Molecular characterization of carrier rabies isolates

Area of Science:

• Veterinary Virology
• Molecular Epidemiology
• Public Health

Background:

• Rabies virus poses a significant threat to canine and human health globally.
• Previous studies failed to differentiate Ethiopian dog rabies virus strains.
• Accurate viral identification is essential for effective disease surveillance and control.

Purpose of the Study:

• To genetically characterize nine dog rabies virus isolates using molecular techniques.
• To determine if restriction fragment length polymorphism (RFLP) and nucleotide sequencing can differentiate closely related rabies virus strains.
• To investigate the genetic diversity of rabies virus in Ethiopian carrier dogs.

Main Methods:

• Comparative genome analysis of nine dog rabies virus isolates.
• Generation of overlapping polymerase chain reaction (PCR) segments covering 97% of the viral genome.
• Restriction fragment analysis (RFA) using AvaII, Bcll, and BamHI enzymes.
• DNA and deduced peptide sequence analysis of a 200-nucleotide segment of the nucleoprotein gene.
• Phylogenetic analysis of molecular data.

Main Results:

• Restriction analysis identified 39 variable sites (5.5% of the genome).
• Sequence analysis of the nucleoprotein gene segment differentiated all isolates.
• Phylogenetic analysis revealed only two saliva isolates from an experimentally infected dog were identical.
• All tested rabies virus isolates, including those from carrier dogs and the tonsil, showed unique genetic profiles.

Conclusions:

• Restriction mapping and nucleotide sequencing of the nucleoprotein gene are powerful tools for individual rabies virus isolate identification.
• These molecular methods revealed genetic variability among dog rabies virus isolates previously considered identical.
• The findings provide a basis for enhanced molecular surveillance of rabies virus in dog populations.