5-10 מושבות של str דלקת הריאותעין להיבדק לרגישות או הפרשת פרומון במדיום טוד יואיט עם שמרי 0.5% תמצית (THY). הערה: בנייה של כתבים מושרה BlpC כבר תוארה בעבר 2 וזנים זמינים לפי בקשה. </li><li style=";text-align:right;direction:rtl"> דגירה 5-10 מושבות בצינורות זכוכית עם 5 מ&quot;ל של THY עם מכסים סגורים היטב באמבט מים 37 מעלות צלזיוס בלי לרעוד. </li><li style=";text-align:right;direction:rtl"> דגירה תרבויות על 37 מעלות צלזיוס עד שהם מגיעים OD 620 של 0.3-0.5. הערה: זה ייקח כ 4-5 שעות בהתאם לזן המשמש. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> בעדינות להפוך את הצינור כמה פעמים לפני מדידת OD. </li></ol></li><li style=";text-align:right;direction:rtl"> אם הניסוי לא ניתן לבצע באותו היום או הזן ישמש פעמים רבות בעתיד, להפוך את מניות גליצרול ולחדש את הניסוי במועד מאוחר יותר. עבור מניות גליצרול, להוסיף גליצרול לתרבויות לריכוז סופי של 20%. תרבויות Aliquot לתוך צינורות 1.5 מ&quot;ל microcentrifuge ולאחסן ב -80 מעלות צלזיוס. הערה: דוגמאות יכולות להיות שלהנמצאת בבמשך חודשים ב-80 מעלות צלזיוס. אם לא עושה מניות גליצרול, להשתמש דגימות ישירות לassay כיסוי. </li></ol> 3 הכיסוי Assay <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> רק לפני כיסוי יישום, לערבב את מרכיבי הכיסוי. בצינור חרוטי 15 מ&quot;ל, להוסיף 5 מ&quot;ל שלך, 3,000-4,000 U של קטלאז, ו200 μl של תרבות מרק מתח כיסוי שגם גדלה באותו יום או מניית גליצרול של התרבות שהיה מופשר בטמפרטורת חדר. אם אתם משתמשים בזן הכתב, להוסיף 50 μl של X-gal (40 מ&quot;ג / מ&quot;ל) לתערובת הכיסוי. השתמש בצינור חרוטי אחד לכל צלחת. </li><li style=";text-align:right;direction:rtl"> לאזן תערובת כיסוי בטמפרטורת חדר לפני תוספת של TSA המותך. </li><li style=";text-align:right;direction:rtl"> הסר את צלחת TSA עם מתח נדקר מחממה. ממסים TSA המוצק במיקרוגל ולשמור על 55 ° C אמבט מים עד מוכן לשימוש. הוסף 3 מ&quot;ל של TSA המותך עם אגר 1.5% מקורר 55 ° C כדי כיסוי תערובת. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> מכין את תערובת הכיסוי מייד לפני pipetting, התערובת תתחיל לחזק מאודבמהירות. הערה: אם השכבה מתחילה לבסס לפני הציפוי, התוצאות תהיה uninterpretable. </li></ol></li><li style=";text-align:right;direction:rtl"> מערבבים את תערובת הכיסוי על ידי pipetting מעלה ומטה מספר פעמים עם 5 מ&quot;ל pipet נזהר שלא להכניס בועות לתוך התערובת. לאט לאט פיפטה תערובת כיסוי ישירות על צלחת TSA נדקרה. שמור את הצלחת על המעבדתיים למאפשרות אגר להקשיח כמה דקות. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> אל תסובב את הצלחת כדי לפזר את תערובת הכיסוי, זה ימשוך צמיחה מהתרבות נדקרה לכיסוי. </li></ol></li><li style=";text-align:right;direction:rtl"> בזהירות להניח צלחת TSA עם כיסוי ל37 חממת ° C המכילה 5% CO 2 O / N (כ 16-18 לשעה). </li><li style=";text-align:right;direction:rtl"> שים לב ללוחות לאחר צמיחת הלילה. הצלחות צריכה להראות אטום מצמיחה של זן הכיסוי למעט באזורים שבם איתות עיכוב או פרומון התרחשה. אלה יופיעו כאזורי או ברורים או כחולים סביב המתח נדקר, בהתאמה. שים לב: למרות measurements של הקוטר של קרחת יער כחול או יכול להיות שנקבע להערכה כמותית, הבדלים בקוטר יכולים גם משתנים בהתאם לכמות חיידקים שנדקרה לתוך הצלחת. Assay הכיסוי הוא assay איכותי, כל הערכה כמותית יש לפרש בזהירות. כל סליקה גלויה בהשוואה לביקורת השלילית נחשבת כפעילות. </li></ol>

