A virologist has a cell-free extract of herpes simplex virus (HSV) that has a titer of 6 x 10^6 infectious virus particles/mL. This virus forms plaques on monolayers of the monkey kidney cell line, CV-1. Following completion of a 10-fold dilution series, the virologist plates 100uL of each sample in duplicate. Which of the following experimental results did he MOST LIKELY observe in the duplicate plates corresponding to his 1:10000 dilution? TMTC = Too Many to Count
(A) TMTC (Plate 1); TMTC (Plate 2)
(B) 61 (Plate 1); 59 (Plate 2)
(C) 96 (Plate 1); 97 (Plate 2)
(D) 8 (Plate 1); 10 (Plate 2)
(E) 26 (Plate 1); 24 (Plate 2)
Answer: (B) 61 (Plate 1); 59 (Plate 2)
The original stock has the concentration 6 × 10^6 infectious virus particles/ mL.
This was diluted by the factor 1:10000
This leaves:
(6,000,000) ÷ 10,000
= 600 inf virus particles/ mL
100 microL (0.1 mL) of this was plated.
Since 1 mL has a count of 600
0.1 mL has a count of 60.
Hence the answer is (B).
Alternatively, if 1 mL was plated,the answer would have been A: TMTC since a count of over 30 - 300 is the countable range.
A virologist has a cell-free extract of herpes simplex virus (HSV) that has a titer of...
You are working in a virology lab and are given a sample of high-titer influenza type A virus and Madin-Darby canine kidney (MDCK) epithelial cells which you seed into tissue culture plates. After culturing the MDCK cells to obtain confluent monolayers, your task is to determine the virus titer and express this titer in pfu/1000uL. You therefore make four 100-fold dilutions and one 10-fold dilution of the neat virus stock and plate 500uL of the final dilution. After 72 hours,...
Dilutions. In the following example: a. What is the titer of the virus? b. Is the virus titer high enough of the newly arrived virus shipment to be used as a control in the experiment? c. Show your work Note: The virus titer needed as a control in the experiment was at least 1 x 10^7 viruses per ml. The control virus stock arrived from the ATCC distributor arrived frozen and was labeled as 3x10^8 viruses/ml (equal to 300,000,000 viruses/ml...