Pre-Clinical Evaluation of a Real-Time PCR Assay on a Portable Instrument as a Possible Field Diagnostic Tool: Experiences from the Testing of Clinical Samples for African and Classical Swine Fever Viruses
TRANSBOUNDARY AND EMERGING DISEASES
Authors: Liu, L.; Luo, Y.; Accensi, F.; Ganges, L.; Rodriguez, F.; Shan, H.; Stahl, K.; Qiu, H. -J.; Belak, S.
Abstract
African swine fever (ASF) and classical swine fever (CSF) are two highly infectious transboundary animal diseases (TADs) that are serious threats to the pig industry worldwide, including in China, the world's largest pork producer. In this study, a duplex real-time PCR assay was developed for the rapid detection and differentiation of African swine fever virus (ASFV) and classical swine fever virus (CSFV). The assay was performed on a portable, battery-powered PCR thermocycler with a low sample throughput (termed as T-COR4 assay'). The feasibility and reliability of the T-COR4 assay as a possible field method was investigated by testing clinical samples collected in China. When evaluated with reference materials or samples from experimental infections, the assay performed in a reliable manner, producing results comparable to those obtained from stationary PCR platforms. Of 59 clinical samples, 41 had results identical to a two-step CSFV real-time PCR assay. No ASFV was detected in these samples. The T-COR4 assay was technically easy to perform and produced results within 3h, including sample preparation. In combination with a simple sample preparation method, the T-COR4 assay provides a new tool for the field diagnosis and differentiation of ASF and CSF, which could be of particular value in remote areas.
Trace amounts of African swine fever virus DNA detected in insects collected from an infected pig farm in Estonia
VETERINARY MEDICINE AND SCIENCE
Authors: Herm, Reet; Tummeleht, Lea; Jurison, Margret; Vilem, Annika; Viltrop, Arvo
Abstract
Background African swine fever (ASF), a severe multi-systemic disease in pigs, was introduced into Estonia in 2014. The majority of outbreaks have occurred during the summer months. Given that ASFV is transmitted in a sylvatic cycle that includes the transmission by African soft ticks and that mechanical transmission by flying insects was shown, transmission by other arthropod vectors need to be considered. Objectives Here, we report the results of a pilot study on flying insects caught on an outbreak farm during epidemiological investigations. Methods In brief, 15 different insect species (flies and mosquitoes) were collected by random catch using an aerial net. Nucleic acids derived from these samples or their pools were tested for African swine fever virus (ASFV) DNA by real-time PCR. Results and Conclusions Viral DNA was detected in small quantities in two samples from flies and mosquitoes. Given the slow spread of virus within the farm, the impact of these findings seems rather low, but a role in local transmission cannot be ruled out. However, given the very low number of insects sampled, and taken into the account that viral isolation was not performed and insects outside the farm were not investigated, future investigations are needed to assess the true impact of insects as mechanical vectors.