<ol>
	<li>Dawid, S., Roche, A. M., Weiser, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+blp+bacteriocins+of+Streptococcus+pneumoniae+mediate+intraspecies+competition+both+in+vitro+and+in+vivo.">The blp bacteriocins of Streptococcus pneumoniae mediate intraspecies competition both in vitro and in vivo.</a> Infect Immun. 75 (1), 443-451 (2007).</li><li>Sawa, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+characterization+of+enterocin+W,+a+novel+two-peptide+lantibiotic+produced+by+Enterococcus+faecalis+NKR-4-1.">Isolation and characterization of enterocin W, a novel two-peptide lantibiotic produced by Enterococcus faecalis NKR-4-1.</a> Appl Environ Microbiol. 78 (3), 900-903 (2012).</li><li>Kochan, T. J., Dawid, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+HtrA+protease+of+Streptococcus+pneumoniae+controls+density-dependent+stimulation+of+the+bacteriocin+blp+locus+via+disruption+of+pheromone+secretion.">The HtrA protease of Streptococcus pneumoniae controls density-dependent stimulation of the bacteriocin blp locus via disruption of pheromone secretion.</a> J Bacteriol. 195 (7), 1561-1572 (2013).</li><li>Lux, T., Nuhn, M., Hakenbeck, R., Reichmann, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diversity+of+bacteriocins+and+activity+spectrum+in+Streptococcus+pneumoniae.">Diversity of bacteriocins and activity spectrum in Streptococcus pneumoniae.</a> J Bacteriol. 189 (21), 7741-7751 (2007).</li><li>Reichmann, P., Hakenbeck, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Allelic+variation+in+a+peptide-inducible+two-component+system+of+Streptococcus+pneumoniae.">Allelic variation in a peptide-inducible two-component system of Streptococcus pneumoniae.</a> FEMS Microbiol Lett. 190 (2), 231-236 (2000).</li><li>Saizieu, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microarray-based+identification+of+a+novel+Streptococcus+pneumoniae+regulon+controlled+by+an+autoinduced+peptide.">Microarray-based identification of a novel Streptococcus pneumoniae regulon controlled by an autoinduced peptide.</a> J Bacteriol. 182 (17), 4696-4703 (2000).</li><li>Barbour, A., Philip, K., Muniandy, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+production,+purification,+characterization+and+mechanism+of+action+of+salivaricin+9+lantibiotic+produced+by+Streptococcus+salivarius+NU10.">Enhanced production, purification, characterization and mechanism of action of salivaricin 9 lantibiotic produced by Streptococcus salivarius NU10.</a> PLoS One. 8 (10), 77751 (2013).</li><li>Wladyka, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation,+biochemical+characterization,+and+cloning+of+a+bacteriocin+from+the+poultry-associated+Staphylococcus+aureus+strain+CH-91.">Isolation, biochemical characterization, and cloning of a bacteriocin from the poultry-associated Staphylococcus aureus strain CH-91.</a> Appl Microbiol Biotechnol. 97 (16), 7229-7239 (2013).</li><li>Shea, E. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bactofencin+a,+a+new+type+of+cationic+bacteriocin+with+unusual+immunity.">Bactofencin a, a new type of cationic bacteriocin with unusual immunity.</a> 4 (6), 00498-00413 (2013).</li><li>Son, M. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conserved+mutations+in+the+pneumococcal+bacteriocin+transporter+gene,+blpA,+result+in+a+complex+population+consisting+of+producers+and+cheaters.">Conserved mutations in the pneumococcal bacteriocin transporter gene, blpA, result in a complex population consisting of producers and cheaters.</a> MBio. 2 (5), (2011).</li><li>Kochan, T. J., Dawid, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+HtrA+protease+of+Streptococcus+pneumoniae+controls+density-dependent+stimulation+of+the+bacteriocin+blp+locus+via+disruption+of+pheromone+secretion.">The HtrA protease of Streptococcus pneumoniae controls density-dependent stimulation of the bacteriocin blp locus via disruption of pheromone secretion.</a> J Bacteriol. 195, 1561-1572 (2013).</li><li>Widdick, D. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cloning+and+engineering+of+the+cinnamycin+biosynthetic+gene+cluster+from+Streptomyces+cinnamoneus+cinnamoneus+DSM+40005.">Cloning and engineering of the cinnamycin biosynthetic gene cluster from Streptomyces cinnamoneus cinnamoneus DSM 40005.</a> Proc Natl Acad Sci U S A. 100 (7), 4316-4321 (2003).</li><li>Begley, M., Cotter, P. D., Hill, C., Ross, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+a+novel+two-peptide+lantibiotic,+lichenicidin,+following+rational+genome+mining+for+LanM+proteins.">Identification of a novel two-peptide lantibiotic, lichenicidin, following rational genome mining for LanM proteins.</a> Appl Environ Microbiol. 75 (17), 5451-5460 (2009).</li></ol>

The authors have nothing to disclose.

assay הכיסוי זוהי דרך מהירה כדי לקבוע את הטווח של פעילות עבור יצרני bacteriocin ולהפגין אינטראקציות תחרותיות שעלולות להתרחש בין זני דלקת ריאות. Assay הכיסוי יכול להיות מותאם לשימוש עבור הקרנת זנים מרובים לייצור bacteriocin על צלחת אחת. יש לנו הוקרנו בהצלחה אוספי מתח גדולים עם assay זה ...

