Comparison Of Reverse-Transcription Polymerase Chain Reaction, Rapid Immunochromatographic Diagnostic Test And Fluorescent Antibody Test For Detecting Rabies Viruses Circulating In Mali

Abstract

In Mali, a rabies reporting procedure is in place but is efficient only in the capital city where the Central Veterinary Laboratory (CVL), which is mandated to diagnose rabies, is located. This has led to an underestimation of the diagnosis of rabies including the genetic characterization of the virus in the country. Therefore, there is need to evaluate the diagnostic methods of rabies for subsequent characterization of circulating rabies virus in Mali. In this regard, the study assessed the suitability of the Rapid Immunochromatographic Diagnostic Test (RIDT), and Reverse-Transcription Polymerase Chain Reaction (RT-PCR) for the detection and characterization rabies viruses circulating in Mali in 2017. A total of 18 samples previous submitted to the CVL in Mali were analysed for rabies virus using the lateral flow device (BioNote, Inc., Seoul, Korea) and RT-PCR. RT-PCR positive samples were sequenced using Sanger sequencing method at Inqaba Biotec and subjected to phylogenetic analysis. In order to compare to two methods, Fluorescence Antibody Test (FAT) was used as the gold standard method. Out of the 18 samples, 16 were found to be positive for rabies virus on FAT. Out of these 16 positives, only 7 (43.8%) samples were positive for the virus on RIDT while 15 (93.8%) samples were positive for the virus on RT-PCR. All the sequences analysed by Blastn shared at least 93.5% nucleotide identity to the rabies nucleoprotein gene thereby confirming rabies infection of dogs in Mali. A phylogenetic analysis revealed that all the sequences belong to the Africa 2 lineage of which five to the sub-lineage H, four to the sublineage F and two to the sub-lineage G. The results of RT-PCR were comparable to those of FAT. However, the positivity detection rate for RIDT was low as compared FAT. The genetic characterization of the virus confirmed previous findings of the circulation of the sub-lineages H, F and G belonging to the Africa 2 lineage in Mali. In conclusion, the RT-PCR could be used together with FAT for the detection and genetic characterization of rabies virus circulating in Mali. Further studies using large number of samples are required to validate the suitability of the new RIDT for the diagnosis of rabies in Mali.