Prevalence of antibody to Japanese encephalitis virus nonstructural 1 protein among racehorses in Japan: indication of natural infection and need for continuous vaccination

Konishi, Eiji; Shoda, Mizue; Kondo, Takashi

doi:10.1016/j.vaccine.2003.10.001

Cited by 25 publications

(26 citation statements)

References 12 publications

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“…Most sera in the present study were the same as those used in a previous survey of NS1 antibodies among horses by the immunostaining method (13), and so their NS1 antibody titers were known. All sera were collected from thoroughbred horses.…”

Section: Methodsmentioning

confidence: 99%

“…Negative-control sera used for determination of the cutoff value differentiating positive from negative samples were obtained from 46 yearlings that had been born and kept in Hokkaido (a area of northern Japan where JE is not endemic) without vaccination with JE vaccine. These controls were negative for HAI antibody and NS1 antibody by the immunostaining method (13).…”

Section: Methodsmentioning

confidence: 99%

“…This indicates that, once infected, horses remain positive for NS1 antibodies for at least 40 weeks. a Collected from horses kept in areas in southern and central Japan where JEV is endemic and used in a previous study (13).…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, detection of NS1 antibodies can identify naturally infected individuals among vaccinated populations. By this technique, a small-scale survey revealed relatively high annual infection rates in humans (5 to 10%) (14) and equines (15 to 67%) (13). Based on these results, it seemed desirable to carry out a larger-scale survey to show more clearly the situation in respect to exposure of humans and equines to natural infection with JEV.…”

mentioning

confidence: 99%

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Development and Evaluation of an Enzyme-Linked Immunosorbent Assay for Quantifying Antibodies to Japanese Encephalitis Virus Nonstructural 1 Protein To Detect Subclinical Infections in Vaccinated Horses

et al. 2004

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Antibodies to Japanese encephalitis virus (JEV) nonstructural 1 (NS1) protein constitute a marker of natural JEV infection among populations vaccinated with inactivated JE vaccine. In Japan, with few recent human JE cases, the natural infection rate is critical to evaluate the necessity of continuing JE vaccination. A sensitive immunochemical staining method for detecting NS1 antibodies in individuals naturally and subclinically infected with JEV was previously established. Here, an enzyme-linked immunosorbent assay (ELISA) to detect NS1 antibodies in equine sera was developed and evaluated as an alternative to immunostaining. By this method, NS1 antigens contained in culture fluids from cells stably transfected with the NS1 and NS2A genes were captured by a rabbit anti-NS1 polyclonal antibody. Three nanograms per well of NS1 antigen, corresponding to 1:2 to 1:8 dilutions of the culture fluid, was sufficient for testing. ELISA values were obtained by a single-serum dilution (1:100), which correlated with ELISA titers obtained by an endpoint method. Under a tentative cutoff value (0.122) statistically calculated from NS1 antibody levels of horses in an area where JEV is not endemic, a high level of qualitative agreement (85.3%) was obtained between the ELISA and immunostaining methods. A significant correlation coefficient (0.799; P < 0.001) was also obtained between the two methods. Three experimentally infected horses seroconverted no later than 13 to 23 days postinfection, whereas 4 field horses infected during an epizootic remained positive for NS1 antibodies for at least 40 weeks. Our results indicate that the ELISA used here was sufficiently sensitive to detect subclinical infections in vaccinated equine populations.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Development and Evaluation of an Enzyme-Linked Immunosorbent Assay for Quantifying Antibodies to Japanese Encephalitis Virus Nonstructural 1 Protein To Detect Subclinical Infections in Vaccinated Horses

et al. 2004

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“…Since most of the recent isolates from pigs and mosquitoes, the natural hosts/amplifiers of JEV, are genotype I in Japan [9,11,13,23], then horses in Japan must also be repetitively exposed to JEV belonging to genotype I [4]. Therefore, while the possibility that the genotype I strains from China might cause a severe disease in horses cannot be ruled out, the findings described in this study indicate that presently circulating genotype I as well as genotype III [7] have the potential to cause a fatal disease in horses and that we should continue our vaccination programs for horses to protect them against JEV.…”

mentioning

confidence: 99%

Full Genome Sequence and Virulence Analyses of the Recent Equine Isolate of Japanese Encephalitis Virus

Shimojima

Nagao

Shimoda

et al. 2011

The Journal of Veterinary Medical Science

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ABSTRACT. In the past 25 years, there has been only one case of Japanese encephalitis in horses in Japan. We determined the full genome sequence of the Japanese encephalitis virus (JEV) strain JEV/eq/Tottori/2003 isolated from an afflicted horse and also analyzed its virulence in mice. The sequence analysis showed that the genome of JEV/eq/Tottori/2003 is similar to that of genotype I, a dominant genotype of JEV presently circulating in Japan. Its neurovirulence, but not neuroinvasiveness, was still as high as it was for genotype III, thus indicating the necessity for continuation of a vaccination program of horses against JEV.

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Mosquito‐Borne Infections Affecting the Central Nervous System

2015

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Prevalence of antibody to Japanese encephalitis virus nonstructural 1 protein among racehorses in Japan: indication of natural infection and need for continuous vaccination

Cited by 25 publications

References 12 publications

Development and Evaluation of an Enzyme-Linked Immunosorbent Assay for Quantifying Antibodies to Japanese Encephalitis Virus Nonstructural 1 Protein To Detect Subclinical Infections in Vaccinated Horses

Development and Evaluation of an Enzyme-Linked Immunosorbent Assay for Quantifying Antibodies to Japanese Encephalitis Virus Nonstructural 1 Protein To Detect Subclinical Infections in Vaccinated Horses

Full Genome Sequence and Virulence Analyses of the Recent Equine Isolate of Japanese Encephalitis Virus

Mosquito‐Borne Infections Affecting the Central Nervous System

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