Streptococcus pneumoniae, קולוניאלי משותפת של קהילת polymicrobial של לוע האף, הוא מסוגל להתחרות עם pneumococci אחר ומינים קרובים באמצעות הייצור של פפטידים מיקרוביאלית מיוצרים bacterially (bacteriocins). כל זן דלקת ריאות באופן מלא רצף שנבחן עד היום מכיל גרסה של מוקד acteriocin- ב אייק l eptide עמ &#39;, BLP. ייצור Bacteriocin ידי pneumococcus הודגם להיות חשוב בתוצאות הן במבחנה בתחרות vivo 1-4. דינמיקה תחרותית מושפעת מהביטוי של bacteriocins המגוון יחד עם חלבוני חסינותו מקור בתגובה לפרומון פפטיד ספציפי. אינדוקציה של מוקד BLP נשלטת על ידי מערכת חישת מניין שבו פרומון פפטיד, BlpC, נקשר לקינאז החיישן, BlpH, ויוזם מפל איתות וכתוצאה מכךשעתוק של 5,6 מוקד BLP. ישנם ארבע וריאציות allelic של BlpC שכל נקשרים לBlpH המקור שלה 6. לתא כדי לשרוד את ההשפעות של bacteriocin משלו, הגנים המקודדים את חלבוני חסינותו מקור מתועתקים באותו אופרון ככל אחד מהגנים bacteriocin. הרג מתרחש אם זן מתחרה הוא לא מסוגל upregulate מוקד BLP בתגובה לפרומון אקסוגניים או, אם הזן חסר את גן החסינות הספציפי הנדרש להגנה. המורכב טרנספורטר, BlpAB נדרש להפרשה והעיבוד של פרומון פפטיד ופפטידים bacteriocin 2,4. לאחרונה, הוכח שחלק משמעותי מזני דלקת ריאות הם &quot;רמאים&quot;, כלומר יש להם מוטציה שמורה בגן blpA אשר הופך אותם מסוגל להפריש פרומונים וbacteriocins 1,2. זנים אלה מסוגלים להגיב לBlpC אקסוגניים 2 מופרש על ידי צהלהזנים משעממים המאפשרים הייצור של חלבוני חסינות. אמנם, הכנות גולמי של bacteriocins מsupernatants ניתן להכין מזני מפיק באמצעות צעדי שיטות ביוכימיות להשגת טוהר, גישה זו אינה שימושית לסינון אוסף גדולה של בידודים ואם רמת ביטוי bacteriocin היא נמוכה בתרבויות מרק גדל 2,7- 9. Assay הכיסוי משמש כדרך מהירה כדי לחקור את הדינמיקה התחרותית בין זנים שעלולים להתקיים במבחנה. לשם כך, מתח דלקת ריאות הוא על צלחת אגר ואפשרו לגדול כדי להשיג ריכוזי חיידקים מקומיים מספיקים לאינדוקציה של מוקד BLP-מחוסן מראש. זן שני הוא מחוסן אז לפתרון אגר רך מותך אשר לאחר מכן מיושם על זן מחוסן מראש לבדיקת רגישות. כדי להעריך את הפעילות של מוקד BLP (עצמאית של פעילות מעכבת), יכולים להיות מעולף זנים בסדרה של הרי זני כתב BlpC שתוארו קודם לכן. זנים אלו נבנו כדי להכיל אחד משלושה אללים blpH שונים שמגיבים לשלושה פרומונים BlpC הנפוצים ביותר מופרשים על ידי pneumococci. יש לי זני כתב גן lacZ משולב שנמצא תחת השליטה של אמרגן תלוי BlpH ולבצע מחיקה בגן blpC המונע גירוי עצמי 10,11.

<table border="0" cellpadding="0" cellspacing="0" width="753">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:212px;">Name of Material/ Equipment</td>
			<td style="width:71px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:351px;">Comments/Description</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:212px;">Trypticase Soy Agar with 5% Sheep Blood</td>
			<td style="width:71px;">Fisher</td>
			<td style="width:119px;">B21261X&#160;</td>
			<td>For growth from freezer cultures</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:212px;">Catalase</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">C100-500mg</td>
			<td>4,741 Units per plate</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:212px;">Todd Hewitt Broth + Yeast Extract (THY)</td>
			<td style="width:71px;">Fisher</td>
			<td style="width:119px;">DF0492-17-6&#160;</td>
			<td>30 g of THB, 5 g yeast extract, 1 L ddH20 autoclave</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:212px;">Trypticase Soy Broth + Agar plates (TSA)</td>
			<td style="width:71px;">Fisher</td>
			<td style="width:119px;">B11768&#160;</td>
			<td>30 g of TS, 15 g agar, 1 L ddH20 autoclave</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:212px;">5-Bromo-4-chloro-3-indolyl &#946;-D-galactopyranoside (X-gal)</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">B4252-50MG</td>
			<td>Dissolve in dimethylformamide</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:212px;">Petri dishes</td>
			<td style="width:71px;">Fisher</td>
			<td>FB0875712</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:212px;">Spectrophometer</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>Measures the OD620 of cultures</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:212px;">37 &#176;C water bath</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:212px;">37 &#176;C incubator with 5% CO2</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:212px;">15 ml conical tube</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

using the overlay assay to qualitatively measure bacterial production of and sensitivity to pneumococcal bacteriocins

