Presence of atypical porcine pestivirus (APPV) genomes in newborn piglets correlates with congenital tremor

Abstract

Pestiviruses are highly variable RNA viruses belonging to the continuously growing family Flaviviridae. A genetically very distinct pestivirus was recently discovered in the USA, designated atypical porcine pestivirus (APPV). Here, a screening of 369 sera from apparently healthy adult pigs demonstrated the existence of APPV in Germany with an estimated individual prevalence of 2.4% and ~10% at farm level. Additionally, APPV genomes were detected in newborn piglets affected by congenital tremor (CT), but genomes were absent in unaffected piglets. High loads of genomes were identified in glandular epithelial cells, follicular centers of lymphoid organs, the inner granular cell layer of the cerebellum, as well as in the trigeminal and spinal ganglia. Retrospective analysis of cerebellum samples from 2007 demonstrated that APPV can be found in piglets with CT of unsolved aetiology. Determination of the first European APPV complete polyprotein coding sequence revealed 88.2% nucleotide identity to the APPV sequence from the USA. APPV sequences derived from different regions in Germany demonstrated to be highly variable. Taken together, the results of this study strongly suggest that the presence of APPV genomes in newborn piglets correlates with CT, while no association with clinical disease could be observed in viremic adult pigs.

Congenital infection with atypical porcine pestivirus (APPV) is associated with disease and viral persistence

“…After initial attempts to isolate APPV had failed and thus confirmed reports of others [6–8], we could show the presence of APPV antigen in SK-6 and PK-15 cells after 5 passages by immunofluorescence (Figure 5) and qRT-PCR. Key to this experiment was the inoculation of cells with an APPV positive serum sample (APPV AUT 646/16) that was obtained from a CT piglet before suckling and hence devoid of colostral antibodies.…”

Atypical Porcine Pestivirus: A Possible Cause of Congenital Tremor Type A‐II in Newborn Piglets

“…All 99 samples (100%) from piglets with disease sampled at 10 different farms were PCR-positive, whereas only six of 66 (9%) of the controls without clinical signs were positive. This strong association was also found by Arruda et al [15]: 15/16 serum samples of congenital tremor piglets PCR-positive, four controls negative; and Postel et al [24]: 6/6 congenital tremor serum sample positive, 2/2 controls PCR-negative.…”

“…Soon thereafter, a link with congenital tremor type A-II was suggested by Arruda et al [15] and Postel et al [24]. The frequent detection and the large genetic variation of the virus in the Netherlands and Spain, in addition to the USA [15,16] and Germany [24,25], shows that APPV has probably spread worldwide. We measured a very strong association with congenital tremor.…”

“…So far, the only study that located the virus at the site of the disease (the central nervous system) was performed by Postel et al [24]. Fluorescent in situ hybridization showed strong staining of the inner granular cell layer of the cerebellum.…”

“…We attempted immunostaining of the virus in the cerebellum, but did not manage to detect the virus due to high background staining. Postel et al [24] suggested that distribution of virus within herds may occur via the orofecal route since a significant amount of APPV genome was present in salivary glands, duodenum, pancreas and colon. This is in accordance with our observation of frequent detection and prolonged shedding of the virus in stool.…”