TITRATION OF ANTIBODIES BY RAPID FLUORESC ENT FOCUS INHIBITION TEST (RFFIT)

Antirabies virus neutralization antibodies in sera and/or transudates modified RFFIT method by Smith et al. (1973). Sera were titrated on La b-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 i ncubated at 37 degrees C during 90 minutes subsequently BHK-21/C13 cel l 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 rang e of view were infected (fluorescent inclusions can be observed). The antirabic reference serum was used as a control in RFFIT in each exami ned serum. To ensure a good control, the serum was diluted to contain 0.5 IU/ml of antirabic virus neutralization antibodies. Sera and/or tr ansudates 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 laborato ries for rabies (NRPB) in Kosice. Samples were examined for the monito ring of efficiency of oral antirabic vaccination. The parallel quantif ication of antirabic antibodies by virus neutralization test (VNT) in vivo was applied to mice and indirect haemagglutination test (NHT). Th e results of these three tests are comparable or in correlation. RFFIT has many advantages. When using highly attenuated strain Vnukovo-32/1 07th passage as the challenge virus in RFFIT method the potentional ri sk of laboratory exposition is absent.