Streptococcus pneumoniae colonizes the highly diverse polymicrobial community of the nasopharynx where it must compete with resident organisms. We have shown that bacterially produced antimicrobial peptides (bacteriocins) dictate the outcome of these competitive interactions. All fully-sequenced pneumococcal strains harbor a bacteriocin-like peptide (blp) locus. The blp locus encodes for a range of diverse bacteriocins and all of the highly conserved components needed for their regulation, processing, and secretion. The diversity of the bacteriocins found in the bacteriocin immunity region (BIR) of the locus is a major contributor of pneumococcal competition. Along with the bacteriocins, immunity genes are found in the BIR and are needed to protect the producer cell from the effects of its own bacteriocin. The overlay assay is a quick method for examining a large number of strains for competitive interactions mediated by bacteriocins. The overlay assay also allows for the characterization of bacteriocin-specific immunity, and detection of secreted quorum sensing peptides. The assay is performed by pre-inoculating an agar plate with a strain to be tested for bacteriocin production followed by application of a soft agar overlay containing a strain to be tested for bacteriocin sensitivity. A zone of clearance surrounding the stab indicates that the overlay strain is sensitive to the bacteriocins produced by the pre-inoculated strain. If no zone of clearance is observed, either the overlay strain is immune to the bacteriocins being produced or the pre-inoculated strain does not produce bacteriocins. To determine if the blp locus is functional in a given strain, the overlay assay can be adapted to evaluate for peptide pheromone secretion by the pre-inoculated strain. In this case, a series of four lacZ-reporter strains with different pheromone specificity are used in the overlay.

ישנן שתי תוצאות אפשריות בassay הכיסוי. זה צריך להיות אפשרי לראות צמיחה של הזן נדקר לאחר דגירה הלילה. באיור 1 א, מתח הכיסוי רגיש לbacteriocins שיופקו. אזור של פינוי יכול להיות דמיין המקיף את המתח נדקר. בנוסף, מתערבל של המתח נדקר לתוך תערובת הכיסוי אפשרי ושניתן לראות <strong...

Watch this Scientific Journal Video about Using the Overlay Assay to Qualitatively Measure Bacterial Production of and Sensitivity to Pneumococcal Bacteriocins at JoVE.com

Using the Overlay Assay to Qualitatively Measure Bacterial Production of and Sensitivity to Pneumococcal Bacteriocins

Competition in Streptococcus pneumoniae is mediated by bacteriocins, small antimicrobial peptides with inhibitory activity towards pneumococcus and other related species.&#160; Here we describe an optimized bacterial overlay assay that allows for the characterization of bacteriocin activity and inhibitory spectrum, bacteriocin-specific immunity, and detection of secreted quorum sensing peptides.

באמצעות assay הכיסוי למדוד את הייצור בקטריאלי ורגישות לדלקת הריאות Bacteriocins איכותי

Streptococcus pneumoniae colonizes the highly diverse polymicrobial community of the nasopharynx where it must compete with resident organisms.  We have ...

using-overlay-assay-to-qualitatively-measure-bacterial-production

Research

JoVE Journal

Immunology and Infection

13.4K Views.  University of Michigan. Competition in Streptococcus pneumoniae is mediated by bacteriocins, small antimicrobial peptides with inhibitory activity towards pneumococcus and other related species.  Here we describe an optimized bacterial overlay assay that allows for the characterization of bacteriocin activity and inhibitory spectrum, bacteriocin-specific immunity, and detection of secreted quorum sensing peptides. 

Video: Using the Overlay Assay to Qualitatively Measure Bacterial Production of and Sensitivity to Pneumococcal Bacteriocins

