Vomiting and wasting disease associated with hemagglutinating encephalomyelitis viruses infection in piglets in Jilin, China

Abstract

One coronavirus strain was isolated from brain tissues of ten piglets with evident clinical manifestations of vomiting, diarrhea and dyskinesia in Jilin province in China. Antigenic and genomic characterizations of the virus (isolate PHEV-JLsp09) were based on multiplex PCR and negative staining electron microscopy and sequence analysis of the Hemagglutinin-esterase (HE) gene. These piglets were diagnosed with Porcine hemagglutinating encephalomyelitis virus (PHEV).Necropsy was performed on the piglets. Major pathological changes included meningeal hyperemia, meningeal hemorrhage and cortical hemorrhage. Minor changes were also observed in other organs. Histopathological changes included satellitosis and neuronophagia in the cerebral cortex.Mice were infected with the isolated virus. Their histopathological changes were similar to those symptoms observed in the piglets, exhibiting typical changes for non-suppurative encephalitis. Thus, Porcine hemagglutinating encephalomyelitis virus mainly causes damage to the nervous system but also impacts other organs. This viral strain (isolate PHEV-JLsp09) found in the Siping area of Jilin Province in China is evolutionally closest to the HEV-67N stain (North American strain), indicating that this viral strain evolved from the PHEV from North America.

Figure 1

Typical coronavirus-like viral particles were observed by electron microscopy. When negatively stained cell culture supernatant was examined under an electron microscope, typical coronavirus-like viral particles with a diameter of about 110-130 nm were observed (bar = 100 nm); these viral-like particles shared similar morphology and size with coronavirus.

Figure 2

Macroscopic lesions. (A) Among the gross defects, all diseased pigs showed meningeal hyperemia, cortical hyperemia and cortical venous congestion. Brain sections showed many dispersed small hematomas, where these were more evident in white matter than in grey matter. (B) The spleen was slightly enlarged.

Figure 3

Microscopic lesions. (A) Histopathological examination of diseased pigs showed cortical neuronal edema and increased peripheral space (H&E, 400×; bar = 100 μm). (B) Small glial cells surrounded neurons and exhibited neuronophagia and satellitosis (H&E, 400×; bar = 100 μm).

Figure 4

Phylogenetic trees of hemagglutinating encephamylitis virus HE sequences. Phylogenetic trees of PHEV based on the complete open reading frames. In trees, the results after bootstrap replicates are indicated, Porcine hemagglutinating encephalomyelitis virus (PHEV-JLsp09/AY07841/AF481863/DQ011855); Bovine coronavirus (DQ915164/EF424615/AF239308); Human coronavirus OC43 (AY585229/AY391777); Influenza C virus (D63469/D63472).

Figure 5

Histopathological examination of infected mice showed typical changes for non-suppurative encephalitis. Cerebral cortical neurons were swollen (H&E, 400×; bar = 100 μm).