Genetic analysis of fish iridoviruses isolated in Taiwan during 2001–2009

To investigate the genetic relationships between field strains of iridoviruses gathered from various fish species in Taiwan, viruses that were collected from 2001 to 2009 were analyzed. Open reading frames encoding the viral major capsid protein (MCP) and adenosine triphosphatase (ATPase) were sequenced for phylogenetic analysis. Our results indicated that iridoviruses from Taiwan aquaculture fishes could be classified into two groups: prior to 2005, the viruses were closely related to members of the genus Ranavirus; and after 2005, they were similar to members of the genus Megalocytivirus. Based on the analysis of MCP amino acid sequences, virus isolates were divided into 4 major genotypes that were related to ISKNV, RSIV, FLIV, and GIV, respectively. Pairwise comparisons of MCP genes showed that the ranavirus was an epidemic pathogen for economically important species in the major production regions and cultured marine fish, while the megalocytivirus isolates were sensitive to host range. In addition, the distribution of synonymous and non-synonymous changes in the MCP gene revealed that the iridoviruses were evolving slowly, and most of the variations were synonymous mutations. The Ka/Ks values were lower than one, and hence, the viruses were under negative selection.

[1]  N. Saitou,et al.  The neighbor-joining method: a new method for reconstructing phylogenetic trees. , 1987, Molecular biology and evolution.

[2]  K. Nakajima,et al.  Cultured Fish Species Affected by Red Sea Bream Iridoviral Disease from 1991 to 1995 , 1996 .

[3]  G. Darai,et al.  The complete DNA sequence of lymphocystis disease virus. , 1997, Virology.

[4]  Hsin-Yiu Chou,et al.  Isolation and Characterization of a Pathogenic Iridovirus from Cultured Grouper (Epinephelus sp.) in Taiwan , 1998 .

[5]  I. Hirono,et al.  Polymerase Chain Reaction (PCR) Amplification of DNA of Red Sea Bream Iridovirus (RSIV) , 1998 .

[6]  A. Gould,et al.  Comparative studies of piscine and amphibian iridoviruses , 2000, Archives of Virology.

[7]  Siu Man Chan,et al.  Complete genome analysis of the mandarin fish infectious spleen and kidney necrosis iridovirus. , 2001, Virology.

[8]  V. G. Chinchar,et al.  Ranaviruses (family Iridoviridae): emerging cold-blooded killers , 2002, Archives of Virology.

[9]  C. Chen,et al.  A Nested PCR for the Detection of Grouper Iridovirus in Taiwan (TGIV) in Cultured Hybrid Grouper, Giant Seaperch, and Largemouth Bass , 2002 .

[10]  A. Hyatt,et al.  Rapid differentiation of Australian, European and American ranaviruses based on variation in major capsid protein gene sequence. , 2002, Molecular and cellular probes.

[11]  S. Murali,et al.  Molecular characterization and pathogenicity of a grouper iridovirus (GIV) isolated from yellow grouper, Epinephelus awoara (Temminck & Schlegel) , 2002 .

[12]  K. Nakajima,et al.  Cultured Fish Species Affected by Red Sea Bream Iridoviral Disease from 1996 to 2000 , 2002 .

[13]  Q. Qin,et al.  Antigenic characterization of a marine fish iridovirus from grouper, Epinephelus spp. , 2002, Journal of virological methods.

[14]  T. Miyazaki,et al.  Viral DNA sequences of genes encoding the ATPase and the major capsid protein of tropical iridovirus isolates which are pathogenic to fishes in Japan, South China Sea and Southeast Asian countries , 2002, Archives of Virology.

[15]  Siu Man Chan,et al.  Sequence analysis of the complete genome of an iridovirus isolated from the tiger frog. , 2002, Virology.

[16]  Sudhir Kumar,et al.  Genomic sequence of a ranavirus (family Iridoviridae) associated with salamander mortalities in North America. , 2003, Virology.

[17]  H. Shih,et al.  Studies on epizootic iridovirus infection among red sea bream, Pagrus major (Temminck & Schlegel), cultured in Taiwan. , 2003, Journal of fish diseases.

[18]  T. Barkman,et al.  Comparative genomic analyses of frog virus 3, type species of the genus Ranavirus (family Iridoviridae). , 2004, Virology.

[19]  Yingeng Wang,et al.  The first report of an iridovirus-like agent infection in farmed turbot, Scophthalmus maximus, in China , 2004 .

[20]  Q. Qin,et al.  Functional Genomics Analysis of Singapore Grouper Iridovirus: Complete Sequence Determination and Proteomic Analysis , 2004, Journal of Virology.

[21]  Chun-Yao Chen,et al.  Histological, ultrastructural, and in situ hybridization study on enlarged cells in grouper Epinephelus hybrids infected by grouper iridovirus in Taiwan (TGIV). , 2004, Diseases of aquatic organisms.

[22]  S. Weng,et al.  Complete genome sequence analysis of an iridovirus isolated from the orange-spotted grouper, Epinephelus coioides. , 2005, Virology.

[23]  Hee-Jung Choi,et al.  Phylogenetic analysis of the major capsid protein gene of iridovirus isolates from cultured flounders Paralichthys olivaceus in Korea. , 2005, Diseases of aquatic organisms.

[24]  Chi-Yao Chang,et al.  Complete Genome Sequence of the Grouper Iridovirus and Comparison of Genomic Organization with Those of Other Iridoviruses , 2005, Journal of Virology.

[25]  V. G. Chinchar,et al.  A decade of advances in iridovirus research. , 2005, Advances in virus research.

[26]  L. Lü,et al.  Molecular epidemiology and phylogenetic analysis of a marine fish infectious spleen and kidney necrosis virus-like (ISKNV-like) virus , 2006, Archives of Virology.

[27]  R. Whittington,et al.  The molecular epidemiology of iridovirus in Murray cod (Maccullochella peelii peelii) and dwarf gourami (Colisa lalia) from distant biogeographical regions suggests a link between trade in ornamental fish and emerging iridoviral diseases. , 2006, Molecular and cellular probes.

[28]  M. Nei,et al.  MEGA4: Molecular Evolutionary Genetics Analysis (MEGA) software version 4.0. , 2007, Molecular biology and evolution.

[29]  S. Jung,et al.  Genetic variation and geographic distribution of megalocytiviruses , 2008, The Journal of Microbiology.

[30]  H. Jeong,et al.  Transmission of iridovirus from freshwater ornamental fish (pearl gourami) to marine fish (rock bream). , 2008, Diseases of aquatic organisms.

[31]  S. Kitamura,et al.  Phylogenetic analysis of lymphocystis disease virus from tropical ornamental fish species based on a major capsid protein gene. , 2008, Journal of fish diseases.

[32]  K. Kawai,et al.  Phenotypic Diversity of Infectious Red Sea Bream Iridovirus Isolates from Cultured Fish in Japan , 2009, Applied and Environmental Microbiology.

[33]  C. Wen,et al.  PCR amplification and sequence analysis of the major capsid protein gene of megalocytiviruses isolated in Taiwan. , 2009, Journal of fish diseases.

[34]  R. Whittington,et al.  Iridovirus infections in finfish - critical review with emphasis on ranaviruses. , 2010, Journal of fish diseases.

[35]  S. Weng,et al.  A new marine megalocytivirus from spotted knifejaw, Oplegnathus punctatus, and its pathogenicity to freshwater mandarinfish, Siniperca chuatsi. , 2010, Virus research.