# How do you calculate TCID50?

## How do you calculate TCID50?

1. Calculate Proportionate Distance (PD) between the two dilutions in between 50%
2. Calculate 50 % end point. Log lower dilution= dilution in which position is next.
3. Add PD and Log lower dilution. Example above: -6 + .375 =-6.375.
4. Calculate TCID 50/ml. Divide by the ml of viral innoculum added to row A.
5. Calculate PFU/ml.

## What is TCID50?

The TCID50 (Median Tissue Culture Infectious Dose) assay is one method used to verify the viral titer of a testing virus. Host tissue cells are cultured on a well plate titer, and then varying dilutions of the testing viral fluid are added to the wells.

What are the units of TCID50?

This assay reports titer in terms of TCID50 units per ml, where TCID50 stands for “tissue-culture infectious dose.” One TCID50 unit per ml is essentially an approximation of 1 pfu per ml, but since plaques are not being scored, the term “pfu” is not accurate.

### What is the Spearman Karber method?

Spearman-Karber method ni = number of animals used in each individual dilution (after discounting accidental deaths); ri = number of positive animals (out of ni). Summation is started at dilution x0.

### How to calculate the TCID 50 end point?

TCID 50 Calculation Example 1. Calculate Proportionate Distance (PD) between the two dilutions in between 50% death: (% next above 50%)- 50% / (% next above 50%) – (% next below 50%) Example above: PD= 80%-50% / 80%-0%= 30/80= .375 2. Calculate 50 % end point. Log lower dilution= dilution in which position is next above 50%

How to calculate the dilution factor of TCID50?

TCID50 calculations, sample in rows A–D: Column 1 dilution Enter as decimal e.g. dilution factor of 1:1250 = dilution of 0.0008 Serial dilution factor Enter as an integer e.g. 1:5 = 5 Wells per dilution Reed-Muench only valid when replicates per dilution are constant, do not use for plates with missing wells Volume per well

## How to calculate the TCID50 of a virus?

Viral Titering-TCID50 Assay Protocol 1 Seed culture plate with host cells. Seed 7 x 10 4 cells per ml in growth media on each well of 48-well plates. 2 Prepare serial dilutions of viruses. Make a series of dilutions at 1:10 of the original virus sample. 3 Infect monolayer cells. 4 Visualization and calculation of TCID50.

## What does TCID 50 mean in tissue culture?

TCID 50 is the tissue culture infectious dose defined as that dilution of virus required to infect 50% of the cell monolayers. There are several statistical approaches for analyzing the data generated (such as Probit formula or Spearman-Karber analysis).