DIAGNOSIS OF FETAL INFECTION WITH PORCINE PARVOVIRUS BY IN-SITU HYBRIDIZATION

In situ hybridization (ISH) for the diagnosis of fetal infection with porcine parvovirus (PPV) was compared with immune electron microscopy (IEM) and serology by immunofluorescence (IF) for its sensitivity and its applicability in a routine diagnostic laboratory. The technique wa s applied to the examination of sections of formalin-fixed paraffin-em bedded tissues from 68 fetuses. Fifty-three of these fetuses were diag nosed serologically since they had a crown rump length of more than 17 cm, i.e. they were mature enough to mount a humoral immune response; 38 were positive and 15 negative. Eleven out of 15 smaller fetuses exa mined for the presence of viral antigen by immune electron microscopy (IEM) were positive and 4 were negative. Heart and lung were found to be the most suitable organs for in situ hybridization. In situ hybridi zation yielded a positive result in 8 of the 11 IEM positive fetuses a nd in 33 of the 38 serologically positive fetuses. No signal was detec ted in any of the 4 IEM or the 13 serologically negative fetuses. Expe nses for IEM were estimated to be 179% of the expenses for ISH. Expens es for serology by IF on the other hand were 67% of the expenses for I SH. From this it was concluded that the most efficient way to diagnose a fetal infection with PPV was serology by IF, if possible with sampl es from several fetuses and that the other techniques, IEM or ISH, oug ht to be reserved for those cases where no immunocompetent fetuses wer e available for diagnosis.