Detection of parvovirus B19 in macerated fetal tissue using in situ hybridisation.

Aims: To compare the application of a non-radioactive in situ hybridisation (ISH) technique with an immunocytochemical technique for the detection of human parvovirus B19 in formalin fixed, paraffin wax embedded sections of macerated fetal tissue.

Methods: Archived samples of liver, lung or kidney from 19 human fetuses were investigated for parvovirus B19 using a full length digoxigenin labelled DNA probe of 5.5 kb; bound probe was detected using an anti-digoxigenin (alkaline phosphatase) conjugate and visualised using NBT/BCIP. Immunocytochemical detection of parvovirus B19 was performed using a monoclonal mouse antiparvovirus B19 antiserum, with a streptavidin-biotin complex (horse radish peroxidase) method. Cases were selected to provide a range of diagnostic certainty and a range of degrees of macerative degeneration.

Results: Parvovirus B19 was found in 15 of 19 cases using the B19 ISH technique compared with 8 of 19 cases using the immunocytochemical technique. The four negative cases were all controls known to be parvovirus B19 free. All ISH positive cases showed excellent staining with low background regardless of extent of maceration and tissue type. In comparison, sections stained by the immunocytochemical method showed considerable non-specific immunoreactivity in many cases, particularly with severe maceration. Kidney and lung tissues gave the cleanest results.

Conclusions: ISH is more effective than the immunocytochemical technique for the detection of human parvovirus B19 in macerated fetal tissue. The lack of detectable background staining with the ISH technique led to easier interpretation suggesting that this technique should be the method of choice for the investigation of parvovirus B19 in macerated postmortem tissues.