Epizootiological studies on stillbirth of swine occurred in Japan during summer months of 1948

Hosoya, Hideo; Matumoto, Minoru; Iwasa, Saburo

doi:10.3412/jsb.5.291

Cited by 4 publications

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“…Investigation of reproductive failure manifested in an increased number of stillborn piglets with neuropathological lesions led to the detection and isolation of JEV as the causative agent. JEV related reproductive failure and stillbirth was first recorded in pigs in Japan (1947–1948), and subsequently JEV was isolated from stillborn piglets [ 23 – 24 ]. JEV can cause stillbirth, mummification, embryonic death and abortion in sows and aspermia in boars [ 25 – 28 ].…”

Section: Discussionmentioning

confidence: 99%

Pathogenic and Genotypic Characterization of a Japanese Encephalitis Virus Isolate Associated with Reproductive Failure in an Indian Pig Herd

et al. 2016

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BackgroundIndia is endemic to Japanese encephalitis virus (JEV) and recurrent outbreaks occur mainly in rice growing areas. Pigs are considered to be the amplifying host for JEV and infection in gestating pigs results in reproductive failure. Most studies conducted on JEV infection in Indian pigs have been serological surveys and very little is known about JEV genotypes circulating in pigs. So the potential risk posed by pigs in JEV transmission and the genetic relationship between viruses circulating in pigs, mosquitoes and humans is poorly understood.Methodology/Principal FindingsThis study was conducted in pigs with a history of reproductive failure characterized by stillborn piglets with neuropathological lesions. Japanese encephalitis (JE) suspected brain specimens inoculated intracerebrally into mice and Vero cells resulted in successful isolation of JEV/SW/IVRI/395A/2014. Clinicopathological observations in infected mice, demonstration of JEV antigen in brain, and analysis of the envelope protein identified the swine isolate as being neurovirulent. Phylogenetic analysis based on prM and E gene sequences showed that it belonged to genotype III. This swine isolate was closely related to JEV associated with the 2005 outbreak in India and JaoArS982 from Japan. Phylogenetic analysis of JEV strains collected between 1956 and 2014 in India categorized the GIII viruses into different clades blurring their spatial distribution, which has been discernible in the previous century.Conclusions/SignificanceIsolation of JEV from stillborn piglets and its close genetic relationship with viruses detected at least three decades ago in humans and mosquitoes in Japan suggests that the virus may have been circulating among Indian pigs for several decades. The close similarity between the present swine isolate and those detected in humans affected in the 2005 outbreak in Uttar Pradesh, India, suggests the need for more intensive surveillance of pigs and implementation of suitable strategies to control JE in India.

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Section: Discussionmentioning

confidence: 99%

Pathogenic and Genotypic Characterization of a Japanese Encephalitis Virus Isolate Associated with Reproductive Failure in an Indian Pig Herd

et al. 2016

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“…Similar to other viral pathogens infecting fetuses in utero, JEV can cause stillbirth, mummification, embryonic death and infertility in pigs (Salmon 1984; Gresham 2003). The first association between JEV and reproductive failure in pigs was observed in 1947–1948 in Japan when there were large outbreaks of encephalitis in humans and horses, concomitantly with outbreaks of stillbirths in pigs, and JEV was subsequently isolated from stillborn piglets (Hosoya et al 1950; Burns 1950). The virus is considered an economically important reproductive pathogen of pigs due to production losses (Platt and Joo 2006).…”

Section: Introductionmentioning

confidence: 99%

Reproductive performance in sows in relation to Japanese Encephalitis Virus seropositivity in an endemic area

