Detection of African horse sickness virus in the blood of experimentally infected horses: comparison of virus isolation and a PCR assay.

The research article compares the efficiency of reverse transcription-polymerase chain reaction (RT-PCR) and virus isolation methods in detecting the African horse sickness virus (AHSV) in the blood samples of experimentally infected horses. The study also examines the impact of sample storage, transportation, and the use of different anticoagulants.

Understanding the Study

• The research involved using a reverse transcription-polymerase chain reaction (RT-PCR) assay. A specific aspect of this method—dot-blot hybridisation—was crucial in detecting African horse sickness virus (AHSV).
• The focus of the RT-PCR test was the S7 gene in the virus, which encodes the VP7 protein, a critical component of AHSV.
• The team compared the efficiency of RT-PCR results with those obtained from the traditional method of virus isolation.
• The researchers infected different horses in a controlled environment with AHSV-4 and AHSV-9 for the experiment.
• The study also explored the influence of transportation and storage conditions on the sample and how different anticoagulants, like EDTA and heparin, could affect the process.

Research Findings

• Results from RT-PCR were returned within 48 hours, whereas virus isolation took a minimum of 15 days, proving that RT-PCR is a significantly faster method.
• Both RT-PCR and virus isolation demonstrated equal sensitivity in detecting AHSV-4.
• For horses infected with the less virulent AHSV-9 isolate, RT-PCR detected viraemia more consistently than virus isolation. However, in one instance, the virus was detected only by virus isolation.
• The sensitivity of virus isolation was increased by passaging samples five times, suggesting that additional rounds of processing may improve the detection rate.
• Overall, the research suggests that while both methods have their pros and cons, RT-PCR stands out as a quicker and arguably more sensitive method in the case of an outbreak.

Implications

• Although RT-PCR emerged as an efficient alternative to detect AHSV in an outbreak scenario, the research highlights its limitations too. While the study does not specify these limitations, a mention of the same indicates that more research may be needed to refine this method for wide-scale implementation.
• The study contributes valuable information towards the development of more efficient diagnostic techniques to detect African horse sickness and could potentially pave the way for better epidemic management strategies.