## How do you calculate TCID50?

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