Using Luciferase to Image Bacterial Infections in Mice

Imaging is a valuable technique that can be used to monitor biological processes. In particular, the presence of cancer cells, stem cells, specific immune cell types, viral pathogens, parasites and bacteria can be followed in real-time within living animals 1-2. Application of bioluminescence imaging to the study of pathogens has advantages as compared to conventional strategies for analysis of infections in animal models3-4. Infections can be visualized within individual animals over time, without requiring euthanasia to determine the location and quantity of the pathogen. Optical imaging allows comprehensive examination of all tissues and organs, rather than sampling of sites previously known to be infected. In addition, the accuracy of inoculation into specific tissues can be directly determined prior to carrying forward animals that were unsuccessfully inoculated throughout the entire experiment. Variability between animals can be controlled for, since imaging allows each animal to be followed individually. Imaging has the potential to greatly reduce animal numbers needed because of the ability to obtain data from numerous time points without having to sample tissues to determine pathogen load3-4.
This protocol describes methods to visualize infections in live animals using bioluminescence imaging for recombinant strains of bacteria expressing luciferase. The click beetle (CBRLuc) and firefly luciferases (FFluc) utilize luciferin as a substrate5-6. The light produced by both CBRluc and FFluc has a broad wavelength from 500 nm to 700 nm, making these luciferases excellent reporters for the optical imaging in living animal models7-9. This is primarily because wavelengths of light greater than 600 nm are required to avoid absorption by hemoglobin and, thus, travel through mammalian tissue efficiently. Luciferase is genetically introduced into the bacteria to produce light signal10. Mice are pulmonary inoculated with bioluminescent bacteria intratracheally to allow monitoring of infections in real time. After luciferin injection, images are acquired using the IVIS Imaging System. During imaging, mice are anesthetized with isoflurane using an XGI-8 Gas Anethesia System. Images can be analyzed to localize and quantify the signal source, which represents the bacterial infection site(s) and number, respectively. After imaging, CFU determination is carried out on homogenized tissue to confirm the presence of bacteria. Several doses of bacteria are used to correlate bacterial numbers with luminescence. Imaging can be applied to study of pathogenesis and evaluation of the efficacy of antibacterial compounds and vaccines.

Methods for bioluminescence imaging of bacterial infections in living animals are decribed. Pathogens are modified to express luciferase allowing optical whole body imaging of infections in live animals. Animal models can be infected with luciferase expressing pathogens and the resulting course of disease visualized in real-time by bioluminescence imaging.

שימוש בלוציפראז לזיהומים חיידקיים תמונה ב עכברים

Imaging is a valuable technique that can be used to monitor biological processes.  In particular, the presence of cancer cells, stem cells, specific ...

A Functional Whole Blood Assay to Measure Viability of Mycobacteria, using Reporter-Gene Tagged BCG or M.Tb (BCG lux/M.Tb lux)

Functional assays have long played a key role in measuring of immunogenicity of a given vaccine. This is conventionally expressed as serum bactericidal titers. Studies of serum bactericidal titers in response to childhood vaccines have enabled us to develop and validate cut-off levels for protective immune responses and such cut-offs are in routine use. No such assays have been taken forward into the routine assessment of vaccines that induce primarily cell-mediated immunity in the form of effector T cell responses, such as TB vaccines. In the animal model, the performance of a given vaccine candidate is routinely evaluated in standardized bactericidal assays, and all current novel TB-vaccine candidates have been subjected to this step in their evaluation prior to phase 1 human trials. The assessment of immunogenicity and therefore likelihood of protective efficacy of novel anti-TB vaccines should ideally undergo a similar step-wise evaluation in the human models now, including measurements in bactericidal assays.
Bactericidal assays in the context of tuberculosis vaccine research are already well established in the animal models, where they are applied to screen potentially promising vaccine candidates. Reduction of bacterial load in various organs functions as the main read-out of immunogenicity. However, no such assays have been incorporated into clinical trials for novel anti-TB vaccines to date.
Although there is still uncertainty about the exact mechanisms that lead to killing of mycobacteria inside human macrophages, the interaction of macrophages and T cells with mycobacteria is clearly required. The assay described in this paper represents a novel generation of bactericidal assays that enables studies of such key cellular components with all other cellular and humoral factors present in whole blood without making assumptions about their relative individual contribution. The assay described by our group uses small volumes of whole blood and has already been employed in studies of adults and children in TB-endemic settings. We have shown immunogenicity of the BCG vaccine, increased growth of mycobacteria in HIV-positive patients, as well as the effect of anti-retroviral therapy and Vitamin D on mycobacterial survival in vitro. Here we summarise the methodology, and present our reproducibility data using this relatively simple, low-cost and field-friendly model.
Note: Definitions/Abbreviations
BCG lux = M. bovis BCG, Montreal strain, transformed with shuttle plasmid pSMT1 carrying the luxAB genes from Vibrio harveyi, under the control of the mycobacterial GroEL (hsp60) promoter. 
CFU = Colony Forming Unit (a measure of mycobacterial viability).

A Functional Whole Blood Assay to Measure Viability of Mycobacteria, using Reporter-Gene Tagged BCG or M.Tb BCG lux/M.Tb lux

We describe an alternative approach to the enumeration of mycobacteria in vitro, which uses reporter-gene tagged mycobacteria instead of colony-forming units (CFU). &#x201C;Survival&#x201D; of organisms as well as host response-markers are measured simultaneously, providing a low-cost, versatile and functional system for studies of host/pathogen interactions in the context of tuberculosis.

Assay פונקציונלית הדם כולו כדי למדוד את הכדאיות של mycobacteria, באמצעות הכתב-Gene Tagged BCG או מ Tb (BCG לוקס / מ Tb לוקס)

Functional assays have long played a key role in measuring of immunogenicity of a given vaccine. This is conventionally expressed as serum bactericidal ...

