Spring viraemia of carp virus: recent advances

Spring viraemia of carp is an environmentally and economically important disease affecting cyprinids, primarily common carp (Cyprinus carpio). The causative agent of this disease is Spring viraemia of carp virus (SVCV) - a member of the genus Vesiculovirus of the family Rhabdoviridae. The disease is presently endemic in Europe, America and several Asian countries, where it causes significant morbidity and mortality in affected fish. SVCV infection is generally associated with exophthalmia; abdominal distension; petechial haemorrhage of the skin, gills, eyes and internal organs; degeneration of the gill lamellae; a swollen and coarsetextured spleen; hepatic necrosis; enteritis; and pericarditis. The SVCV genome is composed of linear, negative-sense, ssRNA containing five genes in the order 39-N-P-M-G-L-59, encoding a nucleoprotein, phosphoprotein, matrix protein, glycoprotein and RNA-dependent RNA polymerase, respectively. Fully sequenced SVCV strains exhibit distinct amino acid substitutions at unique positions, which may contribute to as-yet unknown strain-specific characteristics. To advance the study of SVCV and the control of spring viraemia of carp disease in the future, this review summarizes our current understanding of SVCV in terms of its genomic characteristics, genetic diversity and pathogenesis, and provides insights into antiviral immunity against SVCV, diagnosis of SVCV and vaccination strategies to combat SVCV.