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Molecular and serological epidemiology of Japanese encephalitis virus (JEV) in a remote island of western Japan: an implication of JEV migration over the East China Sea.

Yoshikawa A, Nabeshima T, Inoue S, Agoh M, Morita K - Trop Med Health (2016)

Bottom Line: There were 47 JEV strains isolated in Nagasaki from 2001 to 2014 including the isolates in this study, and they belonged to genotype 1.In the subcluster 1-A-2, three different monophyletic subgroups, 1-A-2-2 (2010), 1-A-2-3 (2011), and 1-A-2-1 (2013, 2014), appeared in Goto.These data strongly suggested that JEV appearance in Goto seems to depend on the frequent introduction of JEV from outside of the island and this pattern is different from what has been observed in subtropical islands in the East China Sea such as Okinawa and Taiwan, where the same populations of JEV (1-A-7 (1998-2008) in Okinawa; genotype 3 (until 2012) in Taiwan) have been maintained for a long period.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, Nagasaki 852-8523 Japan ; Department of Virology, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, Nagasaki 852-8523 Japan ; Department of Public Health, Nagasaki Prefectural Institute for Environmental Research and Public Health, 2-1306-11 Ikeda, Omura, Nagasaki 856-0026 Japan.

ABSTRACT

Background: Japanese encephalitis (JE) is a mosquito-borne infectious disease caused by Japanese encephalitis virus (JEV). About 1-10 cases with severe central nervous system symptoms have been constantly reported every year in Japan. To clarify the mechanism of maintenance of JEV, the present study surveyed pigs for serological evidence of JEV infection and isolated JEV strains from pigs and mosquitoes in Isahaya City (Isahaya) and Goto City (Goto) in the islets of Goto in Nagasaki Prefecture from 2008 to 2014.

Results: The serological survey of pigs showed the increase of IgM sero-positivity against JEV in July or August, and it was maintained until October or November in both Isahaya and Goto every year. There were 47 JEV strains isolated in Nagasaki from 2001 to 2014 including the isolates in this study, and they belonged to genotype 1. Thirty four of the isolated strains were from pigs in Isahaya and were classified under six subclusters (1-A-1, 1-A-2, 1-A-3, 1-A-4, 1-A-5, and 1-A-9). Thirteen strains were isolated from pigs and mosquitoes in Goto and were classified into three subclusters (1-A-5 (2008); 1-A-1 (2009); and 1-A-2). In the subcluster 1-A-2, three different monophyletic subgroups, 1-A-2-2 (2010), 1-A-2-3 (2011), and 1-A-2-1 (2013, 2014), appeared in Goto.

Conclusions: These data strongly suggested that JEV appearance in Goto seems to depend on the frequent introduction of JEV from outside of the island and this pattern is different from what has been observed in subtropical islands in the East China Sea such as Okinawa and Taiwan, where the same populations of JEV (1-A-7 (1998-2008) in Okinawa; genotype 3 (until 2012) in Taiwan) have been maintained for a long period.

No MeSH data available.


Related in: MedlinePlus

Seasonal trend of Pig IgM positivity against JEV in Isahaya and Goto, 2009 to 2014. Ten to 30 swine serum samples were collected every month in Isahaya and Goto, respectively, and P/N ratio of IgM against JEV using IgM-capture ELISA were calculated every month
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Fig2: Seasonal trend of Pig IgM positivity against JEV in Isahaya and Goto, 2009 to 2014. Ten to 30 swine serum samples were collected every month in Isahaya and Goto, respectively, and P/N ratio of IgM against JEV using IgM-capture ELISA were calculated every month

Mentions: During the 6 years (2009 to 2014) of consecutive monitoring of IgM sero-positivity against JEV among 10 to 30 pigs in Isahaya and Goto, a similar pattern was observed almost every year. IgM-positive pigs were detected either in July or August with most of the pigs becoming IgM positive between August and September, and positive detection was sustained up to October or November (Fig. 2). No IgM-positive pig could be detected during winter and spring (December to June) every year during this study. Only a slight difference was observed between Isahaya and Goto, and this was the timing of pig seroconversion which occurred 1 month earlier in Isahaya than in Goto. The seroconversion rates in both Isahaya and Goto in 2014 only reached 40–60 % which was unlike the previous years where the rates were in the range of 80–100 %.Fig. 2


Molecular and serological epidemiology of Japanese encephalitis virus (JEV) in a remote island of western Japan: an implication of JEV migration over the East China Sea.

