The Erns Advantage

The Erns Advantage.png

The IDEXX antigen ELISA is based on the detection of the Erns protein which forms a part of the virus structure. There are several features of the Erns protein that make it the preferred method for detection. 
The BVD virus is an RNA virus; RNA viruses are not as good at ‘proofreading’ when they replicate, and so have much higher mutation rates. Mutation can make testing inconsistent as when mutations occur a test may no longer recognise it. The Erns protein is a structural protein, it is a very important building block of the virus, so it is very stable and less prone to mutation. This is part of the reason the IDEXX test is able to more consistently identify BVD and is able to consistently identify BVD across the different genotypes and strains.

The E in Erns stands for envelope protein and the rns stands for Rnase secreted. Erns is secreted by the BVD virus in vast amounts thus making it an excellent target to test for as it is present in the serum, plasma, whole blood and tissue. Erns is also resistant to changes in temperature and is less influenced by passive immunity which again aids with its stability and availability. 
The Erns advantage is that it’s unique characteristics has allowed IDEXX to develop a high performing, highly standardised, fast and highly accurate test for BVD.


Testing all calves for BVD is an easy and economical way to identify and remove Persistently Infected, (PI), animals from your herd.


To find Persistently Infected BVD calves, test with New Zealand’s superior BVD Ear Notch test, the IDEXX Antigen ELISA.


A recent trial conducted in New Zealand using the IDEXX Antigen ELISA on ear notch samples showed it to be the preferred test for identifying Persistently Infected Calves of any age with a single ear notch sample. For more detail on this study by Dr. Scott McDougall of Cognosco Animal Health and Production Research CLICK HERE to view the webinar.

IDEXX antigen ELISA has a Sensitivity of 100% and a Specificity > 99.7%.  

  • Economical - High sensitivity means no false-negative results and less confirmatory tests. 

  • Fast - High Specificity means you don’t need to worry about false positives

  • Accurate - Gives correct results even with samples of reduced quality (dirty or old samples).

The IDEXX Ag ELISA has been used in millions of tests globally for over 20 years and is used in eradication programs across Europe.