Analysis of yearly changes in levels of antibodies to Japanese encephalitis virus nonstructural 1 protein in racehorses in central Japan shows high levels of natural virus activity still exist.
Recent reductions in numbers of human and equine Japanese encephalitis (JE) cases in Japan have seen calls to end JE vaccination. Here, we analyzed yearly variations of natural JE virus activity, using sera collected serially in 1998-2003 from racehorses residing in Ibaraki and Shiga prefectures, both located in central Japan. A total of 208 sera from 24 individuals in Ibaraki and 259 from 27 in Shiga were examined for antibodies to JE virus nonstructural 1 (NS1) protein, a marker of natural infection. The natural infection rate in epizootic seasons, which was determined by a significant increase in NS1 antibody level, was 4.2-26.7% in Ibaraki and 0-41.7% in Shiga, indicating that high levels of JE virus activity still existed in central Japan.
Konishi
Eiji
E
Department of Health Sciences, Kobe University School of Medicine, 7-10-2 Tomogaoka, Suma-ku, Kobe 654-0142, Japan. ekon@ams.kobe-u.ac.jp
Shoda
Mizue
M
Kondo
Takashi
T
D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis*; D004664:Encephalitis Virus, Japanese / Q000502:physiology*; D004672:Encephalitis, Japanese / Q000276:immunology* / Q000517:prevention & control / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay; D006734:Horse Diseases / Q000453:epidemiology / Q000276:immunology* / Q000517:prevention & control; D006736:Horses; D007564:Japan / Q000453:epidemiology; D022321:Japanese Encephalitis Vaccines / Q000276:immunology; D017361:Viral Nonstructural Proteins / Q000276:immunology*
D000914:Antibodies, Viral; D022321:Japanese Encephalitis Vaccines; D017361:Viral Nonstructural Proteins