Yoshikawa A, Nabeshima T, Inoue S, Agoh M, Morita K - Trop Med Health (2016)

Seasonal trend of Pig IgM positivity against JEV in Isahaya and Goto, 2009 to 2014. Ten to 30 swine serum samples were collected every month in Isahaya and Goto, respectively, and P/N ratio of IgM against JEV using IgM-capture ELISA were calculated every month
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4940834&req=5

Fig2: Seasonal trend of Pig IgM positivity against JEV in Isahaya and Goto, 2009 to 2014. Ten to 30 swine serum samples were collected every month in Isahaya and Goto, respectively, and P/N ratio of IgM against JEV using IgM-capture ELISA were calculated every month
Mentions: During the 6 years (2009 to 2014) of consecutive monitoring of IgM sero-positivity against JEV among 10 to 30 pigs in Isahaya and Goto, a similar pattern was observed almost every year. IgM-positive pigs were detected either in July or August with most of the pigs becoming IgM positive between August and September, and positive detection was sustained up to October or November (Fig. 2). No IgM-positive pig could be detected during winter and spring (December to June) every year during this study. Only a slight difference was observed between Isahaya and Goto, and this was the timing of pig seroconversion which occurred 1 month earlier in Isahaya than in Goto. The seroconversion rates in both Isahaya and Goto in 2014 only reached 40–60 % which was unlike the previous years where the rates were in the range of 80–100 %.Fig. 2

Bottom Line: There were 47 JEV strains isolated in Nagasaki from 2001 to 2014 including the isolates in this study, and they belonged to genotype 1.In the subcluster 1-A-2, three different monophyletic subgroups, 1-A-2-2 (2010), 1-A-2-3 (2011), and 1-A-2-1 (2013, 2014), appeared in Goto.These data strongly suggested that JEV appearance in Goto seems to depend on the frequent introduction of JEV from outside of the island and this pattern is different from what has been observed in subtropical islands in the East China Sea such as Okinawa and Taiwan, where the same populations of JEV (1-A-7 (1998-2008) in Okinawa; genotype 3 (until 2012) in Taiwan) have been maintained for a long period.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, Nagasaki 852-8523 Japan ; Department of Virology, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, Nagasaki 852-8523 Japan ; Department of Public Health, Nagasaki Prefectural Institute for Environmental Research and Public Health, 2-1306-11 Ikeda, Omura, Nagasaki 856-0026 Japan.

ABSTRACT

Background: Japanese encephalitis (JE) is a mosquito-borne infectious disease caused by Japanese encephalitis virus (JEV). About 1-10 cases with severe central nervous system symptoms have been constantly reported every year in Japan. To clarify the mechanism of maintenance of JEV, the present study surveyed pigs for serological evidence of JEV infection and isolated JEV strains from pigs and mosquitoes in Isahaya City (Isahaya) and Goto City (Goto) in the islets of Goto in Nagasaki Prefecture from 2008 to 2014.

Results: The serological survey of pigs showed the increase of IgM sero-positivity against JEV in July or August, and it was maintained until October or November in both Isahaya and Goto every year. There were 47 JEV strains isolated in Nagasaki from 2001 to 2014 including the isolates in this study, and they belonged to genotype 1. Thirty four of the isolated strains were from pigs in Isahaya and were classified under six subclusters (1-A-1, 1-A-2, 1-A-3, 1-A-4, 1-A-5, and 1-A-9). Thirteen strains were isolated from pigs and mosquitoes in Goto and were classified into three subclusters (1-A-5 (2008); 1-A-1 (2009); and 1-A-2). In the subcluster 1-A-2, three different monophyletic subgroups, 1-A-2-2 (2010), 1-A-2-3 (2011), and 1-A-2-1 (2013, 2014), appeared in Goto.

Conclusions: These data strongly suggested that JEV appearance in Goto seems to depend on the frequent introduction of JEV from outside of the island and this pattern is different from what has been observed in subtropical islands in the East China Sea such as Okinawa and Taiwan, where the same populations of JEV (1-A-7 (1998-2008) in Okinawa; genotype 3 (until 2012) in Taiwan) have been maintained for a long period.

No MeSH data available.


Related in: MedlinePlus