Characterization of strain PTV-2 USA/IA65463/2014 and strain PTV-11 USA/IA09592/2013 of Teschovirus A: Experimental inoculation, distribution of nucleic acids and development of Teschovirus encephalomyelitis
Teschovirus A (previously Porcine teschovirus; PTV) is the etiologic agent of Teschovirus encephalomyelitis (TE). Historically, PTV-1 has been recognized as one of the most pathogenic serotypes, although other serotypes have been described to cause TE. Hence, most information about the pathogenicity, epidemiology and control of disease relies on data from studies involving PTV-1.
In recent years, two cases submitted to the Iowa State University Veterinary Diagnostic Laboratory with a history of polioencephalitis and/or myelitis were identified and genomic sequencing characterized these isolates as (sero)types PTV-2 and PTV-11.
Although multiple serotypes have been identified and genetically characterized, the neuropathogenicity of some of these serotypes has not been fully elucidated.
To assess these isolates, we developed an experimental model to determine the neuropathogenicity of the PTV-2 and PTV-11 isolates and observed that both isolates caused histological lesions and clinical disease consistent with TE in cesarean-derived colostrum-deprived pigs. Furthermore, PTV RNA was detected in different tissues, serum and feces in all inoculated animals by RT-qPCR.
The experimental approach used in this research permitted to develop a successful platform to induce clinical disease. This is the first description of a neuropathogenic PTV-11 strain in the U.S. and the first experimental inoculation using a PTV-2 autochthonous U.S. strain after the initial description of PTV-2 strain O3b made by Long at al. in 1966. This is also the first assessment of the viral shedding, viremia and distribution by real time RT-qPCR of nucleic acids of PTV-2 and PTV-11 in experimentally infected pigs with Teschovirus encephalomyelitis.