Development of Polioencephalomyelitis in Cesarean-Derived Colostrum-Deprived Pigs Following Experimental Inoculation with Either Teschovirus A Serotype 2 or Serotype 11

Abstract

Teschovirus encephalomyelitis is a sporadic disease associated with Teschovirus A (PTV) serotype 1 and, less frequently, other serotypes. In recent years, the number of cases submitted to the Iowa State University Veterinary Diagnostic Laboratory with a history of posterior paresis has increased. Submission histories from various regions of the United States suggest a trend for clinical disease to persist in herds and affect a wider age-range of pigs than historically reported. Polioencephalitis and/or myelitis was consistently present and PTV was detected in affected neural tissue by PCR in a portion of cases. Sequencing from two clinical cases identified PTV-2 and PTV-11. To assess neuropathogenicity of these isolates, 5-week-old cesarean derived and colostrum-deprived pigs were assigned to three groups: negative control (n = 4), PTV-2-inoculated (n = 7), and PTV-11-inoculated (n = 7). Three PTV-2-inoculated pigs developed mild incoordination of the hind limbs, one of which progressed to posterior ataxia. While all PTV-11-inoculated pigs showed severe neurological signs consistent with Teschovirus encephalomyelitis, no evidences of neurological signs were observed in sham-inoculated animals. All PTV-2- and PTV-11-inoculated pigs had microscopic lesions consistent with Teschovirus encephalomyelitis. To our knowledge, this is the first description of PTV-11 and experimental study demonstrating the neuropathogenicity of PTV-11 in the United States.

Genetic diversity and recombination of enterovirus G strains in Japanese pigs: High prevalence of strains carrying a papain-like cysteine protease sequence in the enterovirus G population

“…Although porcine teschoviruses and sapeloviruses have been identified as the cause of occasional diverse disorders, including gastrointestinal diseases, polioencephalomyelitis, and respiratory diseases [ 16 – 22 ], clinical relevance of EV-Gs to enteric or other disorders—apart from cases of skin lesion, pyrexia, and flaccid paralysis—has not been elucidated [ 7 , 23 ]. Very recently, the unique EV-Gs that have a papain-like cysteine protease sequence (PL-CP) in the 2C–3A junction region of their genomes were identified in fecal samples from three independent cases of porcine diarrhea in the USA and Belgium [ 24 – 26 ].…”

Development and Large-Scale Testing of a Novel One-Step Triplex RT-qPCR Assay for Simultaneous Detection of “Neurotropic” Porcine Sapeloviruses, Teschoviruses (Picornaviridae) and Type 3 Porcine Astroviruses (Astroviridae) in Various Samples including Nasal Swabs

“…In this study, a novel, highly sensitive one-step triplex RT-qPCR assay was introduced, capable of the simultaneous detection of the selected neurotropic RNA viruses, i.e., porcine tescho-, and sapeloviruses of family Picornaviridae, and type 3 porcine astroviruses of family Astroviridae . These viruses could cause severe CNS infections with high mortality rate and—according to recent studies—are considered to be (re-)emerging pathogens of swine [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. The fluorophore-tagged hydrolysis-probe-based assays were designed to either separately (singleplex) or simultaneously (triplex) detect all known types of species Teschovirus A , B and Sapelovirus A as well as specifically PoAstV-3 from various sample types including faecal, nasal or CNS samples of swine.…”

“…Porcine sapeloviruses (PSV/SV-A) and porcine teschoviruses (PTV/TV-A) of family Picornaviridae and type 3 porcine astroviruses (PoAstV-3) of family Astroviridae are increasingly recognized enteric pathogens associated with a variety of diseases including severe central nervous system disorders (CNS), with a high mortality rate in swine [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ].…”

“…Although all three viruses are able to cause asymptomatic infections, multiple types/strains of PTV (e.g., PTV-2, -3, -11, -13) [ 4 , 6 , 7 ] and PSV [ 1 , 3 ] are detected in various organs/samples (including CNS) from pigs showing CNS-related symptoms (paraplegia, paralysis, paresis and ataxia) with a high mortality rate. Interestingly, from the five known porcine astrovirus types, only type 3 was conclusively detected from CNS samples of swine with signs of meningoencephalomyelitis and, therefore, could have neurotropic potential [ 12 ].…”

Polioencephalomyelitis in Domestic Swine Associated With Porcine Astrovirus Type 3

“…The distribution of histologic lesions in the CNS reported in this study is similar to and likely indistinguishable from those described for other neurologic viral causes of swine including PTV and PSV. 4,5,8,25…”