Real-time RT-PCR for the detection and quantitative analysis of equine rhinitis viruses

Area of Science:

• Veterinary Virology
• Molecular Diagnostics
• Equine Health

Background:

• Equine rhinitis viruses (ERV) are significant causes of respiratory illness and performance impairment in horses.
• Current diagnostic methods for ERV may lack the sensitivity required for accurate detection and epidemiological assessment.
• The economic impact of ERV may be underestimated due to limitations in existing diagnostic tools.

Purpose of the Study:

• To develop a highly sensitive and rapid real-time reverse transcription PCR (rRT-PCR) assay.
• To enable routine diagnosis and epidemiological surveillance of Equine rhinitis A virus (ERAV) and Equine rhinitis B virus (ERBV).

Main Methods:

• Design of TaqMan primer probe sets targeting conserved 5' UTR regions of ERAV and ERBV.
• Validation of the rRT-PCR assays using over 400 samples from clinically affected and asymptomatic horses.
• Verification of positive samples through virus isolation (ERAV) and alternative rRT-PCR (ERBV).

Main Results:

• The developed rRT-PCR assays demonstrated a detection limit of 10-100 genome copies for both ERAV and ERBV.
• Analysis of archival nasal swabs revealed ERAV and ERBV incidence rates of 10% and 1.5% annually, respectively.
• Evidence of co-circulation of ERAV and ERBV with equine influenza virus (EIV) was observed; ERAV was also detected in post-race urine samples.

Conclusions:

• The novel rRT-PCR assays are specific, highly sensitive, and reproducible, surpassing virus isolation methods.
• These assays are suitable for routine diagnosis of ERAV and ERBV in equine populations.
• The developed assays will aid in understanding the relationship between clinical signs and ERV shedding patterns.