Detection and localization of atypical porcine pestivirus in the
testicles of naturally infected, CT-affected piglets
Abstract
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.