DAO 76:193-204 (2007)  -  doi:10.3354/dao076193

Phylogenetic analysis of spring virema of carp virus reveals distinct subgroups with common origins for recent isolates in North America and the UK

O. Miller1,2,*, F. J. Fuller1, W. A. Gebreyes1, G. A. Lewbart3, I. S. Shchelkunov4, R. B. Shivappa1, C. Joiner5, G. Woolford5, D. M. Stone5, P. F. Dixon5, M. E. Raley1, J. F. Levine1

1Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough St. Raleigh, North Carolina 27606, USA
2United States Department of Agriculture, Animal Plant and Health Inspection Service, Veterinary Services, 920 Campus Drive, Raleigh, North Carolina 27606, USA
3Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough St., Raleigh, North Carolina 27606, USA
4All-Russia Research Institute of Freshwater Fisheries, Rybnoe, Dmitrov Region, Moscow Province 141821, Russia
5The Centre for Environment, Fisheries, and Aquaculture Science (CEFAS), Weymouth, Dorset DT4 8UB, UK

ABSTRACT: Genetic relationships between 35 spring viremia of carp virus (SVCV) genogroup Ia isolates were determined based on the nucleotide sequences of the phosphoprotein (P) gene and glycoprotein (G) genes. Phylogenetic analysis based on P gene sequences revealed 2 distinct subgroups within SVCV genogroup Ia, designated SVCV Iai and Iaii, and suggests at least 2 independent introductions of the virus into the USA in 2002. Combined P- and G-sequence data support the emergence of SVCV in Illinois, USA, and in Lake Ontario, Canada, from the initial outbreak in Wisconsin, USA, and demonstrate a close genetic link to viruses isolated during routine import checks on fish brought into the UK from Asia. The data also showed a genetic link between SVCV isolations made in Missouri and Washington, USA, in 2004 and the earlier isolation made in North Carolina, USA, in 2002. However, based on the close relationship to a 2004 UK isolate, the data suggest than the Washington isolate represents a third introduction into the US from a common source, rather than a reemergence from the 2002 isolate. There was strong phylogenetic support for an Asian origin for 9 of 16 UK viruses isolated either from imported fish, or shown to have been in direct contact with fish imported from Asia. In one case, there was 100% nucleotide identity in the G-gene with a virus isolated in China.


KEY WORDS: Spring viremia of carp · SVCV · Phosphoprotein gene · Glycoprotein gene · Phylogenetic analysis · Molecular epidemiology


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