RESUMEN
African swine fever is a viral disease of the family Suidae. Methods to detect and quantify African swine fever virus (ASFV) include qPCR and virus infectivity assays. Individual laboratories often use in-house procedures for these assays, which can hamper the comparison of results. The objective of this study was to estimate the probability of ASFV detection using these assays, and to determine the inter-test correlations between results. This was achieved by testing a panel of 80 samples at three reference laboratories. Samples were analysed using nucleic acid extraction and qPCR, as well as virus infectivity assays. For qPCR, a very high probability (ranging from 0.96 to 1.0) of detecting ASFV DNA was observed for all tested systems. For virus infectivity assays in cells, the probability of detecting infectious ASFV varied from 0.68 to 0.90 and was highest using pulmonary alveolar macrophages, followed by MARC145 cells, peripheral blood monocytes, and finally wild boar lung cells. Intraclass correlation coefficient estimates of 0.97 (0.96-0.98) between qPCR methods, 0.80 (0.74-0.85) to 0.94 (0.92-0.96) between virus infectivity assays, and 0.77 (0.68-0.83) to 0.95 (0.93-0.96) between qPCR methods and virus infectivity assays were obtained. These findings show that qPCR gives the highest probability for the detection of ASFV.
RESUMEN
Following its introduction into Georgia in 2007, African swine fever virus (ASFV) has become widespread on the European continent and in Asia. In many cases, the exact route of introduction into domestic pig herds cannot be determined, but most introductions are attributed to indirect virus transmission. In this review, we describe knowledge gained about different matrices that may allow introduction of the virus into pig herds. These matrices include uncooked pig meat, processed pig-derived products, feed, matrices contaminated with the virus and blood-feeding invertebrates. Knowledge gaps still exist, and both field studies and laboratory research are needed to enhance understanding of the risks for ASFV introductions, especially via virus-contaminated materials, including bedding and feed, and via blood-feeding, flying insects. Knowledge obtained from such studies can be applied to epidemiological risk assessments for the different transmission routes. Such assessments can be utilized to help predict the most effective biosecurity and control strategies.
Asunto(s)
Virus de la Fiebre Porcina Africana/fisiología , Fiebre Porcina Africana/transmisión , Enfermedades de los Porcinos/transmisión , Fiebre Porcina Africana/virología , Animales , Asia , Europa (Continente) , Riesgo , Sus scrofa , Porcinos , Enfermedades de los Porcinos/virologíaRESUMEN
Classical swine fever (CSF) has caused significant economic losses in industrialized pig production, and is still present in some European countries. Recent CSF outbreaks in Europe were mainly associated with strains of genogroup 2 (subgroup 2.3). Although there are extensive datasets regarding 2.3 strains, there is very little information available on longer fragments or whole classical swine fever virus (CSFV) genomes. Furthermore, there are no detailed analyses of the molecular epidemiology of CSFV wild boar isolates available. Nevertheless, complete genome sequences are supportive in phylogenetic analyses, especially in affected wild boar populations. Here, German CSFV strains of subgroup 2.3 were fully sequenced using two different approaches: (i) a universal panel of CSFV primers that were developed to amplify the complete genome in overlapping fragments for chain-terminator sequencing; and (ii) generation of a single full-length amplicon of the CSFV genome obtained by long-range RT-PCR for deep sequencing with next-generation sequencing technology. In total, five different strains of CSFV subgroup 2.3 were completely sequenced using these newly developed protocols. The approach was used to study virus spread and evolutionary history in German wild boar. For the first time, the results of our study clearly argue for the possibility of a long-term persistence of genotype 2.3 CSFV strains in affected regions at an almost undetectable level, even after long-term oral vaccination campaigns with intensive monitoring. Hence, regional persistence in wild boar populations has to be taken into account as an important factor in the continual outbreaks in affected areas.