Detection of rabies virus antigen by the indirect rapid immunohistochemistry test in equines and comparisons with other diagnostic techniques

Abstract

Laboratory diagnosis of rabies in equines is essential for distinguishing the disease from other sources of encephalitis. Diagnosis by conventional techniques such as a direct fluorescent antibody test (dFAT) or viral isolation in mice or cell culture can be difficult, and the application of molecular biological methods may be necessary. We performed an indirect rapid immunohistochemistry test (iRIT) for the detection of the rabies virus (RABV) antigen in the central nervous system (CNS) of equines and compared the results with those of other diagnostic techniques. We reviewed result records from the Rabies Diagnosis Laboratory at Instituto Pasteur, São Paulo, Brazil, of 174 samples of equine CNS from July 2014 to June 2016, which were investigated by dFAT, rabies tissue culture infection test (RTCIT), mouse inoculation test (MIT) and reverse transcription‐polymerase chain reaction (RT‐PCR) followed by genetic sequencing. These samples, 29 presented divergent results among techniques and were selected for the performed in the iRIT. The detected positivity rate was 4/29 (14%) by dFAT, 5/28 (18%) by RTCIT, 10/29 (35%) by MIT and 26/27 (96%) by RT‐PCR. We analysed 29 samples through imprints of the cortex, hippocampus, cerebellum and brainstem in slides fixed in 10% buffered formaldehyde. Eighteen samples were identified as positive (62%) by iRIT assay, representing a greater number of positive cases than that detected by dFAT, MIT and RTCIT but not by RT‐PCR. Among the brain regions, the brainstem presented the highest positivity (78%), followed by the hippocampus (69%), cerebellum (67%) and cortex (67%). Our results provide evidence that iRIT can contribute to a rapid diagnosis of rabies in equines and that complementary tests should be used to improve diagnostic accuracy in this species.

Detection of rabies virus via exciton energy transfer between CdTe quantum dots and Au nanoparticles

“…Before use, bare ITO slices were ultrasonically cleaned by the ultrasonic cleaner (Reliance Digital, England) with an ultrasound frequency of 42 kHz with acetone, 1.0 M NaOH ethanol/water mixture (1:1, v/v), and DI water for 15 min. The samples were then dried at 90 • C. TiO 2 :C-NPs powder (4.0 mg) was ultrasonically dispersed in 2.0 mL of deionized water, and 20 µL of uniformly dispersed TiO 2 :C-NPs suspension (2.0 mg/mL) was drip-coated on an ITO electrode with a modified area of 0.25 cm 2 . After drying at room temperature, the sample was calcined in air at 450 • C for 30 min, and then slowly cooled to room temperature to obtain the resulting TiO 2 :C-NPs/ITO electrode.…”

“…Rabies is caused by the rabies virus (RABV), which infects the central nervous system of almost all mammals with a mortality rate of nearly 100% ( 1 ). Although several effective and fast diagnostic methods have been used to detect RABV ( 2 – 4 ), current methods are limited by the low abundance of RABV in brain tissue and/or saliva samples.…”