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. 2017 Aug 4;15(8):e04952. doi: 10.2903/j.efsa.2017.4952

Table 9.

Performance characteristics for diagnostic tests and comments thereon

Method Commonly tested matrices Se Sp Comments
Agent identification
Virus isolation Serum, buffy coat, leucocytes, whole blood, tissues, semen 100% 100%

  • Historically considered the gold standard Lanyon et al. (2014) but less commonly used now due to issues of time, cost and requirement for cell culture

  • Toxicity to cell cultures can be an issue, especially with semen

  • Maternally derived antibodies (MDA) may interfere with isolation from serum in young calves
Antigen detection by ELISA Serum, plasma, whole blood, tissues (including ear notch) 93.5–100% Hilbe et al. (2007) and Presi and Heim (2010) 99–100% Hilbe et al. (2007) and Presi and Heim (2010)

  • Not intended for the detection of acutely infected animals, although may occasionally do so

  • The Erns ELISA may be less effective in young calves in the presence of MDA when testing serum Fux and Wolf (2013)

  • The NS2‐3 ELISA may be less effective in young calves in the presence of MDA when testing serum or tissue Fux and Wolf (2013)
Antigen detection by IHC Tissue 100% Cornish et al. (2016) Not available

  • Skin biopsies such as ear notch samples have been shown to be useful for in vivo detection of PI animals Cornish et al. (2016)

  • While perceived as robust and suitable for large numbers of tissue samples, it is labour intensive, prone to technical error, relies on a subjective scoring system, requires experienced personnel to ensure accuracy and is unreliable for use on samples stored in formalin for > 15 days Lanyon et al. (2014)
NA detection by real time RT‐PCR Serum, buffy coat, leucocytes, whole blood, tissues, semen, milk, bulk tank milk 97.1–100% Hilbe et al. (2007) and Presi and Heim (2010) 99–100% Hilbe et al. (2007) and Presi and Heim (2010)

  • High analytical sensitivity allows pooled samples (ear notch, serum) and bulk tank milk to be tested

  • Detection of viral RNA does not imply per se that infective virus is present
Detection of immune response
ELISA Serum, milk, bulk tank milk Up to 98% Presi and Heim (2010) Up to 99% Presi and Heim (2010)

  • Both indirect and blocking assays are commercially available

  • Indirect more sensitive for bulk tank testing Foddai et al. (2015)
VN Serum 100% 100%

  • Considered the gold standard test, but time‐consuming and expensive to perform