Lindahl

Boqvist

Ståhl

et al. 2011

Trop Anim Health Prod

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Japanese Encephalitis Virus (JEV) is considered an important reproductive pathogen in pigs. Most studies of the reproductive impact of JEV have been conducted in areas where the disease occurs in seasonal epidemics. In this study, the associations between seropositivity for JEV, measured with an IgG ELISA, and the number of piglets born alive and stillborn were investigated in a tropical area endemic for JEV in Vietnam. Sixty percent of sows from four farms in the Mekong delta of Vietnam were seropositive to JEV and the Odds Ratio for a sow being infected was highest (6.4) in sows above 3.5 years (95% confidence interval 2.2–18.3). There was an association between increasing Optical Density (OD) values from the ELISA and the number of stillborn piglets in sows less than 1.5 years, but no effect of seropositivity could be shown when all sows were studied. OD values had an effect (p = 0.04) on the number of piglets born alive in the statistical analysis only when interacting with the effect of the breeds. An increase in mean OD value of the herd was correlated (p < 0.0001) with an increase in the number of piglets born alive. In this study, there was evidence of a negative association between seropositivity for JEV and the reproductive performance only in sows less than 1.5 years in endemic areas. This could be explained by a year-round infection with the virus, which would lead to immunity in many gilts before their first pregnancy. This, in turn, may imply that JEV infection in pigs is of minor importance for the reproductive performance in endemic areas.

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“…Until now, only a few human cases of congenital JEV infection have been reported, which result in either abortions or the deliveries of a healthy child [ 195 , 196 , 197 , 198 ], possibly depending on the time of infection during gestation [ 197 ]. In pregnant sows, on the other hand, it has been well established that congenital JEV infection causes reproductive losses, such as mummified, stillborn, and abnormal piglets even when they are born alive [ 199 , 200 , 201 , 202 , 203 ]. Therefore, there is a clear difference in the clinical outcome of congenital JEV infections between humans and pigs, both of which are highly susceptible to the virus.…”

Section: Clinical Features In Humansmentioning

confidence: 99%

Mice as an Animal Model for Japanese Encephalitis Virus Research: Mouse Susceptibility, Infection Route, and Viral Pathogenesis

2023

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Japanese encephalitis virus (JEV), a zoonotic flavivirus, is principally transmitted by hematophagous mosquitoes, continually between susceptible animals and incidentally from those animals to humans. For almost a century since its discovery, JEV was geographically confined to the Asia-Pacific region with recurrent sizable outbreaks involving wildlife, livestock, and people. However, over the past decade, it has been detected for the first time in Europe (Italy) and Africa (Angola) but has yet to cause any recognizable outbreaks in humans. JEV infection leads to a broad spectrum of clinical outcomes, ranging from asymptomatic conditions to self-limiting febrile illnesses to life-threatening neurological complications, particularly Japanese encephalitis (JE). No clinically proven antiviral drugs are available to treat the development and progression of JE. There are, however, several live and killed vaccines that have been commercialized to prevent the infection and transmission of JEV, yet this virus remains the main cause of acute encephalitis syndrome with high morbidity and mortality among children in the endemic regions. Therefore, significant research efforts have been directed toward understanding the neuropathogenesis of JE to facilitate the development of effective treatments for the disease. Thus far, multiple laboratory animal models have been established for the study of JEV infection. In this review, we focus on mice, the most extensively used animal model for JEV research, and summarize the major findings on mouse susceptibility, infection route, and viral pathogenesis reported in the past and present, and discuss some unanswered key questions for future studies.

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Epizootiological studies on stillbirth of swine occurred in Japan during summer months of 1948

Cited by 4 publications

References 0 publications

Pathogenic and Genotypic Characterization of a Japanese Encephalitis Virus Isolate Associated with Reproductive Failure in an Indian Pig Herd

Pathogenic and Genotypic Characterization of a Japanese Encephalitis Virus Isolate Associated with Reproductive Failure in an Indian Pig Herd

Reproductive performance in sows in relation to Japanese Encephalitis Virus seropositivity in an endemic area

Mice as an Animal Model for Japanese Encephalitis Virus Research: Mouse Susceptibility, Infection Route, and Viral Pathogenesis

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