Distribution of ranaviruses in Japan
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Distribution of ranaviruses in Japan

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2013 International Symposium on Ranaviruses

2013 International Symposium on Ranaviruses
by Yumi Une

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Distribution of ranaviruses in Japan Distribution of ranaviruses in Japan Presentation Transcript

  • Distribution of ranavirus in Japan The 2013 International Symposium on Ranaviruses Yumi Une Laboratory of Veterinary Pathology, School of Veterinary Medicine, Azabu University
  • The current state of ranaviral disease in Japan Outbreaks of ranavirus infection in Japan 13 episodes (12 locations ) In nature : 8 episodes, only bullfrogs In captivity : 5 episodes, various species : outbreak points in captivity : outbreak points in nature year in nature in captivity 2008 Bullfrog Hynobius nebulosus 2009 Bullfrog Bullfrog Bullfrog Bullfrog 2010 Bullfrog 2011 Bullfrog Bullfrog 2012 Tylototriton (2 spices) Poison Dart Frog (num erous) Poison Dart Frog (num erous) Hynobius hidam ontanus
  • Bullfrog Our aim is to predict the impact of ranavirus on native amphibians and formulate measuresfor its prevention. Habitation area ● Outbreaks often occur in nature. ● Distribution is very wide. ● Exotic species in Japan. (This species was introduced from North America in 1918) To clarify the prevalence and origin of ranavirus in Japan Kidneys of Bullfrog tadpoles. View slide
  • Mao et al.(1997) M 10 11 12 13 14 15 M 10 11 12 13 14 15 M 10 11 12 13 14 15 Result of PCR methods. Left: FV3 primer,Center: JP primer, Right; M68F primer M; molecular-weight marker, Number; case number Profile of primer sets Primer for the major capsid protein gene. FV3 FV3M C P4F 5'-G AC TTG G C C AC TTATG AC -3' 530bp FV3M C P5R 5'-G TC TC TG G AG AAG AAG AA-3' JP RanaJP556F 5'-G G TTC TTC C C C TC C C ATTC TTC TT-3' 217bp RanaJP772R 5'-G G TC ATG TAG AC G TTG G C C TC G AC -3' M 68F M 68F 5'-G C AC C AC C TC TAC TC TTATG -3' 230bp B IVM C P154 5'-C C ATC G AG C C G TTC ATG ATG -3' View slide
  • Jan Feb M ar A pr M ay Jun Jul A ug Sep O ct N ov D ec Atsugi Chiba Tokyo Fukui Shiga Fukui Ehime Hiroshima Saitama Kouchi Gunma Ebina 17.5% 7.5% 0% 28% Infectious prevalence of ranavirus in Bullfrogs (No disease outbreak ) 11 locations, 15 times, n=407, positive 24 (5.9%)
  • 0 10 20 30 40 50 60 70 80 90 100 4/9/2010 5/9/2010 6/9/2010 7/9/2010 8/9/2010 9/9/2010 10/9/2010 11/9/2010 12/9/2010 1/9/2011 2/9/2011 3/9/2011 4/9/2011 n= 429, 4 positive, 0.93% (range 0-5.1%) 30 Sep 24 Dec Monthly collection Infectious prevalence of ranavirus in Bullfrogs (no disease outbreak ) monthly collection
  • Infectious prevalence of ranavirus in Bullfrogs ( With disease outbreak ) 0 10 20 30 40 50 60 70 80 90 100 n= 410, 102 positives mean25%(range 0-96%) 2nd outbreak (2010) no outbreak (2011) monthly collection
  • Conclusion regarding Bullfrogs • Ranaviral disease occurs often in Bullfrog, but this species is not suitable to understand the situation of ranavirus in Japan. • Reason: Infection prevalence is very low. The appropriate time for sampling could not be determined. Only RCV-JP was detected in Bullfrogs.
