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

This research article presents the development and testing of a real-time RT-PCR (rRT-PCR) assay for detecting and quantifying equine rhinitis viruses (ERV) in horses. This method has been proven to be faster, more sensitive, and specific for diagnosing both the A and B variants of ERV than previous methods.

Objective and Methods

• The main objective of the study was to create a real-time RT-PCR assay that is rapid and sensitive enough for regular diagnosis and epidemiological surveillance of the A and B variants of equine rhinitis viruses.
• The researchers designed TaqMan primer probe sets from conserved regions of the ERV genome. These probes sets are used to copy and amplify specific DNA sequences in the ERV, allowing for the identification and quantification of the virus.
• The research team used over 400 samples from both clinically affected and asymptomatic horses to verify the effectiveness of their assays.
• The positive results for ERAV and ERBV obtained through the rRT-PCR method were cross-verified using virus isolation and another set of primers, respectively.

Results

• The detection limit of the developed rRT-PCR assay for both types of ERV was between 10 and 100 genome copies. This shows increased sensitivity in the detection of ERV compared to previous methods.
• Out of 250 archival samples, 29 were found to be positive for ERAV and 3 for ERBV. This indicates an average annual incidence of 10% and 1.5%, respectively, proving the test’s efficacy.
• The study also found evidence of both ERAV and ERBV co-circulating with equine influenza virus (EIV). This highlights the possibility of multiple virus interactions in affected horses, which might impact the progression and treatment of diseases.
• From 100 tested post-race urine samples, 29 were ERAV positive, attesting to the assay’s applicability in various types of biological samples.

Conclusions

• The result of this study suggests that the newly-developed rRT-PCR assays are specific, sensitive, and more efficient than traditional virus isolation techniques in diagnosing ERAV and ERBV.
• These assays are suitable for routine diagnosis and may help in the investigation of links between clinical symptoms and rhinitis virus shedding in horses.
• The new method of detection can help veterinarians and researchers better understand the prevalence and impact of ERV in the equine population, potentially leading to more effective treatments and preventative measures.