A Visual Assay to Monitor T6SS-mediated Bacterial Competition

Type VI secretion systems (T6SSs) are molecular nanomachines allowing Gram-negative bacteria to transport and inject proteins into a wide variety of target cells1,2. The T6SS is composed of 13 core components and displays structural similarities with the tail-tube of bacteriophages3. The phage uses a tube and a puncturing device to penetrate the cell envelope of target bacteria and inject DNA. It is proposed that the T6SS is an inverted bacteriophage device creating a specific path in the bacterial cell envelope to drive effectors and toxins to the surface. The process could be taken further and the T6SS device could perforate other cells with which the bacterium is in contact, thus injecting the effectors into these targets. The tail tube and puncturing device parts of the T6SS are made with Hcp and VgrG proteins, respectively4,5.
The versatility of the T6SS has been demonstrated through studies using various bacterial pathogens. The Vibrio cholerae T6SS can remodel the cytoskeleton of eukaryotic host cells by injecting an "evolved" VgrG carrying a C-terminal actin cross-linking domain6,7. Another striking example was recently documented using Pseudomonas aeruginosa which is able to target and kill bacteria in a T6SS-dependent manner, therefore promoting the establishment of bacteria in specific microbial niches and competitive environment8,9,10.
In the latter case, three T6SS-secreted proteins, namely Tse1, Tse2 and Tse3 have been identified as the toxins injected in the target bacteria (Figure 1). The donor cell is protected from the deleterious effect of these effectors via an anti-toxin mechanism, mediated by the Tsi1, Tsi2 and Tsi3 immunity proteins8,9,10. This antimicrobial activity can be monitored when T6SS-proficient bacteria are co-cultivated on solid surfaces in competition with other bacterial species or with T6SS-inactive bacteria of the same species8,11,12,13.
The data available emphasized a numerical approach to the bacterial competition assay, including time-consuming CFU counting that depends greatly on antibiotic makers. In the case of antibiotic resistant strains like P. aeruginosa, these methods can be inappropriate. Moreover, with the identification of about 200 different T6SS loci in more than 100 bacterial genomes14, a convenient screening tool is highly desirable. We developed an assay that is easy to use and requires standard laboratory material and reagents. The method offers a rapid and qualitative technique to monitor the T6SS-dependent bactericidal/bacteriostasis activity by using a reporter strain as a prey (in this case Escherichia coli DH5&alpha;) allowing a-complementation of the lacZ gene. Overall, this method is graphic and allows rapid identification of T6SS-related phenotypes on agar plates. This experimental protocol may be adapted to other strains or bacterial species taking into account specific conditions such as growth media, temperature or time of contact.

We describe a qualitative assay to monitor bacterial competition mediated by the Pseudomonas aeruginosa type VI secretion system (T6SS). The assay relies on the survival/killing of Escherichia coli target cells carrying a lacZ-reporter. This technique is adjustable to assess the bactericidal/bacteriostasis activity of T6SS-proficient microorganisms.

Assay חזותי לפקח תחרות קטריאלי T6SS בתיווך

Type VI secretion systems (T6SSs) are molecular  nanomachines allowing Gram-negative bacteria to transport and inject proteins  into a wide variety of ...

Using Click Chemistry to Measure the Effect of Viral Infection on Host-Cell RNA Synthesis

Many RNA viruses have evolved the ability to inhibit host cell transcription as a means to circumvent cellular defenses. For the study of these viruses, it is therefore important to have a quick and reliable way of measuring transcriptional activity in infected cells. Traditionally, transcription has been measured either by incorporation of radioactive nucleosides such as 3H-uridine followed by detection via autoradiography or scintillation counting, or incorporation of halogenated uridine analogs such as 5-bromouridine (BrU) followed by detection via immunostaining. The use of radioactive isotopes, however, requires specialized equipment and is not feasible in a number of laboratory settings, while the detection of BrU can be cumbersome and may suffer from low sensitivity.
The recently developed click chemistry, which involves a copper-catalyzed triazole formation from an azide and an alkyne, now provides a rapid and highly sensitive alternative to these two methods. Click chemistry is a two step process in which nascent RNA is first labeled by incorporation of the uridine analog 5-ethynyluridine (EU), followed by detection of the label with a fluorescent azide. These azides are available as several different fluorophores, allowing for a wide range of options for visualization.
This protocol describes a method to measure transcriptional suppression in cells infected with the Rift Valley fever virus (RVFV) strain MP-12 using click chemistry. Concurrently, expression of viral proteins in these cells is determined by classical intracellular immunostaining. Steps 1 through 4 detail a method to visualize transcriptional suppression via fluorescence microscopy, while steps 5 through 8 detail a method to quantify transcriptional suppression via flow cytometry. This protocol is easily adaptable for use with other viruses.

This method describes the use of click chemistry to measure changes in host cell transcription after infection with the Rift Valley fever virus (RVFV) strain MP-12. Results can be visualized qualitatively via fluorescence microscopy or obtained quantitatively through flow cytometry. This method is adaptable for use with other viruses.

