Development of Fluorescein-Labelled Antisera for Rapid Detection of Rabbit Haemorrhagic Disease Virus

The present study was intended to prepare and evaluate the applicability of fluorescein-conjugated anti-RHDV polyclonal antibodies for routine diagnosis and research purposes. A total of 22 animals (10 rabbits, 10 guinea pigs and 2 goats) were immunized subcutaneously with locally prepared RHDV inactivated vaccine containing 210 HAU per ml (rabbits and guinea pigs received 0.5 ml per dose, meanwhile goats received 1ml). Five doses with 7 days intervals were applied. The last dose was simultaneously injected with Montanide™ ISA 206 oil adjuvant. Five weeks post-immunization, RHDV-specific HI antibody titers were significantly increased and reached to the peak level with a mean titer of 7, 8 and 8.5 log2 in guinea pig, rabbit and goat sera, respectively. The globulin fraction of the prepared antisera was calculated, successfully precipitated with ammonium sulphate and then conjugated with flourescein isothiocyanate (FITC). The application of direct immunoflourecent (IF) test on impression smears prepared from tissues of experimentally infected rabbits with RHDV isolate Giza-2006, revealed that positive reactions were obtained with guinea pig, rabbit and goat conjugates up to a dilution of 10^-4, 10^-5 and 10^-6 respectively. These findings clearly indicate that fluorescein-conjugated polyclonal antibodies developed in the present study can be used for accurate and precise diagnosis of RHDV.