Nonsuppurative encephalomyelitis in a calf in Japan and isolation of Japanese encephalitis virus genotype 1 from the affected calf

Abstract

Japanese encephalitis virus (JEV) was isolated from the cerebrum of a calf which showed severe neurological symptoms in late September 2009, and the JEV isolate was revealed to be of genotype 1. This is the first report describing the isolation of genotype 1 JEV from cattle.

Fig 1

Phylogenetic profile showing the relationships among JEV isolates based on a comparison of their E regions (1,500 nucleotides). The bootstrap percentages calculated from 1,000 replications are indicated around the internal nodes. The scale represents 0.05% sequence divergence. Mo, mosquito; Hu, human.

Fig 2

Phylogenetic profile showing the relationships among JEV isolates based on a comparison of the complete genome (approximately 11,000 nucleotides). The bootstrap percentages calculated from 1,000 replications are indicated around the internal nodes. The scale represents 0.05% sequence divergence.

Fig 3

Perivascular infiltration of lymphocytes (A) and a glial nodule (B) in the cerebrum of the affected calf. Arrows indicate the perivascular infiltration of lymphocytes, and an arrowhead points out the glial nodule. Hematoxylin and eosin stain. Bar = 200 μm.

Fig 4

IHC assay results. Detection of JEV antigen in the cerebrum (A to C), cerebellum (D), pons (E), and spinal cord (F) of the affected calf. JEV-positive granules (dark brown) are observed mainly in the cytoplasm of neurons and occasionally in nerve axons. (C) Positively labeled neurons are undergoing neuronophagia. Bar = 100 μm.