# OrthoANI

## What is OrthoANI? <a href="#what-is-orthoani" id="what-is-orthoani"></a>

OrthoANI (Orthologous Average Nucleotide Identity) is a kind of similarity value between two genome sequences. It is an improved version of the original ANI (Average Nucleotide Identity) and is one of the OGRIs. It can be used for classification and identification of Bacteria, and the proposed cutoff for species boundary is 95\~96%. The algorithm was published by [Lee et al. (2015)](http://ijs.microbiologyresearch.org/content/journal/ijsem/10.1099/ijsem.0.000760?ref=blog.ezbiocloudpro.com). Later, we developed a faster version, named OrthiANIu, using USEARCH program instead of BLAST. The software tools are available as a web service and standalone program.

* To calculate OrthoANIu between two genomes, visit [here](http://www.ezbiocloud.net/tools/ani?ref=blog.ezbiocloudpro.com).
* To download the standalone program, visit [here](http://www.ezbiocloud.net/tools/orthoaniu?ref=blog.ezbiocloudpro.com).

OrthoANIu is the standard algorithm used to build the [EzBioCloud database](http://www.ezbiocloud.net/?ref=blog.ezbiocloudpro.com). The publication for the OrthoANIu tool is available [here](https://www.ncbi.nlm.nih.gov/pubmed/28204908?ref=blog.ezbiocloudpro.com).

## **How is it different from ANI?**

The major differences between the original ANI and OrthoANI are:

* For the original ANI, you need to obtain the reciprocal values (i.e., A->B & B->A), and use the mean value for taxonomic use. In contrast, you only need a single value (A<->B) for OrthoANI.
* OrthoANI is faster than the original ANI.

## References <a href="#span-classeztocsection-idreferencesspanreferencesspan-classeztocsectionendspan" id="span-classeztocsection-idreferencesspanreferencesspan-classeztocsectionendspan"></a>

Lee, I., Ouk Kim, Y., Park, S. C., & Chun, J. (2016). OrthoANI: an improved algorithm and software for calculating average nucleotide identity. *International journal of systematic and evolutionary microbiology*, *66*(2), 1100-1103.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://kb.ezbiocloud.net/home/science-blogs/basics/orthoani.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.