[Titration of rabies antibodies with the rapid fluorescence focus inhibition test]

Antirabies virus neutralization antibodies in sera and/or transudates modified RFFIT method by Smith et al. (1973). Sera were titrated on Lab-Tek 8 chamber TC slides. Sera and/or transudates (content of pleural cavity) as well as the challenge virus strain (vaccination strains of the rabies virus Vnukovo-32/107th passage and/or CVS 11/Paris) were incubated at 37 degrees C during 90 minutes subsequently BHK-21/C13 cell culture was added. The cultures were fixed after 24 to 48 hours and stained with antirabic fluorescent conjugate (Bioveta a.s., Ivanovice n. H., Czech Republic). The highest dilution of the virus was used as the challenge dose where 50 percent of the cells in the examined range of view were infected (fluorescent inclusions can be observed). The antirabic reference serum was used as a control in RFFIT in each examined serum. To ensure a good control, the serum was diluted to contain 0.5 IU/ml of antirabic virus neutralization antibodies. Sera and/or transudates which were sent to our Laboratory were examined in this way. We examined 40 sera or pleural transudates of orally vaccinated foxes by those methods. These sera were sent to National reference laboratories for rabies (NRPB) in Kosice. Samples were examined for the monitoring of efficiency of oral antirabic vaccination. The parallel quantification of antirabic antibodies by virus neutralization test (VNT) in vivo was applied to mice and indirect haemagglutination test (NHT). The results of these three tests are comparable or in correlation. RFFIT has many advantages. When using highly attenuated strain Vnukovo-32/107th passage as the challenge virus in RFFIT method the potential risk of laboratory exposition is absent.