Molecular investigations on the prevalence and viral load of enteric viruses in pigs from five European countries.

Enteric viral infections in pigs may cause diarrhea resulting in ill-thrift and substantial economic losses. This study reports the enteric infections with porcine astrovirus type 4 (PAstV4), porcine group A rotavirus (GARV), porcine group C rotavirus (GCRV), porcine circovirus type 2 (PCV2) and porcine kobuvirus (PKoV) in 419 pigs, comprising both healthy and diarrheic animals, from 49 farms in five European countries (Austria, Germany, Hungary, Spain and Sweden). Real-time RT-PCR assays were developed to test fecal samples and to compare the prevalence and viral load in relation to health status, farms of origin and age groups. The results showed that PAstV4 (70.4%) was the dominant virus species, followed by PKoV (56.7%), PCV2 (42.2%), GCRV (3%) and GARV (0.9%). Diarrheic pigs had a higher viral load of PAstV4 in the nursery and growing-finishing groups. Rotaviruses were mainly detected in diarrheic pigs, whereas PCV2 was more often detected in clinically healthy than in diarrheic pigs, suggesting that most PCV2 infections were subclinical. PAstV4, PCV2 and PKoV were considered ubiquitous in the European pig livestock and co-infections among them were frequent, independently of the disease status, in contrast to a low prevalence of classical rotavirus infections.

Development of a loop-mediated isothermal amplification assay combined with a lateral flow dipstick for rapid and simple detection of classical swine fever virus in the field.

Classical swine fever (CSF) is a highly contagious viral disease and may cause heavy economic loss to farmers. The rapid, simple and accurate diagnosis of the disease at the frontline, for example on the farms of concern is crucial for disease control. This study describes the development and evaluation of a new loop-mediated isothermal amplification (LAMP) assay coupled with lateral flow dipstick (LFD) for the detection of classical swine fever virus (CSFV). This RT-LAMP-LFD assay combines the efficient one-step isothermal amplification of CSF viral RNA and the simplicity of the LFD to read the results within two to five minutes. Seven genotypes (1.1, 1.2, 1.3, 2.1, 2.2, 2.3 and 3.1), but not genotype 3.4, were successfully detected by the RT-LAMP-LFD assay, indicating that the method has a broad range of detection and can be applied in different geographical areas where CSFV strains belonging to these genotypes are present. The performance of this RT-LAMP-LFD assay was similar to that of the real-time RT-PCR. The analytical sensitivity was about 100copies per reaction when testing two genotypes (1.1 and 2.3). No cross-reactivity to non-CSFV pestiviruses was observed. This RT-LAMP-LFD assay can be a useful novel tool for the rapid, simple and economic diagnosis of classical swine fever in the field.