Comparative evaluation of some techniques used for the detection of rabies virus.

BACKGROUND: Neurotropic viruses in the family Rhabdoviridae, genus Lyssavirus , are what cause rabies, an acute, progressive, and highly lethal encephalomyelitis.

AIM: Evaluation of the used diagnostic techniques to determine the most simple; rapid and accurate test for rabies virus (RABV) recognition in different specimens aiming to reach a rapid diagnosis as a step aid in the disease control and to prevent or even minimize the suspected hazard.

METHOD: The used techniques included an infection trial of Swiss mice with the mice-adapted challenge rabies virus followed by the detection of the virus in the infected mices' brains. Virus detection was carried out through the application BHK21 cell line infection; fluorescent antibody technique; latex agglutination test (LAT); direct enzyme-linked immunosorbent assay (ELISA); rabies antigen detection kit ELISA; conventional polymerase chain reaction (PCR).

RESULTS: It was found that virus inoculation in mice and BHK21 cell lines needs 5-7 days with positivity of 90% and 100%, respectively. Rapid antigen kit was able to detect rabies antigen in mice brains suspension and BHK21 infected fluid within 3-5 minutes with percentages of 60% and 55.5%, respectively. In 1-1.5 hours, the direct fluorescent antibody method (DFAT) detected 90% and 100% of the rabies antigen in BHK21 cell line infection and brain impressions, respectively. Latex agglutination showed clear results with 88.8% with BHK21 infected fluid within 3-5 minutes while it did not carry out on brain emulsions to prevent falsely positive results brought on by the presence of tissue fragments. Conventional one-step PCR revealed 100% positivity with either brain or cell culture preparations within 2 days. Direct ELISA showed 88.8% positivity with BHK21 infected fluid with 1 day of work.

CONCLUSION: Mice inoculation test, cell culture infection; DFAT and PCR are the most accurate techniques for the detection of RABV with a positivity of 90%-100% followed by LAT and ELISA with a positivity of 88.8%, and lastly, rabies antigen ELISA kit (RAK) with a positivity of 55.5%-60% taking in consideration the required time for each. In addition, the positivity % of the applied tests revealed their sensitivity and specificity.