Detection of atypical porcine pestivirus in Brazil in the central nervous system of suckling piglets with congenital tremor.

Atypical porcine pestivirus (APPV) has been detected in piglets with congenital tremor (CT) from three different continents including North America, Europe and Asia. Thirteen piglets from four farms in two different states in Brazil with CT were sampled. Viral RNA was detected by quantitative real-time PCR in the cerebellum or cerebellum and spinal cord in the 100% of the piglets with CT, and APPV was not detected in any tissue sample from clinically non-affected piglets with the exception of the cerebellum of one piglet from Farm A. Piglets with CT had an odds ratio of 99.0 (95% CI 3.4, 2823.8; p = .0072) compared to piglets without CT to test positive for APPV by qRT-PCR. A subset of positive samples was selected for sequencing of the NS3 gene. Phylogenetic analysis revealed that Brazilian sequences of the NS3 formed an independent cluster and had the highest sequence identity with a sequence from the United States. This is the first identification of APPV infection in piglets with CT in South America.

Detection of atypical porcine pestivirus in semen from commercial boar studs in the United States.

Atypical porcine pestivirus (APPV) has recently been identified as a cause of congenital tremor (CT) in pigs and has been detected in semen and preputial swabs from boars that were known to be clinically affected with CT. Accordingly, the objectives of this study were to 1) detect the presence of APPV in semen, preputial fluids and preputial swabs from adult boars by quantitative reverse transcription PCR (qRT-PCR) and 2) genetically characterize a subset of positive samples to better understand the ecology of APPV in commercial boar studs and the potential risk of transmission of APPV via semen. A total of 597 samples of semen, preputial fluid and preputial swabs each representing a different boar were obtained from four commercial boar studs located in three different states in the United States. Viral RNA was detected by qRT-PCR in 90 samples (15.08%; 90/597), with the greatest per cent positive from preputial swabs (23.81%; 5/21) followed by preputial fluid (22.81%; 26/114) and semen (12.91%; 59/457). The mean cycle quantification (Cq) between sample types was similar while eleven semen samples had Cq values lower than 27.0 corresponding to approximately 2 × 106  copies/ml. Based on phylogenetic analysis of the Npro gene, different viral strains can be on the same farm at the same and different times. This is the first report of detection of APPV in semen from commercial boar studs. Studies investigating the role of semen in the transmission of APPV and production of CT are needed.

Detection of a novel sapelovirus in central nervous tissue of pigs with polioencephalomyelitis in the USA.

An approximately 3,000 finishing swine operation in the United States experienced an outbreak of an atypical neurologic disease in 11-weeks-old pigs with an overall morbidity of 20% and case fatality rate of 30%. The clinical onset and progression of signs in affected pigs varied but included inappetence, compromised ambulation, ataxia, incoordination, mental dullness, paresis, paralysis and decreased response to environmental stimuli. Tissues from affected pigs were submitted for diagnostic investigation. Histopathologic examination of the cerebrum, cerebellum and spinal cord revealed severe lymphoplasmacytic and necrotizing polioencephalomyelitis with multifocal areas of gliosis and neuron satellitosis, suggestive of a neurotropic viral infection. Bacterial pathogens were not isolated by culture of neurologic tissue from affected pigs. Samples tested by polymerase chain reaction (PCR) were negative for pseudorabies virus and atypical porcine pestivirus. Immunohistochemistry for porcine reproductive and respiratory syndrome virus, porcine circovirus and Listeria was negative. Porcine sapelovirus (PSV) was identified in spinal cord by a nested PCR used to detect porcine enterovirus, porcine teschovirus and PSV. Next-generation sequencing of brainstem and spinal cord samples identified PSV and the absence of other or novel pathogens. In addition, Sapelovirus A mRNA was detected in neurons and nerve roots of the spinal cord by in situ hybridization. The PSV is genetically novel with an overall 94% amino acid identity and 86% nucleotide identity to a recently reported sapelovirus from Korea. This is the first case report in the United States associating sapelovirus with severe polioencephalomyelitis in pigs.