|Abstract or Summary
- Mycobacteriosis is a common disease of laboratory zebrafish Danio rerio. Different
infection patterns occur in zebrafish depending on mycobacterial species. Mycobacterium marinum
and M. haemophilum produce virulent infections associated with high mortality, whereas M.
chelonae is more widespread and is not associated with high mortality. Identification of mycobacterial
infections to the species level provides important information for making management decisions.
Observation of acid-fast bacilli in histological sections or tissue imprints is the most common
diagnostic method for mycobacteriosis in fish, but only allows for diagnosis to the genus level.
Mycobacterial culture followed by molecular or biochemical identification is the traditional
approach, but DNA of diagnostic value can also be retrieved from paraffin blocks. Here we investigated
the type of fixative, time in fixative before processing, species of mycobacteria, and severity
of infection as parameters to determine whether the hsp gene PCR assay (primer set
HS5F/hsp667R) could detect and amplify mycobacterial DNA from paraffin-embedded zebrafish.
Whole zebrafish were experimentally infected with either M. chelonae or M. marinum, and then
preserved in 10% neutral buffered formalin or Dietrich’s fixative for 3, 7, 21, and 45 d. Subsequently,
fish were evaluated by hematoxylin and eosin and Fite’s acid-fast stains to detect
mycobacteria within granulomatous lesions. The PCR assay was quite effective and obtained PCR
product from 75 and 88% of the M. chelonae- and M. marinum-infected fish, respectively. Fixative
type, time in fixative, and mycobacterial species showed no statistical relationship with the efficacy
of the PCR test.
- Peterson, T. S., Kent, M. L., Ferguson, J. A., Watral, V. G., & Whipps, C. M. (2013). Comparison of fixatives and fixation time for PCR detection of mycobacterium in zebrafish danio rerio. Diseases of Aquatic Organisms, 104(2), 113-120. doi:10.3354/dao02585
|Funding Statement (additional comments about funding)