Porcine Hemagglutinating Encephalomyelitis Virus and Respiratory Disease in Exhibition Swine, Michigan, USA, 2015

Abstract

Acute outbreaks of respiratory disease in swine at agricultural fairs in Michigan, USA, in 2015 raised concern for potential human exposure to influenza A virus. Testing ruled out influenza A virus and identified porcine hemagglutinating encephalomyelitis virus as the cause of influenza-like illness in the affected swine.

Development of a triplex real-time RT-PCR assay for detection and differentiation of three US genotypes of porcine hemagglutinating encephalomyelitis virus

“…Although PHEV infection has been endemic in different countries for decades and the primary route of PHEV infection is through upper and lower respiratory tracts, only few reports suggest an association of the virus with respiratory disease in swine (Cutlip and Mengeling, 1972). Recently, we have demonstrated that PHEV caused an influenza-like illness (ILI) in affected pigs and provided evidence for the role of PHEV as a respiratory pathogen (Lorbach et al, 2017). In that study, a significantly higher positive rate 38.7% (108 of 279 pigs) was observed in pigs at the Michigan fairs compared to 4.1% (23 of 560 pigs) in Indiana and Ohio, indicating the PHEV-associated epizootic behavior in the Michigan fairs (Lorbach et al, 2017).…”

“…Recently, we have demonstrated that PHEV caused an influenza-like illness (ILI) in affected pigs and provided evidence for the role of PHEV as a respiratory pathogen (Lorbach et al, 2017). In that study, a significantly higher positive rate 38.7% (108 of 279 pigs) was observed in pigs at the Michigan fairs compared to 4.1% (23 of 560 pigs) in Indiana and Ohio, indicating the PHEV-associated epizootic behavior in the Michigan fairs (Lorbach et al, 2017).…”

“…The traditional real-time RT-PCR (rRT-PCR) test currently used in diagnostic laboratories does not differentiate emerged PHEV from classical PHEV strains (Lorbach et al, 2017). The triplex rRT-PCR developed in the present study will fulfill this purpose and can be used to monitor PHEV of different genetic genotypes and differentiate between them.…”

“…Previous genomic characterization and analysis reveal that PHEV is closely related to bovine CoV and human CoV OC43, and have identified truncated NS2 and NS4.9 genes in the PHEV-VW572 strain (Vijgen et al, 2006). Prior to our study (Lorbach et al, 2017), only one complete PHEV genome sequence (PHEV-VW572) was available in GenBank. We completed the full genomic sequencing of 10 PHEV isolates, and the analyses of complete genomic sequences showed that PHEV formed three distinct genotypes.…”

“…We completed the full genomic sequencing of 10 PHEV isolates, and the analyses of complete genomic sequences showed that PHEV formed three distinct genotypes. Interestingly, genotypes 1 had deletions in NS2 and NS4.9, while genotype 3 showed no deletion and genotype 2 has a large deletion in the NS2 gene (Lorbach et al, 2017). The prevalence and distribution of three genotypes remain unknown in pigs in the United States.…”