שימוש בכימיה לחץ כדי למדוד את ההשפעה של זיהום ויראלי בסינתזת RNA Host-Cell

Many RNA viruses have evolved the ability to inhibit host cell transcription as a means to circumvent cellular defenses. For the study of these viruses, ...

Investigating the Effects of Probiotics on Pneumococcal Colonization Using an In Vitro Adherence Assay

Adherence of Streptococcus pneumoniae (the pneumococcus) to the epithelial lining of the nasopharynx can result in colonization and is considered a prerequisite for pneumococcal infections such as pneumonia and otitis media. In vitro adherence assays can be used to study the attachment of pneumococci to epithelial cell monolayers and to investigate potential interventions, such as the use of probiotics, to inhibit pneumococcal&#160;colonization.&#160;The protocol described here is used to investigate the effects of the probiotic Streptococcus salivarius on the adherence of pneumococci to the human epithelial cell line CCL-23 (sometimes referred to as HEp-2 cells). The assay involves three main steps: 1) preparation of epithelial and bacterial cells, 2) addition of bacteria to epithelial cell monolayers, and 3) detection of adherent pneumococci by viable counts (serial dilution and plating) or quantitative real-time PCR (qPCR). This technique is relatively straightforward and does not require specialized equipment other than a tissue culture setup. The assay can be used to test other probiotic species and/or potential inhibitors of pneumococcal colonization and can be easily modified to address other scientific questions regarding pneumococcal adherence and invasion.

Investigating the Effects of Probiotics on Pneumococcal Colonization Using an In Vitro Adherence Assay

In vitro adherence assays can be used to study the attachment of Streptococcus pneumoniae to epithelial cell monolayers and to investigate potential interventions such as the use of probiotics for inhibiting pneumococcal colonization.

חוקר את ההשפעות של פרוביוטיקה על דלקת ריאות התיישבות שימוש<em&gt; במבחנה</em&gt; Assay דבקות

Adherence of Streptococcus pneumoniae (the pneumococcus) to the epithelial lining of the nasopharynx can result in colonization and is considered a ...

Cell-based Flow Cytometry Assay to Measure Cytotoxic Activity

Cytolytic activity of CD8+ T cells is rarely evaluated. We describe here a new cell-based assay to measure the capacity of antigen-specific CD8+ T cells to kill CD4+ T cells loaded with their cognate peptide. Target CD4+ T cells are divided into two populations, labeled with two different concentrations of CFSE. One population is pulsed with the peptide of interest (CFSE-low) while the other remains un-pulsed (CFSE-high). Pulsed and un-pulsed CD4+ T cells are mixed at an equal ratio and incubated with an increasing number of purified CD8+ T cells. The specific killing of autologous target CD4+ T cells is analyzed by flow cytometry after coculture with CD8+ T cells containing the antigen-specific effector CD8+ T cells detected by peptide/MHCI tetramer staining. The specific lysis of target CD4+ T cells measured at different effector versus target ratios, allows for the calculation of lytic units, LU30/106 cells. This simple and straightforward assay allows for the accurate measurement of the intrinsic capacity of CD8+ T cells to kill target CD4+ T cells.

This protocol describes a sensitive, cell-based cytotoxicity assay. By enumerating the decrease in frequency of live target CD4+ T cells in the presence of an increasing number of effector CD8+ T cells, this assay allows for the direct assessment of cytolytic activity of antigen-specific CD8+ T cells.

Cytolytic activity of CD8+ T cells is rarely evaluated. We describe here a new cell-based assay to measure the capacity of antigen-specific CD8+ T cells ...

Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction

There are over 90 different capsular serotypes of Streptococcus pneumoniae (the pneumococcus). As well as being a tool for understanding pneumococcal epidemiology, capsular serotyping can provide useful information for vaccine efficacy and impact studies.&#160;The Quellung reaction is the gold standard method for pneumococcal capsular serotyping. The method involves testing a pneumococcal cell suspension with pooled and specific antisera directed against the capsular polysaccharide. The antigen-antibody reactions are observed microscopically. The protocol has three main steps: 1) preparation of a bacterial cell suspension, 2) mixing of cells and antisera on a glass slide, and 3) reading the Quellung reaction using a microscope. The Quellung reaction is reasonably simple to perform and can be applied wherever a suitable microscope and antisera are available.

Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction

The Quellung reaction is the gold standard technique for serotyping Streptococcus pneumoniae. This technique utilizes a microscope and specific pneumococcal antisera and is commonly used in reference and research laboratories worldwide.

קופסית Serotyping של<em&gt; Streptococcus pneumoniae</em&gt; שימוש תגובת Quellung

There are over 90 different capsular serotypes of Streptococcus pneumoniae (the pneumococcus). As well as being a tool for understanding pneumococcal ...

Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination

Latex agglutination reagents are widely used in microbial diagnosis, identification and serotyping. Streptococcus pneumoniae (the pneumococcus) is a major cause of morbidity and mortality world-wide. Current vaccines target the pneumococcal capsule, and there are over 90 capsular serotypes. Serotyping pneumococcal isolates is therefore important for assessing the impact of vaccination programs and for epidemiological purposes. The World Health Organization has recommended latex agglutination as an alternative method to the &#8216;gold standard&#8217; Quellung test for serotyping pneumococci. Latex agglutination is a relatively simple, quick and inexpensive method; and is therefore suitable for resource-poor settings as well as laboratories with high-volume workloads. Latex agglutination reagents can be prepared in-house utilizing commercially-sourced antibodies that are passively attached to latex particles. This manuscript describes a method of production and quality control of latex agglutination reagents, and details a sequential testing approach which is time- and cost-effective. 
This method of production and quality control may also be suitable for other testing purposes.

Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination

Latex agglutination testing is a simple, rapid and inexpensive method for serotyping Streptococcus pneumoniae, and has also been widely applied in diagnostic microbiology. This manuscript describes the in-house production of latex agglutination reagents, quality control procedures and the application of this technique to pneumococcal serotyping.

קופסית Serotyping של<em&gt; Streptococcus pneumoniae</em&gt; על ידי לאטקס התלכדות

Latex agglutination reagents are widely used in microbial diagnosis, identification and serotyping. Streptococcus pneumoniae (the pneumococcus) is a major ...

Methods to Inhibit Bacterial Pyomelanin Production and Determine the Corresponding Increase in Sensitivity to Oxidative Stress

Pyomelanin is an extracellular red-brown pigment produced by several bacterial and fungal species. This pigment is derived from the tyrosine catabolism pathway and contributes to increased oxidative stress resistance. Pyomelanin production in Pseudomonas aeruginosa is reduced in a dose dependent manner through treatment with 2-[2-nitro-4-(trifluoromethyl)benzoyl]-1,3-cyclohexanedione (NTBC). We describe a titration method using multiple concentrations of NTBC to determine the concentration of drug that will reduce or abolish pyomelanin production in bacteria. The titration method has an easily quantifiable outcome, a visible reduction in pigment production with increasing drug concentrations. We also describe a microtiter plate method to assay antibiotic minimum inhibitory concentration (MIC) in bacteria. This method uses a minimum of resources and can easily be scaled up to test multiple antibiotics in one microtiter plate for one strain of bacteria. The MIC assay can be adapted to test the affects of non-antibiotic compounds on bacterial growth at specific concentrations. Finally, we describe a method for testing bacterial sensitivity to oxidative stress by incorporating H2O2 into agar plates and spotting multiple dilutions of bacteria onto the plates. Sensitivity to oxidative stress is indicated by reductions in colony number and size for the different dilutions on plates containing H2O2 compared to a no H2O2 control. The oxidative stress spot plate assay uses a minimum of resources and low concentrations of H2O2. Importantly, it also has good reproducibility. This spot plate assay could be adapted to test bacterial sensitivity to various compounds by incorporating the compounds in agar plates and characterizing the resulting bacterial growth.

Bacterial pyomelanin production results in increased resistance to oxidative stress and virulence. We report on techniques that can be used to determine inhibition of pyomelanin production and assay the resulting increase in sensitivity to oxidative stress in bacteria, as well as determine antibiotic minimum inhibitory concentration (MIC).

שיטות לעכב קטריאלי Pyomelanin ייצור וקבעו את הגידול המקביל ברגישות לסטרס חמצונים

Pyomelanin is an extracellular red-brown pigment produced by several bacterial and fungal species. This pigment is derived from the tyrosine catabolism ...

Use of the Soft-agar Overlay Technique to Screen for Bacterially Produced Inhibitory Compounds

The soft-agar overlay technique was originally developed over 70 years ago and has been widely used in several areas of microbiological research, including work with bacteriophages and bacteriocins, proteinaceous antibacterial agents. This approach is relatively inexpensive, with minimal resource requirements. This technique consists of spotting supernatant from a donor strain (potentially harboring a toxic compound(s)) onto a solidified soft agar overlay that is seeded with a bacterial test strain (potentially sensitive to the toxic compound(s)). We utilized this technique to screen a library of Pseudomonas syringae strains for intraspecific killing. By combining this approach with a precipitation step and targeted gene deletions, multiple toxic compounds produced by the same strain can be differentiated. The two antagonistic agents commonly recovered using this technique are bacteriophages and bacteriocins. These two agents can be differentiated using two simple additional tests. Performing a serial dilution on a supernatant containing bacteriophage will result in individual plaques becoming less in number with greater dilution, whereas serial dilution of a supernatant containing bacteriocin will result a clearing zone that becomes uniformly more turbid with greater dilution. Additionally, a bacteriophage will produce a clearing zone when spotted onto a fresh soft agar overlay seeded with the same strain, whereas a bacteriocin will not produce a clearing zone when transferred to a fresh soft agar lawn, owing to the dilution of the bacteriocin.

We describe a simple method for screening bacterial cultures for the production of compounds inhibitory towards other bacteria.