Atypical porcine pestivirus (APPV) belongs to the genus Pestivirus within the family Flaviviridae. Recently, APPV has been identified as the causative agent of congenital tremor (CT) type AII. The disease is a neurological disorder that affects newborn piglets and is characterized by mostly generalized trembling of the animals and often splay legs. CT is well known worldwide, and the virus seems to be highly prevalent in major swine producing areas. However, little is known about the epidemiology of the infection, the transmission and spread of the virus between herds. Here, we show the high prevalence of APPV in processing fluid samples collected from Hungarian pig herds which led us to investigate the cellular targets of the virus in the testicles of newborn piglets affected by CT. By the development of an RNA in situ hybridization assay and the use of immunohistochemistry on consecutive slides, we identified the target cells of APPV in the testicle: interstitial Leydig cells, peritubular myoid cells and endothelial cells of medium-sized arteries. Previous studies have shown that APPV can be found in the semen of sexually mature boars suggesting the role of infected boars and their semen in the transmission of the virus similar to many other members of the Flaviviridae family. As in our case, the virus has not been identified in cells beyond the blood-testis barrier, further studies on infected adult boars’ testicles are needed to analyze the possible changes in the cell tropism that enable the virus to be excreted by the semen.
A new Respirovirus, Porcine parainfluenzavirus type 1 (PPIV-1) was first identified in 2013 in Hong Kong and later in the USA. Here, we report the first detection of PPIV-1 outside these two regions. Our research group has analyzed 15–15 (3–3 piglets from five litters) nasal swab samples obtained from three-week-old piglets originating from 22 Hungarian farms altogether from which only one farm was found to be positive. Subsequently, 20–20 nasal swab samples were obtained from 2, 4, 6 and 8-week-old piglets of this farm. Virus detection by qRT-PCR showed that although all investigated age groups were positive to PPIV-1, higher number of infected animals and higher viral loads were found among 4-year-old animals. Based on the phylogenetic analyses of partial F and L genes, the 3 Hungarian strains are almost identical and are highly similar to the very first PPIV-1 genome submitted from Hong Kong in 2013, whereas the overall genetic difference compared to the recently described North American isolates was around 10%.