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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

Phylogenetic analysis of the E gene of Japanese encephalitis virus. The phylogenetic tree was constructed by the maximum-likelihood method using the PhyML ver. 3.0 Software. Bootstrap analysis was replicated 1000 times, and bootstrap value (%) greater than 50 % are shown above branches. Genotype 1 JEVs (268 strains) are shown in this figure. Other genotype, genotype 3 (five strains) was used as out-group. Labels of strains conform to the following format: (GenBank or DDBJ accession no.)_(strain name)_(country-region)_(year of isolation). Thirty-four Isahaya strains, 13 Goto strains, 48 Taiwan strains, and 7 Okinawa strains are indicated as red, blue, green, and purple color, respectively. JEV strains from China and other areas strains are indicated in black
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Fig3: Phylogenetic analysis of the E gene of Japanese encephalitis virus. The phylogenetic tree was constructed by the maximum-likelihood method using the PhyML ver. 3.0 Software. Bootstrap analysis was replicated 1000 times, and bootstrap value (%) greater than 50 % are shown above branches. Genotype 1 JEVs (268 strains) are shown in this figure. Other genotype, genotype 3 (five strains) was used as out-group. Labels of strains conform to the following format: (GenBank or DDBJ accession no.)_(strain name)_(country-region)_(year of isolation). Thirty-four Isahaya strains, 13 Goto strains, 48 Taiwan strains, and 7 Okinawa strains are indicated as red, blue, green, and purple color, respectively. JEV strains from China and other areas strains are indicated in black

Mentions: Twenty-five strains of JEV isolated in the present study and 22 strains obtained from the JEV repository at the NIEP were analyzed for their E gene sequences (1500 nucleotides). All the 47 strains of JEV Nagasaki isolates belonged to genotype 1. JEV genotype 1 isolates analyzed in the present study were classified into nine subclusters (1-A-1 to 1-A-9, Fig. 3) by following the terminology of Nabeshima et al. [26]. Thirty-four strains isolated from Isahaya were classified into six subclusters which were 1-A-1, 1-A-2, 1-A-3, 1-A-4, 1-A-5, and 1-A-9 (Figs. 3 and 4a, b); and 13 strains isolated from Goto were classified into three subclusters which were 1-A-1, 1-A-2, and 1-A-5. In Goto, subclusters 1-A-1 and 1-A-5 were seen in 2009 and 2008 respectively, and subcluster 1-A-2 has been detected since 2010. The subcluster 1-A-2 contains some monophyletic subgroups. The subgroup 1-A-2-2 appeared in 2010, 1-A-2-3 in 2011, and 1-A-2-1 in 2013 and 2014 (Fig. 3).Fig. 3


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)

Phylogenetic analysis of the E gene of Japanese encephalitis virus. The phylogenetic tree was constructed by the maximum-likelihood method using the PhyML ver. 3.0 Software. Bootstrap analysis was replicated 1000 times, and bootstrap value (%) greater than 50 % are shown above branches. Genotype 1 JEVs (268 strains) are shown in this figure. Other genotype, genotype 3 (five strains) was used as out-group. Labels of strains conform to the following format: (GenBank or DDBJ accession no.)_(strain name)_(country-region)_(year of isolation). Thirty-four Isahaya strains, 13 Goto strains, 48 Taiwan strains, and 7 Okinawa strains are indicated as red, blue, green, and purple color, respectively. JEV strains from China and other areas strains are indicated in black
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig3: Phylogenetic analysis of the E gene of Japanese encephalitis virus. The phylogenetic tree was constructed by the maximum-likelihood method using the PhyML ver. 3.0 Software. Bootstrap analysis was replicated 1000 times, and bootstrap value (%) greater than 50 % are shown above branches. Genotype 1 JEVs (268 strains) are shown in this figure. Other genotype, genotype 3 (five strains) was used as out-group. Labels of strains conform to the following format: (GenBank or DDBJ accession no.)_(strain name)_(country-region)_(year of isolation). Thirty-four Isahaya strains, 13 Goto strains, 48 Taiwan strains, and 7 Okinawa strains are indicated as red, blue, green, and purple color, respectively. JEV strains from China and other areas strains are indicated in black
Mentions: Twenty-five strains of JEV isolated in the present study and 22 strains obtained from the JEV repository at the NIEP were analyzed for their E gene sequences (1500 nucleotides). All the 47 strains of JEV Nagasaki isolates belonged to genotype 1. JEV genotype 1 isolates analyzed in the present study were classified into nine subclusters (1-A-1 to 1-A-9, Fig. 3) by following the terminology of Nabeshima et al. [26]. Thirty-four strains isolated from Isahaya were classified into six subclusters which were 1-A-1, 1-A-2, 1-A-3, 1-A-4, 1-A-5, and 1-A-9 (Figs. 3 and 4a, b); and 13 strains isolated from Goto were classified into three subclusters which were 1-A-1, 1-A-2, and 1-A-5. In Goto, subclusters 1-A-1 and 1-A-5 were seen in 2009 and 2008 respectively, and subcluster 1-A-2 has been detected since 2010. The subcluster 1-A-2 contains some monophyletic subgroups. The subgroup 1-A-2-2 appeared in 2010, 1-A-2-3 in 2011, and 1-A-2-1 in 2013 and 2014 (Fig. 3).Fig. 3

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