  • Distribution of ranavirus in Japan Indian rice frog (Fejervarya kawamurai) • Classification: Ranidae • Small and brown • A common species in rice fields in western Japan • Southern strain • Hibernates • Breeding season: long, from April to August ★ Currently, its habitats are expanding in Japan. It is considered a domestic exotic’ species. Distribution of in Indian rice frog ■ Naturally habitation area ■ Area of invasion Infection prevalence is high in the Indian rice frogs
  • Material & Methods 1. Survey in 13 locations in 8 Prefectures between May 2011 and October 2012 (Tochigi, Tokyo, Aichi, Kyoto, Hyogo, Okayama, Ehime, Nagasaki) 2. 3 seasons( spring, summer, autumn) 3. Maximum 30 individuals per collection time 4. PCR method (3 primer sets) 5. Kidneys (plus liver, and spleen) Shikoku island Kyushu island Main island
  • Results 1. All 8 Japanese Prefectures: Ranavirus (+) 2. Infection prevalence of ranavirus :12.9% (152/1,177) 3. Annual variability: 2011 8.7 % (47/541) 2012 16.5 % (105/636) ↑ ↑ 4. Seasonal variation: prevalence greatest during autumn
  • Seasonal variation in each location (8 locations that could be surveyed in two successive years) Tochigi Tokyo Aichi Hyogo Kyoto Okayama Ehime 1 Ehime 2 Rapid rise in prevalence in autumn
  • 0 10 20 30 40 50 60 70 80 90 100 Spring Summer Autumn 0 10 20 30 40 50 60 Spring Summer Autumn 0 5 10 15 20 25 30 Spring Summer Autumn 0 5 10 15 20 25 Spring Summer Autumn 2011 2012 2013 Ehime 2 Tochigi Ehime 1 Okayama Annual variability of prevalence in each location
  • 0 10 20 30 40 50 60 Spring Summer Autumn 0 10 20 30 40 50 60 70 80 90 100 Spring Summer Autumn 0 5 10 15 20 25 30 Spring Summer Autumn 0 5 10 15 20 25 Spring Summer Autumn 2011 2012 2013 Ehime 2 Tochigi Tokyo Okayama Annual variability of prevalence in each location 0% 10.7% 31.3%
  • 1. Rana catesbeiana ranavirus (RCV-JP) Une(2009) 2. Hynobius nebulosus ranavirus (HNV) 3. Fejervarya kawamurai ranavirus (FKV) 4. Tiger frog ranavirus (TFV) He (2002) RCV-JP HNV FKV TFV The phylogenetic tree of ranavirus
  • Tochigi Tokyo Aichi KyotoHyogo Okayama EhimeNagasaki RCV-JP HNV FKV TFV Virus type by location
  • 0% 20% 40% 60% 80% 100% 2012 2011 Hyogo 0% 20% 40% 60% 80% 100% 2012 2011 0% 20% 40% 60% 80% 100% 2012 2011 Tokyo 0% 20% 40% 60% 80% 100% 2012 2011 Kyoto Okayama 0% 20% 40% 60% 80% 100% 2012 2011 Aichi 0% 20% 40% 60% 80% 100% 2012 2011 Ehime ■ RCV-JP ■ HNV ■ FKV
  • Nagasaki 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Autumn Summer Spring RCV-JP FKV TFV 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Autumn Summer Spring Autumn RCV-JP FKV HNV Aichi 2012 2012 2011
  • Conclusion Our results show that 1. Ranavirus is distributed widely in Japan. 2. In nature, the prevalence of ranavirus is rising steadily. 3. Multiple variations of the virus are circulating in amphibian communities. 4. Within a short period, the virus type has changed in wild Indian rice frog communities. Regarding the spread of ranavirus in nature, the role of this frog has not been determined. But given that the Indian rice frog is an invasive species with rapidly expanding distribution and also a suitable host for ranavirus, we postulate that it may contribute, or have contributed, to the emergence of ranavirus in native amphibian communities in Japan.
  • Thank you for your attention. Contact:une@azabu-u.ac.jp